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mphatc
01-28-2004, 08:39 PM
With all this discussion on fuel tanks . . how have folks been installing replacement units.

Foam?

Straps ?

Welded and bolted to the stringers?

Should the new aluminum be coated or painted ? and if so with what? What about Hard Anodizing?

TIA,

MPHATC

rickrsbro
01-28-2004, 09:08 PM
foam does not look like a good idea from your shots on the tank removal thread.:(

mphatc
01-29-2004, 06:33 AM
You're right, foam does not look good, but this is an install done in 1969 . . that's 34 years old . . I'll be dead when my son needs to install the next tank! He has already asked for this in my yet to be written will! Little Baahstaad!

I like the support and load distribution offered by a foamed in place tank . .

here's why, and some one correct me if I am wrong!!

A 40 gallon tank haging on the stringers . . .concerns me. that's alot of stress on the tank where the brackets are welded on.

supported below with rubber blocks, rubber will dry and shrink, and in the meantime it transfers stress points to the hull . . I see spider crazing / hairline cracks in the hull bottom . .

40 X 6.1 = 244 lbs plus tank weight, now start pounding over waves.

What does the factory do?? Where's CDMA when you need him? :)

mphatc

MOP
01-29-2004, 08:43 AM
Mario people still foam in tanks, what most do is to clean the exterior very carefully then apply three coats of zinc chromate primer let dry thoroughly, then apply two coats of epoxy tar. As long as that surface is not damaged in anyway it will not corrode. Most aluminum tank corrosion is crevice corrosion caused by water being trapped against the surface. A properly mounted tank without foam or surface protection will also do very well if supported off the hull and kept dry and has some air flow to the compartment. You avoidance of rubber products is well founded, rubber has corrosive properties. Look at any old tank install they are always corroded by the rubber under the strapping. A lot of shops now use Starboard glued to the tanks to support them off the hull. While you have it gutted a nice trick is to cut out the limber holes far enough to get clean wood, then make a tight fitting filler block of Starboard with a U shaped hole so no water what soever will stay in the compartment and glass it in place. Nearly all manufacturers drill the limber holes and do not seal them properly which lets water soak into the bulkheads. A similar procedure should be done by the drain at the transom, most transoms wet out from the bottom up. Not sure if you have any stringer work, but if so where a stringer meets other wood it should be insulated by a layer of glass and resin to avoid water from wicking into the adjacent wood, many an engine bed stringer has ruined a transom.

Old fart insights!