raise new fuel tank up from bottom?

[rothfm]

Almost ready to install my new Alum 100gal tank. The enclosure is a fiberglass coffin rectangle. It will have appx 2" free on all sides except the bottom. Never any foam at all. good breathing space, drains to Bilge.

The original sat flat on the bottom fiberglass of this "coffin" area..I was thinking of installing alum 1.5" x 1/4" Alum strapping along that coffin bottom spaced 6" apart or so. Logic here was to keep it raised off the bottom for drainage and ventilation to avoid corrosion again.

Then thinking about it, any slight movement will be metal on metal, and may damage the tank.

Thoughts on this?

common sense says its a new tank, place it flat on the fiberglass bottom as it was, re-install the stainless straps protected at the corners with a plastic backing etc.

Thanks

 

[achris]

Layer of insertion rubber between bottom of tank and hull to reduce 'abrasion wear'...2mm or 3mm rubber would be perfect.

 

[Bondo]

Ayuh,..... Or plastic strips,..... I used some 3/8"x 2" strips of snow plow face,.....

 

[Scott Danforth]

a few pieces of HDPE (Synthetic deck material) held in place to the bottom of the tank with either 5200 or butyl tape will raise it up and prevent chaffing

aluminum on aluminum will result in chafing the aluminum

 

[ahicks]

Horse mat (rubber)?

The mud flap material used for semi trucks cut into strips?

 

[dingbat]

I was thinking of installing alum 1.5" x 1/4" Alum strapping along that coffin bottom spaced 6" apart or so. Logic here was to keep it raised off the bottom for drainage and ventilation to avoid corrosion again.

Then thinking about it, any slight movement will be metal on metal, and may damage the tank.

Thoughts on this?

common sense says its a new tank, place it flat on the fiberglass bottom as it was, re-install the stainless straps protected at the corners with a plastic backing et

Aluminum is highly susceptible to crevice corrosion.

https://www.nace.org/resources/general-resources/corrosion-basics/group-1/crevice-corrosion

Avoid surface to surface contact of materials where possible.

The last time my tank was out for inspection there was no sign of corrosion except where the tank laid on the rubber strips under the tank. Aluminize straps/spacers would be a disaster waiting to happen

 

[dingbat]

Horse mat (rubber)?

The mud flap material used for semi trucks cut into strips?

Aluminum is susceptible to a number chemical components of rubber compounds.

Neoprene is typically use in this application. Your mud flap may work as well, just don’t know what chemicals make up of the compound.

 

[rothfm]

Thanks everyone for weighing in. I wound up placing the tank directly in the "coffin" directly onto the fiberglass. This area is glassed up from the actual hull bottom and open at both ends. I figured it has plenty of air around it, and cannot hold any water. There is 2-3" all around it, and 4 at the top, no foam. I an pull the hatch for full inspection at will, thankfully.

I did run bands of 5200 around it to mount a plastic 2" firing strip. This was just used as a backing for the heavy Stainless straps that crank down tight against the tank, to the floor of the coffin. Keeps the strap isolated from the tank aluminum.

Its in, solid, stationary, tested....and filled up...Glad Fuel prices are down!!