Fuel Tank Installation without Foam

Repair or modification of Boston Whaler boats, their engines, trailers, and gear
Spc337
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Fuel Tank Installation without Foam

Postby Spc337 » Fri Sep 21, 2018 1:24 pm

Has anyone [installed a fuel tank without foam to surround the fuel tank]?

[Are there any] photos of how the work was completed?

I'm back and forth on foam and partial foam--that is, foam in the corners for stability.

Also on adding a drain.

And also on figuring out how to install in a cradle of some form.

And I also need to avoid over engineering this :)
Boston Whaler 1979 V-22 Outrage

jimh
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Re: Fuel Tank Installation without Foam

Postby jimh » Fri Sep 21, 2018 5:59 pm

In regard to your survey question about installing fuel tanks without surrounding foam, I don't think Boston Whaler uses foam anymore on their newer products.

For pictures of the installation of a fuel tank without a foam surround, see below:

Image
235 CONQUEST hull prior to installation of fuel tank

Image
235 CONQUEST hull with fuel tank installed without a foam surround

These pictures originally appeared in an article about touring the Boston Whaler plant. See
http://continuouswave.com/whaler/reference/factory.html

Spc337
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Re: Fuel Tank Installation without Foam

Postby Spc337 » Fri Sep 21, 2018 7:50 pm

Looks nice. Even has a pump installed from what I can see. Any idea who makes that tank? I doubt it fits my cavity but anything is worth a try to avoid aluminum again.
Boston Whaler 1979 V-22 Outrage

NLA01
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Re: Fuel Tank Installation without Foam

Postby NLA01 » Fri Sep 21, 2018 10:51 pm

I am very interested in this thread's topic. I am looking at replacing [the fuel] tank in my 1995 Outrage 24.

Has an aluminum fuel tank ever been replaced with a poly[ethylene fuel tank]?

My concern is that there will be several inches of open space on all sides of the new tank. There are no perfect fit tanks. There are several smaller polyethylene fuel tanks that will fit.

How does one secure [a replacement fuel tank] if [the replacement tank] is smaller than the [fuel tank cavity] opening?

I know you have to allow for expansion--maybe be an inch of expansion.

Foaming the corners may not allow expansion and may make the tank buckle.

I thought of putting in larger KING StarBoard blocks on the sides for a boxed-in fit.

Has anyone done [put in a smaller tank and them used KING StarBoard blocks on the sides for a boxed-in fit]?

--Archie

Spc337
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Re: Fuel Tank Installation without Foam

Postby Spc337 » Sat Sep 22, 2018 12:16 am

I really wanted a poly tank for my Outrage 22. To get a custom tank made, the initial $3,000 to $10,000 cost of the mold has to be absorbed.

A few weeks back I inquired in a posting if there was any interest but didn't get a response.
Boston Whaler 1979 V-22 Outrage

GeorgeUtah
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Re: Fuel Tank Installation without Foam

Postby GeorgeUtah » Sat Sep 22, 2018 11:19 am

I have just about completed the restoration of a 2000 Ventura 180 which included the replacement of the Moeller roto-molded 61-gallon fuel tank with a new Moeller-brand tank. Clips which were original to the boat were used to hold down the replacement [Moeller-brand fuel tank]. Some 3M4200 adhesive-sealant was also used on two sides to keep [the replacement Moeller-brand fuel tank] centered.

I [do] not [recommend] use of foam; most of the [foam] you can buy, squirt, or pour yourself will absorb water.

jimh
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Re: Fuel Tank Installation without Foam

Postby jimh » Sat Sep 22, 2018 3:00 pm

Acassidy wrote:...you have to allow for expansion--maybe be an inch of expansion.


I am not clear if you are talking about the volumetric expansion of the liquid fuel in the tank with temperature increase, or if you are talking about the the metal or other solid material from which the tank is made expanding with temperature. Please clarify.

Assuming the base temperature for the fuel tank is 20-degrees-C or 68-degrees-F, how much increase in temperature do you anticipate will occur?

Considering the color of most Boston Whaler boats is white, the deck color is white, the internal fuel tank is not exposed to the sun, and hull surrounding the fuel tank is immersed in water with moderate temperatures, probably about 68-degrees, I would not expect the temperature of the fuel tank to rise significantly. Also, a large volume of fuel in the tank tends to mean that any heat affecting the tank has to warm a large volume of fuel.

NLA01
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Re: Fuel Tank Installation without Foam

Postby NLA01 » Sat Sep 22, 2018 4:10 pm

Jimh, Moeller ask that we leave 3% space for exansion.

http://moellermarine.com/customer-resou ... ions/#perm

So if I get a 70 inch tank. It may expansion 2.1 inches once I put fuel in it--plus differences in temperatures will change it. Moeller is unclear about how to install a fuel tank to allow this. They show side clips which will not work for a V bottom. I also may have 3 or 4 inches of empty space on the sides.
Thanks
Archie

NLA01
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Re: Fuel Tank Installation without Foam

Postby NLA01 » Sat Sep 22, 2018 5:03 pm

This is one of the few videos on youtube replacing an aluminum tank with a poly tank. Interesting story plus a video of the repair at the end of the video. It is an aluminum boat.

Archi
https://www.youtube.com/watch?v=cPGfwQQ1EFs

jimh
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Re: Fuel Tank Installation without Foam

Postby jimh » Sat Sep 22, 2018 5:56 pm

I now think that the cited three-percent allowance for expansion must be due to the actual material of the tank deforming under the load of the fuel and its weight--here assuming its a polyethylene tank, not an aluminum tank.

Thanks for the pointer to the FAQ, but is there other literature, such as the installation instructions, that inform a buyer of the tank how to install it and to allow for the expansion? The FAQ seems to talk about the three-percent expansion as if it was common knowledge.

jimh
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Re: Fuel Tank Installation without Foam

Postby jimh » Sat Sep 22, 2018 6:12 pm

If the Moeller installation instructions require that their polyethylene fuel tanks must be installed in such a way that there is sufficient clearance around them to allow for a three-percent expansion, following that advice would be prudent.

As the image (above) of a Boston Whaler boat with a polyethylene fuel tank shows, the tank is not encapsulated with a foam surround. The tank appears to be retained by two rather large and thick aluminum cross bars. I suspect that there may be some channel or relief molded into the tank in which those cross bars are resting. (If I can find an higher resolution version of that image in my archives, I will see if it shows more details.)

Blackduck
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Re: Fuel Tank Installation without Foam

Postby Blackduck » Mon Sep 24, 2018 4:11 pm

I installed an aluminum 40 gallon tank without foam into a 1973 19'. This works well in this boat as water does not pass over the top of the tank like it does on newer Outages. I left a 1" plugged, access hole in the cover for checking and water removal by pump. Tank was just block shimmed in all four corners. This has worked out just fine in for two years.

floater
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Re: Fuel Tank Installation without Foam

Postby floater » Wed Sep 26, 2018 5:39 pm

I reinstalled my rebuilt fuel tank on my 1988 Revenge WT without using expanding foam. I used the original retaining straps and multiple sheets of those foam pads that parents put on the floor of their kids play rooms. I cut them into strip and jammed them around the tank leaving space at the bottom for water flow. It worked out really well and the tank hasn't moved in two years.