Propane locker and wet exhaust - SailNet Community
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post #1 of 5 Old 07-22-2007 Thread Starter
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Propane locker and wet exhaust

I am looking for the best place to install a proper ABYC compliant propane locker on my boat (and not stick it on deck, which, though to me seems ABYC compliant, is not acceptable to insurance, apparently).

I found two locations, both allow me to put a recessed vapor-tight locker opening "to the sky", and fit a decent cylinder. The problem is - both are not too far from wet exhaust (of course half the damn boat is). One (carving space out of cockpit locker) would put the propane tank above a run of the hose, some 3-6" higher (may be a bit more but not by much). The other (transom) is somehwat above (but much higher and separated by a shelf) but would set the locker something like 5" to the side of the exhaust pipe riser. Great choices.

Now, normally wet exhaust isn't particularly hot - but occasionally it can overheat (in itself a lovely problem). I am wondering if 5" of air (or another material, though its hard to imagine better isolation than air, vacuum perhaps ) would provide sufficient insulation in case exhaust overheats.

Last edited by brak; 07-22-2007 at 01:03 AM.
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post #2 of 5 Old 07-22-2007
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Propane is heavier than air and needs to be vented on both the top and bottom to the exterior of the boat. So you might want to look for another location, where the locker can also drain over the side of the boat.


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post #3 of 5 Old 07-22-2007
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I don't think that you need to worry about the proximity to the exhaust line, as the air is indeed a good insulator. Your engine is going to sieze before it gets hot enough to make the exhuast line into a torch.

When I was hemming and hawing about sticking with propane or converting to alcohol (I'm a bit nervous about sailing with a big tank of pressurised, volatile gas) I had some email correspondence with a person who installs these things on land and in marine environments. He stated that a propane explosion can only occur when the correct mix of propane and air occurs. If there is too much air - the stuff won't blow up, and if there is too much propane - it can't blow up.

I think that the thing to concentrate on is ensuring that the vent you run from the bottom of the locker is as far from the exhaust as you can get it.

Also - if you are planning on installing a propane sensor as a safety measure, I recently learned that they can be set off by a lot things other than propane, so you might want to bear that in mind when you are locating it. I put two sensors on my boat and one works well, but the other one goes off everytime I plug the batteries in to charge as they produce gas during the process.

When the batteries are not connected to shore power, and there are no other fumes: i.e.: when we are sailing and there is air moving through the boat, there is no problem.

Good Luck !
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post #4 of 5 Old 02-22-2008
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I'm curious about this and haven't really found a definitive source of info on this subject. I currently have a small 3lb bottle on the stern rail. While it works, i absolutely hate looking at it all the time, and it's even less comfortable to lean against. I'd like to build my own locker into the hull, but i'm looking for information on proper venting.

I have a great spot in the storage locker underneath the helm seat, and i'd like to box it in and glass it up so that i could put a bottle in there with a fume detector and solenoid as well. There is a perfect spot to put a decent sized (4") vertical vent overhead of the tank, but i can't seem to find good info on what the size of the lower vent needs to be. I've heard about some out there using the cockpit drains as the lower vents, but that idea doesn't thrill me too much.

I'm curious as to what you guys have on your boats that have these lockers in them; or those who have built them. Would it be possible to install two of the fuel-overfill type vents into the transom (perhaps about 1/2" each?)- and that would be adequate venting? Would I need to go upsize into something like a 1" thru-hull? I'm either going to be sticking with the 3lb (most likely) or up-sizing to a 5lb - not sure if this makes any difference.

My problem here is that I have a rather small transom in which to mount thru-hulls, and on top of it I have a black hull, so large gaudy holes and white/chrome thru-hulls don't necessarily work for me. I want this to be absolutely safe as possible and I will go whichever route that proper venting dictates. but exterior aesthetics are definitely of some mild concern to me.

Lil help?
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post #5 of 5 Old 02-22-2008
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well for both of you here is what the ABYC Standards says: (I'll probably get slapped for copying this but it's easier than trying to paraphrase it)

1.8.1 Lockers used to contain LPG cylinders, cylinder valves, regulating equipment and safety devices shall be
designed to minimize the likelihood of use as a gear storage locker and shall be, vapor tight to the hull interior, and located above the waterline, and constructed of, or lined with, corrosion resistant materials, and shall open only from the top with a gasketed cover that shall latch tightly, and shall be capable of being quickly and conveniently opened without tools.
1.8.2 Installation LPG lockers shall be installed so that the locker opens only directly to the outside atmosphere, and If a LPG locker is installed inside a boat locker, the LPG locker shall be located as high and as close to the
boat locker’s opening as possible in order to comply with
1.8.3 When means of access to the LPG equipment locker or housing is open, the cylinder valves shall be
capable of being conveniently and quickly operated, and the system pressure gauge dials shall be fully visible.
1.8.4 Lockers shall be vented at the bottom by a dedicated vent, with a minimum diameter of any component in
the vent system that shall be not less than 1/2 inch (12.5 mm) inside diameter.
1.8.5 Locker vents shall be led outboard, without pockets, through the hull to a point lower than the locker bottom
and above the waterline with the boat in the static floating position.

ABYC H-27 Seacocks, Thru-Hull Connections and Drain Plugs, for requirements for seacocks.

1.8.6 Locker vent openings shall be located at least 20 inches (508 mm) from any hull opening to the boat interior.
1.8.7 LPG lockers shall not be used for storage of any equipment other than LPG cylinders, cylinder valves,
regulating equipment, and LPG safety devices. See
1.8.8 Storage provisions for unconnected reserve cylinders, filled or empty

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