Foam and structural weep holes back to transom?

[nurseman]

Check out Trooper82's thread. He had an interesting/clever way of allowing for some limited drainage under his foam. Not sure how effective it will be, I'm with jigngrub on the seal it up and fill it with foam. I would think that from a safety standpoint, you would not want to have the potential for flammable liquids/and or fumes to accumulate in your bilge. Also, why risk pumping fuel contaminated water into a lake/river/ocean? Just doesn't make sense to do that.

 

[jigngrub]

but I thought I was supposed to provide a way for condensation to drain from the gas tank area. I am foaming everything in except the tank area.

Sorry kcassells, I don't mean to highjack your thread, but I don't want to do the wrong thing, especially if it's dangerous.

I don't want to sound harsh, but common sense will tell you that if your fuel tank leaks into your bilge (and they can and will leak) it will pretty much turn your boat into a potential bomb.

Condensate is supposed to drain from the top surface of the tank when the boat is in the static floating position, not from the fuel tank compartment. Here's a link to some good info with illustrations:
http://www.uscgboating.org/assets/1/assetmanager/abyc.1002.01.pdf
Pages 63 and 66 have good drawings.

You should consider foaming in your tank too, expanding urethane foam is gasoline resistant and will act as a secondary barrier should your fuel tank ever leak. I know some people will screech and squeal that foaming in a below deck fuel tank is a "death sentence" for the tank, but when properly done it is a secondary barrier against spills and will actually increase the life span of your tank. There are good reasons that foamed in below deck fuel tanks are OEM on todays boats.

Here's some more good info on below deck fuel tanks:
http://www.uscgboating.org/assets/pdf/recalls/BSC79.pdf

 

[jc55]

My new tank is coming epoxy coated. The last one lasted 24 years, this one will last even longer. If you keep a plug in your tank compartment drain, you will know if you have a leaking tank. Many people may not know they have a leaking tank...I didn't... more dangerous yet.

 

[Mikeopsycho]

Useful feedback coming, good thread kcassells.

I don't want to sound harsh, but common sense will tell you that if your fuel tank leaks into your bilge (and they can and will leak) it will pretty much turn your boat into a potential bomb.

Hmmmm, my cousin has nineteen-ninety-something 28' Bayliner that has the gas tank in the engine space, just ahead of the engine, completely open to the bilge.

I agree nurseman, pumping contaminated water from the bilge into any body of water would be a concern. I always have an oil wick pad secured in my bilge in case of an oil leak or spill, and I think it would absorb gasoline too.

I know foaming in gas tanks is an accepted practice, but after digging out gasoline saturated foam from under my deck I'm determined there will be no foam around either my aluminum water tank nor my gas tank.

I like jc55's suggestion to plug the drain and use it only for "end of season" maintenance purposes. My mind is made up, the plug is the way I'm going. That's exactly what I did with my water tank compartment, installed a PVC drain line from it, through the foam and ribs under the gas tank support floor, and into the bilge, with a plug in it. The reason I plugged it is that I don't want water from the bilge to be able to get to the water tank space, so as routine maintenance I'll unscrew the plug and see what comes out.

I also don't want water to get from the bilge to under the deck, which is why I'm not installing any drainage from these areas, and I'm foaming and sealing them up.

 

[jigngrub]

I just feel that something like this would tend to ruin a nice day of boating:
https://www.youtube.com/watch?v=LmJwEL_jHqw

... so I tend to err on the side of caution when it comes to flammable liquids and their containment.

When it comes to displacing water I tend to err on the side of overfilling it with foam by 10% and cutting off the excess.

 

[kcassells]

Well,
All be said, responses, interactions were greatly appreciated form everyone. Thank you! Lots more to study and fuss about here in regards to the subject matter.
Go IBoats!

 

[jigngrub]

My new tank is coming epoxy coated. The last one lasted 24 years, this one will last even longer. If you keep a plug in your tank compartment drain, you will know if you have a leaking tank. Many people may not know they have a leaking tank...I didn't... more dangerous yet.

I some how skipped over this reply...

Coating a below deck fuel tank is one of the most important things you can do to prolong the life of it and is mentioned in both the links I provided back in post #22.

I really like what Zool did to his tanks with the POR 15, he shouldn't ever have to worry about them:
http://forums.iboats.com/forum/boat...perial-280sf-engine-swap-and-restoration-pics

 

[jc55]

Sometimes, I wish I was a little smarter, but alas...I am not. I am a big dummy who dabbles in a little of everything. Something deep inside of me says that your bare aluminum tanks surrounded by water and held there by foam(electrolyte), and hooked to the negative post of your battery becomes a sacrificial anode due to the natural voltage potential of aluminum. Like actual magnesium sacrificial anodes placed in the ground to protect pipelines, they are placed to be "less noble" or negative than the voltage potential of mild steel (which is -.7 or so volts). Please, I am not an expert and have only taken pipe to soil annual corrosion readings. But I did notice that my tank was "eaten away" beyond normal exposure to water. Check out the links below. So yes, coat your tanks.

http://www.corrosionist.com/Corros1.gif
http://www.corrosionist.com/Cathodic_Protection_Sacrificial_Anodes.htm

 

[kcassells]

Sometimes, I wish I was a little smarter, but alas...I am not. I am a big dummy who dabbles in a little of everything. Something deep inside of me says that your bare aluminum tanks surrounded by water and held there by foam(electrolyte), and hooked to the negative post of your battery becomes a sacrificial anode due to the natural voltage potential of aluminum. Like actual magnesium sacrificial anodes placed in the ground to protect pipelines, they are placed to be "less noble" or negative than the voltage potential of mild steel (which is -.7 or so volts). Please, I am not an expert and have only taken pipe to soil annual corrosion readings. But I did notice that my tank was "eaten away" beyond normal exposure to water. Check out the links below. So yes, coat your tanks.
http://www.corrosionist.com/Corros1.gif
http://www.corrosionist.com/Cathodic_Protection_Sacrificial_Anodes.htm

Hey JC,
If everyone was proficient at everything then there wouldn't be any Einsteins. Metal, salt water, fresh water, moisture, condensate, temperature.....tough stuff what can happen that's for sure. There is even an anode rod in every hot water heater. Every single one! ; to grab the ions, metals and reduce corrosion to the elements and tank lining.
Thanks for the read.