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When we first took up sailing we learned quickly that there was a whole new set of words that we needed to add to our vocabulary. In addition to the boat terms though we have also come to realize that there is a complete set of boating products that we need to familiarize ourselves with too. Such is the case with marine adhesive sealants.

The above pic shows a sampling of the various types of adhesives and sealants that are available. The trick is to know the properties of each of them so that we choose the right product for the job. As an example, the infamous 5200 made by 3M is essentially permanent. Use this to bed something to the deck and you will NOT have a fun time trying to get it back off. Unfortunately (because I am now trying to remove it), I’m pretty sure that is what was used to seal the stainless steel hawsepipe cover to our boat’s deck!

In addition to the holding power of the sealants there are other qualities to be aware of too, one of which is UV resistance. I have two jobs in “the queue” that may require both UV resistance and the ability to remove the items (fasteners) at some point in the future. Because of these two requirements I “think” the product for the job is 3M’s 4000 (it’s not in the above photo because it is actually on the boat right now).

3M isn’t the only manufacturer of products like this of course. Sika’s Sikaflex is another line of sealants that I have seen on the chandlery’s shelves, and I’m sure there are others too. It would be super convenient if there was just one product that could suit every application but it doesn’t appear like that’s the case. I guess I’ll just have to go against my manly nature and actually read the packaging to know which one to use.


    Butyl rubber tape is another. Great for through-bolted items you will remove someday, like winches, cam cleats, and jammers. Not for windows, screw-mounted hardware, or…
    * heat
    * gasoline exposure
    * anything that requires adhesive properties
    On the other hand…
    * no low-temperature limit
    * no drying time
    * never hardens
    * long shelf life

    I might even take silicone off the list. Something else is generally better, and once you use silicone, nothing else will stick, even silicone.

    • I saw a mention of butyl tape on a forum. I made a note after that to buy some but then the other day while searching through lockers on the boat I found that the previous owner had actually left me some. 🙂

    • On the walls where the main cabin door is (cockpit into salon), the top part of the walls that the slider rests on when closed is starting to come loose where whatever adhesive was used is giving way. What would you use for that application? 4000?

  2. Mike –

    Boy you hit that nail on the head. Great subject. There are so many kinds of sealants and adhesives that the folks on shore have never heard of…

    But it has been fun learning. If you don’t want that wall to come loose again, use 5200. I love this stuff for permanent repairs… let me give an example from the non-boating world:

    The top on my wife’s old ratty VW cabriolet was cracked, right where it folded when you put it down… probably because this is where the flex and stretch concentrate. I put on a dab of 5200 and gave it a couple of days to cure. It is doing just fine, and is far, far stronger than the original top material!

    I think I have gravitated pretty much to two basics: polysulphide for non-permanent sealing jobs, and 5200 for the permanent. I use silicone in only two places on Eolian: To seal our Beckson ports to the hull – because Beckson requires it.
    When making up head hoses, I use it as a lubricant (during assembly), and as a sealant (afterwards). It works well there because the heat gun I use to soften the end of the hose does not harm the uncured silicone.

    Oh yeah – for attaching wood to lumpy uneven fiberglass, I use Gorilla Glue because it foams and fills the gaps (but not for structural things – that would require fiberglass tape and epoxy). And for teak joinery, I use 5 min or 30 min epoxy. There. That is pretty much the whole list.

    And then there is paint – another whole new world.


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