Venting lower compartment that houses gas and batteries.

[Goatman]

We sail a 17 Siren sailboat which I recently purchased a 6hp Mercury 4 cycle motor. I previously had used only a trolling motor but found the battery drain was too substantial.

Our lower compartment houses my batteries on both sides underneath the cockpit. In the center area and slightly forward is where I have my small gas container with ventilation cap. I run a line through the hatch door and to the motor for the gas supply.

I have made rubber coverings over all of the connections to keep from inadvertently getting a spark and use plastic ball stretch cords to secure the batteries instead of metal S-hook bungies.
I am planning on making a custom vent about 12- 15" wide which will be on the hatch door.

There is a small cabin vent and the cabin door is always left open when sailing. This is where the intake of air would be coming from. My plan was to have the vent I make facing aft and to pull air from under the cockpit/cabin area.

Questions I have:
Is there a hose that is made to attach to the fuel container cap which can run out of the boat? (I once over-filled the container and found that some gas had spilled out through this vent and onto the boat floor.)
Should I install a bilge blower under the vent to increase the efficiency of the vent?
Should there be something that attaches to the vent which pulls the air from the lowest area in this compartment? (I've read that the gas fumes find the lowest areas.)

Any help would be appreciated.

 

[Ken Cross]

Many of us use diesel these days. Our first sailboat had an outboard. It was a MacGregor D model and the fuel can (portable) went in the lazarette which was in the aft part of the boat. It had no wiring running through it except the depth sounder transducer. Ours had a horn type vent facing forward and one facing aft. The aft one had a dryer vent hose which went to the bottom of the Lazarette. It appeared to not be connected to the cabin, but once when I slopped a small splash of fuel in there, the cabin smelled strongly of fuel. Not a good thing. It needed a bilge blower.

Sorry, but I don't have a good idea of the layout of your boat.

Ken

 

[kloudie1]

Woof.. not to be Chicken Licken here but please don't put a tank of gasoline below deck.. You are correct in that the vapor is a good bit heavier than air so it will go down as far as it can and then pool.. any spark from static electricity could set it off.. It would take the top deck off the boat .. best to keep it in the cockpit where the vapors can vent through the cockpit water drains.. Make a loose cover (think flat top stool) so the tank is protected from direct sunlight.. and you can sit/stand on it. Not familiar with the construction of that boat, but be very cautious with storage of gasoline.. In the summer (and all year, really) gasoline blenders dissolve as much propane into gasoline as they can and still make specification (it is cheap and has a good octane rating).. That is the first thing that boils out of gasoline in a hot tank.. so treat that tank as if it was a propane tank that vents..