Fuel Tank Location

[zack]

I am in the process of refitting a 1977 26' John Allmand with a single 350 Crusader. The boat came from the factory with a 60 gallon fuel tank mounted in the stern. Due to limited range I am planning on installing two new 50 gallon tanks, one mounted on the port side and one on the starboard. I estimate there will be approximately 18" clearance between the tanks and the exhaust manifolds on the engine. My question is does anyone see a problem with this configuration, or is anyone aware of any regulations requiring a minimum distance between tanks and engines? Any help or comments would be greatly appreciated.

zack

[Portager]

I am not sure about any regulations regarding spacing, but 18” sounds pretty good. I would check the tank temperature after various run times the first time out and again on a very hot day and see if it is getting too hot. Heat sensitive paint if a great indicator. If the tank gets too hot to touch, or the paint turns brown, then add a radiation shield, consisting of polished aluminum or stainless steel sheet metal mounted approximately midway between the heat source and the tank and no conduction path to either.

I would be more concerned about the affect of the additional weight on trim. You are going from 360 lbs of fuel to 600 lbs or a delta of 240 lbs in the stern. That sounds like a lot for a 26’ boat. It would be best to locate the tanks at or near the center of gravity. If that isn’t possible, you could transfer a comparable weight a comparable distance forward of the CG? i.e. you want to match the product of the mass and the distance to the CG. Maybe get the mother-in-law to sit in the bow . Are you sure your boat can handle the additional weight? You could test it by placing 240 lbs such as bags of sand in the appropriate area.

I would also be concerned with the affect on transverse trim. If you have a transfer line between the two tanks it should be closed while underway to prevent fuel from transferring from the high side to the low side and destabilizing the boat. Rather than having a valve, that I’d eventually forget to close, I’d use a transfer pump. Then if your engine takes more fuel from one side than the other or the mother-in-law sits too far to port or starboard, you can correct the trim with the push of a switch.

Regards;
Mike Schooley

[zack]

Good advice I appreciate your input. I think I will be O.K. on temp, manifolds are freshwater cooled and never too hot to touch. I am concerned if there is any Coast Guard regs that this would violate. I would sure hate to do it only to get gigged during a vessel stop.

Originally Posted by Portager

I am not sure about any regulations regarding spacing, but 18” sounds pretty good. I would check the tank temperature after various run times the first time out and again on a very hot day and see if it is getting too hot. Heat sensitive paint if a great indicator. If the tank gets too hot to touch, or the paint turns brown, then add a radiation shield, consisting of polished aluminum or stainless steel sheet metal mounted approximately midway between the heat source and the tank and no conduction path to either.

I would be more concerned about the affect of the additional weight on trim. You are going from 360 lbs of fuel to 600 lbs or a delta of 240 lbs in the stern. That sounds like a lot for a 26’ boat. It would be best to locate the tanks at or near the center of gravity. If that isn’t possible, you could transfer a comparable weight a comparable distance forward of the CG? i.e. you want to match the product of the mass and the distance to the CG. Maybe get the mother-in-law to sit in the bow . Are you sure your boat can handle the additional weight? You could test it by placing 240 lbs such as bags of sand in the appropriate area.

I would also be concerned with the affect on transverse trim. If you have a transfer line between the two tanks it should be closed while underway to prevent fuel from transferring from the high side to the low side and destabilizing the boat. Rather than having a valve, that I’d eventually forget to close, I’d use a transfer pump. Then if your engine takes more fuel from one side than the other or the mother-in-law sits too far to port or starboard, you can correct the trim with the push of a switch.

Regards;
Mike Schooley

[Portager]

They why not go to your local Coast Guard office and ask the guys that would do the inspection?