IMHO it's a really bad idea to put any kind of valve or screen in tank
vents. It's all too easy to plug up the vent and collapse the tank, or
have some other type of failure, even without those things. Plus the
ABYC takes a dim view.

Actually, all of the standard vents I've seen do have a screen at the
exterior portion of the vent to keep the bugs out.
I/ve seen a valve intended to keep water from entering the vent, I just need
it in reverse (and in a small area).



You seem to have an inherently poor design.

I agree that this is a poor design but---

Is there any possibility of raising the vents, or piping them to opposite
sides? --NO, not without lowering the 15 ft of hose required for each tank
and trapping any sloshing fuel in the lowered portion of the hose

The only other thing I can think of is to not fill the tanks so full
Fair Skies
Doug King

..--- YES, the original owner suggested that but at the time I didn't know I
was only to expect around
2 mpg and with my intended use (up to 15-20 miles out in the Gulf of Mexico)
I need more fuel.
LD