Sealants

[Gary H]

As I get ready to reassemble my CD22D, I want to make sure to use the most appropriate bedding sealants. I have read the chapter in Casey's book on the subject but could still use some more advice on bedding each of the following :
-bronze portholes
-hood for sliding companionway hatch
-coamings
-toe and rub rails

(3M 4200, silicone, 5200, something else?)

Thanks.

[craig]

gary
for the bronze portholes you might consider getting some of the butyl tape from maine sail.
i used life caulk for my sea hood but found it to be very difficult to work with. it is incredibly sticky. thats a good thing i guess. however, i used a whole roll of paper towels just on the sea hood project. very difficult to tool the joint.
the cockpit coamings would also be a good place to use a polysulfide like the life caulk. if you don't want to go with the life caulk the sika 291lot is more user friendly. it is a low strength polyurethane.
for the toe and rub rails you could use a higher strength polyurethane like the the 3m 4200. others on this board may know more about the uv characteristics of these products and if that is a concern. i noticed that sika has a 521uv which is a low strenght polyurethane.
silicone tends to get mildewy and darken. 3m 5200 is extremely difficult to remove if you have to make a repair. good luck.

[tmsc]

3M's 4200 below the waterline and 4000UV above the waterline if the bead will be exposed to the sun. It lasts way longer in those applications. Butyl tape is great stuff for ports. I use it in combination with 4000 UV. We also used a combination of butyl tape and 5200 for the hull to deck joints when I was at Island Packet. Ge Ultra Glaze or Silpruf for Lexan. Well that's my two cents worth for what every it is worth. Good luck and have plenty of paper towels or rags. PS. spray anything in the area you don't want to get the stuff on with WD40 first.

[Maine Sail]

For above waterline applications:

Butyl Tape
Sika 291 (low adhesion polyurethane)
Sika 295UV (lower adhesion polyurethane that is also UV Stable)
Life Caulk (used to be 3M 101 but it was discontinued)

Products that will never come aboard my boat:

3M 5200 = Satan's Glue
Silicone (exceptions include proper use for acrylic hatch lenses etc. and I would then use DOW 795)

Was just dealing with a CD 36 today that has port light bedding failures and they were bedded with clear silicone. The owner spent over 1 hour on one port, after it was already out, just trying to get the gelcoat clean and it is/was still contaminated. NOTHING will stick to it until it is CLEAN and we are going to need to sand the gelcoat to get rid of the last of the silicone contamination. Had to take the trim rings to my bench grinder with Scotch-Brite wheel to get the silicone off of them. Fun stuff on top of seacocks that had been serviced with the incorrect grease and likely not lapped in 32 years.

[SPIBob]

I've heard that toluene solvent is effective in dissolving and removing silicone residue. I think it was in a discussion of how to prep fiberglass for painting and a wipe down with a toluene soaked rag (turned often) was recommended to remove any silicone left over from previous waxings and polishings. FWIW

[tjr818]

I purchased some Silicone caulking remover at Lowes. It comes in a tube like caulking. Just lay down a bead over the caulk, wait an hour and peel off the old silicone. There is little or no residue.

[Ken Cave]

Try Http://blog.dankim.com/2009/04/24/marine-sealants/

Dan Jordon has an article on the above called Marine Sealants in a Nutshell which will answer a lot of questions about sealants.
(Adrift at Sea-Dan's blog on dankim.com. )

Hope this helps

Ken Cave
CD#227

[sharkbait]

Butyl tape can usually be acquired from the RV supply store at half the price asked by the marine supply house.. Much easier to work with if you keep it in the refrigerator until needed.

[Markst95]

Gary- if you haven't already read Mainsails articles on re-bedding deck hardware. Countersinking all the holes is the way to go, keeps the gelcoat from cracking and gives you a great seal. I followed his advice on my restoration 3 years ago, even the toe rail and it hasn't leaked a drop. You can find a link on the bottom of his post under "how to".

[Joe Myerson]

I had been using butyl tape from a nearby RV store, but you can buy a much higher quality tape from Maine Sail. Check it out on his website, the stuff is really good!

--Joe
P.S. I have no interest in Maine Sail's business--but his butyl is better for bedding hardware than the stuff from the RV store, IMHO.