Myths

[Woodonglass]

A good Read...
New Boatbuilders Home Page - Boating and Boat Building Myths

 

[Bondo]

Re: Myths

Ayuh,... Good read,....

 

[GT1000000]

Re: Myths

Yep! +1

 

[jbcurt00]

Re: Myths

Thanks!

 

[jimbo_jwc]

Re: Myths

Should stop some challenges on the quest for boating knowledge . As I would stand to be corrected . That is why I don't build boats just continue fixing them and try to improve what I can.

By gone days with granpa's only source of horsepower was a kid learning what makes blisters

 

[GA_Boater]

Re: Myths

Good reading, Wood. For one thing, I'm glad he said ABYC are only guidelines in one place. USCG (and states) are the rule makers.

 

[tazrig]

Re: Myths

Some interesting stuff in there for sure.

 

[jigngrub]

Re: Myths

I like the Myth about foaming in a fuel tank is a death sentance for the tank, it's quite obvious this guy doen't know what he's talking about and needs to do some more research.

We all know that if we take care of our boats and keep them covered or garaged our foam won't get wet and we don't have to worry about stuff like wet foam corroding our fuel tank.

Fuel tanks can also be painted before foaming them in to prevent corrosion and extend the life of the tank.

Anyone that's interested in what destroys a below deck aluminum fuel tank and what you can do to extend the life of your tank should read this:

http://www.uscgboating.org/assets/pdf/recalls/BSC79.pdf

 

[tpenfield]

Re: Myths

I came across that guy's web site about 6 years ago and have it in my "favorites" ever since. It sounds like he gets the 'myths' from reading boating forums . . .

Perhaps an extension of our ill-informed boat knowledge thread

 

[rickryder]

Re: Myths

Ok so after reading your link JNG seems the best thing to do is keep the tank high and dry.....not to trap moisture between the tank and any contact surface... If you don't let water sit on it it won't rot.... I would think that the less contact the tank has with anything other than air would be best.... Without the proper prep foaming a tank in would do more harm then good.....back yard DYIers are more likely to foam it in incorrectly and have failure sooner than if you just applied plastic strips to the bottom of the tank with 5200 so water cant get between the strips and tank and left ample air space around the tank so it can dry quickly letting the aluminum do it's job as a self protecting metal. My conclusions are from reading the last paragraph on page 4 of your link.

 

[tpenfield]

Re: Myths

I like the Myth about foaming in a fuel tank is a death sentance for the tank, it's quite obvious this guy doen't know what he's talking about and needs to do some more research.

We all know that if we take care of our boats and keep them covered or garaged our foam won't get wet and we don't have to worry about stuff like wet foam corroding our fuel tank.

Fuel tanks can also be painted before foaming them in to prevent corrosion and extend the life of the tank.

Anyone that's interested in what destroys a below deck aluminum fuel tank and what you can do to extend the life of your tank should read this:

http://www.uscgboating.org/assets/pdf/recalls/BSC79.pdf

Yes, I also noted that myth, and would agree that it is a controversial topic, based on my first hand knowledge of replacing my tank. I see that the problem with foamed in tanks is a result from insufficient design on the builder's part. The moisture that results from the typical daily condensation cycle has no place to go and eventually settles into the foam at the bottom of the fuel bay, providing a source of moisture for the tank.

the builders generally provide no escape route for moisture that collects at the bottom of the fuel bay. This not only impacts the tank, but also effects the main bulkhead that separates the engine compartment/bilge, causing it to slowly absorb moisture through the polyester resin. The main bulkhead eventually feeds the moisture into other structural components that are in contact with it, such as stringers, etc.

So, structural issues and tank issues usually go hand in hand . . . Based on a boat's designed-in ability to retain moisture in the fuel bay and other areas.

 

[jigngrub]

Re: Myths

Ok so after reading your link JNG seems the best thing to do is keep the tank high and dry.....not to trap moisture between the tank and any contact surface... If you don't let water sit on it it won't rot.... I would think that the less contact the tank has with anything other than air would be best.... Without the proper prep foaming a tank in would do more harm then good.....back yard DYIers are more likely to foam it in incorrectly and have failure sooner than if you just applied plastic strips to the bottom of the tank with 5200 so water cant get between the strips and tank and left ample air space around the tank so it can dry quickly letting the aluminum do it's job as a self protecting metal. My conclusions are from reading the last paragraph on page 4 of your link.

DIYers are going to screw it up half the time anyway even when given sage advice (we've seen several instances of that right here).

Painting before installation works, if it's a good paint job.

Doubling the tank thickness extends the life span by 8x... so how long would a well painted double thickness tank last?

Like I said at the begining, if your boat is well cared for and you keep it dry when not in use you don't have to worry about any of that stuff... and you would think that someone blogging about boat building myths would realize that.

 

[rickryder]

Re: Myths

.. and you would think that someone blogging about boat building myths would realize that.

Maybe he was thinking about the DIYers that's why he doesn't recommend foam

 

[jigngrub]

Re: Myths

Yes, I also noted that myth, and would agree that it is a controversial topic, based on my first hand knowledge of replacing my tank. I see that the problem with foamed in tanks is a result from insufficient design on the builder's part. The moisture that results from the typical daily condensation cycle has no place to go and eventually settles into the foam at the bottom of the fuel bay, providing a source of moisture for the tank.

the builders generally provide no escape route for moisture that collects at the bottom of the fuel bay. This not only impacts the tank, but also effects the main bulkhead that separates the engine compartment/bilge, causing it to slowly absorb moisture through the polyester resin. The main bulkhead eventually feeds the moisture into other structural components that are in contact with it, such as stringers, etc.

So, structural issues and tank issues usually go hand in hand . . . Based on a boat's designed-in ability to retain moisture in the fuel bay and other areas.

The main thing about below deck aluminum fuel tanks is that they're not an "install it and forget it" item, they require periodic inspections and maintenance... and full access for inspections and maintenance. Owner neglect is the main killer of these tanks... like this one:
http://forums.iboats.com/boat-topic...-topics/what-growing-my-fuel-tank-591468.html

Foaming in a fuel tank is the most efficient way to secure and isolate it from vibrations, vibrations that can cause other means of securing it to fail or create "wear" holes in the tank.

 

[rickryder]

Re: Myths

The main thing about below deck aluminum fuel tanks is that they're not an "install it and forget it" item, they require periodic inspections and maintenance... and full access for inspections and maintenance.

OK so then tell me if you foam in a tank how do you inspect and maintain something that you can't remove and it's covered in foam?

 

[tazrig]

Re: Myths

.
Doubling the tank thickness extends the life span by 8x... so how long would a well painted double thickness tank last?

20 years ago (approx.) The original aluminum tank went in my 1976 Formula. I had the same tank fabricated in surgical stainless steel at 3X the thickness of the original. My dad owned a machine shop at the time so I had access to the materials. It weighed 9X the weight but the welder, and later the group that installed it told me that would be the last tank I ever had to put in that boat. So far so good. If I remember correctly they beefed up the fiberglass cradle for it for extra strength and foamed in the bottom and sides too. That was one the part of the guys post I questioned. I thought good quality stainless didn't rust or corrode.

 

[Woodonglass]

Re: Myths

Uhmm... in addition Condensation below totally sealed decks occurs in every boat. That's why it's always recommended to Seal the bottom of the deck with CSM and Resin. When the foam cracks and separates from the tank ( and it ALWAYS does. (The flexing of the hull and the expansion and contraction of the tank and the foam is the root cause.) Never seen one older than 10 years where this did not occur), Moisture from the natural occuring condensation will penetrate the cracks and cause corrosion of the tank, not conjecture, not supposition, FACT.

 

[tpenfield]

Re: Myths

When I pulled out the fuel tank on my Formula 242 after 21 years of age the foam was still well secured to the walls of the tank. The most significant areas of corrosion were where the tank was butted up to a 2x4 wood spacer and the aft 1/3 of the keel line of the tank, where moisture had settled in the foam. All other areas of the tank were pristine.

If a hull were to flex too much, I could see that it may cause separation of the foam from tank and the surrounding structure. In my experience it seems that the foam separates more readily from the fiberglass & resin surfaces than it does from the tank. Either way, there is the path for the moisture to go down to the bottom of the fuel bay and build up over time with little or no hope for evaporation.

 

[jigngrub]

Re: Myths

When I pulled out the fuel tank on my Formula 242 after 21 years of age the foam was still well secured to the walls of the tank. The most significant areas of corrosion were where the tank was butted up to a 2x4 wood spacer and the aft 1/3 of the keel line of the tank, where moisture had settled in the foam. All other areas of the tank were pristine.

Your problem was that your tank wasn't completely encapsulated on all 5 sides as recommended in the USCG/UL circular.

Talk to anyone that has removed a foamed in fuel tank and most will tell you it was a fight to get the tank removed and to remove all the foam from the tank. One of the guys on here in another thread stated that his foamed in tank was such a PITA to get out that he went with sheet foam instead when he reinstalled it just so he wouldn't have to fight the expanding foam if he ever had to remove it again.:laugh:

 

[rickryder]

Re: Myths

Still doesn't answer my question how do you maintain and inspect something that's wrapped on 5 sides with foam? Guess you look at the top and pray the rest is good