gas tank ventilation??

[marshman]

how much ventilation do i need for a 6 gallon tank?? i want it in the hole next to the transom, but i want to build a deck across the back... so, it will end up being enclosed...ill slpit the deck with hinges, or build a hatch or something...

i know the "below deck" tanks you buy are vented above deck via hose/vent....

if i just cut some 2 or 3 inch holes in the the corners and screw down some old school clamshell vents, will that be enough ventilation??

because, to be honest, the new tanks dont even have a vent, kinda confuses me...

 

[FerrisBueller]

I was in the same position, I added a deck onto my boat and now the 6-gallon tank sits underneath. the tank itself doesnt have any vents so I really should get the vented cap so it doesn't swell up as much. What I did was put a 3" slotted vent on the front side of the bench so there was some extra ventilation for any fumes that may build up. It's better to have vents towards the bottom because gas fumes are heavier than air so they will collect on the bottom of the boat.

It's really not a problem with those kind of gas tanks and decks because before you go to start your engine you will need to open up the deck hatch and pump the gas ball anyhow, so you will ultimately be venting out much of the compartment then anyhow, but it's always a good idea to have an inlet/outlet for airflow at all times.

 

[FBRDrifter]

ALL fuel tanks, regardless if the application, vent. As fuel is used, air has to be able to get inside to take it's place. Otherwise, the engine will die at some point from fuel starvation. That's not to say that there couldn't be a one way air valve but that would be stupid and would not allow for heat expansion and air to escape. But, I have seen stupid things before. :roll:

 

[chevyrulz]

yea the vents on an outboard engine's fuel tank are not there to reduce flammability, they're to ensure the fuel will flow.

you only have to worry about the flammability if you have an inboard motor or if you have it setup so that something could ignite in the bilge area, think battery sparks or cigarette ashes

so with a 6 gal tank under a deck in a tin boat, unless the battery's in the same compartment or you plan on using it as an ashtray, it's fine without any additional vents

 

[FerrisBueller]

Very true, if you don't have a battery back there in that compartment then there's no need for "extra" ventilation. If you don't have any source of ignition then there's no worries about ventilation, as opening up the door will suffice enough.

I would advise to check your state regulations however, as many states require you to have a fire extinguisher on hand if you have any sort of enclosed gas tank, including being under any sort of decking. This is also a requirement if you have any sort of decking that could trap any gas vapors.

 

[marshman]

ill have a fire ext on board...along with a horn, flares, and pfd's...our game wardens around here love to do "courtesy checks" for required safety equipment... (not that i only carry it because its required, i believe in being prepared for anything)

good info on the venting....thanks...

 

[Ranchero50]

All compartments should be vented somewhat to prevent humidity issues.

Compartments that leaked fuel can get to really need to be vented. Gas floats on water so it can travel around the hull if there's water in the bilge. Vapors are heavy so they tend to wander as well.

If you pop you hatch and smell fuel you need to vent it better if the fuel system isn't 'leaking' If it's leaking you need to fix that before hitting the water.

 

[marshman]

im gonna vent it....i prefer not to be an example of what not to do!! in fact, i just ordered some vents...im still finishing my front deck...ill be on back deck tomorrow or next day...

 

[FerrisBueller]

im gonna vent it....i prefer not to be an example of what not to do!! in fact, i just ordered some vents...im still finishing my front deck...ill be on back deck tomorrow or next day...

Always better to be safe than sorry! It's easy installing vents and like Ranchero said it's always good to have venting in compartments for airflow to elimimate mildew, especially in the back of the boat where water can pool once out of the water!

I usually crack open my compartments with a piece of wood when not in use for that very reason.