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Gemini 105Mc Owner’s Manual 

41

Copyright © 2004 Performance Cruising Inc. 

Docking 

To secure a boat to the dock, a line from the bow 
and stern will keep the boat in. A spring line from 
the bow running down the side of the boat to the 

dock, and another from the stern also running along 
the side of the boat going forward to the dock, will 

stop the boat moving backward or forwards. The 
lines to the bow and stern holding the boat in should 
go to the hull away from the dock so that these lines 

are long and can accommodate any rise or fall of the 
tide. The stanchion bases are through-bolted and can 
be used for additional mooring cleats. 

When coming into the marina, have two lines se-

cured to the bow and stern ready to either give to a 
bystander or to be ready to take ashore. When the 

boat is in position, reverse the lines leaving the ends 
tied to the dock with the slack left on board. This 

stops people stealing the excess, tripping over them, 
or tying another boat with them.  

Always make sure that the lines are removable from 

one end even if the lines are under tension. Do not 
pass the loop of the lines through the cleat. If the 

boat is tied to the dock and the tide goes down, the 
mooring line needs to be able to be untied slowly 
lowering the boat down the wall. At night if the boat 
is moving, it is a good idea to be able to retie the 
boat while still on the boat, without having to go 
onto the dock, which could be dangerous in the dark. 

Heaving Lines 

Novice sailors sometimes panic as the boat is coming 
in to the dock and are often unsuccessful in attempt-
ing to throw a line to a dock attendant. The best 
method of throwing a line is to simply coil it up, split 
the coil and throw half of the split coil. Hold onto 
the end of the other half. The weight of the half 

Docking and Mooring 

being thrown uncoils the half still being held. The 
momentum of the half being thrown will then uncoil 
that half once the first half has been uncoiled. 

Picking up a Mooring

Always approach an open mooring at a slow speed 
and note how other boats are positioned relative to 

their buoys.  The boats will be pointing into the wind 
or with the current.  Always stay well clear of oth-
ers’ mooring lines so as not to cut or foul the lines.  
In the event that there are no other boats by which 

to gauge an approach, pass by the intended mooring 
once to gauge the effects of current and wind so 
that your approach will be correct. 

As you motor up to pick up the mooring, shift into 
neutral when the boat has enough forward momen-
tum to reach the mooring.   

Have a crew person stand on the bowsprit ready to 

pick up the pennant float with a boat hook.  Commu-

nication between the captain and crew is essential.  
It is beneficial to agree on a set of hand signals 
rather than yelling back and forth.  Do not expect 

the person on the bowsprit to be able to hold the 
boat in position once in contact with the pennant 
float. 

If you expect the boat will overshoot the mooring, 
shift into reverse or, inversely, shift into forward to 
gain enough forward momentum to reach the moor-
ing.  Keep the engine running and ready until you are  

sure that the pennant eye has been secured to the 
anchor cleat.  Even after securing the pennant eye, 
be careful not to scrape against the buoy.  

If you do under or over-shoot the buoy, calmly fall 
off and get clear for another try. 

Summary of Contents for Gemini 105Mc

Page 1: ...ation Number Documentation Number 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 info performancecruising com ...

Page 2: ...er 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 ...

Page 3: ...learance 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 Cons...

Page 4: ...en 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 th...

Page 5: ...y 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 ...

Page 6: ...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...

Page 7: ...e 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 i...

Page 8: ...ed 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 ...

Page 9: ...ter 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 righ...

Page 10: ...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...

Page 11: ...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 ...

Page 12: ...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 ...

Page 13: ...ise 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...

Page 14: ...th 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 unnec...

Page 15: ... 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 sh...

Page 16: ...f 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 accompl...

Page 17: ... 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...

Page 18: ...e 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 ...

Page 19: ...es 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 5 For motoring at night Stereo AM FM CD The Gemini 105Mc now comes standard with an AM FM stereo CD player with two spea...

Page 20: ...are 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 yello...

Page 21: ...Gemini 105Mc Owner s Manual 21 Copyright 2004 Performance Cruising Inc Mast Wiring ...

Page 22: ...ld be checked as part of the 6 month mainte nance schedule We recommend the use of a tensioning gauge for adjustments to the rigging Both sets of cap inter mediate and bottom stays are initially tightened by checking the number of threads visible at the base of each stay Following initial tightening the following details in order the tensioning on each of the stays It is important to adjust the st...

Page 23: ...il doesn t get caught up in between the backstays there is a single backstay with a tensioner about 15 up The backstays only need to be tensioned during up wind work and should be slack at the dock Boom The boom is 15ft long and is secured to the mast at the gooseneck with a clevis pin The boom has three pulleys at the stern end and three jam cleats at the underside of the boom at the gooseneck en...

Page 24: ...rward 45º engages forward The rest of the Engine Drive Leg Fuel movement increases the engine speed Moving the lever back engages reverse Fuel Tanks Gauges The Gemini 105Mc has 2 two 18 gallon fuel tanks each located either side of the engine under the aft deck The fuel gauges are located on the instrument panel There are 2 two fuel selector valves located under the engine hatch on the center ster...

Page 25: ...ck the leg up in case of a leak in the pump seal Lowering the Leg 1 Turn the small red lever to the horizontal posi tion in line with the hydraulic line 2 Loosen the black knob on the pump and the leg will drop into place You should hear it lock into place 3 If the boat is still moving forward as the leg is lowered it likely will not lock into position as Engine and Drive Leg it drags through the ...

Page 26: ...oxi mately 45º back and the exposed centerboard is in the shape of a quadrant or fin coming out of the bot tom of the hull Most of the slot is still filled with centerboard this prevents turbulence and gives a strong bearing surface The centerboards go down 4 below the keel There is a 3 1 2 solid PVC drum inside the case up at the top 2 back from the front of the case 3 8 rope is connected to the ...

Page 27: ...Gemini 105Mc Owner s Manual 27 Copyright 2004 Performance Cruising Inc Centerboard Design Centerboard Clutch Assembly ...

Page 28: ...g the load on the rudders With strong winds there are big seas and it is these seas that can cause a problem as the boat tries to broach when the leeward bow digs in Of course with the boards up on a broad reach the boat will travel per haps 14 knots which is also putting stress on the rudders Lowering the leeward centerboards part way reduces the top speed perhaps to 12 knots but Centerboards and...

Page 29: ... The sheet stopper prevents the rudders from raising However do not over ten sion the stopper as the lines could jam and cause breakage in the rudder system Be sure to lower the rudders when leaving the boat particularly in deep or choppy water Leav ing the rudders in the up position for long periods of time causes unnecessary strain on the up rope There are no holes drilled below the water line s...

Page 30: ...o helps transmit the load Back ing plates are academic because a failure would almost certainly be a large chunk of deck being ripped out much larger than the actual backing plate The only time there is a good reason to have a backing plate is for items that are being pulled at right angles to deck or hull such as rudder gud geons A backing plate would stop the bolts pulling through the hull Unfor...

Page 31: ...than a monohull of the same size The extra surface area of Gemini means that if Gemini is built with the same lay up as the monohull then Gemini will be a lot heavier than the monohull even with the keel on the monohull taken into consideration Fortu nately Gemini does not have to be strong enough to take the high point loads of a keel so can be of lighter construction However the lighter construc...

Page 32: ... cabin lights This mold also has a glassed in flange to take the main bulk head The refrigerator mold is 7 wide and high and cov ers the main cockpit bulkhead This mold has a box to enclose the refrigerator and another box for stor age or an air conditioner This mold is glassed into position and ensures that the refrigerator vents to the outside This mold also has the grooves for the Construction ...

Page 33: ... are three types of sailing rigs Masthead fractional and rotating The rotating rig is the most efficient with the mast being supported by a single large shackle on the front of the mast with the base sitting on a ball The mast which is normally wing shaped can then rotate in line with the wind The main sail has a large roach and full battens The jib is fractional As there are no backstays with a r...

Page 34: ...sert which helps keep the sail flat as it is rolled in The sail has a strip of Sunbrella cloth on the leach and foot of the sail which is the longest lasting sun protection material available Reefing the genoa is a simple matter of pulling on the roller furling line after having let loose or eased the genoa sheets Regarding the furling drum it is highly advised to leave a small amount of tension o...

Page 35: ...t is necessary to move the slider forward The approximate slider position when the tack of the genoa is in line with the shroud is with the slider level with the checkstay eye The reason for the correct position of the slider is to put roughly equal tension on the leach and the foot of the sail This position will change in different wind strengths In lighter winds the slider is further aft putting...

Page 36: ...ing the testing they should be recti fied and made stronger This is not the responsibil ity of the boat builder unless the boat was sold spe cifically as suitable for offshore racing With today s high tech sailboat incorrect sailing techniques will easily break the boat Running back stays have to be correctly set up along with the rig ging otherwise the mast can easily fail Today s mast is much th...

Page 37: ...g by looking for loose cotter pins or shackles problems with the rivets in the mast and any other hardware issues Inside the boat periodically check under the floorboards for leaks If a small puddle of water is discovered it is possible to find the source by tracing back the flow of water If this leak is left until the whole area below the floorboards is full it is impossi ble to find the source p...

Page 38: ... cruising x Radar Reflector x Solas Flares red white and orange x Safety Harness x Bilge Pumps x GPS x Single Sideband x Life raft x Emergency Water and Food in Containers x Water Maker x Solar Power x Storm Sails x Charts and Reeds Almanac and other local pilots x Navigation Equipment such as Dividers x Ships Log x Hand Bearing Compass x First Aid Gear x EPIRB x Life Sling man overboard recovery ...

Page 39: ...r The standard boat comes with a short length of chain and 100 of 1 2 nylon rope This is adequate for nor mal anchoring in sand or mud The nylon will stretch to absorb the shock loads of rough sea The chain helps to keep the stock down to make the anchor plough in For anchoring in coral where the anchor line can rub across the coral and get cut it is recom mended that all chain be used Chain will ...

Page 40: ...anchor line at 10 ft intervals Retrieving the Anchor The solid bridge deck of the Gemini provides a sta ble platform for easily raising the anchor Have the helmsman drive the boat slowly towards the anchor with the person raising the anchor giving directions toward the anchor The person raising the anchor only has to flake the loose line into the anchor locker As soon as the anchor line goes verti...

Page 41: ...t ing to throw a line to a dock attendant The best method of throwing a line is to simply coil it up split the coil and throw half of the split coil Hold onto the end of the other half The weight of the half Docking and Mooring being thrown uncoils the half still being held The momentum of the half being thrown will then uncoil that half once the first half has been uncoiled Picking up a Mooring A...

Page 42: ...s boats are struck more often than ungrounded boats The main purpose for grounding is to protect people The height of the mast gives a cone of protection with the base the same diameter as the height of the mast In over 800 Geminis only a very few have been hit by lightning People inside one boat reported a loud bang all fuses being blown everything magnetic demagnetized some electronics lost and ...

Page 43: ...ng up with scheduled bottom cleaning and painting Care and Cleaning of Fiberglass For more information on bottom painting see the bottom paint FAQ on page 59 of this manual Blisters Many years ago blisters were probably caused by inferior perhaps filled resins A few years ago a new problem started With the explosion of the small powerboat market resin and gelcoat manufacturers started to reformula...

Page 44: ...for sanding 3 4 around the void before applying the paste is to blend the repair into the surrounding gelcoat Care of Cleaning of Teak All interior teak on the Gemini is covered with sev eral coats of Tip Top teak oil The teak oil is ap plied with a rag and simply wiped over the teak The surrounding surfaces are wiped with a clean rag to remove the excess teak oil Mat varnish is another possible t...

Page 45: ...l Trucking the Gemini At 14 wide the Gemini can be trucked anywhere far easier and for less expense than any other cruising catamaran However the transom and rudders must be lifted above the rear wheels of the truck The flat bed of the truck is normally 8 wide but the keels of each hull are 10 apart This requires two large timbers placed on the flat bed for the boat to sit on These timbers should ...

Page 46: ...se end as a backup to the seacock Fill the bucket with a 50 50 mix ture of fresh water and antifreeze Attach the hose with the male fitting to the female receptacle on the three way engine cooling water seacock Turn the seacock handle to the middle position which will draw from the hose Place the unattached end of the hose in the bucket Starting the engine will immediately start draw ing the coola...

Page 47: ...clude when and where you are leav ing from when and where your destination is and a description of your boat Coast Guard Safety Kit see page 36 and all safety equipment onboard in working order Make sure you have charts of the area and com pass on board Check marine weather forecast Make sure your registration certificate is visible or documentation is onboard and available A second person onboard...

Page 48: ... information 1 9 October 21 2003 Added description and illustration of how a propane refrig erator works to the addendums section 2 0 January 22 2004 Added Westerbeke Diesel Engine 30B Quick Notes covering breaking the engine in oil changes fuel filters and the Westerbeke Spare Parts Kit 2 1 May 28 2004 Added Sillette drive leg propeller specifications and rec ommended tools list to the Operationa...

Page 49: ...the top of the leg 6 When refitting the drain plug use PTFE Teflon Tape and keenol grease on the threads Centralize the taper plug into the hole and turn clockwise Resistance should be light until fully inserted Note the taper plug is difficult to cross thread accidentally as the plug draws itself in on the thread when turned clockwise Do not use copper based anti seize compounds as this causes co...

Page 50: ...sure sufficiently to allow the liquid ammonia to evaporate The evaporation of the ammonia extracts heat from the evapo rator which in turn extracts heat from the food storage space as described above thereby lowering the temperature inside the refrigerator The mixture of ammonia and hydrogen va por passes from the evaporator to the ab sorber Entering the upper portion of the absorber is a continuo...

Page 51: ...s 15 FT EXT 8 30760 Silencer Air Intake 36342 Harness 15 FT EXT 4 36557 Solenoid Fuel Shut Off Heat Exchanger 37564 Solenoid Preheat 24639 Heat Exchanger End 22850 Spare Parts Kit A 37118 Heat Exchanger Gas 22851 Spare Parts Kit B 37119 Injector 37091 Starter Motor 34552 Injection Pump 37103 Starter Solenoid 36218 Injection Hardware Kit 37121 Tank Coolant Recov ery 24977 Injector Nozzle 36935 Ther...

Page 52: ...com ENGINES 1 Distributor Covers Delaware District of Columbia Georgia Maryland North Carolina South Caro lina Virginia West Virginia 3504 Shipwright St Portsmouth VA 23703 Contact Information Main Contact s Mr Tim Walters Phone 757 673 7200 Fax 757 673 7211 Email engines1 wbdiesel com Web www engines1 com HANSEN MARINE ENG INC Distributor Covers Connecticut Maine Massachusetts New Hampshire New J...

Page 53: ...d Sun Prairie WI 53590 Contact Information Main Contact s Mr Brian Hunter Phone 608 825 3878 Fax 608 825 2790 Email bhunter marysvillemarine com Web www marysvillemarine com R B GROVE INC Distributor Covers Florida 261 SW 6th Street Miami FL 33130 2991 Contact Information Main Contact s Mr Tom Piper Mr Chris Herting Phone 305 854 5420 Fax 305 854 0532 Email sales rbgrove com Web www rbgrove com SE...

Page 54: ...rnia Northern 1941 Walters Court Fairfield CA 94533 Contact Information Main Contact s Mr Henry Bramhall Mr Arley Harty Mr Jeff Hemmerlin Phone 707 426 6670 Fax 707 426 0206 Email sales marinegate com GALLERY MARINE Distributor Covers Alaska Idaho Montana Washington Wyoming 717 NE Northlake Way Seattle WA 98105 Contact Information Main Contact s Ms Barbara Jordan Phone 206 547 2477 Fax 206 547 218...

Page 55: ...hange the engine oil and filter according to manufacturer s recommendations for oil type and fil ter number 4 When required as per your manual re torque cylin der heads and manifolds to engine manufacturer s specifications in proper sequence Readjust tappets if necessary This job is typically performed by a quali fied mechanic Westerbeke Spare Parts Kit Performance Cruising does resell the Westerb...

Page 56: ...ose belts clamps fittings wires Monthly 1 Check zinc anode in heat exchanger After 50 Hours Initial Operation 1 Change engine lube oil filter 2 Replace fuel filter elements 3 Torque cylinder head bolts 4 Adjust valve clearances 5 Adjust drive belts 6 Check electrical connections 7 Lubricate control cables 8 Change transmission fluid 9 Check idle speed After Every 100 Hours 1 Change engine lube oil...

Page 57: ...ount may be 10 coats or the first coat may delaminate This is the related to how good the original surface preparation was and how it is maintained between recoating Sanding when recoating will add to the longevity of the bottom jobs By sanding the bottom in the spring you will get more coats to adhere and forestall the day when you must remove all the antifouling paint from the surface Soft rosin...

Page 58: ...ize the surface Prevention is there fore better than the cure of having to remove the fouling by scraping There are a number of key reasons to keep your hull free from fouling Safety Heavy fouling growth reduces responsiveness of the craft The added weight of the fouling can make the boat sit lower in the water than intended This can have obvious implications in heavy weather conditions Protection...

Page 59: ...es this happen Antifouling paints in general perform admirably even when faced with overwhelming fouling pressure Early fouling is often attributed to silt or slime clogging the pores of the antifouling paint reducing its efficacy This is why it is im portant to maximize the service life of the antifouling paint by lightly scrubbing periodically to remove slime or dirt accumulations How long will ...

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