sealant

My new thru-hull transducer is coming today and I was wondering what is the sealant of choice for the install. this is a first time project for me. I will have a hole after I remove the old ducer from a Garmin unit that was replaced with a Furuno.

3m 4200

David I thought 4200 was for UV resistance.

I'd be think'in Sika Flex 291 bedding compound.

manyboats said:

David I thought 4200 was for UV resistance.

I'd be think'in Sika Flex 291 bedding compound.

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The 3M 4000 is UV the resistant stuff. The 4200 just doesn't have the tenacity that 5200 has.

5200.

Real men use 5200. Looks like young Oliver is the only real man here.

HopCar said:

Real men use 5200. Looks like young Oliver is the only real man here.

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I only mess with that stuff when I have the following tools: at least a roll of paper towel and acetone. Otherwise I'm in the girl camp, been there done that wayyyyy to many times.

4200

Steve, seriously I think any of the modern marine sealants will work well in that application. I would avoid silicone rubber because it doesn't adhere very well but it would probably work anyway.

I was thinking about the 4200 because I used it around some window frames. I thought the 5200 was for things you never want to remove. maybe it's not quite as permanent as I thought.

Slowboat 37 said:

I thought the 5200 was for things you never want to remove. maybe it's not quite as permanent as I thought.

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Pretty close to permanent. There is something now called "DeBond" but it's still a PITA.

I went with 5200, not planning on having to remove it. It was an expensive and large broadband transducer with a hole 2 3/8" in diameter. There are some pretty good ways to remove it if you have to. A piece of braided spectra will slice right through the seal in the 5200 when used like a saw with a handle on each end. Taping before you apply the sealant will minimize the mess and the excess sealant lifts right off with the tape. Saw that in a YouTube video and it works as well as the video. Very clean install. Anything above the waterline I think I would use butyl tape by preference.

The key to any sealant is to realize unless it is something like the hull/deck seal, there will come a time when it needs to be removed.

5200 is great if you want almost forever.

4200 was creates so the bond could be broken (with much effort) but at least the pieces stayed intact.

Use whatever you like , but remember nothing is "forever" .

On deck and where appropriate I prefer the old style goop Dolphinite, that can easily be taken apart.

It is a sealant , but not a glue.

Slowboat 37 said:

My new thru-hull transducer is coming today and I was wondering what is the sealant of choice for the install. .

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Steve...
Here is a pretty good summary of properties & recommended uses for the 3M sealant / caulks

Why all this talk (me included) about high performance adhesive type sealants?

Think Dolfinite.
Don't see any reason why it wouldn't be perfect for the job. You don't need an adhesive at all. The large nut clamps the through hull fitting securely to the hull. Could'nt take it out w a crowbar.

All that's needed is a sealant to keep it from leaking. Dolphinite seals very well. And it's never going to dry out under water. I've seen Dolphinite last decades even on deck fittings. And of course it would be very easy to remove many years later.
What think?

Actually roofing tar would probably work well too.

I had mine installed by the yard so don't even know what's down there.

I will have a hole after I remove the old ducer

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How big a hole is left when you install the new one? Some glass / epoxy work may well be in order.

5200, 4200, Dophinite, Sikaflex, chewing gum, etc. They all will work.

For our boats, 4200 below the waterline or for any above waterline fittings without a good mechanical connection, UV 4000 for sealing the seam between our pilothouse and upper deck (needs to be redone every few years, but it is now glassed on the newer Nordic Tugs), and good butyl for everything else (i.e., above waterline with good mechanical connections like windows and deck hardware).

5200. 4200 is for wimps.

To my mind, 4200 is more than adequate for a through bolted transducer.

4200 is what we used at the marine electronics place....but most things will work

5200 is the best adhesive sealant on the market today. Why people insist on using something arguably second, third, or fourth best is beyond my understanding.

"5200 is the best adhesive sealant on the market today. Why people insist on using something arguably second, third, or fourth best is beyond my understanding."

Its very simple , sometimes a sealant is needed with out the adhesive portion.

FF said:

"5200 is the best adhesive sealant on the market today. Why people insist on using something arguably second, third, or fourth best is beyond my understanding."

Its very simple , sometimes a sealant is needed with out the adhesive portion.

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