Fuel tank venting pressure and vacum separately FL14LS +10%

Boats up to 15' for oars, power or sail. Please include the boat type in your question.
VT_Jeff
Active Poster
Active Poster
Posts: 438
Joined: Fri Oct 25, 2019 6:32 pm
Location: vermont

Fuel tank venting pressure and vacum separately FL14LS +10%

Post by VT_Jeff »

I'd like to vent for pressure outboard and vent for vacum inboard(under the deck where the tank is) to eliminate the chance of siphoning water if/when I bury the bow. The P-trap style vents don't give me a lot of confidence that they will work in a submersion situation, they seem more geared to keep spray out.

For it to work, I'd need one-way valves on both sides, one outgoing and one incoming. Can anyone tell me if the appropriate valves exist and where I might find them? I'm concerned about the fuel pumps ability to overcome whatever resistance a check-valve may have and allow free air flow. On the pressure side, not as much of a concern, I think.

Thanks,

jeff


There are only two seasons in Vermont: boating season, and boat-building season.

fallguy1000
Very Active Poster
Very Active Poster
Posts: 6370
Joined: Tue Jan 12, 2010 12:25 am

Re: Fuel tank venting pressure and vacum separately FL14LS +10%

Post by fallguy1000 »

VT_Jeff wrote: Tue Nov 17, 2020 6:08 pm I'd like to vent for pressure outboard and vent for vacum inboard(under the deck where the tank is) to eliminate the chance of siphoning water if/when I bury the bow. The P-trap style vents don't give me a lot of confidence that they will work in a submersion situation, they seem more geared to keep spray out.

For it to work, I'd need one-way valves on both sides, one outgoing and one incoming. Can anyone tell me if the appropriate valves exist and where I might find them? I'm concerned about the fuel pumps ability to overcome whatever resistance a check-valve may have and allow free air flow. On the pressure side, not as much of a concern, I think.

Thanks,

jeff
Not allowed if I am following you correctly.
My boat build is here -------->

viewtopic.php?f=12&t=62495

VT_Jeff
Active Poster
Active Poster
Posts: 438
Joined: Fri Oct 25, 2019 6:32 pm
Location: vermont

Re: Fuel tank venting pressure and vacum separately FL14LS +10%

Post by VT_Jeff »

fallguy1000 wrote: Tue Nov 17, 2020 7:23 pm
Not allowed if I am following you correctly.
Maybe thats why I'm not finding any info on doing that. Appreciate it.
There are only two seasons in Vermont: boating season, and boat-building season.

fallguy1000
Very Active Poster
Very Active Poster
Posts: 6370
Joined: Tue Jan 12, 2010 12:25 am

Re: Fuel tank venting pressure and vacum separately FL14LS +10%

Post by fallguy1000 »

If you bury the bow; it is a pretty dangerous situation. If you bury the stern; the boat sinks. Any way you can move the vent further aft?
My boat build is here -------->

viewtopic.php?f=12&t=62495

VT_Jeff
Active Poster
Active Poster
Posts: 438
Joined: Fri Oct 25, 2019 6:32 pm
Location: vermont

Re: Fuel tank venting pressure and vacum separately FL14LS +10%

Post by VT_Jeff »

fallguy1000 wrote: Tue Nov 17, 2020 8:20 pm If you bury the bow; it is a pretty dangerous situation. If you bury the stern; the boat sinks. Any way you can move the vent further aft?
I can. Would I need to step up the diameter as the length increases to avoid resistance? Tank is in front.
There are only two seasons in Vermont: boating season, and boat-building season.

fallguy1000
Very Active Poster
Very Active Poster
Posts: 6370
Joined: Tue Jan 12, 2010 12:25 am

Re: Fuel tank venting pressure and vacum separately FL14LS +10%

Post by fallguy1000 »

VT_Jeff wrote: Tue Nov 17, 2020 8:36 pm
fallguy1000 wrote: Tue Nov 17, 2020 8:20 pm If you bury the bow; it is a pretty dangerous situation. If you bury the stern; the boat sinks. Any way you can move the vent further aft?
I can. Would I need to step up the diameter as the length increases to avoid resistance? Tank is in front.
Nope
My boat build is here -------->

viewtopic.php?f=12&t=62495

TomW1
Very Active Poster
Very Active Poster
Posts: 3304
Joined: Sun Apr 19, 2015 10:57 pm
Location: Bryson City, NC

Re: Fuel tank venting pressure and vacum separately FL14LS +10%

Post by TomW1 »

I can only type one handed due to my shoulder replacement surgery. This has been discussed a lot on here, do search. Go to the store also to get an idea of the hoses and vents you will need. The vent for the tank will need to face to back as as will the fill vent. You will make a loop in both hoses to keep water from coming in.

Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

VT_Jeff
Active Poster
Active Poster
Posts: 438
Joined: Fri Oct 25, 2019 6:32 pm
Location: vermont

Re: Fuel tank venting pressure and vacum separately FL14LS +10%

Post by VT_Jeff »

TomW1 wrote: Thu Nov 19, 2020 11:52 pm I can only type one handed due to my shoulder replacement surgery. This has been discussed a lot on here, do search. Go to the store also to get an idea of the hoses and vents you will need. The vent for the tank will need to face to back as as will the fill vent. You will make a loop in both hoses to keep water from coming in.

Tom
Appreciate the input, esp under duress!
There are only two seasons in Vermont: boating season, and boat-building season.

User avatar
BarraMan
* Bateau Builder - Expert *
* Bateau Builder - Expert *
Posts: 1625
Joined: Tue Dec 11, 2012 3:44 pm
Location: Australia

Re: Fuel tank venting pressure and vacum separately FL14LS +10%

Post by BarraMan »

You're overthinking it! :D

User avatar
cape man
* Bateau Builder - Expert *
* Bateau Builder - Expert *
Posts: 6988
Joined: Sun Jan 20, 2008 12:02 pm
Location: Lithia, Florida

Re: Fuel tank venting pressure and vacum separately FL14LS +10%

Post by cape man »

DO NOT LOOP THE FILL LINE! You will not be able to fill the tank. Once full you close it, so you don't need the loop.
The world always seems brighter when you've just made something that wasn't there before - Neil Gaiman

Post Reply

Who is online

Users browsing this forum: No registered users and 4 guests