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Sealant

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mm2347

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Oct 21, 2008
238
oday 222 niagara
I need to reinstall thru hull fittings, rudder, and swim ladder. Whats a good sealant?
 
Jan 24, 2005
4,881
Oday 222 Dighton, Ma.
I need to reinstall thru hull fittings, rudder, and swim ladder. Whats a good sealant?
I used 3-M 4000 uv adhesive sealant on my gudgeons and gunwale moldings. 3-M makes a 4200 and a 5200. I've used Boat-Life and found that the shelf life of this product is a lot less than the 3-M. For gudgeons, swim ladders, gunwale moldings, and through hull fittings, I stick with polysulfide caulking. For deck plates, the manufacturers recommend silicone caulking.
 
Dec 8, 2006
1,085
Oday 26 Starr, SC
mm2347:

Boat Life makes Life Caulk and Life Sealant. I have complained to them that a quick look at the package/labels and it is hard to tell the difference. Stay away from the Life caulk. The Life Sealant is a proprietary silicone polysulfide blend which is a good product.

As to 3M products. Boat manufacturers used to use 5200 which you need to stay away from. It is a permanent product which is difficult to repair later. The 4000, which I do not think that I have used sounds like a good product.

Consider butyl tape for deck fittings with its associated lap sealant. This combination is noteworthy for hatches and ports.

Ed K
26
 
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Dec 8, 2006
1,085
Oday 26 Starr, SC
Thank you for making me go back and look at the ingredience of these two products.

They make Life Caulk and Life Seal. I have used both. The Life Seal did as advertized. The Life caulk did not.

Why it did not, I do not know. Let me just say that after a few months it leaked. Later when evaluating the leak, I saw that I had used Life Caulk rather than the previous product Life Seal. The packaging is too similar on the products and I was not aware of the differences.

I was working on a project and needed more sealant and quickly grabbed the caulk off the shelf instead of the sealant. I wrote the company about the packaging and they never responded.

In summary, the Life Seal did as advertized. The Life Caulk did not. I do not know reasons. The usage in both was above waterline as surface sealant/adhesive on old fiberglass boats.

I am still replacing the the Life Caulk. At least it is easily replaced compared to 5200. My comments are based on my experiences only and in each case may be do to working on old sailboats and due to idiosyncrasy of that boat.

See their web site for accurate discription of uses and products:
http://boatlife.ipower.com/shop/index.php?main_page=index&cPath=6

However, the Life Seal is a 'marine silicone and polyurethane' whereas the caulk is a 'flexible marine polysulfide sealant'.

I would use the Life Seal again, but not the caulk. At least until someone shows me that it works on another boat. Who knows, maybe it was just an old tube? I guess I will have to look at expiration dates now.

Ed K
26
 
Feb 6, 1998
11,436
Canadian Sailcraft 36T Casco Bay, ME
Ed

Life Calk or polysulfide is generally considered the better product and I would guess that it was the method over the product. Silicone on boats makes future repairs very, very difficult as NOTHING sticks to silicone and as of yet we have not found a safe and effective way of cleaning up silicone contamination from gelcoat other than judicious sanding.

Bedding is much more about procedure than the sealant though a good sealant should be used not an acrylic product from a home center.

Polysulfides are excellent products and my personal bedding choice for anything but certain plastics or when I'm not using butyl. I prefer 3M 101 to life Calk as it seems to have a better shelf life, turns yellow less and is thicker in consistency, but others have had very good luck with it. Unless you are installing acrylic or Lexan hatches, Beckson ports or some plastic parts silicone should generally be avoided. Dow Corning 795 is the choice of most builders for acrylic hatches & ports. It is the only silicone I use..

These below waterline chain plates were sealed with polysulfide (same basic product as Life Calk) nearly 7 years ago and remain 100% bone dry despite being submerged. I used the countersink/chamfer method and they were then tightened down immediately..

Inside:
 
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Dec 8, 2006
1,085
Oday 26 Starr, SC
Maine Sail Moderator:

Thanks for the come back on the products.

I am familiar with the issue of what sticks to what. Sometimes it is a challange. Often the manufacterers just leave recommended adhesive/sealant blank.

I have been using acetone as cleaner to prep surfaces. In reviewing the Boat Life web site they have two interesting products. Look under 'Solvents & Removers' where they have a cleaner that is Acetone free formula. Cleans surfaces prior to caulking with Life-Calk or LifeSeal. Safe for fiberglass. Removes uncured polysulfide sealant and grease from tools and equipment.

I already use a acetone free cleanup product for working with epoxy that is non hazmat. I suspect that the proprietary formula is an alcohol based product. The important thing is that the stuff works.

Your comment on silicone residue made me wonder if silicone may have been used on the problematic surfaces I worked. I have no real idea what was there before. Maybe on of Life Boat's clean up products might help.

What are your experiences using butyl tapes?

Ed K
26
 
Jan 24, 2005
4,881
Oday 222 Dighton, Ma.
Re: Ed

I recently bought a tube of Dow Corning 795 black off Rudy and used it to seal my forward hatch after I rebuilt it. Rudy also mentioned that this is what they use on forward hatches. I had bought an old forward hatch off Rudy that had the parts that I needed. I used the Lexan lens from my old hatch cover and made one good hatch out of the two.
 
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