tank embedded in foam, need removal

[Sailor Simon]

The sewage tank is located under the v berth structure. It was lais in a bed of expanding foam, left to set and had the hoses connected, in and out. The fitting are made from mild steel and have corroded to nothingness. I intent to remove the tank, clean up the interior of the hull, clean the tank and have stainless steel nipples installed, instead of the exisiting steel assembly.

The tank is fairly deep, approximatly 20 inches, and is sloped to the contour of the hull. Should I cut the foam out with a sawzall blade on a wooden handle,then apply my horse power at heaving it up and out? Use an expanding foam disolver? Suggestions?

Thanks in advance, Sailor Simon

Big waves and big wind make swell stories...I'll let you know which ones are true

[radicalcy]

I've found the best tool for cutting expanded foam is a serrated bread knife. Cuts like butter and no fear of cutting thru the hull, unlike a sawzall.

[earlylight]

I have an old electric carving knife in my shop that I use for cutting foam. Works like it was made for the job.

[Rachel]

If there are places you can't reach with the aforementioned tools, you might be able to make use of a long wire run between two dowel handles that you can get under there and kind of saw/pull on. Kind of a cheese slicer effect.

You might want to look closely at the stainless where it was in contact with the foam; it's possible there could be crevice corrosion of there was moisture held up against it with little/no air flow.

[Quetzalsailor]

Boy! If ever one needed a reminder about 'permanent' installations, this is a good one!

I'll bet the thing sat on something and then was foamed in. You'll find those blocks or whatever, and probably at inopportune moments.

It'll be interesting to hear how your removal goes. I think the sawzall blade on a stick sounds line an awful aerobic exercise, but probably cannot hurt much if you don't insist on sawing where the blade does not seem to advance very fast. The electric knife sounds worth trying but will be more or less successful depending upon the density of the foam and the resultant drag. The wire sounds like way too much like work but worth trying, if only for the bragging rights. It'd probably snag on something.

I'd imagine that a little of each of these ideas might be useful. And any would be made easier, I think, by removing a slice of foam: two parallel cuts and dig out the bit in the middle. This would reduce friction for the next pass, as well as give some room for gently prying and tipping the tank a bit.

Take som pics; we'll enjoy suffering at a distance.

[Tim]

You should be able to cut/dig that foam easily with just about anything; just hack away and dig the stuff out. It'll take a pair of seconds. I took out a partially-foamed tank a few months ago, and didn't have to do anything to the foam to release the tank.

You'll only need to do so much before you can rip the tank right out--just loosen the grip enough, or dig yourself a place to get some leverage. The fact that the tank's tapered as it extends downward will make easy to get it out, since once the grip (such as it is) is released, it'll pop right up and out with minimal effort.

Don't make it into something bigger than it is.