Screwing into under floor plastic gas tank? Is that how they built them?

[Waitara]

A previous owner replaced the floor with aluminum. I pulled it back up to replace the very wet foam and found the gas tank screwed down with little aluminum plates. The screws go right into the tank?! They don't leak. I have the tank full and the boat is tilted pretty good so the rearmost ones have gas sitting right on the other side of them. No evidence of leaks even when I accidentally step on the tank and make the breather vent gurgle. Is that how they built them or was this done by PO? At this point replacing the tank would be super easy, but not cheap. To do it later will be both hard and expensive. Thoughts? It's a 1990 SmokerCraft SFS16. In attached picture, look just to the left of the pink foam.

 

[GA_Boater]

The only way screws can be used on the plates on top of the tank is if the tank has threaded bosses in it. Can't recall seeing a tank with bosses like that. No way screwing directly into the tank is right or safe.

Stepping on the tank and hearing the vent gurgle doesn't mean much.

 

[jbcurt00]

The tank should have a label on it. Try to find and post a clear pix of that label, perhaps find evidence that there are mounting bosses on that tank. I agree w GA, though, that seems unlikely.

What is the pink in the pix.you posted?

If the PO re-decked the boat in aluminum, everything below deck that isnt stuck in place foam or firmly held in place by the foam, is likely to have had the PO change or modify it.

 

[GA_Boater]

I agree w GA, though, that seems unlikely.

It is? :lol:

Presence or absence of bosses can be quickly checked by removing the two screws and bending the tab up.

 

[jbcurt00]

Yeah, I see what you did there ^^^

 

[shaw520]

Possible that the poly tank has mounting blocks inject molded on the inside for that very reason,.. but agree with the above that there should be brass bosses in them.

 

[Waitara]

I'll check it. I was thinking I didn't want to disturb whatever seal might have been there if they were just drilled through. The pink stuff is foam board. Squished to fill the half inch gap between tank and floor. (Previous owner)

 

[jbcurt00]

^^^ Then its fairly likely the PO screwed the tank down

 

[Waitara]

No Title

I pulled one of the screws. There is no brass insert, but it sure looks like the tank was made to have screws there. I don't think the tank is that thick everywhere, so I guess it's built for this. The hole has a bottom (paper clip wire verified that - see picture) I guess this is how it is supposed to be. There is nothing else locating the tank fore and aft other than these brackets. That fits with the design of the bracket, I suppose. I couldn't find a manufacturers decal for the tank, but I still have more pink foam to remove. The screw had good purchase and snugged down nicely. I still don't KNOW it's supposed to be this way, but at least I know I don't have leaks. I'll pull all the screws before replacing the floor just to make sure.

 

[Waitara]

Possible that the poly tank has mounting blocks inject molded on the inside for that very reason,.. but agree with the above that there should be brass bosses in them.

Looks like you win! You get choice of: A: A textbook-sized chunk of wet, moldy flotation foam. B: Brown wires ran outside of existing harness that are not connected to anything at either end. C: A zillion drilled-out pop rivets.

 

[GA_Boater]

That's a one new on me. Hope the tank has a label, it will be interesting to see who made it.

Not being a trusting soul, I would clean the holes and use some 3M 4200 to ensure a good seal before screwing it down again.

 

[shaw520]

Looks like you win! You get choice of: A: A textbook-sized chunk of wet, moldy flotation foam. B: Brown wires ran outside of existing harness that are not connected to anything at either end. C: A zillion drilled-out pop rivets.

Um,... How bout D...the shiney new Pittsburgh pinch bar ???

 

[Waitara]

No Title

Um,... How bout D...the shiney new Pittsburgh pinch bar ???

Heck no, I spent $3.99 on that and got a free multimeter too!

Here is a picture of the hull all de-foamed.

 

[Waitara]

No Title

3 lb chunk of foam. If this boat was swamped I think it would have went straight to the bottom.