He has already tested by leaving the cap loose and it corrects the problem. Obviously you can't leave the cap loose all the time because moisture will eventually accumulate in the tank.
I did find a vented filler neck that should alleviate the problem.

CB, the vented cap you show...is it somehow vented with the cap on, or does it vent for the purpose of filling the tank only?...

MJ, one thing to consider is gas expansion...when fresh from the pump, it just came outta the ground and is cold...sits in your tank for a while, warms up and expands, finding its way up your vent-line and out. Do you store the boat w/a full tank?...or fill it on the way to the ramp?...if you store full, try not topping it off at the pump...I know you want all you can get in there, but if it's burping it back out, you're losing what you would have left out by not topping up...and you don't pay for what went on the ground...

If you fill on the way to the ramp, you'll probably be burning it off before it has time to warm and expand...

I have a similar issue with my V20, when I try to fill up at the pumps I have to trickle it in slow or fuel will back right up my vent and splash out, this is the second V I have had that does it. I am wondering about relocating or some other alternative to the current vent set up.
Am I the only one that has had this problem?

Have you checked the vent hose for water, a pinch or some other obstruction...I've heard to put a loop in a vent line to keep water outtta the tank, but that just gives water a place to hold in the vent hose...unless the loop goes UP...

Mine will leak out the vent if I fill it too much. I always know about how many gallons will fill it so I listen very closely while filling and one I hear a gurgle I stop. Have not had any problems with it ever since.

I would think that if you use the vented filler that I showed and run another vent line from that filler to the outside as a second vent, it would probably solve the problem when sitting on the trailer. This way, with the filler in the from of the tank he could raise the tongue of the trailer up and it would still vent from the larger filler hose in the front of the tank.

Thanks all!!

I fill it and leave on the trailer so I don't have to find a gas station at 3 am
I put the bow own last night to un block the vent, but I bet I have a boat full of water right now!!

CB I saw that vent cap also, but was thinking it needed a hose from the tank to the cap?? If you just put a hose there and on side of the boat it would be great!

I have tryed to not filling it all the way but I not to good at it, it really doesn't make muc h noise till pop

The boat is going to be on a slip this year, at least in part, I am worried that its going to do it there? And I have to fill it there as the gas dock isn't going to be open in the early morning.

Just run a vent hose from the small fitting on that filler to a vent outside the boat. Done.

Mine does it on the trailer, on the water, don't make a diff. I think I will try running a new hose this season.
Can't believe I have had two V's with six years age diff and they both do the same thing and no one else here has run into it.
Maybe it was just Jersey delivery boats, b@stards.:you:

MJ, you going to get one of those gas caddy things to fill up the Ox? My old man used to fill up his (now my) V while it was moored out in the harbor. He was too cheap to go to the marina for a fill (can't blame him really). Anyway, we would row out in our little Dyer pram with 3 or 4 5 gallon cans and use a hand pump to pump it in. Got a little dicey if there was any chop coming across Scituate harbor. Nary spilled a drop though.