3M Marine Grade Silicone or Butyl Tape

C

capt. meares

New member
I am refinishing the wood rails on my 22 cruiser. I am trying to decide which is the better option when mounting them back. All input and advice is appreciated. Thanks
 
I'm not sure, my rails are stainless, but I think your cabin rails are through bolted into the cabin roof since they would be designed to take a lot of force and are safety features. I'd check inside the cabin for evidence one way or the other. I would not use silicone at all. If I just wanted to adhere the rails rather than through bolt, I'd use either 5200 or 4200.
 
Not silicone, in my opinion. Why? First of all, it doesn't make a good, long-lasting bedding compound. Worse (much worse), it will leave a residue you will basically never be able to remove, and which will greatly hamper ever painting, re-bedding, etc. The contamination is miserable to deal with.

I generally liked to use a bedding compound such as Dolfinite (with some sealant on the wood such as varnish so that the wood won't just dry out the compound by soaking it up). It's been a while since I had any teak to bed though! Now I would definitely consider butyl.

Something easily removable/clean-uppable is good because it's a job that will need to be done again (you'll probably want to refinish the rails again if nothing else). Silicone doesn't fall into this category.
 
Concur with Sunbeam. Silicone is a huge PITA because of the residue. Dolfinite if you imagine you will pull the rails to refinish them sometime in the future. 4200 if not. 5200 is overkill for rails, I feel.
 
I recently rebedded everything on one of my sailboats with butyl tape and never will go back to anything in a tube again if at all possible. The ease of use and lack of mess alone is worth it, but it is a proven longlasting method.

Whatever, I also would stay away from any silicone.
 
Recently completed same rail project on my 22 and used butyl when remounting. Much better solution IMHO. Just take a few days and cinch down daily for best results. Clean, effective and long lasting
 
I should mention that I use good quality butyl for most bedding now. I may have made it sound like I would only just barely consider trying it, or was lukewarm on it - not at all! In fact use it for anything where it isn't contraindicated.

Mainly I detest silicone (so that was my emphasis). Although I probably would use a bedding compound and not an adhesive polyurethane or the like, simply because I wouldn't feel the adhesive property was necessary and it makes life a bit more difficult when the time comes to re-bed/re-finish the rails (but nothing like the agony of silicone). I'm pretty spoiled by the ease of re-bedding with things like Dolfinite, butyl, and polysulfide.

There are times when I use adhesive polyurethanes or polyether though, so it's not like I have anything against them.
 
My problem with butyl tape is that you have to have it in compression. It has little if any adhesive property. If fittings loosen, then you can have a leak. This is where there have been a number of failures in RV's where the butyl is used because of the ease of application. (and less cost factor).

I realize it has achieved popularity in boats recently--I feel that there are better compounds.

I prefer 4000, because of the UV resistance. It has a cohesive factor with teak and fiberglass which is about the same in peel strength tests.
 
Absolutely, it is mostly a bedding compound, not an adhesive. My rails are all through bolted, so no adhesive is needed - but every situation is different.

I have not had one single failure/leak (yet) (knock on something!) on two boats, an RV, and a camper trailer (all fiberglass). I've bedded quite a few things (mostly aluminum/stainless/fiberglass, with a bit of plastic for variety). What I did find out is that 99.99% of the "butyl" sold at camper stores is inferior - truly horrible. I had five ancient rolls from work, and you could stretch them out to like five FEET without them breaking. When those ran out I bought rolls from a number of sources and they all broke with about a 4" stretch, if that. Horrible. I started buying it from Maine Sail (the pbase link above) and the rolls I get from him are just like the "good old" rolls I had at work. Stretch till the cows come home. And I like the ease of removal/re-doing when the time comes.

I experimented on some Starboard (in a spot where a leak would not be disaster) and so far it has gripped that tenaciously (surprised even me!?).

Everyone has their favorites though - and lots of things work well, especially with good prep. Just no silicone :amgry :wink
 
I, myself would not trust anything short of thru-bolts for a handrail. If you need them, you will want them bombproof ! Maybe this is due to my rock climbing years. Bombproof redundancy was the key to longevity. I use the same logic offshore. But that's just me. Vern
 
Vern, I believe that all of the handrails in the C Dorys are bolted. But there may be some which are not. Many of the SS railings, have a nut welded into the void, or a bolt thru the teak, with a bung on the top. If they are screwed, then they should be thru bolted.
 
Thank you all for the input. I know it is a debatable topic, I just needed a little help making my mind up. I should add that the rails were originally mounted with screws up though the inside, into the wood. I also forgot to mention that they had silicon when I removed them. I do not know if the silicon was original from the factory but was still holding a good seal, with zero signs of moisture on any of the screws. I have decided to go with butyl. I think it will work fine for something that will not be receiving any stress. From what I have gathered, a small bevel in the fiberglass will compress the butyl well when squeezing it down. Worse thing that could happen is it may leak and I will try something else.
 
The Teak caabin handrails on my 1987 Cruiser are held on with long lag-screws, and have never leaked after being taken off and refinished with 7 or more coats of clear polyurethane.

Don't remember what I used for a sealer, but it works (!). :lol: (It's hell getting older!) :smileo

Joe. :teeth :thup
 
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