Fuel tank restraint, padding, anti-chafe

Designs for inboard or outboard power

Moderator: BruceDow

Post Reply
TomB
Posts: 577
Joined: Wed Jan 18, 2017 4:07 pm
Location: Holland, MI

Fuel tank restraint, padding, anti-chafe

Post by TomB » Fri Jun 28, 2019 1:08 pm

I am trying to finish up my fuel tank install. Where do I need to pad it?
tank restraint.jpg
The tank bottom is serpentine because of the baffles (there is a pair of baffles on the back side too). The tank sets on plywood. Do I have to put something between the tank and the ply? It seems like any compression of a foam pad would cause unwanted movement.

The blue rectangles represent blocking on the backside that keep the tank from slipping toward the stern. I plan to pad them.

The orange lines represent wooden front and top restraints and they will be padded as well.

Athwartship movement is restrained by the orange lines and the wedge shape pushing up against the top restraint.

I assume that the pads will take up tank expansion and provide chafe protection. Is the pad to be in contact now or should it stand off for expansion?

I have a small roll of tank padding foam (neoprene, I think, 2"x7/32"x6'). How do I attach the foam?

Thanks,

Tom

User avatar
DrBryanJ
Posts: 938
Joined: Fri Jul 22, 2011 6:05 am
Location: Pompton Plains, NJ

Re: Fuel tank restraint, padding, anti-chafe

Post by DrBryanJ » Fri Jun 28, 2019 3:22 pm

Moeller says to allow for expansion in all directions. For my tank (a 19 gallon bow tank) that is about 1". I have 1/2" neoprene pad under the tank and I cut strips of the same pad to place under the straps. It takes about 1 month for the expansion at which point I expect the padding to be mostly compressed.
unnamed (11).jpg
Your tank is a little bigger, you might need thicker padding.
Bryan

Building a malahini "Mona Lisa"

My wife said "If I build a boat, she's getting a divorce."

User avatar
hoodman
Posts: 2199
Joined: Thu Nov 10, 2011 8:48 am
Location: Lafayette, IN

Re: Fuel tank restraint, padding, anti-chafe

Post by hoodman » Sun Jun 30, 2019 3:25 pm

I did as doc says and put neoprene under the tank and between the straps and tank. A cheap source of neoprene is the anti stress floor mats sold almost everywhere. Easily cut to fit. The foam actually helps to prevent tank movement. Make the straps snug but not tight. The tank will expand after it has gas in it for a while.
Matt

Building a Geronimo......!
viewtopic.php?f=2&t=25139

TomB
Posts: 577
Joined: Wed Jan 18, 2017 4:07 pm
Location: Holland, MI

Re: Fuel tank restraint, padding, anti-chafe

Post by TomB » Sun Jun 30, 2019 3:51 pm

Thanks Bryan and Matt. I've done a little more reading. Moeller says to allow for 2-3% expansion. My tank is 12" fore and aft or about 3/8" expansion allowance, 16" tall at the restraint or about 1/2" expansion allowance. The tank centerline to vertical restraint is 15" so about 1/2" of horizontal movement each way.

I bought a tube of 3M neoprene adhesive and plan to glue the 7/32" foam be the tabs and restraints... unless somebody steers me a different direction.

Tom

Post Reply

Return to “Power Boats”