sisu 22 fuel tank replacement

aweigh again

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my 1983 sisu is 31 years old ,i am thinking that replacing its aluminum fuel tank this year is long over due. it has a 40 gallon tank in the bilge . has anyone replaced theirs, and if so, are there any recommendations for aluminum versus plastic, and any particular welding, or tank company?
 

Keelboater

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I've built several over the years. 5052 is the material you want if you go aluminum. Most companies will build to your sketch with dimensions. Measure up what you have and look for a stock off the shelf tank of similar size. If you can't find one, then a custom job may be required. I have heard good things regarding plastic, but have no experience with it. Call me old school because I stick with aluminum. Is this gas or diesel?
 

aweigh again

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its a gas tank for a 115 hp outboard. as soon as I get a chance ,i am going to take the sole off, empty the tank , and pull it out. it has not given me any trouble, but I think its time.
 

Tuckerman

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I'm replacing a tank in a friends boat. He had it built by Luther in RI. The tank is very nice and it was reasonably priced and quick turn around.

image.jpg
 

aweigh again

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I will keep luthers welding in mind.do they recommend coating that tank,or just as is?
 

Keelboater

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I have heard both sides of that one. Bare finish, ventilated compartment, nothing but plastic contacting the tank at support points. No rubber stripping. Then there are many who barrier coat or paint the tank before installing it. I think it depends on the actual installation conditions for each boat. The last one I built was coated with Rhino liner simply because my boat has a wet bilge, and the tank is mounted very low. There is always water sloshing around and contacting the bottom surface of the tank. The original tank was glass, and water was never an issue. I did not use barrier coat because I think it becomes brittle and can crack with tank expansion. But that is just my opinion. The Rhino liner is bullet proof and remains flexible. If this tank ever fails from corrosion, it will be from the inside.......and even then the Rhino liner will act as a "fuel bladder".
 

aweigh again

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are the triple m tanks heavier duty than say a moeller tank.i have read about having to install them with reguards to expansion,and movement.
 

Beamie

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are the triple m tanks heavier duty than say a moeller tank.i have read about having to install them with reguards to expansion,and movement.


Yes they are. I would say the MMM tanks are probably far superior to a Moeller tank. But for a 22' Sisu I bet you can find a stock Moeller tank that will do just fine for much less $$$.
 

BillD

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Yes they are. I would say the MMM tanks are probably far superior to a Moeller tank. But for a 22' Sisu I bet you can find a stock Moeller tank that will do just fine for much less $$$.

If you do a "previous post search" on Raider Ronnie you'll come across his 28 BHM "wet feet" project. His 28 was built with MMM tanks back in 2001. Ronnie had MMM cut tops off, add inches for extra gallons. He may have adjusted install for expansion ??

I will have a MMM tank in the 25 T Jason...diesel.
 

shoes

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Not sure about the new low perm tanks that Moeller just came out with, but the previous plastic tanks would emit faint gas fumes. If you do use plastic, check into this as I read some pretty specific guidelines in the CG's boatbuilding regs regarding ventilation required for non-metallic tanks, especially if a bilge pump is also in the equation.
 

seahaven

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Tank installation advice

Another recommendation for Luthers Welding in Bristol, RI. I had twin tanks made by them a few years back. As far as installation is concerned, it isn't the tank getting splashed or occasionally wet that you are worried about. What you does aluminum tanks in is anywhere that moisture is trapped against the tank with no way for air to dry it out. Anyone that has removed an aluminum tank can attest to this. The corroded spots are always where it sat on the stringers, or was against a bulkhead, etc... This is why you don't want the tank sitting directly on anything that can trap moisture. The recommendation is to take plastic strips and glue them to the tank using an adhesive like 5200. Be generous with the adhesive. Now the tank will sit on the strips, with no way for water to be trapped against the tank. Any water that gets on the tank will simply dry off. When you attach the strips, be sure keep in mind how the tank will sit in the boat - for example, if you were attaching to the vertical side of the tank, putting the strips vertically would make more sense than running them horizontally- less chance of water puddling.

An aluminum tank with airflow around it will not have corrosion problems.

Just don't use rubber against the tank- allegedly it is cathodic to aluminum.
 

aweigh again

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thanks for all the replies so far,its nice to get information coming different perspectives.
 

Tuckerman

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I've used Atlantic coast in the past also. That's what I installed in my Webbers cove for the previous owner 8 years ago , when I removed floor last year tank looked brand new. This one is epoxy coated. There are many options. Pick one and go boating! The most important thing in my opinion , no matter which material or coating you pick ,is to install it correctly.
 

Toro

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i have a moeller 3o something gallon , used, doesn't fit under my sole...
 

Keelboater

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Triple M Plastics in Kennebunkport Me fabricate plastic welded fuel tanks.

Hi Bill -

Just out of curiosity, do you know if these plastic tanks made from anti-static material?
Do they dissipate any static charge like an aluminum tank does once grounded? I would have to assume that they are, especially for gasoline use. Do they have bonding wire connections? I just had an application at work that required an anti-static UHMW-PE instead of the more common variety of UHMW. It made me wonder about the tank material here.
 
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