Gas tank compartment ventilation

Given the following 5 conditions, and the vessel is under 24meters and has no more than 6 passengers, the space the gas tank is in does not require natural or mechanical ventilation.
1) The fuel tank vents to open space.
2) Electrical components are ignition protected.
3) Permanent tank.
4) No connecting compartment that requires ventilation.
5) Metallic or non-metallic tank meeting certain permiability requirements.

But as soon as the vessel carries 7 or more passengers tank space vessel ventilation is required. Where is the rational behind this? Is it more of a construction issue, or political?

I have been getting this from the Code of Federal Regulations 33CFR183.610 to 33CFR183.630.

Thanks for any insight...its not exactly riveting topic.

 

You're talking about a small boat. Think about the difference between what happens to gasoline vapour in, say, a 17' boat with a permanently installed tank, and the same boat with portable tanks. Is there really that big a difference?

 

The regulations say that if the tank is permanent and such as I listed above, and there are no more than 6 passengers, the tank space does not have to be vented. Say the boat is 20 feet and made of aluminium.

Now, if you want to have 7 people on board, tank compartment space has to be vented. What is the reasoning behind that? I realize I am not listing all the regs and issues, I was hoping that someone has run into this before, dealing with USCG and CFR regulations.

The rules for venting seem to be more governed by the number of passengers on board.

Another way to put it I guess.

-You buy the 20' boat for your family and go fishing with it, never have more than 6 people on it. The tank space does not have to be vented.

-You buy the same boat and set it up for dive charters, that size of boat can carry 6-8 divers plus a couple crew. Tank space has to be vented, more than 6 passengers.

Both these boats are taken to the dealer to be serviced. The mechanic does not follow the hot work procedure while working. He services the dive boat with no problem, he services the pleasure boat...maybe it blows up...maybe not.

I think I am getting lost in things. The more I think about it the more confusing it gets. Better just to do what the regulations say and forget about it I guess.

 

Do not stay confused...

It's just a problem of limits for qualifying a boat. As to cut a passenger in 2 pieces before embraking is not politically correct, 5.5 is not a good cipher.

And it's very difficult to be sure that the boat is or will be used in pro or pleasure purpose. So:

99 % of small personal boats can carry less than 6 passengers so the reglementation is simplified. Generally members of a family of a family, or friends do not sue each other. (in the States it's maybe different...)

99 % of the profesional boats can carry more than 6 passengers. The passenger is often insured when he buys his ticket, and he can also sue... So for liability problems with insurance companies and passengers, the reglementation is harder.

For the others is better to follow the harder reglementation...

 

Thanks, that does clear some things up. It is difficult to find regulations for boats under 24 meters and even more difficult to find the technical data that supports said regultions. Right now between Canada and the US the regulations are not the same. A pleasure boat made in the US does not meet Transport Canadas regultions all of the time. There are various European standards that just reference ISO, ABYC references USCG-CFR. I have only ever seen tecnical data from the USCG, but is is almost 20 years old.

Anyway, its Friday and there is beer to be had now, worry about it next week .