Fuel tanks sloshing

[Mariner]

When I trailer my boat, fuel comes out the vent when I brake. Happens sometimes while underway in choppy seas. I've been using vise grips to pinch it off while trailering, and remove them when I put the boat the in the water. That seems to help out alot. Short of buying a one way check valve,what are you guys doing? Is anybody else having this problem?

[tsubaki]

Locating them up higher (thanks to the wisdom of MJ and reel) improved the problem greatly!
Where is the link?
http://www.wellcraftv20.com/community/showthread.php?t=2808&highlight=specs&page=12

[Mariner]

Ya know...sometimes the answer is sooo simple you overthink the solution. Thank you!!!!