Performance Cruising Gemini 105Mc User manual

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Gemini 105Mc
Owner’s Manual
Manual Version: 2.5
Publication Date: 3/4/2005
7364 Edgewood Road Annapolis Maryland 21403
Phone 410.626.2720
www.performancecruising.com
Owner InfoCenter: www.performancecruising.com

Gemini 105Mc Owner’s Manual
2Copyright © 2004 Performance Cruising Inc.
Congratulations on the purchase of your new Gemini 105Mc cruising catamaran and
welcome to the Gemini family. There are over 800 Gemini catamarans cruising all over
the world, and we’re pleased to include you as a member of this select group of
discriminating sailors who appreciate performance, value, form, and function. To better
your appreciation of the Gemini’s qualities, we encourage you to thoroughly read through the
entire manual before getting underway on your new boat.
This manual covers the proper operation and maintenance of all the aspects and systems aboard
the Gemini 105Mc. If a particular topic isn’t covered in enough detail, let us know via e-mail. We
regularly update the manual and make new versions available through the Performance Cruising
Owner InfoCenter website (http://www.mypci.net). The InfoCenter website also hosts an owners’
technical forum that addresses specific questions with correct and safe answers as well as advice
from the factory or even other Gemini owners.
Whether this is your first boat or your first multihull, we encourage you to obtain handling and
operating experience before assuming command of the boat. Your dealer or the factory can
recommend local sailing schools and/or competent instructors.
Be sure to keep this manual onboard for quick reference. You can always download and print an
extra copy from the website. The manual will help you get better, more trouble-free performance
and long life from your boating investment.
We wish you and your crew many years of enjoyable, safe sailing on your Gemini.
PerformanceCruisingInc.
Note: Third-party items on the boat are individually warranted. Where such items are discussed in the manual, a
symbol appears to indicate that further contact information is available on the contact page at the end of the
manual.

Gemini 105Mc Owner’s Manual
3Copyright © 2004 Performance Cruising Inc.
Topic Page
Quick Start 4
Batteries and Switch 4
Engine 4
Electric Panel 4
ShorePower 4
Water 5
Propane 5
Stove 5
Refrigerator 5
Hot Water Heater 6
Toilet 6
Centerboards 6
Rudders 7
Sails 8
Plumbing, Head, and Fresh Water 8
Water Fill 8
Water Tank Selection 8
Pressure Pump 8
Galley Tip Toe Pump 8
Shower/Sump 8
Toilet 8
Hoses / Clamps 9
CockpitShower 9
Holding Tank 9
Mains Adapter 9
Water Maker 9
Saltwater Pump 9
System Overview 11
Propane 12
Safety 12
Xintec Control Panel 12
Tanks 12
Junction and Solenoid 12
Copper and Fittings 13
Checking for Leaks 13
Stove 13
Refrigerator 13
Refrigerator on 110v 14
Shore Power 15
Air Conditioning 16
12 Volt Power 17
Batteries 17
Battery Switch 17
25 Amp Fuse 18
WiringCode 19
Switch Panel 19
VHF 19
AM/FM Stereo 19
CabinLights 19
Bulbs 19
MastWires 20
Mast Wiring Diagram 21
Mast and Rigging 22
Bridge Clearance 22
Rig Tensioning 22
Boom 23
Topic Page
Engine 24
Cooling Water 24
Gear Lever / Throttle 24
Fuel Tanks/Gauges 24
Hot Water / Cabin Heater 24
Sonic Drive Leg 24
Centerboards and Rudders 26
Operation 26
Maintenance 26
Illustrations 27
Performance and Use 28
Motoring / Winds / Offshore 28
Rudders 28
Construction 30
Deck & Hull Construction 30
Stress & Movement 30
Constructions Differences 31
Design Considerations 32
Interior Molds 32
Buoyancy Tanks 32
Leaks 32
Sails and Sailing 33
Sailing Rig Types 33
Main Sail & Reefing 33
Headsail & Reefing 33
Spinnaker s 34
Heavy Weather 35
Offshore Cruising 36
Notes on Sailing a New Boat 37
Coast Guard Kit 38
Offshore Sailing Kit 38
Anchoring 39
Setting the Anchor 39
Retrieving the Anchor 40
Docking & Mooring 41
Heaving Lines 41
Picking up a Mooring 41
Sea Anchors 42
Effects of Lightning 42
Maintenance 43
Cleaning and Care of Fiberglass 43
Bottom Paint 43
Blisters 43
Teak Cleaning 44
Window Care & Maintenance 44
Hauling and Trucking 45
Winterizing 46
Operational Checklists 47
Contact Information 48
Addendums 53
Westerbeke 30B Quick Notes 58
Bottom Paint FAQ 60
Table of Contents

Gemini 105Mc Owner’s Manual
4Copyright © 2004 Performance Cruising Inc.
Gemini Quick Start Guide
Batteries and Battery Switch
The Gemini comes with three (3) number 24 deep
cycle marine batteries. These are located under the
navigation table in the port hull with the main battery
switch just above them. There is room for an addi-
tional battery in the compartment.
To turn the batteries “On”, turn switch to position '1'
(which includes (2) two batteries). Everything on the
boat will go through battery
'1' including engine start.
Switch position '2' includes (1)
one battery. Never leave the
switch in the “Both” position
as there is no reserve bat-
tery. When switching from
position '1' to position '2',
move the switch through the
“Both” position, not “Off.”
Failure to do so while the engine is operating can re-
sult in damage to the alternator.
Westerbeke Diesel Engine
Before starting the engine, always make sure that the
cooling water will reach the engine by turning the
engine seacock lever to the allow water from the sea
to flow. The engine seacock is under starboard aft
bunk towards the front. The seacock has three posi-
tions:
1. In from the sea
2. Closed
3. Fresh Water Intake (for winterizing)
Placing the handle all the way up brings seawater in
to cool the engine if the hose is facing aft. (With the
hose facing forward, the handle needs to be down for
open) With the handle pointing straight out away
from the hull the seacock is closed and with the han-
dle all the way down, a fresh-water hose can be
hooked up to the seacock to flush fresh water into the
engine for winterizing. (Handle up if hose faces for-
ward).
There is also an inline water strainer. The strainer
reservoir should be full of water.
Regarding fuel; inside the center top hatch on the
stern are two (2) valves to select the fuel from either
the port or starboard 18-gallon tank. These two valves
must point the same way. One is fuel feed the other
is return. These valves simply point to starboard or
port. The short, pointy end of the handle indicates
which tank is in use.
To lower the sonic drive leg turn the red stopcock
lever in the starboard cockpit locker inline with the
hydraulic line and then loosen the black valve on the
red hydraulic oil reservoir. The leg will begin to drop
and then lock into position with a loud click. Once in
position, re-tighten the black knob.
To start the engine, make sure gear lever is in neu-
tral. With the lever vertical, use both hands, and with
the left hand pull the throttle lever 1/4" outward
while the right hand pushes the lever forward to an
angle of 45º. With the throttle in the “out” position,
the gears are not engaged.
Next, turn the ignition key to run and the buzzer will
sound. First, press the preheat button for approxi-
mately 15 seconds then, while still pressing preheat,
press the start button to turn the engine over. Follow-
ing starting, you should always check that cooling
water is coming out of the exhaust on the transom
beside the drive leg. If no cooling water is coming
from the exhaust, the engine seacock is in the incor-
rect position or clogged in which case you should turn
off the engine and correct the problem.
To engage the gears and propeller, move the gear
lever back and the lever will set into position. Push
the handle forward for forward movement and back-
ward for reverse.
To stop the engine, first return the throttle to neu-
tral. Next, lift the silver knob on the right above the
instrument panel, which stops fuel from getting to
the engine. Turning the key to the “off” position will
not turn the engine off. Following turning the engine
off, turn the key to the “off” position to stop the
buzzer. Turning the key to the “off” position with
the engine running can result in damage to the alter-
nator. Remember to push the silver “kill” knob back
down, otherwise the engine will not re-start.
To raise the leg following motoring make sure the
black knob is tightened on the hydraulic oil reservoir.
Pull out the chrome knob in the back of the locker to
release the reverse lock, and then pump the red han-
dle. The first pump will be hard and then it should be
possible to feel the leg slip out of reverse lock and
start to come up. At that point, let the chrome knob
go and continue pumping. Once the unit is up, turn
the red stopcock vertical to stop any fluid loss
through the pump so that the leg will stay up.
Electric Panel
There are 2 - 12-volt electric panels with circuit
breakers for the following:
x Compass Light
x Masthead Lights
x Running Lights
x Anchor Light
x Instruments
x Fans
x Shower Pump

Gemini 105Mc Owner’s Manual
5Copyright © 2004 Performance Cruising Inc.
x Cabin Lights
x VHF Radio
x Deck Lights
x Gas Valve (for Propane Monitor)
x Stereo / Television
x Spare
Both 12-volt outlets located next to the panel and
above the refrigerator run from the cabin lights cir-
cuit breaker.
There is a 25-amp fuse (with spare) located under the
battery switch protecting the switch panel. This fuse
handles all 12 volt appliances.
Shore Power
The Gemini shore power inlet is rated for 30 amps (24
amps continuously) and is run with 10 gauge wire.
The switches on the 110v panel are all circuit break-
ers.
The top two are linked together as the main breaker.
In the “ON” position, a green light indicates proper
operation while a red light indicates a bad connection
or possibly a badly wired marina.
Under the main breaker are circuit breakers for the
port outlets, starboard outlets, refrigerator, water
heater, and spare (usually used for air conditioning).
The 110v panel has a slide to prevent using the refrig-
erator, water heater, and air conditioner all at the
same time. Two of the three can be operated at the
same time, however, all three would require an ex-
cess of 24 amps.
The optional microwave operates on the starboard
outlet breaker.
Water
The Gemini has two translucent 30-gal tanks under
the port and starboard aft bunks. The tanks are filled
individually from the water intakes on either side of
the mainsheet track.
Only one tank is used at a time and is selected using a
'Y' valve to select water draw from either the port or
starboard tank. Turning the valve (which is mounted
on the wall in the port aft cabin) clockwise selects
the starboard tank. Turning it counter-clockwise se-
lects the port tank.
There is an electric 12-volt pump for pressure water
to each sink, the shower, and the hot water heater.
There is a dedicated pressure water switch on the 12
volt panel.
There is a foot pump in the galley to manually pump
water from the selected tank if the pressure water
pump is not on.
Important: Be sure to have the cold-water faucet
open in the galley when using the foot pump. Fail-
ure to do so can result in breakage.
Propane
In the starboard aft cockpit locker there are two, 20
lb. vertical propane tanks with overfill protection.
Only one tank can be connected to the propane sys-
tem at a time. The propane comes from the tank via a
regulator and rubber hose to a junction box. From
the rubber hose the propane can either go through
the solenoid or through the by-pass.
From the back of the junction box are 2 copper hoses
going to each appliance.
The propane monitor is switched on at the 12 volt
switch panel. The solenoid opens and closes with an
audible “click.” The solenoid requires one (1) amp
per hour to remain in the open position. With such a
relatively high power requirement, there is a by-pass
valve intended for use while sailing. To use the by-
pass, move the connection lever so that it is inline
with the bypass copper pipe and turn off the solenoid
on the propane panel.
Caution: If the boat is unattended and connected to
shore power, it is highly advisable to turn the solenoid
on along with a battery charger to avoid depleting the
batteries.
Stove
The Gemini comes standard with a two burner, broiler
and oven unit.
To operate burners on top of unit, as well as in broiler
and oven, push knobs in to override flame failure
safety cut off device. Turn to 'on' position, and apply
a flame. Hold knob in for a few seconds then set knob
to desired setting.
The oven has a thermostat. Turning the knob on the
front of the unit sets thermostat up to 480º.
Refrigerator
The refrigerator operates on 110v (shore power) or
propane. Before lighting the refrigerator on propane
or turning on with 110v, make sure the refrigerator
vent (located under the wheel in the cockpit) is re-
moved and the 12V refrigerator fan is on. The switch
for the fan is inside the shelf unit at the side of the
refrigerator. Be sure to turn on the “Refrigerator”
switch on the 12v panel.
The refrigerator operates automatically when con-
Gemini Quick Start Guide

Gemini 105Mc Owner’s Manual
6Copyright © 2004 Performance Cruising Inc.
nected to either shore power or propane. The unit
will prefer electric power if connected. Otherwise,
the refrigerator will use propane and light itself auto-
matically. To use the refrigerator on shore power,
turn the refrigerator breaker on the shore power
panel to “On”. Also, turn the Refrigerator breaker on
the 12 volt panel to “On”. The 12 volt breaker oper-
ates the cooling fan and lighter. To use the refrigera-
tor on propane, turn the shore power refrigerator
breaker to “Off” and select “Propane” on the refrig-
erator control panel. You may hear the unit click
several times as it attempts to light itself. Be sure
that the propane bottle is open and that propane is
getting to the unit. If the refrigerator is not success-
ful in lighting itself, the “Check” light indicator will
come on. In most cases, turning the unit “Off” and
then back on will reinitiate the automatic lighting
procedure and the unit will operate normally.
As the refrigerator operates completely silently, the
means by which to tell if it is operating correctly
(besides the interior getting cold) is to feel the chim-
ney flashing on the back of the refrigerator. The
chimney is accessible through the refrigerator ventila-
tion hatch in the cockpit.
Hot Water Heater
The hot water heater is a six-gallon tank stored in
front of the water tank under the bunk in the port aft
cabin.
When the engine is running, a heat exchanger coil
coming from the engine heats the water in the heater
tank. There is a red handled valve in the front end of
the engine compartment that is used to shut off the
hot water going to the water heater tank. When the
handle is pointing down, the engine is not heating the
water. When the handle is horizontal, the water in
the tank is being heated.
When on shore power, a switch on the main 110V
panel turns on a 110V electric element in the tank,
which heats the water.
Caution: Do not operate the hot water heater on 110v
without water in the heater tank—otherwise you will
likely burn out the heating element. To fill the heater
tank, turn on a hot water faucet until water comes
out, indicating the tank is full. Just as important is to
make sure you do not run out of water in your 30 gal-
lon tanks resulting in an empty hot water tank.
Toilet
There is a ¾” inlet and a 1 1/2” outlet seacock be-
hind and below the toilet. With the handle to the
left, the ¾” inlet seacock is allowing water in from
the sea. With it coming straight out it is closed and
with the handle pointing to the right it is allowing
fresh water to be pumped into the toilet from the
sink. Pumping fresh water into the toilet is to pre-
vent odor from the bacteria in seawater when the
toilet is left for any length of time.
There is a 3-way seacock located in a cabinet just
outside the head, opposite the navigation station.
This seacock controls the drain from the sink and has
three positions: Off, Overboard, and “Fresh Water
Flush.” In order to pump fresh water from the sink
into the toilet: fill the sink with water, turn the sea-
cock to “fresh water flush,” and pump the toilet flush
handle until all the water from the sink has been
sent through the system. You can add a small amount
of bleach to the water to further clean the lines out.
The Y valves behind the toilet directs the toilet wa-
ter either overboard or into the holding tank. (The
long end of the handle points to the hose in use; i.e.
pointing right pumps overboard and pointing left
pumps into the 18 gallon holding tank).
Turn the dial on top of toilet counterclockwise to
flush the toilet or clockwise to close the incoming
water and pump the toilet dry.
Caution: When sailing in rough weather, close this
dial to stop water from flooding back into the toilet
and flooding the boat.
The deck pump out is on the side of the foredeck
next to the sail locker.
Centerboards
The centerboards are located within a case in each
hull. A winch handle in the socket lowers and raises
the centerboard. The centerboard is locked into posi-
tion with a wing nut going over the 3/4" nut.
Releasing the wing nut and turning the socket ap-
proximately two turns counterclockwise will fully
lower the centerboard (it should not be lowered too
much). Tightening the wing nut will lock the board
down.
Raising the board is simply reversing the procedure.
Turn clockwise two turns until the board comes in
contact with the top of the case. Be careful when
unlocking the board from the down position as the
board is very buoyant and will begin to lift up quickly.
The board will float if left unlocked in the up posi-
tion but the back of the board will still be hanging 9"
down out of the hull if not locked up. Therefore,
after raising the board, be sure to tighten the wing
nut with the board fully raised.
The boards are designed to push up if run aground.
The boards are only necessary for windward work or
when close maneuvering in a marina. Only the lee-
ward board is necessary but it is acceptable if both
are used. If traversing a narrow area, put both down 1
Gemini Quick Start Guide

Gemini 105Mc Owner’s Manual
7Copyright © 2004 Performance Cruising Inc.
Gemini Quick Start Guide
1/4 turns.
Caution: The boards are designed to only be in the
down position when necessary. Do not leave the
boards in the down position for an extended period as
there is a small tolerance between the board and the
centerboard case. If barnacles and growth build up
on a board left in the down position, it will be diffi-
cult to impossible to raise the board without first
scraping it clean.
Rudders
The Gemini’s rudder system is mechanically joined
through the steering system and will steer the boat in
3’ of water in the down position or 18” of water in
the up position.
To raise the rudder, simply pull the control lines on
the transom. One line pulls the rudder up, while the
other pulls the rudder down.
The sheet stoppers/jammers are used for holding the
rudders in both the up and down positions. When
locked in the down position, it’s important not to lock
the jammers down completely as the rudders are de-
signed to kick-up if run aground. Locking the jam-
mers down completely will prevent the sheet from
coming loose. However, lightly closing the jammers
down will provide enough stopping power to keep the
rudders in the down position as the boat moves for-
ward.
Lower the rudders when leaving the boat—especially
if the boat is kept in deep or choppy water. This re-
lieves the tension on the rudder ‘up’ line.
The engine is connected to the tillers on the top of
the rudders and will steer whatever the depth of the
rudder.
Sails
Sail Square Footage
Genoa 350 sq. ft.
Jib 220 sq. ft.
Main 340 sq. ft.
Screacher 420 sq. ft.
Reefing Recommendations:
As a general rule, reduce sails when heeling at or over
7º and/or according to the following wind strengths:
Sails Wind
Full Main and full genoa Up to 18 knots
Full Main and jib or reefed genoas 22 knots
1st reef in main and jib 26 knots
1st reef in main and storm jib 30 knots
2nd reef in main and storm jib Gale
If using the main alone in winds over 30 knots, a sin-
gle reef will suffice.

Gemini 105Mc Owner’s Manual
8Copyright © 2004 Performance Cruising Inc.
Fresh Water System
The Gemini has (2) two 30 gallon fresh water poly-
propylene tanks located under each of the aft cabin
bunks. There are (2) two 1 ½” fresh water fills on
the aft coaming for each tank. Each fill also has a
½” tank vent built into the cap. When filling the
tanks, the fill line is located just under the vent
line. Take care not to overfill the tanks. If the
tanks are overfilled, they will leak through the in-
spection port on top of the tanks. If when filling
the tanks you discover the water backing up in the
fill line, it’s likely there’s water in the vent line.
To clear the vent line, detach the vent tube from
the tank (loosen hose clamp and work hose off
barb), and blow air through the line to clear it.
When using these water fills, push a hose all the
way into the hole to avoid spraying water into the
vent at the top of the fill. A 1’ section of garden
hose with a stopcock on one end makes filling the
tanks an easy job. Insert the flexible end into the
fill and the connect the stopcock end to the water
hose.
Cold Water System: Coming from each tank is a
draw hose which meet at the tank selector “Y”
valve located in the port aft cabin. Continuing
from the “Y” valve, the water travels back under
the aft port bunk through to a strainer and then to
the Flojet pump. The pressure pump is primarily
used for showering and has a non-return valve in-
side the pump to maintain pressure in the system.
From the pump, the water travels to (2) two “T”
connectors. The first “T” connects to the cold wa-
ter line for the head. The second “T” connects to
the galley cold water line and the (6) six gallon
water heater.
The cold water line to the galley travels through a
tiptoe foot pump located on the floor beneath the
sink and then to the faucet. Caution: When using
the foot pump, make sure that the cold water knob
on the faucet is in the “open” position to avoid
undue pressure in the line which could damage the
pump and/or faucet.
The water tanks are constructed of ABS plastic, and
the hoses are designed as taste free. Theoretically
these materials do not impart a taste into the wa-
ter. Additives are available to help reduce the taste
of plastic in the water. After water is stored for
long periods, chlorine may be necessary to make
the water useable. For occasional use, bottled wa-
ter is good for drinking and the tank water will do
for washing.
Hot Water System: The (6) six gallon hot water
heater is heated from the engine cooling water or
from the 110 volt electric water heater. Hot water
travels out of the heater to a “T” connector which
splits the line to both the head and galley. The pres-
sure pump must be “on” to use hot water.
There is a red handled valve in the front end of the
engine compartment that is used to shut off the hot
water going to the water heater tank. When the
handle is pointing down, the engine is not heating
the water. When the handle is horizontal, the water
in the tank is being heated.
When on shore power, a switch on the main 110V
panel turns on a 110V electric element in the tank,
which heats the water.
Caution: Do not operate the hot water heater on
110v without water in the heater tank—otherwise
you will likely burn out the heating element. To fill
the heater tank, turn on a hot water faucet until
water comes out, indicating the tank is full. Just as
important is to make sure you do not run out of wa-
ter in your 30 gallon tanks resulting in an empty hot
water tank.
Pressure Water Pump
The water pressure pump is situated under the port
aft bunk. Gemini comes with a Flojet pressure pump
for fresh water. The main reason for pressure water
is to use the shower and hot water. The pressure
pump has a non-return valve that keeps the pressure
in the line. The pump has a pressure switch that
switches the pump on when the pressure drops to 15
psi and off when the pressure reaches 25 psi. If the
pump cycles on and off every few seconds, first
check for a leak in the system. It also could be that
for some reason the non-return valve in the pump is
not holding pressure. If so, disassemble the pump
and clean the debris out of the valves.
The pressure pump should be turned off when not
needed because even in a perfect system it will
come on and off periodically wasting battery power.
Galley Toe Tip Pump
There is a Whale foot pump in the floor beside the
galley. This pump does not have a diaphragm. In-
stead, the pump is like a bicycle type pump that can
take pressure. This pump is in the line direct from
the pressure pump to the cold faucet in the galley.
This pump can only be used when the pressure pump
is not in use. The purpose of this pump is to conserve
battery power and water and to be able to get water
from the tanks if the pressure pump does not work.
Turn 90º and press to lock in the down position.
Reverse the procedure to enable the pump.
Plumbing, Head, & Water Systems

Gemini 105Mc Owner’s Manual
9Copyright © 2004 Performance Cruising Inc.
Plumbing, Head, & Water Systems
Shower Sump Pump
The shower in the Gemini is mounted to the wall
with a door that can be opened to close off a sepa-
rate area for showering and leave a dry area for
clothes and towels.
The shower water collects in the sump which is capa-
ble of holding (6) six gallons. To empty the sump
press the switch on the wall below the sink. The
pump is a Gulper 220 under the floor of the naviga-
tion station. This pump is self-priming and drains the
grey water directly overboard. The pump is power-
ful enough to serve as a auxiliary bilge pump. Simply
disconnect the shower hose and connect a second
hose.
Toilet
The toilet is a Raritan PHII, (Practical Sailor recom-
mended). This is a marine toilet with a lever handle
that gives a mechanical advantage making pumping
the toilet easier. An electric motor can be added to
pump the toilet; however this is not an option from
the factory.
The pump has a dial, which is turned counterclock-
wise to flush the toilet and clockwise to close the
incoming water to pump the toilet dry. Caution:
When sailing and pitching in rough water, always
close this dial on the top of the toilet pump to stop
water flooding back into the toilet and flooding the
boat.
A ¾” inlet seacock and 1½” outlet seacock are be-
hind and below the toilet. With the handle to the
left the ¾” inlet seacock is allowing water in from
the sea. With it coming straight out it is closed and
with the handle pointing to the right it is allowing
fresh water to be pumped into the toilet from the
sink. Pumping fresh water into the toilet is to pre-
vent odor from the bacteria in seawater when the
toilet is left for a long period of time.
To use the fresh water flush, set the 3-way seacock
located in a cabinet just outside the head, opposite
the navigation station, to “Fresh Water Flush.” This
seacock controls the drain from the sink and has
three positions: Off, Overboard, and “Fresh Water
Flush.” In order to pump fresh water from the sink
into the toilet: fill the sink with water, turn the sink
seacock to “Fresh Water Flush,” turn the 3/4” toilet
seacock to the right, and pump the toilet flush han-
dle until all the water from the sink has been sent
through the system. You can add a small amount of
bleach to the water to further clean the lines out.
The Y valve behind the toilet directs the toilet wa-
ter either overboard or into the holding tank. (The
long end of the handle points to the hose in use; i.e.
pointing right pumps overboard and pointing left
pumps into the holding tank.) Below are all the pos-
sible valve configurations for the toilet:
* See overview illustration on page 11
Holding Tank
The holding tank is located directly behind the toilet
and is on the same level as the sail locker base. The
holding tank is 18 gallons with a 1 ½" inlet at the top
against the outside of the hull. The 1 ½" outlet is at
the bottom against the outside hull. The vent is on
the same side with a ½" hose going across the tank
to a through hull fitting under the sink. The holding
tank can be inspected visually through the Plexiglas
bulkhead in the sail locker. It may be necessary to
shine a flashlight behind the toilet from the other
side of the tank to illuminate the fluid at the same
time.
In the top of the tank is a 4" inspection cover. The
tank can be inspected by unscrewing the top shelf in
the sail locker. The tank can be removed through the
sail locker by cutting the marine sealant tabbing that
holds the vertical Plexiglas wall below the shelf in
the sail locker.
Combination Shower Pump /
Bilge Pump System
Your new Gemini 105Mc comes with an upgraded
Overboard
Into Holding Tank
Gravity Drain Holding Tank

Gemini 105Mc Owner’s Manual
10Copyright © 2004 Performance Cruising Inc.
shower and bilge pump system which enables you to
get “double-duty” out of the Gulper 220 pump. This
powerful pump is capable of pumping 12’ of head,
can be run dry without damage, and transfers about
1 gallon of water per minute.
The pump is located under the port dinette and is
accessible from the cabinet door closest to the
head. Through the use of the two diverter handles
located on the outside of the cabinet, you can con-
vert the pump to act either as a shower bilge pump,
or as a port or starboard bilge pump. There are two
6’ section of hoses housed in the same cabinet as
the pump (on the port side) and in the correspond-
ing cabinet on the starboard side. You can move
the end of these hoses to the area of the boat you
would like to pump out and even add a hose exten-
sion to reach the cockpit lockers.
Configurations:
The two-way diverter handles enable the following
selections:
Diverter 1 – one end of handle always points to Di-
verter
1. Pump from Starboard Bilge
2. Pump from Port Bilge
Diverter 2 – one end of handle always points to
Pump:
1. Pump from Shower
2. Pump from Bilge (Port or Starboard)
Mains Water Adapter
It is possible to fit a Mains water adapter on the aft
deck and run a hose to just after the pressure pump.
However, if this is done the mains pressure must be
reduced to prevent damage to the ships hoses. This
option is not available from the factory.
Water Makers
Provision has been made for the installation of a
modular water maker around the starboard aft wa-
ter tank under the starboard aft bed. The water
intake can be easily installed under the aft bed.
Hoses and Hose Clamps
The water hoses used are reinforced plastic, suit-
able for drinking water and to take hot water.
The hoses are secured with clamps to the various
attachments. These clamps may need tightening
periodically, particularly if the boat was built in the
Plumbing, Head, & Water Systems
winter when the hoses were stiff. They can be tight-
ened with a screwdriver or 5/16 wrenches.
Cockpit Shower
It is possible to tap into the cold-water hose just
after the pressure pump and run a hose to the aft
deck for a shower.
Salt Water Pumps
A flipper-type pump that is compatible with salt wa-
ter can be installed in the galley counter. A 1/2"
through hull can be installed below the starboard aft
bunk.

Gemini 105Mc Owner’s Manual
11Copyright © 2004 Performance Cruising Inc.
1. 1 ½” Water Fill Hose and ½” Vent Tube
2. Water Draw from Tank
3. “Y” Valve Tank Selector Knob
4. Particulate Water Filter
5. FloJet Water Pressure Pump
Figure A
Plumbing, Head, & Water Systems
Figure B
1. Sink Water Valve: Controls where the sink water
drains to. Turning the lever to the right drains
overboard. Turning the lever straight up closes
the valve. Turning the level to the left drains the
sink to the fresh water flush line.
2. Seawater Valve: Controls toilet water intake. With
the lever to the left, the seacock is open to the
sea for flushing with sea water. Turning the lever
upright is the closed position. Turning the lever to
the right opens to the fresh water line for flushing
with fresh water.
3. Toilet Exhaust: Controls the toilet discharge.
Turning the lever upright (inline with the hose)
opens the seacock. Turning the lever down closes
the seacock.
4. Waste Water Selector Valves: Controls the destina-
tion of toilet water discharge. See photos and
explanation on previous page for possible configu-
rations.

Gemini 105Mc Owner’s Manual
12Copyright © 2004 Performance Cruising Inc.
Propane System
Propane System
Propane is recognized by most yachtsmen, as well
as the Coast Guard, as the best fuel for use on
boats. It is the easiest to obtain, economical, and
has more heating per pound than natural gas. In
terms of safety, propane will only explode if there
is a ratio of between 12,000 and 65,000 parts per
million of propane and air. There are three major
built-in safety systems to minimize any risks associ-
ated with the propane system:
x Flame Failure Overrides
x Xintec Propane Detector and Solenoid
x Propane Pressure Gauge
Although propane is odorless, an identifying odor
(mercaptan) is added so the gas can be readily de-
tected. Should a propane leak ever occur, the odor
is easily detectable at very low levels and over-
whelming at just 600 parts per million. Each pro-
pane bottle contains 20 pounds of propane and
takes a long time to escape from a bottle in the
event of a broken pipe. This is unlike gasoline
which, with a small spill, instantly evaporates to an
explosive mixture.
Always store the propane bottles in the cockpit
locker on the bridge. The locker contains ventila-
tion ports down through the bridge deck.
The pressure gauge is an essential safety feature
and is the first thing connected to the valve on the
bottle. The gauge does not indicate the level of the
gas in the tank; weighing the tank determines the
amount of propane in the bottle. The pressure
gauge provides easy and frequent leak testing of
the LPG system. After using the system and turning
off both the refrigerator and stove, and turning off
the gas at the bottle, the system should hold the
same pressure for at least 10 minutes. The pres-
sure reading will vary depending on the ambient
temperature. Warmer temperatures will cause the
pressure reading to increase while colder tempera-
tures will lessen the system pressure.
There is a separate and continuous copper line
from the propane junction to both the stove and
the refrigerator. There are no joints in the lines
except at the appliance.
Each appliance has a flame failure cut out. In the
event the flame is extinguished on either the stove
or the refrigerator while the unit is still in the “on”
position, the cut out system stops the propane from
flowing to the appliance.
Xintec Propane Control Panel
The Xintec Propane Fume Detector and Control Sys-
tem consist of two detectors located in the aft cabin
of each hull, the Control Panel mounted on the switch
panel, and the solenoid in the propane locker.
When the 12-volt Xintec Detector ‘Gas Valve’
breaker is first turned on, the propane detector goes
through a checking system and stabilizes with a green
light over the number of each sensor on the control
panel. The Xintec detector requires 200 milliamps to
operate. Pressing the left hand end button on the
Xintec control panel marked 'Solenoid', switches the
solenoid open. There is a loud click in the propane
locker when the solenoid opens.
In the event the detectors determine the existence of
3000 parts per million of propane fumes (25% of the
lower explosion point), the control panel will sound
an alarm and automatically close the solenoid which
cuts off the propane to the entire boat.
The Xintec owner’s manual has complete instructions
on system use and maintenance.
Propane Tanks
There are two (2) 20 lb. vertical bottles with a 5 year
rust protection and overfill protection. Note: New,
unfilled tanks are delivered with compressed air and
must be purged the first time they are used.
A rubber tube connects to the fitting that has a pres-
sure regulator. There is a special left-hand thread
that is first screwed into the bottle to connect the
tube and regulator.
Propane Junction And Solenoid
The rubber hose coming from the regulator is con-
nected to the solenoid and solenoid by-pass. The
solenoid bypass is intended for use when sailing with
no method of charging the batteries. The solenoid,
which takes (1) one amps per hour to keep open, can
be turned off. This system enables using the solenoid
when the boat is on shore power and when there is
the likelihood that the boat may be unattended. If
the propane is turned on, which would be the case for
a live aboard, and there were to be a leak, the pro-
pane detector would shut off the solenoid. When sail-
ing, the boat is attended and therefore any leak
would be detected by either the odor and/or the Xin-
tec alarm and the propane could be turned off manu-
ally at the tank. The bypass is opened by turning the
lever in line with the pipe that is bypassing the sole-
noid.

Gemini 105Mc Owner’s Manual
13Copyright © 2004 Performance Cruising Inc.
Propane System
Carbon Monoxide
When propane burns with a blue flame, only carbon
dioxide and water vapor are produced. However, a
yellow flame is an indication that carbon monoxide
is being produced. Carbon monoxide can also be
produced if there is a 5% depletion of oxygen in the
cabin while propane is burning.
All internal combustion engines produce carbon
monoxide. A gas engine is worse than a diesel en-
gine. The largest cause of carbon monoxide poison-
ing is from gasoline-powered generators because
they are left running for long periods of time.
Propane units, if properly maintained, will not pro-
duce carbon monoxide. Proper maintenance in-
cludes keeping the system clean and maintaining
good airflow. If you are at all nervous, you can try a
carbon monoxide detector, but unfortunately these
detectors are not 100% reliable and can be affected
by atmospheric conditions. In addition, carbon mon-
oxide detectors have to measure the time exposure
as well as the amount of carbon monoxide. Thor-
ough ventilation is the best safeguard against a
build-up of carbon monoxide.
Copper and Fittings
The copper in use is 3/8", K type. Most of the copper
fittings are connected to the various appliances with
3/8" flare fittings.
Checking for Leaks
To check for propane leaks all the line connections
should be tested. With the propane on, use a small
paintbrush and liberally coat the joints with a mix-
ture of dishwashing soap and water. A leak is identi-
fied by bubbles in the solution generated from the
escaping propane.
Stove
The stove is an English unit with 2 burners, a broiler,
and an oven. The unit includes a flame failure device
to each burner so that if the flame were to blow out,
after about 10 seconds the heat sensor beside each
burner will cool down and the propane will automati-
cally cut off.
To light each unit there is a flame failure override
procedure. In the case of the stove turning the knob
counterclockwise to full “ON” and pressing the knob
in allows propane to flow. Light the propane and
hold the knob in for a few seconds This warms up the
heat sensor and the unit will continue to run. Com-
pletely turning the knob counterclockwise turns the
flame up. To turn the flame down or off, turn the
knob clockwise.
Refrigerator
The refrigerator provides 4 cubic feet of storage
space and a freezer compartment in the top. The
refrigerator is completely silent when operating. The
refrigerant uses ammonia, water and hydrogen and
operates through an absorption process. The applica-
tion of heat acts like a pump and starts the process.
Heat applied by a small propane flame or an electric
heating probe boils ammonia out of the solution of
ammonia and water. Air circulating over the fins of
the condenser removes heat from the ammonia va-
por to cause it to condense to liquid ammonia from
where it flows into the evaporator. After taking heat
from the refrigerator, the ammonia returns to the
reservoir near the bottom of the refrigerator, remix-
ing with the water.
This system is especially suitable to the Gemini as
there is minimal heeling so the reservoir stays at the
same level as the point where the ammonia is boiled
out of the solution. With excessive heeling, the am-
monia would not cycle through the system. This
type of unit is very reliable and efficient. Any failure
is normally associated with switches or the thermo-
stat.
Running the Refrigerator
Press the AUTO button to the “Down” position which
illuminates the “Auto” light indicator. If shore power
is available, the unit will select A/C operation. If
shore power is not available, the unit will automati-
cally switch to propane operation. Within 45 sec-
onds, the burner should ignite and operate normally.
If the “Check” indicator light comes on, the control
has failed to light the burner on propane. To reset
when the “Check” light comes on, press the main
power button to the “Off” position and then “On”
again which re-initiates the automatic lighting proce-
dure.
On the initial start-up, after switching propane bot-
tles, or if the refrigerator has not been used in a
Oven Setting Fahrenheit
1230º
2266º
3302º
4338º
5374º
6410º
7446º
8482º

Gemini 105Mc Owner’s Manual
14Copyright © 2004 Performance Cruising Inc.
long time, it may take several attempts for the re-
frigerator to prime itself with propane and light cor-
rectly. You may reset the unit as many as four times
to purge the air from the propane lines and light the
burner. This is normal.
The shut down the refrigerator, press on the “On”
button so that it is un the “Up” position—which is
“Off”.
The refrigerator temperature is controlled by a fac-
tory preset and cannot be adjusted manually.
While waiting for the interior of the refrigerator to
cool, the only way to know if the unit is correctly
working is to feel the chimney flashing on the back
of the unit. The chimney flashing is accessible
through the ventilation hatch in the cockpit. The
flashing will be warm to touch when the refrigerator
is correctly operating.
* For an in-depth description of how a propane
refrigerator works, turn to the back of this man-
ual.
Running the Refrigerator on 110v
To run the refrigerator on 110 volt,
IMPORTANT: When leaving the boat, turn the re-
frigerator to the “OFF” position first then turn the
propane off at the bottle. Reversing these steps,
while not a problem, will burn out the propane in
the line and make re-lighting the refrigerator an
unnecessarily long process as the gas line will need
to re-prime.
The refrigerator is vented to the cockpit. Fresh air
comes in through the hatch near the cockpit floor.
The hot air is then vented out through openings
above the steering wheel. An additional chimney
vents to the top of the canopy and can be opened or
closed with the included cap.
The refrigerator operates most efficiently with a
thorough through-flow of air. Always keep the venti-
lation hatch open and turn the 12-volt refrigerator
fan on when the refrigerator is running.
When leaving the boat for long periods of time, re-
insert the refrigerator air intake hatch cover.
Propane System

Gemini 105Mc Owner’s Manual
15Copyright © 2004 Performance Cruising Inc.
Shore Power
Shore Power
The Gemini is wired for 110-volt shore power with a
30 amp current rating. The female plug on the comb-
ing behind the mainsheet traveler is 30 amps. We
suggest the use of a 50 foot shore power cable. Take
care to keep the cable clean, dry, and in good work-
ing order to avoid arcing between the plug prongs.
Caution: While rated for 30 amps, the shore power
plug should not have more that 24 amps running
through it continuously.
The color codes of the wires are:
Black: Live
White: Neutral
Green: Ground
The 110v circuit panel with breaker is just inside
the main door to port. The top of the panel has a
green light to indicate power coming into the boat.
A red light is located just below the green light and
will light if the external power source is incorrectly
wired. If the red light comes on, unplug from the
shore power outlet and try another outlet.
The top 2 switches are the main inlet switches rated
to 30 amp.
The switches under the main switches have differ-
ent ratings up to 20 amps.
Switch Rating
Port Outlets (2) 10 amps
Starboard Outlets (4) 15 amps
Refrigerator 20 amps
Water Heater 15 amps
Air Conditioner / Spare 20 amps
There are duplex outlets in the head, master cabin,
galley, refrigerator area (close to main door), and
navigation area. The outlet by the navigation area is
ideally suited to plug in a battery charger.
The outlet in the navigation station and master bed-
room are GFI outlets. The navigation station outlet
protects the head outlet while the master bedroom
outlet protects the outlet in the galley.
Before connecting the shore power cord, always turn
the AC circuit breaker “Off.” Once connected,
switch the breaker “On.” Similarly, always remem-
ber to turn “Off” the AC circuit breaker before dis-
connecting the shore power cable.
Power Inverters
Power inverters transform battery supplied power
known as direct current (DC) into Alternating Current
(AC). An inverter is not available as a factory-
installed option but can be installed by a trained
marine electrician.
An inverter/battery charger must not be used when
the boat is connected to shore power. Today’s in-
verter is designed to take the shore power into it so
that it can sense if the shore power is on. Today’s
inverter is so quick that if there were to be a failure
on the incoming shore power the inverter would
switch over to battery without a computer failing. If
a high demand shore power item is installed such as
air conditioning that would take more power than
the inverter is capable of supplying, then a separate
line from the inlet should go to that appliance by-
passing the inverter. This is because the inverter
would try and supply the power necessary to run that
appliance if there were to be a shore power failure
and would keep over heating and shutting down.
When testing electronic equipment, be careful that
stray fields from the shore power cables do not influ-
ence sensitive equipment.
The wire used is 3-core, 10 gauge, 600º stranded
marine-grade cable.

Gemini 105Mc Owner’s Manual
16Copyright © 2004 Performance Cruising Inc.
Air Conditioning
Air Conditioning
Power Requirements: 110 Only
Starting: 24 Amps
Running: 15 Amps
The Gemini has an optional Mermaid 16,500 BTU
air conditioner with reverse cycle for use on shore
power only. The unit is installed in the seat hous-
ing below the switch panel. The Mermaid air condi-
tioner fan is set to a fixed speed and cannot be
adjusted.
The air conditioner cooling water lines and strainer
must be primed with water prior to turning the unit
on. By opening up the seacock to let water in, the
system may prime itself. If the lines and water
strainer do not fill entirely with water, it is neces-
sary to complete the prime by opening the strainer
lid slightly until the strainer fills with water. Re-
member to tightly close the strainer lid after it fills
with water.
When turning the unit “ON”, switch the thermostat
to “COOL” and then press and hold the “down”
button on the thermostat to change the thermostat
setting to a temperature below the ambient tem-
perature. Next, turn on the air conditioner by flip-
ping the breaker “On.” After the unit starts, the
first thing to check for is the sound of the cooling
water exhaust coming from below the bridge deck.
The sound is audible from the back steps on the
transom. If you do not hear the water exhaust,
turn the unit “OFF” and correct any problems be-
fore restarting.
Most problems associated with the air conditioner
are the result of an insufficient prime, a clogged
strainer, or a kink in the water lines. To clean the
strainer, simply unscrew the strainer lid, then take
out the strainer and clean it thoroughly. Don’t for-
get to replace the strainer before restarting the
unit. Kinks in the cooling lines are possible follow-
ing working on the water, heating, or air condition-
ing systems. Take care to see that all lines are free
of obstructions or kinks.
Caution: If the system is insufficiently primed and
cooling water is not running through the system
there is the risk of freezing the air conditioning
coils. Should this happen, wait until the coils have
thawed before you again attempt to prime the
lines.
Alternatively, the system can be primed by turning
on the pump alone – without turning on the air con-
ditioning unit. To accomplish this, you will need a
110v extension line to plug in to. Unplug the water
pump from the air conditioner and connect to the
extension line to prime the lines. Once the system
is primed, return the pump plug to the air condi-
tioning unit and operate as usual.
Yet another means of priming the system is to dis-
connect the cooling water “in” line from the air con-
ditioner and turn the system on. Wait until the
pump primes itself and a small “geyser” of water
comes from the hose, then quickly reconnect the
hose to the “In” line on the air conditioner.
The air conditioning condensation pan is located
under the unit and drains along with the system’s
cooling water.
To avoid losing the system’s prime while sailing, we
recommend closing the three-way seacock before
sailing.
Reverse Cycle—Heat
During colder weather, the air conditioning unit can
be used in reverse cycle for heating. To engage the
reverse cycle, switch the thermostat to “Heat” and
turn up the temperature setting higher than the am-
bient temperature. Read the owner’s manual for a
complete description.
Winterizing the Air Conditioning System
The air conditioning unit should be included in the
winterizing process by filling the lines with a 50/50
mixture of fresh water and coolant. Simply place
one end of a standard hose into a one-gallon bucket
containing the mixture and connect the other hose
end to the flushing seacock. Next turn the seacock
to the flush position. Prime the system with the
coolant mixture by unplugging the pump from the air
conditioner and connecting to a 110v extension cord.
The system will use the entire gallon of the coolant
mixture.
Air Conditioning System Overview

Gemini 105Mc Owner’s Manual
17Copyright © 2004 Performance Cruising Inc.
Batteries
The Gemini comes with (3) three batteries #24 Deka
Deep Cycle Marine Batteries. There is room for (1)
one additional battery.
The batteries are number 24, deep cycle with a
capacity of 85 amps each. On the battery switch,
“Battery One” refers to two batteries connected
together while “Battery Two” refers to the singular
battery.
A Note on Deep Cycle Batteries: Unlike conven-
tional car batteries, deep cycle batteries hold a
charge better and retain an almost constant voltage
until just before the battery dies. However, in re-
taining an almost constant voltage, it is difficult to
tell how much charge is left in the battery. The
only accurate way is with the use of a hydrometer
to check the acidity of the battery fluid. Battery
managers that measure the flow of current into and
out of the battery are good for continuous use but
do not work well if the boat is left for long periods
of time without use. Batteries lose charge by inter-
nal degradation at the rate of as much as 1/8 am-
pere an hour. As batteries are used, the distilled
water changes to sulfuric acid and eventually the
formation of sulfate crystals coats the plates in the
battery and the capacity of the battery is reduced.
For example, if the battery is left at 60% charge for
long periods of time, then the battery will not ac-
cept a charge of more than 60% while charging. It
is possible to tell when the battery is near dead
when it can be fully charged in a short time.
Solar power is an efficient way to keep batteries in
good condition as solar power puts out low current
at high voltage. The solar panel, available as an
option, charge at up to 10 amps per hour.
A battery can be charged to 80% easily but the last
20% of charge requires a lot of time so that the bat-
tery is not overheated. That is why running the
engine to charge the batteries is not efficient no
matter what capacity alternator is in use.
The new smart chargers require a thermometer on
the battery.
Gel cell batteries are expensive and can be dam-
aged by over heating and theoretically can only be
charged and discharged one quarter as many times
as deep cycle batteries.
Checking Battery Levels
Deka recommends checking the electrolyte fluid in
your batteries weekly and/or before any prolonged
battery charging, such as extensive motoring.
Checking the batter level simply means ensuring
the electrolyte is filled to the indicator line on the
battery case (which covers the plates). If the bat-
12 Volt Power
tery needs fluid, use only distilled water. To go a
step further, you can use a hydrometer to test for a
specific gravity of 1265 following a charge. Start
with the cell closest to the (+) terminal. The spe-
cific gravity reading should be between 1.100 and
1.300 (Specifically 1.265).
Be sure to keep the battery connections clean as this
will help ensure longer battery life.
Battery Monitors
Battery monitors measure everything that goes in
and out of a battery through the negative side. This
is a highly effective way of keeping track of available
power. A voltmeter is not accurate enough as it will
not tell you what state of charge your battery is in.
Battery Switch
The battery switch is located above the batteries.
Caution: Never switch from position “1” to posi-
tion “2” through “OFF” – especially when the en-
gine is running as damage to the alternator could
occur.Always switch through the “BOTH” posi-
tion.
With Battery “1” selected on the battery switch, all
12 volt power is coming from the first set of batter-
ies and only the first set of batteries are receiving a
charge from the alternator with the engine running.
Battery “2” is not in use. When battery “2” is se-
lected all 12 volt power is coming from the single
battery and the single battery is receiving a charge
from the alternator with the engine running.
If battery “1” is used and left fully charged before
switching to battery “2”, then there will always be a
full spare battery and vice versa.
The Gemini does not make use of a designated en-
gine starter battery as the smaller Westerbeke en-
gine does not require a large amount of current to
start. In addition, a designated starter battery re-
quires the use of an automatic switch. With an auto-
matic switch, once the engine is started, first the
engine battery is fully charged and once it reaches
13.8 volts then the other ship’s batteries are
charged. The problem with this system, as discussed
earlier, is that it is easier to charge a flat battery

Gemini 105Mc Owner’s Manual
18Copyright © 2004 Performance Cruising Inc.
12 Volt Power
than a fully charged battery. A yachtsman who does
not use the engine for an appreciable amount of
time may never put any charge into the ships bat-
tery and of course there is some degree of ineffi-
ciency in the switch.
25 Amp Fuse
There is a 25-amp fuse between the live red 8-gauge
wire going up to the switch panel and the battery.
This fuse with a spare is down beside the battery.
There is no fuse between the battery and the en-
gine because in the event of a short at the engine
the battery cables are so large that the battery will
quickly die before the cables over heat and cause a
fire.
Individual components are fused as necessary.
Solar Panel (Optional)

Gemini 105Mc Owner’s Manual
19Copyright © 2004 Performance Cruising Inc.
Wiring Code
The standard code for 12-volt is red positive and
black negative. Unfortunately the boat cable sup-
plied sometimes comes red and black and some-
times white and black. We have chosen:
BLACK = NEGATIVE
RED OR WHITE = POSITIVE
Note that the color coding is different to shore
power where black is live and white neutral.
The European system is different and electronic
equipment that comes from Europe has the code:
BROWN = POSITIVE
BLUE = NEGATIVE
Switch Panel
The switches on the two 12-volt panels are also
circuit breakers and vary from 5 amp to 20 amp.
See table below.
VHF Radio
The VHF is recessed into the switch panel above the
12-volt panel. Consult the included owner’s manual
for information on operation.
Switch Rating (amps) Purpose
Compass Light 5Red light to illuminate compass at night
Masthead Lights 10 For sailing at night— 25 watt tri-color masthead light
Anchor Light 5For anchoring—10 watt masthead light
Instruments 5Backlight for TriData, AutoHeml, and instrument panel
Fans 15 Optional Fans — Includes through-flow refrigerator fan
Shower Pump 15 Also operates port and starboard bilge pumps
Deck Lights 10
Cabin Lights 20 Includes both fluorescent and incandescent
VHF 15
Gas Valve 20 Turns power on/off to Xintec Propane Monitor
Stereo/TV 15 Turns power on/off to AM/FM Radio / CD Player
Spare 20
Heater 20 Optional heater
Running Lights 5For motoring at night
Stereo AM/FM/CD
The Gemini 105Mc now comes standard with an
AM/FM stereo CD player with two speakers mounted
on the main bulkhead. Consult the included owner’s
manual for information on operation.
Cabin Lights
The Gemini has three (3) fluorescent lights in the
main cabin over the galley, navigation station, and
saloon table. The fluorescent bulbs take an ex-
tremely low power draw and are intended as task
lighting. Each light draws 1/3 amps. Note that fluo-
rescent lighting is known to sometimes interfere with
VHF reception. Turning off the light corrects VHF
reception issues.
There are also six (6) 12-volt incandescent dome
lights, each located in the head, master bedroom,
each aft cabin, over the refrigerator and in the cock-
pit. Each light draws 1 amps. Red bulbs can be in-
stalled to maintain good night-vision.
Replacing Light Bulbs
Individual bulb specifications are subject to change.
When replacing a bulb, always remember to have the
original bulb with you when buying a replacement.
Related Topics:
See Mast Wiring on following page.
12 Volt Power

Gemini 105Mc Owner’s Manual
20Copyright © 2004 Performance Cruising Inc.
Mast Wiring
After the mast is erected, the wires in the mast are
routed through a 2-inch tube. These wires terminate
in the roof of the master cabin and are accessible
behind a removable panel.
Mast wires connect as follows:
The coaxial cable for the VHF is screwed to the coax-
ial cable that terminates at the radio by the switch
panel.
The wire from the electronic equipment is con-
nected color to color either side of the connecting
block supplied. The ground wire is a few unshielded
strands of wire that should not be ignored, but at-
tached to connecting block as shown in the illustra-
tion.
There are 3 twin core wires coming from the switch
panel one labeled 'steaming' and the other labeled
'tricolor and spare'. These are attached to the con-
necting strip.
The twin core wire labeled 'steaming' has its individ-
ual wires labeled:
White:
Steaming
Black:
Ground or negative for all three lights up the mast.
The twin core wire labeled tricolor has its individual
wires labeled:
White: Tricolor
Black: Anchor (this is the only time a black wire is
live supplying power to the anchor light)
The twin core labeled spare only uses white for deck
light. (The black is spare)
From the mast there are two sets of wires:
1. Brown and blue from the steaming light partway
up the mast. The brown is the positive to the steam-
ing light and the blue is the negative.
2. Brown, blue and strip yellow from the combina-
tion tricolor and anchor light at the top of the mast.
The blue is the negative to both anchor and tricolor,
with the brown being the positive to the anchor and
the yellow being the positive to the tricolor.
3. Brown and blue from the deck light. Brown is
positive and blue is negative.
The wires from the Autohelm wind are connected to
the instruments through the connecting block.
Mast Wiring
Match the wires to their partners based on color
through the connecting block. Do not forget to
group together and connect the ground wire
strands.
Most of the 12-volt wires in the coax are under the
roof molding. There is little chance of failure with
the wiring except for the connections to the various
pieces of equipment. All the connections are acces-
sible.
The 12-volt wire used is 16 gauge 600º boat cable
wire (The 110 volt wires are 3 core and mainly un-
der the dinette).
Masthead Lights
The masthead lights are supplied with the mast
from Selden Masts. Selden has been known to
change the make of the masthead lights without
warning. At present (2004) , the light is an Aqua
Signal masthead light. The bulb specifications are
as follows:
Anchor Light: 10 Watt (Part SW40)
Masthead Light: 25 Watt (Part TDH40)
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