Venting a locker

[steve yates]

On my little brad well 18, the stern locker holds the gas bottle, the 10lfuel tank for the on, (petrol) and 2 5l petrol cans among other stuff. There is a hose going from the cockpit drain through the locker to the stern, I presume to allow the cockpit to drain after waves come aboard.

Does this need venting somehow? And if so, how would I do it?

Thx, steve

 

[VicS]

Hopefully your gas bottle is within its own "locker" with an appropriately sized overboard drain but other wise sealed to above the height of all high pressure components.

if that is a fixed petrol tank then presumably has its own external vent and deck mounted filler. The petrol cans then are the biggest concern. It should havea drain and some ventilation .

The Boat Safety Scheme, chapter 7 will give you all the guidance you need for gas safety. Chapter 5 gives guidance on portable fuel tanks and spare fuel cans.

http://www.boatsafetyscheme.org/media/180428/bss guide 2005 complete web.pdf

 

[pvb]

if that is a fixed petrol tank then presumably has its own external vent and deck mounted filler.

Outboard fuel tanks don't usually have either of these. There's certainly a need for ventilation, but I'm not sure the OP is thinking of complying with BSS requirements.

 

[steve yates]

No, I'm not looking to comply with them, just be sensible and not build a bomb (not having read them, that may come to the same thing, but regulations have a habit of going for the lowest common denominator, and if in doubt, say no.)

 

[pvb]

No, I'm not looking to comply with them, just be sensible and not build a bomb (not having read them, that may come to the same thing, but regulations have a habit of going for the lowest common denominator, and if in doubt, say no.)

OK, that's what I guessed. But you need some sort of vent. You need a vent as low as possible on the transom, so that any gas fumes can escape. It needs to be about 20mm diameter, and obviously above the waterline (including when heeled). For safety, the gas bottle needs to be restrained in some way if it isn't already, so it doesn't wander around the locker. Similarly, the fuel tank and spare cans need to be restrained by straps, etc. You should also check that the locker is sealed from the rest of the boat, so that any fumes can't escape into the boat.

 

[steve yates]

Ok, is venting just a case of drilling a hole through the hull? are there ways of making it one way to stop waves from behind coming into the locker area?

And to strap stuff down means putting some kind of restraing fastener, im thinking d rings would be preferable to u bolts? is there some kind of no nails mastik applicant that would stick them down securely to fibreglass to avoid more holes?

thx

 

[pvb]

The vent should ideally be open, as any sort of one-way valve might stop fumes escaping freely.

You could make plywood holders for the tanks and glue them in with epoxy or sikaflex.

 

[doug748]

It can be difficult if not impossible to achieve a fully sealed and properly venting box on a small boat. As you suspect, just putting in a hose, to drain low on the transom, will lead to flooding at sea. I have left mine to drain into the cockpit, this is a common compromise and most people are not blown up.

You do need to exercise great care though and fitting an in line gas leak detector is a good idea. Always turn off at the bottle which is not so hard on the smaller boat. The alternative is to use a Trangia, or similar, and get rid of the complication of gas.

 

[Strolls]

And to strap stuff down means putting some kind of restraing fastener, im thinking d rings would be preferable to u bolts?

If you google "building a boat gas locker" and "yacht propane locker" you'll find lots of blogs in which other people show you how they've done it.

Variations on this seem quite popular:

 

[jwilson]

On my little brad well 18, the stern locker holds the gas bottle, the 10lfuel tank for the on, (petrol) and 2 5l petrol cans among other stuff. There is a hose going from the cockpit drain through the locker to the stern, I presume to allow the cockpit to drain after waves come aboard.

Does this need venting somehow? And if so, how would I do it?

Thx, steve

On many older and smaller boats it is effectively impossible to make a stern locker vent safely without being in danger of sinking the boat. The problem is freeboard. You just have to turn off the gas bottle every time when not in use and make sure your petrol canisters are well sealed.