fuel tank securing, what bolts to use?

[Ekea]

for those that use aluminum banding or angle iron to secure a fuel tank to the stringers, what type of lag bolt do you use to go through the aluminum and into the stringer? i can find 304 stainless, but i think i would prefer 316. would either be acceptable? would either cause issue with being in contact with aluminum?

 

[SkunkBoat]

BoltDepot has 316 SS
https://boltdepot.com/Lag_bolts_Hex_head_Stainless_steel_316

 

[Fishtales]

Can use some composite blocks as well.

 

[wspitler]

Aluminum and stainless do not play well together. The aluminum will corrode. If you can put rubber washers or some kind of synthetic non-conductive material between the two, it will last longer. I used phenolic washers/spacers on my aluminum boat when mounting anything stainless.

 

[Hookup1]

for those that use aluminum banding or angle iron to secure a fuel tank to the stringers, what type of lag bolt do you use to go through the aluminum and into the stringer? i can find 304 stainless, but i think i would prefer 316. would either be acceptable? would either cause issue with being in contact with aluminum?

This not how you want to mount that tank if you are interested in a 20 year solution. Attach neoprene strips to the tank with 3M4000 wherever the tank comes into contact with anything! Water trapped against the tank will lead to crevice corrosion and premature failure. Aluminum banding isn't that strong. Use glassed over wood notched to the tank and screwed into the stringers. Buffer under it with neoprene strips.

I did my tanks last summer. Checkout the project.

268 Islander Fuel Tank Replacement

Decided that this is the year to replace my 25 yo fuel tanks. No leaks. I plan to keep the boat. I'll document the process here. Pulled the hatch. This hatch was rebuilt a few years ago with Coosa board. Looks good and feels solid. Hatch was set with 3M 4000 - kept everything sealed. Some...

www.greatgrady.com

 

[PointedRose]

Use tefgel for stainless to aluminum and it’ll help prevent galvanic corrosion

 

[Ekea]

This not how you want to mount that tank if you are interested in a 20 year solution. Attach neoprene strips to the tank with 3M4000 wherever the tank comes into contact with anything! Water trapped against the tank will lead to crevice corrosion and premature failure. Aluminum banding isn't that strong. Use glassed over wood notched to the tank and screwed into the stringers. Buffer under it with neoprene strips.

I did my tanks last summer. Checkout the project.

268 Islander Fuel Tank Replacement

Decided that this is the year to replace my 25 yo fuel tanks. No leaks. I plan to keep the boat. I'll document the process here. Pulled the hatch. This hatch was rebuilt a few years ago with Coosa board. Looks good and feels solid. Hatch was set with 3M 4000 - kept everything sealed. Some...

www.greatgrady.com

nothing is touching my tank other than 5200 (used to secure closed cell high density neoprene). 3 aluminum bands over the top of the tank should be more than enough to hold the tank down. it was recommended by the company that fabricated my tank

 

[Hookup1]

Those aluminum straps should have neoprene under them.

 

[DennisG01]

Another easy option to secure the tank is a simple PVC or fiberglass L-channel secured to the stringers and just resting against the tank. About 3 or 4 of them per side (about 4" long each) will be MORE than enough. And, as you're already planning on doing - either use your neoprene in between... or even just a pad of 5200 by itself.

You can get heavy nylon washers from places like McMaster online - if you do decide on using aluminum strapping. Use the washers between the SS bolt head and strapping. You can really crazy and coat the shank of the bolt with Tef-Gel or even a thin layer of 5200.

 

[DennisG01]

This is a minor point... but as long as you're attempting to do everything "best practice"... I noticed a spot on your neo/5200 where the 5200 is "bubbled" out a bit. That "could" collect a little water - especially since the neo padding is rather thin (not a whole lot of space between the neo and the floor). Make sure to "fair" the edge of the neo like you would caulking a seam/corner. Again, this isn't 100% imperative to do... but "as long as you're there"

 

[Ekea]

Those aluminum straps should have neoprene under them.

they will have plastic "edge protectors" over the corner of the side corners of the tank where the straps would have contacted the tank. the edge protectors will also have 5200 under them