Fuel system

[Todd j]

I started a discussion in my build thread, but I think with as many projects that are under way it was good to start a new thread. 
I’m trying to order goodies for the next push.  All of my tank fittings will be accessible after being covered with the cockpit sole. 
I want the the shortest runs for fuel fill and vent.    For me that means 2 each fill on the sheer deck and vent just below on the side of the hull. 
    My concern is a full tank belching gas out on to my painted boat.   I’ve seen this happen on several boats.  That is why I really want a vented deck fill.   I also want the fill to be flush.  I’m not sure I can have both.  I’ve looked high and low and have found 2 versions I like the look of.   It’s are unobtanium.  My guess is they didn’t work.  I also kinda don’t want water in my tanks. So a o-ring fill is a must, I think?
   Can you guys take a minute and let me know the route you took or are planning to take?
    Maybe I should just vent to the splashwell?  Your .02 please

TIA

[json]

I was going to run my fill and vent to the back of my boat but then reconsidered, as I didn't know if I could put myself into a situation where the fuel in the tank ended up being higher than the fill or vent (on a steep ramp for instance). I ended up scrapping that plan and running it to the side. Maybe put your vent(s) higher than your fill on the side (I am still considering putting my vents on the side of the house as opposed to putting them on the side of the hull, I don't really like that option that much though). The other option you could consider is to run a loop higher than the fill with the vent hose, then you could still put the vent low but the fuel would have to overcome the top of the loop to spill.

[Todd j]

I had a jetboat with the fuel fill and vent on the transom.  Maybe 3-4” above the tank top.  It never spilled fuel on any ramp.   It never leaked on to the boat for what it’s worth.   However, water would climb the transom on deceleration and it would be at or below the waterline and I hated that

[Brian.Dixon]

My favorite setup is a) separate fill and vent, and b) both fill and vent on the side of the pilothouse, rather than on the sheer deck.  Why?  Dry, and I just personally prefer having the fill and vent further apart and don't like water on the sheer deck running over the top of the fuel fill.  That said, I am not aware of issues if you DON'T do it this way, but it's still what I prefer!

[Todd j]

In my case on the side of the PH would be a rascal.  All my hoses are aft the PH bulkhead.  That does make a lot of sense having the fill on a vertical surface.  I will look into that before I buy too much stuff. 

[tom e]

This looks like a good option: Racor LG 100 Fuel/ Air Seperator.  I bought one for each vent (saddle tanks), thinking that it would go a long way to solving that problem  It is larger than you might guess.  However, I'm at a place where I can make the chase big enough to accommodate them.   If anyone has experience with them in practice, chime in here.

"When the Racor LG 100 is installed in the fuel tank vent line, the Fuel/Air Separator efficiently separates air from fuel forced into the line. Air is vented, and fuel is returned to the tank. The Fuel/Air Separator captures fuel normally discharged due to agitation and thermal expansion."

te

[Todd j]

Tom, I like that product.   I did notice there was a baby brother to the piece you posted.  Much smaller, it’d take someone smarter than me to tell if it could move enough air, but it was much smaller.   Either way, this product is cheaper than the charcoal canister and I can understand how it works. 

FWIW I am exploring a little box on the sheer and aft edge of the PH side panel behind the bulkhead with a access panel inside  the cockpit.  I can make the entire hose compartment part of my mechanical  vented plenum.  That doesn’t mean I’m not still considering other options

[Todd j]

Anyone care to weigh in?   Are fuel tank vents that are mounted on the side of the PH considered overboard enough?

[Rbob]

Never seen a fuel vent on the side of a pilot house, maybe someone will chime in with better info.
Bunch of info here:  https://newboatbuilders.com/pages/fuel.html

[Grady300]

The attached is pretty much what I am doing ( not doing the vented cap) I think you only need to make sure your vent will ALWAYS be higher than the fuel inlet to your outboard (read that somewhere) and your vent should be at least 18" away from the fill (read that somewhere too) don't ask me where 

[Todd j]

Great discussion.   I am leaning toward fill and vent on the side of the PH as Brian suggested.  Easy to reach from the dock, and there is room for absorbing pads or whatever on the sheer.  Easier to catch a wayward drip I think.   It won’t be as bad to route  as I thought.  It just means I invited part of the fuel system into the house.  The fills and vents will be in the compartment with the diesel and the portapoti

[rhenryinoregon]

Filing this away for future reference. Thanks guys.

[Dan Boccia]

From experience:
If your fill is on the sheer, and your vent is below that through the hull, when you fill the tank, you WILL have some fuel come out the vent, at some point, unless you have an automatic valve as Grady posted, which I chose to avoid even though that is the code-required setup that all commercial builders are supposed to follow, and we should follow if we ever feel we will be inspected or be selling in a more critical market than me in Alaska.

If I was starting fresh, I'd be happy with the fill on the sheer and vent on the "wing" aft of the cabin (essentially a cabin extension matching the angles of the boat, see my pics). The vent would be 8-12" higher than the fill. If you could put the fill on the vertical wing down low, that would also be fine.

Make sure your tank vent is located to avoid vapors from entering the cabin through a window or heater air intake. This topic is actually a very challenging geometry problem on our smaller boats and I will be spending WAY more time incorporating this into the design on the next build, if/when that ever happens.

Remember to electrically bond ALL the metal fuel fittings and tanks all the way back to your final neutral/ground/bonding point.

[Grady300]

Dan, I have that situation on my WideBody. The fill is about 4" higher than my vent on a nearby vertical surface, I have to watch real close not to overfill my take or it comes out the vent on my locker face. I won't make that mistake again, I like your idea coming up the wing. I will have to look at that