s/v TWIG

Saga 43 - Hull #39

Propane System


Correct operation and regular maintenance of the Propane (LPG) system is critical to safety. Obviously the presence of an open flame aboard a yacht presents numerous hazards, from personal injuries, to fire and even explosion. It must be treated with utmost respect. Always be vigilant when operating.


Propane gas is heavier than air and colourless. As a result any leakage will flow down (towards the bilge) and can occur undetected until it accumulates in sufficient quantities to become a explosion hazard. Therefore the Propane tank is located in a specially engineered locker in the cockpit. This locker is sealed from the interior of the boat and contains a drain hose in the bottom (Propane is heavier than air} which is vented overboard aft where any leaking Propane cannot get back into the yacht. Inside this locker there are two valves to control the flow of LP gas to the stove. One valve is electronically controlled from the panel in the galley, the other is manual and located on the tank itself.

An additional safety feature is a “gas sniffer” device located in the galley connected to an alarm and automatic shutoff. The drain hose in the Propane tank locker should be checked each time the boat is used. Dirt, leaves, and insects have all been known to clog the drain hose. An easy test is to run a water hose in the Propane locker each time the water tanks are filled or the decks washed and check for adequate drainage. Do not store anything in the locker that could possibly cover or seal the drain, such as cleaning rags, sponges, clothing, sail bags etc. Nothing should be stored in the locker except cans or bottles of volatile solvents or butane and propane canisters.

Stove Operation

  2. Switch on the breaker on the main breaker panel to supply 12 volt DC to the small Propane control panel mounted in the galley.
  3. At the Propane tank open the manual valve located on the tank. (Only one turn is necessary.)
  4. At the Propane panel, turn on the sniffer by depressing the button depicting a battery (left). Sniffer will go through a 60 sec. system check before activating the valve, if gas is detected, an alarm will sound and the system will be inoperable.
  5. Then depress the button depicting a Propane tank (right button). The LCD will change from an X to a check mark, indicating the system is operational.
  6. Light the stove according to the stove manufacturer’s instructions.

System Shutdown

  2. Depress the button depicting the Propane tank (right button). The LCD will T change from a check mark to an X, indicating system gas flow is off.
  3. Close manual valve on tank in the Propane locker. ._
  4. Leave Propane control panel and sniffer operational when operating boat. Turn off only if you are leaving the boat.

Leak Testing

At least once a month, check the Propane system as follows:

  1. Close all burner valves.
  2. Activate the entire system as above.
  3. Check and note gauge pressure.
  4. Close manual valve on tank.
  5. Wait 5 minutes and check gauge pressure.
  6. If gauge pressure is 90% of original pressure noted in Step 3, system is leak free. Switch off LP controls.
  7. If pressure has dropped, then there is a leak. Do not use the system until leak has been detected and eliminated! Gas leaks can be detected by a simple “soap test”. This involves brushing a soap solution over all of the joints and fittings in the LP system, with the system activated and looking for small bubbles to appear. All fittings are located inside the LP cockpit locker plus one connection on the rear of the stove.

Use a solution of 2/3rds liquid dish washing detergent and 1/3rd water. NEVER USE A MATCH, LIGHTER OR OPEN FLAME TO LOCATE LEAKS! m 7-5 Gas Detector Alarms The gas detector is effective at sniffing most vapours, volatile or not. The alarm may be caused by something as innocuous as high humidity or cooking steam, NEVER assume an alarm is false. Treat all alarms as significant and run a leak test as above.

Pressure Gauge

The pressure on the gauge does not indicate the exact quantity of LP remaining in the tank. The gauge is installed as an aid in checking for leakage in the system. Gauge pressure will vary with ambient temperature but is normally in the range 100-150 PSI. To determine the quantity of Propane in the tank, the tank must be weighed and the tare weight (indicated on the tank) subtracted.

Electric Conversion

It takes us around 80 days to use a full 20 pound (max 4.3 usable gallons) tank. Propane contains around 21,500 BTU per pound or 91,000 BTU per gallon. There are 3,413 BTUs per kilowatt hour so 26.7 kWh per gallon of propane. One full propane tank has roughly 115 kWh worth of energy. So we should budget around 5,400 BTU per day. That rounds up to 1.6 kWh of electric usage per day for cooking. Or 0.25 pounds per day.

Cost for a tank refill itself is $16-24. Occasionally it will be $30. Transportation to refill can be $40 round-trip. Plus time disconnecting tank, locating a facility that does refills, waiting for it to be filled and finally reconnecting the tank and checking for leaks. It takes around 3-4 hours every fill. 3 minutes per day. $0.26 to $0.96 per kWh.

Using 1/2 gallon diesel running the engine will make a minimum of 4 kWh to 6 kWh. At $4/gallon cost estimates are $0.30 to $0.70 per kWh. At $2/liter it’s $0.80 kWh. If creating electrical power and propelling the boat at (less than hull speed) the same time the cost to create the energy is a pennies per kWh. 1 liter of diesel is 5-11 kWh.