Fuel tank as flotation

I'm about to ask a question that may be so obvious to many that it's obsurd to even ask but, I honestly don't know.

Being that gasoline is lighter than water would a fuel tank that is secured to the boat serve as SOME flotation?

Here's the reason that I ask. I aquired a 1648 lowe big jon and I want a minimum of a 10 gallon fuel tank however, because of the space between the rear bench and transom coupled with the support brace and location of the drain plug neither of my 12 gallon fuel tanks will fit in that location. Being that I want to keep as much weight in the rear I have considered removing the bench and installing a fuel cell under it however, this will remove a substantial amount of the floation. I will be adding flotation under the floors and sides of the boat with or without removing that under the bench.

Thoughts??

Hmmmm...I have the same hull .. 1648 Lowe. Mine is configured similar to a bass boat though.

The area in the stern is tight. I have a 6-gallon tank in there and also carry a full 2.5-gallon gas can for emergencies. The emergency gas tank is filled with pre-mixed oil/gas. I plan on simply pouring its contents into the 6-gallon if I see my regular tank is getting low. It fits in the same space and rides on top of my bilge pump.

The nice thing about this arrangement is, if I am simply going out for a short run, I can remove the mini-tank if I choose.

As far as flotation, the difference in weight of gasoline versus water is approximately two lbs. per gallon. I really don't understand why your proposal would help flotation for any more than the 20 lbs. difference, if you found a way to put a ten-gallon tank under the rear deck. That is assuming that the tank is full. But, I've been wrong before....

regards, richg99

Take your fuel tank out, fill it with gas, and then throw it in the water. If it floats see how long. Gas is lighter than water. When the tank hits the water, some of the water will try to get in through the vent. The water goes to the bottom, displacing gasoline. After a while it sinks. Seen this happen when a guy was acting stupid going over a class III rapid in a tin flatbottom boat. Boat overturned, fuel tank came out. By time I got to it, the sheen was all over the river and the tank sinking. This is also how I found that particular boat manufacturer has enough floatation in the boat so that it will float more or less level when completely swamped (plug out, boat floats-barely).

I don't believe the USCG considers fuel tanks as "floatation".

I can see it causing some flotation as long as it is sealed. The less fuel you have the more flotation it would have as long as it is sealed. The problem is that it will not be sealed. You have to have the vent open so your motor can run. If a catastrophic situation occurs you may not be able to or be in the right mind to remember to seal the tank before your boat sinks. I would not depend on a fuel tank for flotation in a boat.

Put foamboard under the floor.

I read a story about a guy that used a Jerry can to survive a sinking but they are sealed.