Foam or not to foam

snapperbait

snapperbait

Vice Admiral
Joined
Aug 20, 2002
Messages
5,754
Re: Foam or not to foam

Dang it... I can find the instruction sheet... I think what they mean be saying not to foam the tanks in is because the expansion of the foam may cause the plastic to buckle... I've seen where fully glassed in floors bust out after foam was poured in...<br /><br /> Anyway, U.S.C.G. regulation says fuel tanks must be securly attached to the boat... My tanks came with aluminum brackets that hook on to a notch in the tank and the brackets are screwed into my stringers... I'm going to use some sheets of foam and cut & fit it around the tanks... <br /><br />You could make some hold down straps out of aluminum if your tanks don't have straps...
 
F

Firewood

Petty Officer 2nd Class
Joined
Jun 4, 2001
Messages
117
Re: Foam or not to foam

I believe my tanks are made by Moeller. I mail order them. $135 plus 15 for shipping. Check Cabelas marine. My tanks a dropped down through the floor 8 or 10 inches. I guess I could strap them in place, I had planned on foaming inbetween<br />the tank and the freeboard. Maybe I'll cut some 2 thick rigid foam into wedges and glass that in place instead. I'd think the plastic tanks would want support against pounding waves. I guess they're designed to handle it. Also my tanks came with no instructions. I was also looking at the spray cans of foam at Depot, they have waterproof low exspansion foam. Who'd think putting the tanks in would be such a question.
 
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Homerr

Commander
Joined
Mar 4, 2002
Messages
2,281
Re: Foam or not to foam

If i have some aluminum tanks built, I'd definately have straps built into it somewhere.<br /><br />The original steel tank was only held in by two very thick pieces of laminated plywood. Then these were laminated to the stringers and flooring (not very well I might add)<br /><br />I have a ton of room for the tank. Question is what type of tank. I guess it really doesn't matter. Price is probably going to be around the same. <br />I wonder if I should go with one big tank, or two smaller ones? The original was about 75 to 80 gallons.<br /><br />I think most of the new boats are going poly.<br />The only thing that worries me about aluminum is that it can get eaten by salt. I've seen this happen. (Not on a gas tank, but an antenna in a coastal area)Slim chance it would happen to a tank below deck, but there's always the chance.<br /><br />Anyone have opinions on the poly vs. aluminum tanks? Lets get a debate going...<br /><br />H.
 
D

DJ

Guest
Re: Foam or not to foam

Homerr,<br /><br />POLY, POLY, POLY. Aluminum is still subject to corrosion whether it's exposed to the environment or not. Corrosion is a sneaky enemy.<br /><br />I would go with two tanks.
 
S

SCO

Lieutenant
Joined
Aug 19, 2001
Messages
1,463
Re: Foam or not to foam

If you go with aluminum, be sure to isolate it from any and all different metals. I would design for easy access and replacability and would use poly in a standard generic size so you can replace it in a few years as needed. You could go with aluminum at some later date. With poly you can delay the aluminum or steel decision. I like the idea of poly because its cheap, a great material, non conductive , wont corrode. I worry about poly splitting at seams, becoming brittle in time. Id try to find a seamless( at least in the container portion) tank if such things are available. Another issue is static electricity. Can someone talk about that? Is static e a problem with poly vs metal. Do you have to and how do you ground a poly tank. My steel tank and fuel nozzle area is grounded to a bronze bolt that is through bolted through the transom to the outside of the boat under water. There are bound to be well manufactured and thought out poly designs. Ive seen poly tanks with grooves molded in for straps.
 
C

crab bait

Captain
Joined
Feb 5, 2002
Messages
3,831
Re: Foam or not to foam

yea, i wrote about not foamin' in tanks a long while ago..<br /><br />DON'T DO IT..!! <br /><br />you'll have a condensation nitemare...<br /><br />i read many articles on this subject <br />[ i guess it's done so much.. seems likea clever thing to do.. BUT IT AIN'T ]<br /><br />an mine ,too came with a big warnin' sticker that said not to..<br />i'm talkin' poly tank ,here.. but i would assume aluminum would be worse..!!<br /><br />it's because of the expansion & CONDENSATION.. <br /><br />i suppose a little foam ,,say at the corners is ok..<br /><br />if'n it's a vee tank.. make a craddle out of wood.. an strap down<br /><br />if it's a flat tank,, epoxy down a couple/3 strips of ply.. the glue down a ply sheet on top [ the strips are to raise it up with room underneath.. <br /><br />then take some cheap ''rachettin' straps''<br />an go underneath platform / an/or vee cradle an sintch tite.. the rachet part will be on top of tank ,, never/hardly<br />get wet ,, last a lifetime..<br /><br />can put some indoor/out carpet on the base first..<br /><br />don't need to worry about 'static' only metal on poly ,, or poly on poly [ poly/snythethic].. plus it's not NOW slidin' around..<br /><br />no need to ground poly.. the sending unit has a ground.. when you do that,, it taken care of..
 
H

Homerr

Commander
Joined
Mar 4, 2002
Messages
2,281
Re: Foam or not to foam

At Marlin, We use to take a ground wire and wrap on the inside of the inlet hose and clamp it in place. <br /><br />We would then ground it to something metal, like the main ground harness, or engine, etc...<br /><br />(I think today's modern hoses have wire wound into them for this)<br /><br />This would keep static buildup off the hose when you fill it.<br /><br />And speaking of static...<br /><br />TIP: While working on your boat (especially on concrete) I always grounded the boat hull out by running a wire from the bow eye, (or any available eye) to the ground. I typically would wrap the wire around a u-bolt or large hex bolt and make sure it contacts Earth ground.<br /><br />If you ver hopped out a fiberglass boat after sanding or vaccuming, and touched something metal...<br /><br />ZAP !<br /><br />Ya'll know how that feels...<br /><br />So you think 2 tanks is better? I can see that I suppose. If one happen to fail (and I'm still alive) I could have a backup.<br /><br />The space I have for the tank is approx. 30" wide by 6 to 7 ft. long.<br />Do you know if they make a rectangular poly tank in a 35 gallon capacity that I could fit side by side?<br /><br />The tank would be flat on bottom. A perfect rectangle more or less...<br />If I could squeez 2 of them in there, it would be nice.<br /><br />H.
 
H

Hawkeye1

Petty Officer 2nd Class
Joined
Jan 15, 2002
Messages
142
Re: Foam or not to foam

You want to line the tank hole with 1/2 to 1" neopream strips. Block it in lining the blocks with the neopream also. You can order the neopream in all kinds of thickness and hardness from mcmaster carr. I used the firm or 60 duromater hardness stuff. There is the link below. I used 2" wide strips every 10" or so. Once these tanks expand over the 1st 30 days gas is in them they stop expanding. I blocked mine temperarly at 1st then blocked it permently. I would not let anything touch that poly tank that isn't lined with neopream. I will put a link to a picture of my tank hole for a 100 gal moellar poly tank. Hum fishingworks photo is down so I will have to link to a yahoo photo page.<br /><br /> http://www.mcmaster.com/ <br /><br /> http://photos.yahoo.com/bc/formula2...otos.yahoo.com/bc/formula2332000/lst?&.dir=/F ormula%2bproject%26.src=ph%26.view=t
 
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