Rebedding a Leaking Deck Prism - Advice ?

[windsaloft]

I've read the one thread about possibly needing some 500 solvent to get the prism out in the first place ----

But, am about to light into removing, cleaning up the hole and dealing with any rot in the deck core, then re-bedding the deck prism on my Mason 33.

My basic plan is to remove it, to use a dremel to rough up the coring, and "rout" out any rotten stuff, use a penetrating epoxy to "seal" the core from future potential leaks, use stiff epoxy to re-create my square hole into which I'll re-bed the prism.

Any tips, tricks, or warnings?

[Charlie]

I don't know what mine was bedded with but here's how I got it out two weeks ago. First thing I did was cut arouund the edge with a razor knife. I did this repeatedly. Next I got a bottle jack and a length of 2x4. I set the jack below the prisim and the 2x4 on topof the jack. The plan was to raise the prisim and then to slip wedges under the prisim so it wouldn't fall back into place when the jack was removed. Didn't need the weges. It came uout easy. I like the idea of the penetrating epoxy.

[bstreep]

Dang Charlie, I'm dyslexic. I read "bottle jack" and saw "bottle OF jack". That's what I used on mine!

I rebedded mine (3) about 6 months ago. All 3 came out rather easily. I used the razor blade/knife blade/screwdriver trick to pop up the stainless steel trim around it. Then I used the razor blade/knive blade to remove as much of the old sealant as I could, went below and gave it a gentle push and they each popped right out.

Straightening the trim was as simple as a light touch, repeatedly, with a hammer. I used a piece of cardboard to protect it. I figure about 2 hours each.

[Charlie]

I like the Bottle of Jack even better than the penetrating epoxy.

[windsaloft]

Hmmm. A hammer, a razor, a jack, a board, a bottle of jack, penetrating epoxy, getting board, use the hammer, get hammered......it is so easy to confuse all these directions!

So, for rebedding, after prepping the hole with penetrating epoxy and making sure I have a nice square into which to bed it ----- Dolfinite Bedding Compoud work, or do you use something far more water tight and industrial?

[Charlie]

Don't know anything about Dolfinite. I used Sikaflex (Ithink the number is correct) 295uv. Can't tell you if it is any good b/c we haven't had any weather yet.

[windsaloft]

Follow up -- popping out prisms reveals that (a) if you put the work into removal, they don't break, (b) on our Mason 33, the deck is already molded for the prisms, so no worries about the core and sealing...........it is all gel coat.........and (c) bedding with generous dolfinite and plans for cleanup will allow us to simply maintain these prisms.....

[s/v Jedi]

I would not even use dolfinite if they gave me money with it. What's next, tar?

Use a polysulfide bedding compound, like LifeCaulk from BoatLife or 101 from 3M.

cheers,
Nick.

[hanschristian38]

Try butyl mastic to bed it. It is the same product that thet use to seal electrical wires through a cement wall. It does not harden and is very easy to replace in the future as it comes out like plumber's putty.
It was the only thing that worked on my chain plates.

[CorrinaCorrina]

Windsaloft,

I live on a mason 44 in annapolis and I know exactly what you are going through. Both of my deck prisms were "fixed" before I bought the boat and I came to the discovery that you can only do so much with silicone.
In this repair, the devil is in the details if you want it done correctly. Remove the stainless steel cover from the light. Then you should be able to pop each one out from below deck with the palm of your hand.
Once they are removed, clean the glass as well as you can. Anykind of solvent will work and if there is any sealant still attached to the glass, carefully use a razor to remove it.
Preparation of the cavity is very important. Remove any rot that you see and all previous attempts to cure the leak, aka silicone, 5200, 4200, ductape!
Once the cavity is clean and all wood is dry(important), sand the inside of the cavity and if you have teak deaks, sand the edge of the teak. Then clean all dust and residue off by using acetone. Let the area dry for about 15 minutes. Once dry, apply west epoxy around the exposed wood, deck core and anywhere else you are affraid water might penetrate.
Let this cure for a day and then you will be ready to seal. First lightly sand the epoxy to remove the wax. Clean the dust off with acetone. For the seal I used 4200 for the seal and it has worked just fine. use the 4200 liberally applying it all on the inside of the cavity and on the sides. Lay a good bead down where the prism will lay. Place the prism in the cavity and press down on it evenly to seal correctly. Inspect the edges of the prism and if there are gaps fill them. You can use a syringe filled with 4200 to minimize the mess.
Apply the Stainless Steel cover and screw down dabing the screw in 4200.
Now, here is detail that is often overlooked, once everything is back in place, take blue masking tape and out line the outside edge along the deck of the stainless steel cover but leaving just a little gap between the cover and tape on the deck. Also cover the stainless steel with tape as well because you are going to smear 4200 around the edge. Its a finishing touch and it seals just a little more.
Also do the same for the seam between the glass and SS cover. Tape the edge of the glass and the edge of the stainless steel cover. You should see the seam between the glass and cover. Smear 4200 around this seam.

[bstreep]

One other pointer: If you bend the stainless taking it out, take it to a very flat piece of wood, place upside down. A few hundred light taps with a hammer - I mean LIGHT taps, will flatten out well without hurting the stainless.

[Christian Van H]

It wouldnt hurt to remove the first 1/4" or more of coring, then paint in your penetrating epoxy. After that, paint in regular epoxy and fill the void with epoxy thickened to peanut butter with colloidal. No worries, no more! P.S. I would use Lifeseal as the sealant...

[Geoff H.]

I hope there's still someone out there interested/knowledgable in this thread, as I've just purchased two new prism kits (with bronze trim) to install on my sailboat. They are ABI stock (I understand ABI is out of business) and the "glass" is actually synthetic crystal. I was told by someone who installed these a long time ago to go with glass, not acrylic, as the glass will hold up much longer. My question is, is the synthetic crystal the same as glass (it's the only material available from what I can tell...?

[MoonlightSailor]

I have two 7 1/2" deck prisms that need to be replaced. They both have cracks and are leaking. The cracks are in about the same place on both of them. Odd. Does anyone have a good source for new ones?

[pepperhamilton]

Mine is relatively new, as I just had them embedded.