SJ23 Tech Tip C07, (Reissued 2014-12-15, Bob Schimmel, Joe Thomas & Jim Thompson)

Force 10 Cozy Cabin Bulkhead Heater and Vented Propane Locker.

INDEX - recommendations, pros & cons, installation, thermal protection, stack, deck cap, fuel storage, propane locker, gas sniffer, manual

A cabin heater gives you more early and late season time to enjoy your boat.  You can be comfortable onboard while others stay home.  It is probably the most comfortable way to extend your sailing into the shoulder seasons.  A warm, dry cabin can change a marginal day into a good day and we all know that any day spent on the water is a good one. 

Using a cooking stove to heat your cabin may be quick but it's also dangerous due to the lethal carbon monoxide gas that quickly accumulates in a closed cabin.  If you adhere to this practice you will likely find yourself on the list of those who visit St. Peter each year, in which case you better know the answer to the secret question or he's not letting you in!  Succumbing to carbon monoxide poisoning is very preventable.  The other problem of heating with a stove is the moisture that an open flame produces.  A purpose made bulkhead cabin heater with a chimney to vent the dangerous exhaust gas outside is safe and clean, assuming you allow make up air to enter the cabin. 

The Cozy Cabin heater is designed to operate when the boat is on a relatively even keel but an occasional roll from a wave doesn't bother the flame as it can stay lit and the chimney draft isn't affected.   Before I installed my heater I tested it to 30 degrees for 15 seconds.  It operated without a problem.  However, continued operation with the boat heeled over is inviting trouble.  You'll find these heaters used most often at the dock or anchored somewhere in the rain.  Float into a rainy anchorage and watch which boat has people onboard.  Nine times out ten they'll be on the heated boat, regardless of its size.  I've seen people doing maintenance, partying or reading a book in an anchorage.  There is probably nothing more soothing than reading a good book in a warm cabin with a coffee in hand.  Makes you feel snug and cozy all over doesn't it?  Motoring in the drizzle inside a warm cabin is another experience not to be missed.  Sometimes I wonder if these aren't the best parts of sailing!  Alternatively there is nothing more miserable than a cold, damp cabin in a boat without a heater to drive you off the water.  Given that situation I would much rather be on land where my activity can keep me warm.  This is precisely the reason why I installed a heater on Panache. 

When the Cozy Cabin heater was introduced in the 1970s it was available in four fuel models, diesel/kerosene or propane/compressed natural gas, with an adjustable heat output of 4000 to 6000 BTUs.  To roughly calculate how many BTUs are required to heat a cabin, calculate the cabin volume by (H x W x D) = V ft3, then multiply the volume by 10 if the cabin is insulated, or by 15 if it is not insulated.  The SJ23 volume calculates to (7.5W x 16.5H x 7D)=189 ft3, where the required heat is 12,000 BTU.  From my experience a Force 10 heater produces adequate heat in the shoulder seasons.  I even use it during the winter while working on the boat. 

PARTS & SERVICE - This popular 1970s bulkhead cabin heater was originally manufactured by FORCE 10 in British Columbia, Canada but as of 2000 the unit was manufacture discontinued.  Currently, Sig Marine sells parts and service at their Surrey, BC (Canada) location.  You may also contact Sig Marine for technical assistance.   Force 10 has changed their product line to stoves shown on their web site. 

Height 16.25"
Width 7.75"
Depth 7.25"
Cook Top 4" x 5"
Fuel Consumption 3.3 hr/lb
Safety Flame out thermocouple & O2 Depletion
Power Consumption 0 Amps


  1. SPECIFICATIONS - Height 16.5", width 7.5", Depth 7", weight 11 lbs, cook top (4x5)", heat 6500 BTU.
  2. CLEARANCE - Ideally, you should leave 6" of clearance from the sides and the bottom of the heater to any combustible material, 36" from the floor to the top of the heater and 24" or more of clearance above the heater.  72" of headroom is ideal.  To prevent the bulkhead from overheating Force 10 supplies insulating washers to use behind the feet of the heater.  To protect the wood bulkhead against heat discoloration it is recommended to install ceramic tile or a sheet of stainless steel behind the heater.  Since the majority of the heat is radiated from the top plate and from the flame, pay particular attention to a combustible material close to either.
  3. DECK CAP - The chimney stack must be mounted through a 2" ID hole drilled through the deck or side wall.  Seal the edge of the hole with epoxy to protect the wood core.  The chimney or deck cap MUST be mounted on top of a tapered hardwood spacer ring with a gasket between them for insulation.
  4. STACK - This heater requires a 1" stainless steel flue or stack.  Ideally the stack should not have a bend greater than 450 at any one turn.  To vent horizontally out the hull requires two 450 bends.  For a side vent installation the ideal vertical rise is 3' and the ideal horizontal run is 1' or less.  Too much rise will draw excess warmed air out.  Too long a horizontal run will hold hot air back.  A chimney damper is not allowed. 
  5. FUEL (Diesel/kerosene) - The pressurized fuel tank for the diesel/kerosene heater should be installed lower than the burner as an extra measure of safety to prevent fuel being siphoned onto the cabin floor.  Diesel/kerosene is always a liquid feed from the bottom of the tank through an internal dipper tube through the top of the tank.  The manufacturer recommends a 1/4" rubber fuel line BUT make sure the rubber is rated for the type of fuel you are using.  Most fuel hoses are compatible with only one type of fuel like diesel/kerosene.  A gasoline hose is NOT compatible with diesel/kerosene.  Above all, don't install an old propane hose for diesel/kerosene simply because you are too cheap to buy the correct hose.  The problem is that the fuel will slowly dissolve the rubber which will plug the hot burner holes.  This problem may take a few years to manifest itself.  It's a very frustrating problem to resolve when cause and effect are so far apart in time.  While the fittings on a propane hose are usually crimped, those on a diesel/kerosene hose may be attached with barbed fittings and hose clamps.  This combination is well within the 30 psi system operating pressure of the air pump on the fuel tank.
  6. FUEL (LPG/CNG) - The pressurized fuel tank for the propane or compressed natural gas heater must be installed in a vented housing to keep unburned heavier than air propane gas from entering the cabin or bilge.  LPG or CNG fuel is always a gas feed from the top of the tank so install the tank upright.  Force 10 recommends a flexible hose e/w crimped connectors approved for LPG or CNG.

USING THE HEATER - Regardless of which version of Cozy Cabin bulkhead heater you have, they all produce enough heat for an SJ23 cabin.  However, the secret to a successful installation is to install a small whisper quiet fan above and to the side of the heater to drive the hot air down to the cabin floor.  This is the only way you will ever warm your tootsies that will be immersed in the three foot deep layer of cold air below the heater!  If the top of the bulkhead is open to the ceiling then you can pivot the fan 1800 to send the hot air forward to dry the berth.  It's so nice to crawl into dry bedding on a rainy day.  The other reason for a full articulating fan is to satisfy all those 'adjusters' out there!  I've never seen a fan that somebody didn't want to point in another direction.  If it can oscillate, then all the better.  By the way, the fan is great for cooling you off in hot weather. 
- The height of the flame is adjustable by the red control knob in the photo above.  The propane version will operate at full throttle for about 15 hours on a one pound disposable bottle.  The diesel/kerosene version will operate about 24 hours on one US gallon of fuel, provided you maintain tank pressure.  The propane version can burn unattended till the fuel is consumed.  You will have to pump the tank pressure every few hours or so. 
- You can restore and preserve the steel top plate of the stove with Stove Polish.  This is a paste that easily restores the lustre to a black finish. 
- SMART IDEA  It is very advisable to leave a hatch 'cracked' open to let some fresh air in.  Oxygen deprivation can sneak up on a person, making you feel lethargic and dropping your defences to where it can be dangerous. 
- DUMB IDEA  It is NOT recommended to hang wet clothing above the heater.  The smart idea is to hang the clothing to the side and blow hot air at it with the fan you installed. 
- It is NOT recommended to use the heater while sailing, despite the fact that the flame can stay lit at 300 of heel.  The problem is that the hot exhaust gas will escape out the lower side of the hooded vent holes, overheating the wall and dumping dangerous fumes inside the cabin.  I can only imagine the problems that can arise when wind and waves combine with fire and carbon monoxide in the cabin.  You are welcome to it.  The safer thing to do is pack the sails, drop the anchor, light the heater, make a pot of coffee/tea and enjoy life. By the way, this heater will keep a pot of coffee warm. You just have to find a 4" diameter pot that can fit inside the fiddles.  I've also heard of people who warm soup on the stove.  A can of beans would fit nice as long as you don't let it boil over.   TOP 

PROS & CONS - The FORCE 10 Cozy Cabin Heaters were manufactured in four fuel types, each with their pros and cons. All are bulkhead mounted. They are now manufacturer discontinued but parts are still available at the time of this writing. 

and CONs of the Different Fuel Types.


LIQUID FUEL - Diesel or Kerosene


 Preheat The burner MUST be preheated by burning a combustible paste spread in the basin under the burner.  If the preheat is incomplete (burner too cold to support combustion) then the fuel will not ignite when it comes out the burner.  If the burner temperature is almost hot enough then it will produce a low yellow flame that will burn sooty till the burner heats up.  The flame may also flare up while the burner heats up.  Flaring can be dangerous in a confined cabin and the valve should be shut off immediately.  The problem can be minimized with a judicious application of the volume of paste.  Soot coming out the chimney will stick to things on deck.
Preheat is not required.  The LPG & CNG versions start immediately, provide virtually instant heat and burn clean all the time.  However, LPG is heavier than air making it dangerous when accumulated in the bilge.  CNG is lighter than air, making it safer.  Both gasses are very explosive.
 Operation The flame should burn with a solid blue colour.  You may see the occasional yellow tipped flame which is OK.  The tank looses pressure as the fuel is consumed but with a bit of experience you'll know when to apply a few more strokes on the pump to maintain a hot, clean burning blue flame. Usually every 90 minutes, modified by gas consumption and flame height.
The heater will burn as long there is fuel in the tank since the evaporating gas in the tank is what creates the pressure at the burner.
 Fuel Tank
  • The pressurized tank for the diesel or kerosene versions must be installed lower than the burner as an extra safety measure to minimize the risk of liquid fuel flowing on the cabin floor after the flame goes out.
  • The tank must be installed (clamped) with the hose at the bottom to achieve a liquid feed.
  • All fuel must be filtered to prior to going into the tank.
  • If you equip the heater with a refillable propane tank, it must be stored in a vented locker.  (see propane locker).
  • All styles of propane tanks must be clamped vertical with the hose at the top to achieve a gas feed.
  • The propane supply line should have an automatic shutoff valve to protect against a leaking hose.
  • Spilled diesel or kerosene is unlikely to ignite and less dangerous than propane gas settled in the bilge.  However, it MUST be wiped up immediately. 
  • On land it is OK to use a liquid fuel to preheat the burner.  On a rocking boat you must use a paste that can't spill.
  • The starter paste must be lit with a flame from a BBQ lighter or a match, not a spark lighter.  See safety note below.
  • Heater is equipped with an automatic fuel shut off to guard against a flame out or oxygen depletion.
  • If the internal piezo-electric igniter fails to spark the gas can be lit with a BBQ flame lighter (not a spark igniter).  Use a flame, not a spark, since leaked raw propane gas will collect in the bilge where it can accumulate to a potentially dangerous quantity.  See safety note below.

It is arguable which type of fuel poses the greatest potential hazard.  There are pros and cons to each type and your operating knowledge of your heater, along with proper maintenance, are key.  Neither of the liquid fuels are as explosive as the gaseous fuels but if they puddle that fuel can also be dangerous.  Regardless of which type you have, it is a wise to stay awake (both feet on the floor and sitting upright) while the heater is burning.  It is also wise to install a carbon monoxide detector in the cabin, especially if you intend to nap, even if for only five minutes!  Thankfully not many people can sleep comfortably with a heater burning, however slight the hissing noise of the flame is.  The smartest thing that most people do is keep the cabin heated till the sun fizzles below the horizon and then snuff the flame, preferring to rely on the warmth of a good sleeping bag and the comforting knowledge that you won't succumb to carbon monoxide poisoning overnight.  I consider the heater both a safety feature and a luxury in marginal, damp weather. 

BULKHEAD INSTALLATION in a SJ23 - While an SJ23 has a roomy cabin for its length, there is really only one practical place to mount a bulkhead heater, against the port bulkhead.  If you find this spot too intrusive you may want to invest in a portable heater like an Origo alcohol stove that can be placed on the floor.  However, if you operate your boat in an area with lots of marginal weather then a permanent cabin heater is the best way to go.  The FORCE 10 diesel/kerosene heater shown at right was installed on "Gecko" by the original owner who worked for Clark during the summer.  Joe Thomas now owns her and has sailed her out of Seattle for many years.  The FORCE 10 propane heater shown below was installed on "Panache" by Bob Schimmel.  TOP 



FIRE PRECAUTION - Fire at sea is the most feared of all hazards for a sailor. There is virtually no way to escape from it.  Going over the side it hardly a solution and riding it out in the dinghy is only marginally better.  Fire prevention is everything.  For this reason you MUST install this heater with ALL the safety precautions recommended by the manufacturer, plus any other that are required due to unique requirements on your boat.  This is your responsibility to figure this out and definitely NOT a time to make a short cut. 

THERMAL PROTECTION for TABLE - A section of the port leaf of Panache's table was cut out to clear the body of the heater.  Ooh it hurt to cut such nicely finished wood work!  However, the cut out section created the required 2" air gap around the heater, thereby keeping the edge of the table cool when it is up.  Long term heating of the table fiddle shouldn't be a problem.  However, I will apply duct tape (reflective aluminum) to the fiddle as a precaution.  I may not be onboard if someone else operates it!  The top metal plate radiates lots of heat sideways and a lot of hot air passes out of the heat exchanger holes at the top.  The flame also radiates heat sideways but not nearly as much the plate and the holes at the top.  At the height shown in my installation, it is quite easy to light or service the burner, which is an important consideration.

THERMAL PROTECTION for BULKHEAD - Use high temperature fiber washers under the mounting feet to insulate them from the bulkhead (shown below).  To keep the bulkhead cool I mounted sheet metal behind the heater (shown at left) but I've also seen ceramic tile used.   This is important if you operate the heater for an extended time, especially if it's a really good book!  If you use sheet metal, install it loose against the wall so the slight air gap behind it can't conduct the heat to the bulkhead.  Most of the heat will be reflected if the sheet metal is shiny.  Panache's installation shown at left is polished aluminum (light sand paper) and the wood bulkhead always stays stone cold.  Maybe I am anal about this stuff but I regularly check the heater for over heating while it runs.      TOP 


STACK - The chimney stack doesn't have to go straight up as shown in Joe's installation at right.  To keep hot exhaust gas away from poly deck lines I installed Panache's deck cap about 8" off to the side of the heater.  This was beyond the limits of a bender so I cut the stack in two places, 300 each, and welded the assembly back inline.  Polishing was accomplished with a Dremel tool using successively finer compounds.  As an alternative to offsetting the deck cap you could use a straight stack and raise the deck cap above the deck lines with a thick wood spacer ring.  The extra height has the added benefit of keeping more solid water out.  As you can see in the photo below I offset the stack and raised the deck cap. 



If you wish to make smooth bends then use a stainless steel tube bender on the stack.  Don't use an electrician's conduit bender as it does not grip the tubing which will kink it due to the properties of stainless steel.  An alternative to bending is to cut and weld the tubing, especially if the desired turning radius is tighter than the limits of the bender, which is usually a 5" radius.  Grind the welds smooth to eliminate hot spots, meat hooks and to improve the cosmetics.  The maximum number of bends allowed are two, 450 each.  You could split a single 450 bend into two 22.50 bends to achieve a smoother transition, but this complicates the welding more and adds to the labour costs.  Still, certain installations might require it.  Leave about a 1/8" air gap between the end of the stack and the bottom inside of the cap for thermal expansion.  This helps to protect the cap from being pushed up off the deck and maintains the deck seal.



THERMAL PROTECTION for the DECK HOLE - The deck hole for the chimney must be 2" ID which creates 1/2" clearance all around the 1" OD stack.  A hole saw is perfect for this job.  Drill half way through from the top then finish the hole from the bottom.  The ceiling finishing ring is missing on Joe's chimney at right but it illustrates the installation.  Seal the exposed deck core in the stack hole with epoxy to maintain the strength.  If the cap is to be installed where you expect solid water to come over the deck, then I suggest using at least a 2" thick wood spacer ring to minimize the amount of water that can find its way below.  Taper the sides of the ring to 300 so a deck line can slide over the cap.  The cap is fastened to the top of the ring with three wood screws and a fibre thermal washer between them.  Do not use sealant here.  The wood ring is fastened to the deck with three wood screws from below (inside the cabin) and sealed with Sikaflex to the top of the deck, forming a fillet around the base of the ring to keep water out.  The thickness of an SJ23 deck adjacent to the mast is 5/8".  Remember to face the cap opening aft to keep spray out.  Position the bottom ring mounting screws between the cap screws for maximum strength.  The stainless steel inside finishing ring also keeps the stack centered in the deck hole and in the chimney cap. Use it as a template for the bottom ring mounting screws.  Judging from the cap diagram the chimney stack ends right at the top, inside the cap.  This keeps the exhaust fumes from entering the cabin, protecting the crew.  With all the exhaust gas evacuated outside, the deck hole should stay relatively cool.  A favourite trick is to line the perimeter of the deck hole and wood ring with thin aluminum or stainless steel sheet metal.  The metal reflects most of the radiant heat keeping the deck cool.  This is very important if you operate the heater for an extended time.  If the chimney stack is a wee bit short of the cap then stuffing loosely crumpled aluminum foil inside the deck hole should create a seal to prevent fumes from entering the cabin.  If you ever have to service the heater or the stack, remove the heater from the bulkhead and allow the stack to drop out of the cap.  This maintains the water tight integrity of the cap to the deck.  If you have to remove the cap then release the three screws on top of the ring, leaving the wood spacer ring sealed to the deck.  If the cap is sheared off in an accident, seal the deck hole with a rag or tapered wood plug. Now aren't you glad you sealed the edge of the deck hole with epoxy!   TOP 


WHERE TO INSTALL THE DECK CAP (Charlie Noble) - Remember to mount the deck cap with the opening facing aft and to use a hard wood ring under the cap for thermal insulation to the deck.  If you sail in an area where you expect to receive lots of spray or solid water over the deck, then make this ring at least 2" thick to minimize the amount of water that can flow down the chimney.  The higher the cap is off the deck the less water you will take in.  Use Sikaflex to seal the ring to the deck.  Coat the ring with Sikkens Cetol as this is the only finish that will survive the heat of the chimney whereas varnish will flow off.  Install guard rings over the deck cap so you have to make fewer trips to release a snagged line.  Keep in mind that the system isn't perfect!  I don't want to hear any swearing about this! 
The cap at right belongs to Joe's boat.  The cap to the left belongs to Panache.  The spacer and guard rings are my design.  For service I simply remove the guard rings and cap screws.  The spacer is fastened with screws from the bottom, inside the cabin, and sealed to the deck with Sikaflex.  I doubt the spacer ring will ever be removed.  The reason why I used such a thick spacer ring is to vent the hot exhaust above the deck lines.  If I ever kick it, well the spacer can stand up to the force better than the cap and I will probably utter a few words in the process! So far it is totally out of the way.  I'm happy about this because I spent a fair amount of time assessing this location, going through all my usual motions and contortions.  I found this spot to be ideal for both venting and foot clearance.  It's not often that you can satisfy all requirements.      TOP 

Fuel Storage for Diesel/Kerosene.

The diesel/kerosene pressure tank is best nstalled in the port locker, up off the floor so it stays dry and where the air pump is easy to reach.  This is also a relatively safe place to fill the tank since fuel spills stay inside the locker where they can be wiped up and fumes can evaporate, staying outside the cabin.  The fuel system operates at approximately 30 psi so all lines and fittings must be in good order. 














Vented Propane Locker.

Propane is a very convenient fuel to use but it is potentially dangerous on a boat in that it is heavier than air.  If it accumulates in the bilge you have a very dangerous situation.  Oh joy, another bomb waiting for a spark to ignite it!  For this reason the best place to store a propane bottle is on deck where fumes can vent overboard.  If you want to hide (cosmetically) the bottle or protect it from the heat of the sun then install it inside a propane storage locker that is vented outside the hull AND SEALED from the cabin.  Since propane gas is heavier than air the tank must be installed high and the drain vent MUST be installed low, at the bottom of the locker.  The drain vent MUST also remain open when the boat is heeled.  This is one of those cases where the tank cannot be stored low in the hull to become part of the ballast.  You also have to decide which type of tank to use; disposable or refillable steel/aluminum, which determines where and how  it can be stored and how it is to be vented.  This decision is not to be taken lightly. 

The propane tank, refillable or disposable, must always be clamped vertical inside the locker to achieve a gas feed from the top of the tank, unless you have a tank that is designed to be installed horizontally.  The first device out of the tank valve should be a pressure gauge (connected to the valve) to allow you to easily and frequently leak test the gas distribution system for a leak.  Immediately after the gauge, you should connect an electric solenoid valve for emergency shutoff controlled by a gas detector.  Finally there is the supply line to the appliances.  The supply line that is ported out through the propane locker wall, MUST go through a gas tight bulkhead fitting.  Consider one of the following ideas for a locker: 

INSIDE LOCKER THAT VENTS OVERBOARD - A good place to install a propane storage locker on an SJ23 is inside the port locker just aft of the opening under the seat.  Build a strong sealed box and mount it securely so it and the bottle stay put regardless of how much motion the hull goes through.  The box MUST be 100% vapour sealed except for the purpose made vent holes.  In addition, the forward facing door should be easy to operate so you can reach inside to operate the valve or replace the bottle.  The box may be made from fibreglass, heavy duty vinyl or plywood that is saturated with epoxy to seal the wood.  If you have to go through all the work of fabricating a box then you may as well make it big enough to house a 5 lb refillable bottle.  Remember to leave some room above the bottle for a  pressure gauge and a shutoff valve.  The preferred method of venting this style of locker is from the bottom of the locker to the transom via a 1/2" ID hose.  Install the drain vent fitting on the port side of the transom, away from the outboard engine, below the bottom of the locker and above the water line on all angles of heel.  Install the inlet vent line from the top of the compartment to a fitting installed high up on the transom.  It is OK to include an upward loop to prevent water from coming in.  Now your propane storage compartment can vent heavier-than-air fumes over the side, which is the safest place. This is a very safe installation for an SJ23.  You might also consider making the locker removable so you can crawl into the locker and go aft to inspect the nuts and bolts through the transom.  This will require some creativity.

INSIDE LOCKER THAT VENTS INTO THE COCKPIT - A variation on the locker described above is to vent into the cockpit.  This method uses the cockpit drains as the final path to vent the heavier than air propane fumes overboard and is acceptable ONLY IF your cockpit drains go through the transom and you anchor bow into the wind.  HOWEVER, the propane locker will also  become part of the cockpit water draining path.  See Tech Tip B17 for installing cockpit transom drains.  In this configuration the bottom of the locker must be about 1/2" above the cockpit sole.  Drill a 1" hole, about 1/2" above the cockpit floor, through the cockpit wall into the propane locker.  Cover the vent hole with a small stainless steel clamshell vent.  Fumes more than 1/2" deep inside the locker, can flow out the drain hole and down the cockpit drain.  Thanks to Jim Thompson for this idea. 
Just to be on the safe side, Jim also installed a Zintex propane/gasoline sniffer in the cabin that detects the smallest whiff of propane from careless operation of the cabin heater.  In two years of use his custom fuel locker has been 100% effective at keeping noxious and dangerous fumes out of the cabin as detected by the Zintex sniffer.
NOTE - While venting propane fumes into the cockpit may be acceptable if your cockpit drains through the transom, any fumes lingering in the bottom of the locker could be blown into the cabin through an open companionway.  It is for this reason that I caution you that venting into the cockpit is NOT the most ideal solution, as it may fill the cockpit and the cabin if the tank or hoses were to develop a major leak.  (Murphy's Law).  While many people have used it with no problem, you should check your local regulations for storing propane on a boat.

TANK MOUNTED ON THE PUSHPIT - Another common storage place is to clamp a 5 lb bottle to the stern rail or transom. This is not as elegant as a concealed storage compartment but definitely safe, serviceable and easy to install.  A variation of this technique is to clamp the bottle upright at the aft end of the cockpit sole.  This location is suitable ONLY if the cockpit drains through the transom. 

TANK MOUNTED IN THE ANCHOR LOCKER - Another ingenious idea is to store the propane bottle in the bow anchor locker.  This works ONLY IF the locker is totally sealed from the rest of the boat AND the locker has a drain hole to spill propane fumes overboard.  You must ensure that the drain hole is NEVER plugged with mud or weeds.  See Tech Tip B11.  As an added benefit, you might be able to smell leaking propane fumes if the bow is upwind of you.  Due to the humid conditions in the anchor locker, I recommend using an aluminum tank.

DISPOSABLE BOTTLES - If you decide to use a disposable propane bottle because you don't want the complexity of constructing a vented storage locker then consider one of the following solutions.  You will run out of propane one day so carry a spare!  If you carry disposable propane bottles they should be stored outside the hull in case one of them starts venting.  I have no idea how a business is allowed to store boxes of bottles inside a retail store full of unwary customers.

  • BOTTLE BAG - Sling a disposable propane bottle in a cloth bag hung on the stern rail or a life line.  Any fumes that leak will automatically spill outside the hull to be blown away.  These "bottle bags" are commercially available at a chandler. 


  • 4" PVC STORAGE TUBE - The horizontal PVC storage tube shown at right is fastened to the swim grid with two stainless steel U bolts and two formed wood spacers.  Located on the swim platform it can vent overboard while the ladder affords protection.  This particular tube is long enough to hold two disposable bottles and stays cool in the sun.  It could easily be adapted to the transom of an SJ23! 






  • TRANSOM MOUNTED "LOCKER" - Similar to this horizontal PVC storage tube but installed vertical against the transom to function as a propane locker that safely vents overboard.  If the 4" diameter PVC locker is mounted close to the boarding ladder it will be far enough from the rudder so as not to interfere with turning.  On Panache there is 3/8" of clearance when the rudder is pulled hard over.   Use a plumbing end cap for the bottom and drill a 1/4" hole through it to vent gas.  Use an inspection plug at the top for a removable cap.  The cap screws on tight enough to hold a bottle secure and keep the weather and corrosion out.  Take a propane bottle with you to the plumbing department to ensure it fits through the fittings as there are many different styles.  If you decide to store two bottles in the tube (one spare at the bottom) then keep a vinyl cap on the bottom bottle to protect the thread and place a wood spacer between the bottles for protection.  Unfortunately an SJ23 transom is too small for a two bottle locker. 
    While I could direct my propane line out of the existing hole in the back of the cockpit and over the transom (see picture below), I might run it under the cockpit and through the transom via a vapour tight fitting.  This way the hose is totally protected from UV damage and out of the cockpit for a clutter free installation.
  • PVC COCKPIT MOUNTED "LOCKER" - Shown here is a view of my temporary "cockpit propane locker" to determine feasibility.  Later I made this locker functional as I wanted cabin heat for the end of the sailing season and into the winter when I completed some interior work, this time with warmth!  During the short time I used it in the summer, I had no problems with it.  The bottle was protected from people and the heat of the sun.  The PVC tube has a false floor to keep the bottle up off the wet cockpit sole.  I also drilled holes at the bottom perimeter of the tube to maintain the cockpit drain and added formed a wood cap to keep the sun off the regulator.  What makes this "locker" design possible is the combination regulator and shutoff valve that you see at the top of the bottle and the approved brass adapter for the propane supply line.  I scrounged this valve from an old BBQ.  Considering that this bottle is permanently connected to my heater, I feel very safe with an accessible shutoff valve outside the cabin. This same valve will be used when I relocate the "locker" to the transom as I like my foot room in the cockpit.

PROPANE (LPG) SUPPLY LINE INSTALLATION - Having decided on a storage place for your propane bottle, you next have to consider the supply line.  Support and protect it along its full length and check it regularly for chafe and leaks. This being the case, it should be installed where it can easily be inspected.  Consider one of the following safety tips: 

  1. If you install the heater on the port bulkhead and the tank at the transom, then the continuous supply line must be 20' feet long.  This will give you about 2' of slack at the transom to connect to the tank. 
  2. Lines are manufactured in multiples of 5 feet.  The line MUST be continuous (one piece) to eliminate any hidden couplings that can leak propane into the bilge.  No point in joining the heavenly hosts before your time! Buy a commercial made line with crimped fittings for peace of mind AND compliance with your insurance policy. 
  3. The preferred supply line is a UL listed thermoplastic LPG hose because it can't corrode or develop stress or fatigue cracks like rigid copper tubing can.  It is also easier to install than rigid copper tubing. 
  4. A commercial made hose is fully assembled with solid brass fittings and leak tested to 100 psi.  Specifications are: 1/4" ID with a 3/8" female swivel flare fitting on the heater end.  The tank end fitting must be ordered to fit to either a POL or the disposable bottle type connecter.  Adapters are available to convert a fitting. 
  5. Install the supply line along the inside of the settee and cockpit locker inside a "wood tray" to keep it away from items stored there. Make the wood tray from two 42" long sections so they can slide in through the settee holes.  I fastened mine with stainless wood screws through the settee wall.
CARBON MONOXIDE - A carbon monoxide detector is recommended in the cabin to warn and protect the occupants.  More heavenly host advice! 

OXYGEN CONTENT - The Force 10 propane heater consumes cabin air and is equipped with an oxygen depletion device that shuts off the heater when the cabin oxygen level falls below 95% of normal.  Mine works very well.
NOTE - If you want to see how quickly the oxygen level in a cabin can drop, just close all the openings and light a few lanterns.  Now watch the flames lower in about 5 to 10 minutes.  The amount of time this takes depends on how many flames are burning and how quickly people consume air in the cabin; i.e. how quickly the oxygen content is reduced.  If you open the sliding hatch the flames will pop up instantly to normal height.  If you stick your head outside the cabin just then, you will experience that rush of fresh air going into your lungs that feels so refreshing.  What's interesting is that humans can survive at the lower oxygen content at which a flame cannot burn.  However, with time you will feel lethargic which is a dangerous situation to be in. 

If your internal tank is not vented outside the hull, please install vents immediately.  I prefer not to read about an SJ23 sailor in the obituary column! Besides, it's too nice a boat to blow up!    TOP 

  1. Include a 2 foot long strip of orange surveyor's tape attached to the inside of the propane locker lid.  When you reach in the locker to turn the valve on, pull the tape out as you close the locker door.  This leaves the tape showing which is your indication that the valve is open.  It can be seen from most anywhere onboard the boat.  After you close the valve, tuck the tape inside the locker to remove the warning indication.  This simple, convenient and very effective operation will become automatic very quickly.  If you really want to improve the warning, write PROPANE ON, on both sides of the tape. 
  2. There is absolutely no reason to open the propane or natural gas tank valve all the way.  Cracking it open half a turn is sufficient to supply enough gas for all the appliances on a boat.  The advantage of this practice is that if you have to close the valve in a hurry, then 1/2 a turn can be done very quickly.  Speed is usually a great safety advantage on a boat.
  3. The tank must be clamped upright for gas delivery.  Any other direction will create a liquid feed which is extremely dangerous. 
  4. GAS SNIFFER - If you have a propane appliance on board it's a good idea to also install a gas sniffer to keep you from joining the heavenly bunch prematurely.  The Zintex gas sniffer was the flagship product of its kind in the West Marine catalog around 1998.  I can't find Zintex on the Net, but I believe there are several competing products.  I can get you the snail mail address if you want it.  This particular sniffer bellows at every little puff of propane I happen to let off while firing up the cabin heater.  The technology seems to be near perfect and it cost approximately $220 US in 1998.  Jim Thompson. 
  5. As part of your operational shutdown procedure, you should burn off the line pressure to prevent leaking unburned propane into the bilge when you inadvertently open the appliance valve.  Burn the pressure off till the pilot light just extinguishes.  This reduces line pressure to equal atmospheric pressure while retaining propane in the line.  This simple procedure prevents you from having to purge the line every time you wish to light an appliance.  In the same line of thought, you should always use a flame from a match or a BBQ starter to light the heater, especially if it is gas fueled.  NEVER use a spark igniter.  Have the flame touching the pilot light burner BEFORE you turn the gas valve on so you ignite the very first bit of gas coming out of the supply line.  This is probably the best way to keep propane gas out of the bilge. 
  6. If you store your boat on the trailer for the winter, remove the through hull knot meter impellor to drain any propane fumes out the hull. 
  7. Have a fire extinguisher handy at the companionway, away from the heater.  This way you are close to an exit and safety while still being able to fight the fire.  At least you can still get out.  Fire on board a boat must be the worst type of disaster.  There is no way of getting away from it short of diving overboard, which has its own set of problem! 

FORCE 10 HEATER MANUAL - Want to buy a manual for your Cozy Cabin Heater?  Please specify which fuel your heater uses, diesel/kerosene or LPG/CNG, because the description in the manual matches the fuel.  No point in buying the wrong manual.  I manage this web site during my spare time and share the information freely.  It takes a lot of work to measure, record and document the information accurately.  Such is also the case with these two manuals that I reproduced.  For this reason I charge $5.00 for a soft copy that you can print.  
NOTE - if you print the manual on (8.5x11)" paper the page numbers will not match the original (5X7)" manual.  If you would like a soft copy please
Email me 

Return to Techtip Index. . . . . . . . . . . . . . . Have a Question?