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Lately had some conversations about qualities of different Marine caulking/bedding compounds..
And in some of the replies on the subject had me thinking that there are some pills for the kind of behaviors observed in the responses.
Willing to hear of the latest "wonder" products for the kind of marine sealing and bedding done here,the question remains.
I have used a number of products throughout the years with different degrees of success for lasting integrity.
Did try the 3M 4200 and 5200 with great success,
Sykoflex bedding and sealing compounds has also been very good for repairs here.
What has been serving you well in sealing and what have you been disappointed with?
Looking to fill mini gaps bordering the gunwale wood garnishes on my Classic here.
Something transparent perhaps?

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I have always been aware that 3M 5200 is called an adhesive/sealant because it is a bear to remove. That is precisely the reason I have always used it. I also realize that 3M 4200 is more easily removed than 5200 and that's still another reason I use 5200. Either is good as a marine sealant as are several others such as BoatLife caulk. I do draw the line at silicone and never use it anywhere on my boat but save it for the bathroom and kitchen.

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Well, I disagree. 5200 and 4200 is a super strong ADHESIVE GLUE, for permanent assembly in boat building. I would never use it as a sealant or caulking material if permanent bonding is not desired. Of course, because of it's permanent bonding capability, it works as a sealant, but that is not it's purpose. It's purpose is to bond two components of a boat together, and achieving a no leak situation at the same time.

I have found the "Life Seal" and "Life Caulk" products to be about the best for sealing out water in unwanted places, including outboard engine mounting bolt holes. It has an indefinite life.

There are a few applications when you need to PERMANENTLY attach something in a non-exposed place on your boat. I have used 5200 for glueing a wood pad to the inside skin of a center console, so I could mount a fuse block. I also use it to glue on those plastic snap tie pads for securing wires inside the console.

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3M Corporation says their product, 5200, is an adhesive sealant so that's why I call it an adhesive sealant. I've used it as such for 45 years. I've never, ever had any damage to my boat from use of the product. Yes, it's hard to remove, that's why I use it.

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You are all correct in your opinions as to what has worked best. For the rest of us, take a look at the chart contained in this article for a better understanding of the differences and similarities between caulks and sealants.

http://www.goodoldboat.org/reader_ser...ealant.php

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For quick use, in a pinch, when removing and bedding screws, I have used plumbing mildew resistant tub and tile caulk. Boat Life is my go to product. Cleans up well with water when setting.

Garris

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Lawrence you are correct that Life Caulk is one of the best sealing compounds out there, it still performs good after 50 years. I used it for many years on my classic and antique Chris-Crafts keeping water out. It is a great bedding compound that can be much easier removed in the future than the great 3M 4200 & 5200 adhesives.
If you're looking for a bedding/sealing compound use Life Caulk, if you are looking to glue two boat parts together and seal it at the same time use the 3M products.

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When I bought my Outrage 21 "Ribside" ten years ago, it came with a little used 1988 Mercury 150 V-6. When I looked at the installation in detail I was shocked at the hack job the Mercury installer had done. The original engine on this old, shallow spashwell boat, was a Bearcat 85HP, and the newer Mercury replacement had the current B.I.A. deeper bolt pattern. Not having a clue as to how to install the lower engine bolts, he simply drilled a 5" diameter hole in the inside transom area glass skin at a foam "box" area (and where the factory HIN was located) and scooped out a 12" depth of foam to get back to the transom plywood for the lower bolt nuts. I was totally shocked when I saw it, and since it was also wet, knew I had to fix it right away by removing the engine and making this large repair.

I then quickly learned that the rest of his hack work was to use gobbs of 5200 as the engine bolt hole sealer. After removing the four engine bolts, the engine, weighing in at 400#, still hung on the transom and would not budge!! The 5200 had glued it to the glass transom skin!! Using a hammer and assorted chisels and screwdrivers, we finally broke the engine loose, along with several chunks of transom glass. What a disaster, all caused by some idiot who didn't have a clue what he was doing. Refinishing the transom for a new installation turned out to be a lot of glasswork.

So, go ahead and use 5200 for engine bolts and other simple caulking jobs if you insist, but beware the damage you will cause to your boat if the engine ever has to come off (and it will).

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I disagree - The mistake was using "gobs" of 5200.

I have used 5200 and 4200 for engine mounting bolts and have never had a problem with damage and I have used these products multiple times for this purpose and removed the engine multiple times without damage. I do prefer 4200 because it is softer than 5200. The nice thing about polyurethane adhesive/sealants is that they swell as they cure which means they do a GREAT job at sealing.

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The point for me in using the 3M 5200 will reside in the DURABILITY of the seal..
I have seen some noticeable shrinking of the seal when using the 4200 and..had to give it another coat to fill the void created.
It is not a practice that I like doing as I prefer applying one bead and wiping the surplus with a clean cotton rag.
Minimum shrinkage has been seen using the 5200 product.
I fell secure in knowing that the seal done in this manner will last for several decades.