Tank vents

[RDB]

I am wondering about the advantages of multiple vents for fuel tanks (2000 USG). Is this in the event that one is clogged? Common practice or redundant? Thanks

[Thunderhead19]

I often specify two vents in situations where the customer may make a change in powering later, or is rigging the boat themselves. Tank vents and fills should be arranged so that you don't get blowback at a regular fill rate. In a large tank, you may choose to put two or three vents in in order to avoid having your vent covered by fuel when your boat is heeled over. You don't want to start dumping fuel out your vent.

[RDB]

I think what it is an ABS suggestion but not mandatory on larger vessels. Thanks for the info, I can see putting a vent on either side of the tank so that under heel one vent is always clear.

[FAST FRED]

The biggest hassle with multiple tank vents (besides the ability of water to enter the vents) is the overfill hassles.

Here in the US the sheen cops will give tickets if fuel is spilled while fueling.

$10,000 is the most often seen fine on marina posters.

Mfg have created ball floats to go into the vent line , the ball floats on fuel , shutting off the overboard vent.
Raycor makes 2 sizes.

Whatever you select , be sure you can fill with out flowing fuel overboard , when the tank gets overfilled a bit.

FAST FRED

[RDB]

Thanks for the reminder on the ball floats. This is the first time I've dealt with vents this size so pardon the ignorance. From what I understand these vents have to be custom built for pipe sizes above roughly 1"? If not, who makes fuel vents for 1-2" pipe sizes? Thanks again for the help, much appreciated.

[Thunderhead19]

Marine or ship chandlers can fix you up, or you can go to a welding shop like Tom Mac in ...Delta?!? ahh I forget....they can make one for you cheap though.

[RDB]

Thats what I figured, these don't really come off the shelf. So all these mega yacht builders have custom SS fuel vents built every time, or maybe thats why they all double up on 1-1/2" vents. Anyways, thanks for the tips.