Bunded fuel tank

[Out-Station]

Smakka, heaps of custom plateys are built witht he fuel tank housed within theor own dedicated sealed capsule, filler, suction, breathers passing through some type of gland in the outer skin. Top of such capsule is usually a section of floor sealed down. I'm no expert but i believe it is a requirement in classes of commercial survey to have fuel bunded in this way. Is this what you are talking about, if it is its not that unusual.
Scott

[disorderly]

Is this what you mean smakka..?...

This is the fuel compartment on my new boat... its located between the seats in the cockpit...
The tank is fixed down inside and a cover plate with inspection hatch is sealed and screwed on top...
On either side are fully welded ,foam filled buoyancy chambers and behind is the kill tank..
If water was to get in from say a badly sealed cover or around the inspection hatch or if there was fuel leaking, it should run right down the back along the keel line through drain holes in the transverse ribs and be pumped out by a bilge pump located at the lowest point inside the transom cavity directly in front of the motor...


friday3_Moment(3).jpg

[brett62]

Rob you are correct unless the USL code has changed since I was building boats under survey.

When it came to petrol tanks they either had to be above deck with the filler and vents outside or if the fuel tank was under deck it had to be in a sealed compartment also vented to outside.

I seem to think I have heard about fuel tanks needing to be bunded for some particular aspect of survey???

just seems to be in the back of my mind, no idea where I have heard it from though..

could be way off.

Rob

[Smakka2301]

I didn't actually question what the actual tank was made of at the time. I'm assuming it is a bladder inside an aluminium bund. He's a very experienced builder on the Sunshine Coast so I just took it as being good workmanship at the time.

It may also be that it is a vent more than a drain although I can't see a compelling reason to vent outside the rear of the boat given the pipe to the rear may crack. Perhaps to function as a warning ?

Perhaps it is an unnecessary extra. Certainly I think most opinion on this thread seems to deem it unnecessary. I'll tick it off as so.

Brett62 and OutStation confirm it is part of a survey requirement.

[stevej]

Would not be a bladder as they have a fixed life,

Every boat that isn’t using tote tanks already vents to a external surface.
How can anyone think not venting external is a good
Fuel vapour ignites more readily then raw fuel Does

[peterbo3]

Fisher & Origin were all built with an outer coffin tank for the main fuel tank. Actually simplifies the mounting of the main tank.

[inveratta]

Could be to prevent the fuel turning the underfloor buoyancy foam to mush in the event of a leak ????

well said...this is what we found while restoring an old Haines....the factory fitted foam held the tank in place but that encourages corrosion in the wall of the ally tank and eventually fuel leaks out into the foam.It was the way they set up the tanks at the time that is the problem.Although people always look the floor and transom of these old boats...I would also include a good look around the fuel tank ...which you cant look at unless you destroy the foam!

I urge anyone with an older boat to know whats happening under the floor around the tank...