Underfloor fuel tank breather/vent

[Kiwifisher]

Hi folks,

I'm busy installing an underfloor fuel tank and am looking at ideas of where on the boat to place the vent fitting for the tank breather pipe. Somewhere where it a) will not have water ingress b) somewhere where the fumes would not accumulate in the boat. I've been thinking about through the transom or under the outboard engine cover even?

Any suggestions gladly received!

Thanks

 

[Chris1956]

Re: Underfloor fuel tank breather/vent

It needs to vent outside the hull. Thru the transom is OK. Most of the time thru the side of the hull is also OK. You should not have water infiltration, unless you have a real low profile boat.

 

[Kiwifisher]

Re: Underfloor fuel tank breather/vent

Thanks Chris.

 

[Triton II]

Re: Underfloor fuel tank breather/vent

K-F, as Chris says, a common location is through the hull, but I suggest high up and towards the stern. My boat has a vent each side of the stern for its 150L underfloor tank. Use proper vent(s) on the end of the hose(s) to prevent water ingestion...

http://www.ebay.com.au/itm/STANDARD...at_Parts_Accessories_Gear&hash=item2eb5e2873d

TII

 

[cr2k]

Re: Underfloor fuel tank breather/vent

Where did you find a floor in a boat? They have decks or soles not floors.

 

[foodfisher]

Re: Underfloor fuel tank breather/vent

If an outboard,vent into the splashwell, on the side. Up/down loop in the hose will help against water intrusion.

 

[Gun Dog]

Re: Underfloor fuel tank breather/vent

I have a big 30 gallon tank in my bass boat. It requires two vents. Factory install plastic style P trap gas vents are installed high in the splash well port and starboard. No need for a loop. I take on water over the transom all the time and never had a problem with the vents. They work well.

 

[Chris1956]

Re: Underfloor fuel tank breather/vent

A 30 gal tank does not require two vents due to it's size. There must be some other reason. Are the vents tied together, or do they both end at a tank vent fitting? My boat has a single vent is it is 63 gal tank.

 

[Triton II]

Re: Underfloor fuel tank breather/vent

Where did you find a floor in a boat? They have decks or soles not floors.

It's a terminology thing cr2K. Here in Australia we too call the deck of a boat a deck, but the tank, if fitted beneath the deck, an "underfloor" tank. Below is an example.

http://www.4seasonsboats.com/cuddy.htm

Look at the features. Third last in the Sea Dragon 4.75 list.

TII

 

[Gun Dog]

Re: Underfloor fuel tank breather/vent

A 30 gal tank does not require two vents due to it's size. There must be some other reason. Are the vents tied together, or do they both end at a tank vent fitting? My boat has a single vent is it is 63 gal tank.

My tank runs the width of the beam and has a saddle bag on each side. The vents both end in a tank fitting. And each have a separate P trap.They were custom tanks made for Cajun by Moeller
I can't see any real reason for them to use two vents ether. Just a note. I don't use plastic filters.This was just a test to see the residue effects of Ethanol in the fuel.

 

[Kiwifisher]

Re: Underfloor fuel tank breather/vent

Thanks guys for all comments, links and pics. My outboard is mounted on a pod or pedestal (best get the terminology right ) so terminating the vent in the splash well is not an option. I guess high on the transom would be the only option. I am also considering mounting it inside the outboard engine cover but have not seen any done like that.

 

[Gun Dog]

Re: Underfloor fuel tank breather/vent

Mounting it on the motor! Don't be silly. You don't see it because it's not an option. Anyone whose tried that probably is no longer around.

 

[Stachi]

Re: Underfloor fuel tank breather/vent

^^^ boom !

 

[sschefer]

Re: Underfloor fuel tank breather/vent

Solve your problem quick with a Perko Fill Cap with the built in vent. I've been using them on boats for the past 6 years and it's by far the easiest and most evironmentally friendly method I've found. You never have to worry about over filling and having fuel go out the vent and into the water. Many of the manufacturers now use the same fill cap systems.

iBoats may also have them so check here first. Here's a link so you know what your looking for:

http://www.wholesalemarine.com/pc/P...s/Perko+Vented+Gas+Deck+Fill+&+Tank+Vent.html

 

[barbosam]

Re: Underfloor fuel tank breather/vent

ya def should not be done, the whole idea is to vent the fumes away from the engine!

 

[sschefer]

Re: Underfloor fuel tank breather/vent

ya def should not be done, the whole idea is to vent the fumes away from the engine!

I'm pretty sure it's also illegal. Might want to check the USCG regs first.