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From: Tom (no email)
Date: Tue Oct 03 2006 - 14:38:12 EDT
At 12:58 PM 10/3/2006, wrote:
>I looked into all the options on the holding tank. After talking to the
>tech people at West systems, I decided to do the epoxy over blue foam. I
>was a bit afraid that I'd need an exotic epoxy for the holding tank, but
>they assure me that the normal epoxy is fine for that. They also say that
>normal glass is fine, I don't need anything exotic for that, either.
>
>I'll probably be building it in about 2 weeks. I'll take pictures and post
>the results.
>
>By the way, this is a replacement for the tank I built of aluminum about
>10 years ago and re-built about 5 years ago for Rainbow Chaser. I have her
>sold, but one of the things I must do is replace the holding tank for the
>new owner. He's talked to a surveyer, who also recommended this method.
>
>Gene Gruender
Glad to hear my suggestion was helpful and you are going forward with
this. What layup schedule did they suggest? They will probably suggest
something pretty much bullet-proof based on the old saying popular among
Maine boatbuilders "Nothin' too strong evah broke". :)
I do not know what they suggested re: a layup schedule, but I would
strongly consider incorporating at least one layer of 6 to 12 ounce kevlar
in the bottom or sides of the tank nearest the hull. If the tank supports
ever failed and the tank settled against the hull or any support stringers,
the scuffing/abrasion of the tank caused by vibration and boat motion would
wear through the epoxy glass layers given enough time, but would come to a
screeching halt when the kevlar layer was exposed. You could drag that
full for several miles on concrete behind your car and not grind through
kevlar. Perhaps I exaggerate. ;)
West System epoxy does not produce much of an amine blush when laminating
like some epoxies do, but I would still recommend that if you let any
significant time pass between layup layers, you wash the tank with soap and
water, then let it dry before resuming the layup.
I would suggest laying up access port collars in the primary layup instead
of adding them later. Almost any thick, solid plastic material except
polyethylene will work as a collar material. Do not even think about using
wood. You just need something to bulk up the collar area and hold the
bolts for the access plate(s). Further, if it were me, I would pre-drill
the collar and tap the blind holes to accept the hold-down bolts. (I would
make the collar thick enough to not have to drill completely through it and
blind tap the holes before layup.)
Melt candle wax in a tin can with a bit of heat. Pour the wax into the
pre-tapped holes, completely filling them, before epoxying the collars
into the tank shell. That will keep you from having to worry about getting
epoxy in the threads while you are doing the layup.
Make the collar seal like Norm, Lew, and others have already posted. This
will avoid having any metal in either the tank interior or in the layup.
Will pretty much last forever.
Tom
Tom & Jackie O'Meara
ex-Seaskate, Searunner 40 Tri
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