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Catalina/Capri 25/250 Sailor's Forums

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Sealants above the waterline

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Jeff McK
Captain

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USA
389 Posts

Initially Posted - 10/25/2004 : 14:33:45

While I'm sure everyone has a favorite, does anyone have a general purpose favorite for bedding & sealing hardware to the topsides (fiberglass) where a fastener penetrates through to the interior. There are so many choices.

Quicker curing is good.

Thanks

Jeff McK
Formerly Event Horizon (sold)
C250 WK #805

Edited by - on

Oscar
Master Marine Consultant

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USA
2030 Posts

Response Posted - 10/25/2004 : 15:22:40

Polysulfide, or silicone....(marine grade of course). Read the labels for curing time.

In Lisboa making BU's...

Oscar
C42 # 76 "Lady Kay" (Formerly C250 WB #618)

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John Mason
Admiral

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USA
687 Posts

Response Posted - 10/25/2004 : 15:38:09

I put everything down with LifeSeal. It's a polyurethane/silicone hybrid.

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aeckhart
Master Marine Consultant

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USA
1709 Posts

Response Posted - 10/25/2004 : 18:08:59

LifeSeal - Let it cure a minute or so before securing your hardware, then tighten down. Cut away excess after total cure.

Al
GALLIVANT #5801

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Leon Sisson
Master Marine Consultant

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USA
1893 Posts

Response Posted - 10/25/2004 : 19:14:20

I bed deck hardware or wooden trim with polysulfide or silicone, as Oscar said.

-- Leon Sisson

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frankr
Captain

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256 Posts

Response Posted - 10/25/2004 : 20:35:11

Watch - some items like Spin Lock line clutches advise against using polyurathane/polysulfide sealants.

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Mark Loyacano
Navigator

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USA
247 Posts

Response Posted - 10/25/2004 : 21:16:06

There is an excellent article about this in this month's GOOD OLD BOAT magazine.

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 10/25/2004 : 22:40:23

Most anything but staight polyurethane caulk (like 3M 5200)--it's much too agressive as an adhesive and makes removal or rebedding almost impossible without damaging the gelcoat or, if the fitting is plastic, the fitting itself.

I use polysulfide (Life Caulk, etc.) for most deck stuff, and silicone where the sealant is completely hidden from the elements and I want maximum flexibility--for example, under the plates where the upper shroud chainplates go through the deck. (They want to move up and down a tiny bit, which can break the seal of ordinary caulk.) Silicone is very tough to clean up completely, and discolors to gray from sun exposure. I've favored Life Caulk over Life Seal based on the characteristics of polyurethane and of silicone I mentioned, but not based on any adverse experience with Life Seal.

I like the idea (which I picked up here) of drilling a shallow countersink where a bolt goes through the deck--just an indentation in the fiberglass. The idea is to give some extra room for caulk to surround the shaft of the bolt. Also, after the caulk has cured with the bolt just finger-tight, tighten the nut from below while preventing the bolt from turning from above, to maintain the integrity of the seal around the bolt as you compress the "gasket" created by the cured caulk.

Edited by - Dave Bristle on 10/25/2004 22:50:54

Jeff McK
Captain

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USA
389 Posts

Response Posted - 10/26/2004 : 09:12:08

Frank,

You've pointed out a potential problem for me. I was planning on swapping out the single spinlock on the starboard cabin top for a double. Since the Life Caulk that many seem to favor has polysulfide this might not be such a good choice. SpinLock recommends a silicone sealant in their literature. Other items will be a bullseye fairlead & a double cheek block to replace the current single near the mast on starboard.

Will the PU in LifeSeal cause a problem here? If so, would a straight marine silicone would be a better choice?

Edited by - on

John Mason
Admiral

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USA
687 Posts

Response Posted - 10/26/2004 : 15:31:49

LifeSeal can be used on plastic. I put my rope clutches on with it, also the cabin top Lewmar 7s, which have a plastic base. No problems. It doesn't cure very fast, so I finger tighten, then a coupla days later snug 'em down.

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John G-
Admiral

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793 Posts

Response Posted - 10/26/2004 : 17:55:21

I have to replace a stanchion.
Two questions.
Is it necessary to epoxy the holes and redrill?
What sealant? Lifeseal?
Please use brand names.
Thanks.

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Derek Crawford
Master Marine Consultant

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USA
3324 Posts

Response Posted - 10/26/2004 : 19:38:12

John - I rebedded my stanchions about 8 years ago and never redrilled and epoxied. I haven't had any leaks since.
Derek

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Leon Sisson
Master Marine Consultant

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USA
1893 Posts

Response Posted - 10/26/2004 : 19:55:38

John G-,<blockquote id="quote">quote:<hr height="1" noshade id="quote">I have to replace a stanchion. Is it necessary to epoxy the holes and redrill? What sealant?<hr height="1" noshade id="quote"></blockquote id="quote">I's say stanchions are second only to bow cleats in the importance of over-drill, fill, and redrill before bedding. The combination of a long lever arm and a small footprint greatly increases the likelihood of a leak in the bedding causing the plywood deck core to rot. I have replaced small areas of rotted deck core on a couple of boats, and it's such a horrible job that almost any effort is justified in reducing the chances of it ocurring.

After drilling 2x over and capping the bottom of each hole with tape, I coated the inside of the hole with WEST epoxy resin. I then mixed additional resin with lots of milled fiberglass, until it would barely self level and release trapped air. I put it in the holes with either a disposable wooden stick or a syringe.

The first time I rebedded my stanchions, I used some thin slimy white sealant the local boat yard suggested. That didn't work out well at all. Subsequently I've been bedding deck hardware with polysulfide sealant such as 3M 101, BoatLife LifeCaulk, or a polyurithane-silicone such as BoatLife LifeSeal with good results. To get the thick gasket effect that others have recommended, I use 3 or 4 small popsicle stick shims under the very edge of the stanchion base as far as possible from the mounting bolts. (I pull the shims out after the goo has cured and before final tightening of the fasteners.) I also countersink the tops of the poured epoxy bushings to create an O-ring of sealant as others have mentioned.

-- Leon Sisson

Edited by - on

John G-
Admiral

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793 Posts

Response Posted - 10/26/2004 : 21:03:38

<blockquote id="quote">quote:<hr height="1" noshade id="quote">I also countersink the tops of the poured epoxy bushings to create an O-ring of sealant as others have mentioned.
<hr height="1" noshade id="quote"></blockquote id="quote">
 
Leon,
Thanks for the detailed description.
Sorry to ask so many questions.
When you say you countersink the epoxy bushings do you mean after the epoxy is hard you take a large bit or a countersink bit and create a slight depression then drill the correct size hole for the bolt?

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ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 10/26/2004 : 21:58:44

Back to the original question.. I'm a fan of 3M 101 Sealant. Why? It goes on and sets up thicker than most of the other products I've tried, giving more of a 'gasket' effect.
Downside is that it's a slow cure.

Note that it (and other polysulfides) are incompatible with certain plastics... like the popular Spinlock clutches.

Edited by - on

Leon Sisson
Master Marine Consultant

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USA
1893 Posts

Response Posted - 10/26/2004 : 22:52:24

John G-,<blockquote id="quote">quote:<hr height="1" noshade id="quote">When you say you countersink the epoxy bushings do you mean after the epoxy is hard you take a large bit or a countersink bit and create a slight depression then drill the correct size hole for the bolt?<hr height="1" noshade id="quote"></blockquote id="quote">If you're a real artist (and/or consistantly lucky) you can ever so slightly underfill the overdrilled holes, leaving a hemispherical depression in the curing epoxy. I slightly overfill them, forming a dome but without creating a run. After the epoxy cures, I use a drum sander in a drill motor to carefully level the epoxy plug before redrilling the original size and location hole. Once the hole is drilled, I use a countersink bit to chamfer the weather end of the hole. The O.D. of the chamfer is no greater than the diameter of the cast in bushing, so as not to risk unsealing the deck core.

By the way, these cast in glass and epoxy bushings also serve as compression sleeves, allowing you to firmly tighten the fasteners without cracking or distorting the surounding fiberglass.

-- Leon Sisson

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John G-
Admiral

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793 Posts

Response Posted - 10/27/2004 : 03:27:08

Thanks Leon,
I knew you would have the technique down.
That really explains it.

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Jeff McK
Captain

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USA
389 Posts

Response Posted - 10/27/2004 : 12:46:46

Leon,

Good advice. Neat techique with the popsicle sticks. I assume you are using a Dremel or similar type device to smooth down the epoxy bumps. I've found a right-angle attachment or a flex cable extension is very helpful in tight spaces.

I'm no artist, so for the slight underfill technique, I've used a really complex tool with pretty good results: a plastic spoon & a paper towel. This gives a nice smooth depression, is easy to wipe clean, and is disposable.

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