Gas tank, cover or not?

[Goldie627]

My brother is a mechanic by trade, he cautions me against covering my gas tank permanently during the restoration. He feels i should do a hatch instead. For water proofing and long term protection, a removable hatch is undesirable. What are your thoughts?

 

[glenn property of pam]

depending on the size of the tank. I would install a hand hole at least over a large tank to be able to get to the level sensor and tank connections. They do make nice hand hole covers so it doesn't have to look messy and they are water proof.

 

[jigngrub]

I agree with your brother.

If you have a hatch you'll be able to make periodic inspections and repairs/maintenance, without a hatch you'll have to tear up the deck to get to it if anything goes wrong... and that does happen.

Your fuel tank and tank compartment should be built to withstand any exposure that may crop up. If your tank is aluminum it should be painted to resist corrosion. Foaming your tank in place will displace water that could accumulate in the tank compartment, it'll also seal the outside of the tank. Cutting the foam off flush with the top of the tank and providing drainage off the top of the tank will keep your tank dry.

 

[Goldie627]

pic for referecnce

 

[glenn property of pam]

that's a large tank. I think a hatch that large could allow the hull to flex unless it was part of the original design. I would still go with hand holes as its a pain to have to have to drill them later when something goes wrong.

 

[Rickmerrill]

Just my opinion, cause that's what you asked for. I'd just put it back the way it was built originally. Mine has something like an 8" screw-on round plastic hatch so you can get at the hose connections and the sender, hopefully your's does to. I'd consider that mandatory. They also cut a separate piece of ply to cover the tank, screwed it down, filled the gap around it with resin (no cabosil or chopped fibers) and then covered it with CSM. When I was doing my demo I had a heck of a time getting the tank out, actually had to cut out the forward bulkhead and get a big crowbar under it because it was wedged in there so tight. I remember thinking there was probably no way I could replace that tank without doing some cutting. I don't recall ever seeing a 20' or so bow rider with a hatch over the entire tank. I have to ask, is your brother prone to jive talking? Now that song will be stuck in my head for days just like the Saturday Night Fever song you had when you modeled your Tyvek suit.

 

[Woodonglass]

I would not use a Hatch for this tank or your boat. I WOULD use small access hatches for the critical areas. I would Not use pour in foam to secure the tank.

 

[kcassells]

I would not use a Hatch for this tank or your boat. I WOULD use small access hatches for the critical areas. I would Not use pour in foam to secure the tank.

Hi Wood,
I've been contemplating the same scenario. My boat did have a hatch over an 80 gal tank and it was terrible. Saggy and soft and leak to say the least. If it's a new tank I understand that now it should be new, secured and safe. But why no foam as you referenced in areas like the corners? Just wondering. If so what are the best alternatives to secure the tank {with inspection plates} whether it's aluminum or plastic. IYHO? Right now I'm between a rock and a hard place in regards to an aluminum tank or plastic tank. Sorry if this is a bump.
Thanks!

 

[jigngrub]

Take a look at this Cass:
http://www.uscgboating.org/assets/pdf/recalls/BSC79.pdf

 

[kcassells]

Take a look at this Cass:
http://www.uscgboating.org/assets/pdf/recalls/BSC79.pdf

JnR, Thanks. saved and will read.

 

[dude11]

Without any doubt at all,,your brother has cussed engineers in the past for designing stuff & not thinking of future maintenance .I'm with him,fix it so you have good access later on.My buddy & I worked in maintenance for 30 plus yrs.Never fails,we'll talk about poor design on just about anything.Repairmen see the world in a different light than engineers.lol

 

[Woodonglass]

Hi Wood,
I've been contemplating the same scenario. My boat did have a hatch over an 80 gal tank and it was terrible. Saggy and soft and leak to say the least. If it's a new tank I understand that now it should be new, secured and safe. But why no foam as you referenced in areas like the corners? Just wondering. If so what are the best alternatives to secure the tank {with inspection plates** whether it's aluminum or plastic. IYHO? Right now I'm between a rock and a hard place in regards to an aluminum tank or plastic tank. Sorry if this is a bump.
Thanks!

Every tank, and I mean EVERY tank, I've ever seen that was encased in foam and removed from an old boat was suffering from MAJOR corrosion. IMHO it's the quick and easy way to do it and NOT the best way. I'd refer you to this...http://www.yachtsurvey.com/fueltank.htm
This is how I ALWAYS recommend installing a large, below Deck Aluminum Tank. It's written by one of the most respected and Published Boat Surveyors in the industry with over 40 years experience. The Coast Guard Article is 17 years Old. A lot has been learned in those 17 years about tank installation and how it should and should not be done. Boat surveyors see this kind of stuff on a daily basis and form their opinions based on their learning experiences. I tend to go with their findings. But Hey, as I always say, It's your boat, and you're free to do as you see fit. Just saying I wouldn't foam in a below deck Aluminum Tank. You can if you want. A lot of people do!!!

 

[kcassells]

Every tank, and I mean EVERY tank, I've ever seen that was encased in foam and removed from an old boat was suffering from MAJOR corrosion. IMHO it's the quick and easy way to do it and NOT the best way. I'd refer you to this...http://www.yachtsurvey.com/fueltank.htm
This is how I ALWAYS recommend installing a large, below Deck Aluminum Tank. It's written by one of the most respected and Published Boat Surveyors in the industry with over 40 years experience. The Coast Guard Article is 17 years Old. A lot has been learned in those 17 years about tank installation and how it should and should not be done. Boat surveyors see this kind of stuff on a daily basis and form their opinions based on their learning experiences. I tend to go with their findings. But Hey, as I always say, It's your boat, and you're free to do as you see fit. Just saying I wouldn't foam in a below deck Aluminum Tank. You can if you want. A lot of people do!!!

So the entire tank has air movement around it, of course it's been etched and sealed by this point and the strips/5200 keeps the tank in place with out any movement. When my tank came out it was buried in wet foam. Pitting was beyond repair. I see the logic but..My minds eye is saying "Holy Cow, will that tank stay in place and not get loose?"
Just on this forum I've seen so many attempts at installing tanks with use of foam, straps, wood.
Thanks for the info.

 

[jigngrub]

The fear of foam around a gas tank becoming saturated is utterly ridiculous.

This only happens to neglected boats left exposed to the elements, and when it does happen you're going to have other and probably bigger problems like rotten stringers and transom... plus more saturated foam in other areas.

Keep your boat sheltered and dry when not in use and you won't have any worries. All experienced boat owners and restorers are supposed to know this.


There are reasons why foamed in below deck tanks are OEM in todays boats, and those reasons are:
1. The foam will hold the tank in place securely
2. The foam will displace any water that could get into the fuel tank compartment.

 

[Woodonglass]




 








 










"It's all about how you design you tank installation. Lot's of good examples here and elsewhere. Do some research. You'll see what I mean. Your Foamed In tank should tell you what you Shouldn't do again!!! Lets take a look at what the Coast Guard Brochure actually says about Foaming in your tank...

"A tank should be installed so that water will drain off quickly." Hmm, isn't this a bit counter intuitive?? How can water drain off quickly from a foam encased tank? I suppose it drains off OVER the foam.
The aluminum surfaces must be prepared carefully and thoroughly (degreased and primed or etched) to assure a bond of the foam to the tank, prevent attack of the aluminum by the substances in the foam and to preclude moisture. Ok we can do that.
The foam must meet certain requirements concerning cell structure, moisture resistance, and density such that the foam will bond without voids, there will not be damaging water absorption and there will be certain inherent strength to preserve the bond to
the tank. Ok, all of this is well and good EXCEPT for the VOIDS. If you've ever tried to pour foam around a tank you KNOW that is next to impossible to do this withou getting voids and herein lies the problem. These voids WILL create condensation points for even the best cared for boats. When the natural heat and cool down of the tank and surrounding areas occur, condensation occurs and moisture will form in those voids. Over time this moisture WILL attack the tank and corrosion WILL occur. It can take a LONG time but it WILL happen.

Now, on at Strapped in tank, it will happen too. The contact points for the straps will also have condensation and when the straps are removed more than likely there will be corrosion under the contact points. It's just the natural course of events. There's just no way that I know of to totally prevent corrosion. I don't like foaming in tanks for the reasons stated. Others DO for the reasons they state. It's a preference thing. I'll say it again. You can research the facts from both sides, and make your own decision. It's your boat and you are free to do with it as you see fit.

 

[jigngrub]

The drainage isn't that hard to figure out if you'll think about it, pour the foam so it rises above the tank and come back and cut it off flush with the top of the tank after it sets up. Paint the cut top of the foam. Drill drain holes in the aft bulkhead of the tank compartment with the bottoms flush with the top of the tank/foam. Seal edges of drilled drain holes.

There is a trick to pouring the foam with no voids, and for $5 I'll tell you what that trick is.... nah, I'll tell you for free. Mix up and pour your foam on one side of the tank only, the foam will push itself over to the other side as it expands... but you have to be sure to mix up enough foam so it will travel to the other side and start pushing up on the other side.

 

[kcassells]

Goldie, Sorry about bumping in on you but the fact is there is a lot of information here everyone can use. Thanks JnR and Wog, of course it is my boat etc.. Just always seeking info from the best of the best before I er from ignorance. Take a pc. of this, take a pc. of that and make something out of it.