How to bed hardware?

[JeffM]

I've never done this before, and I suspect its too important to risk screwing up: how do you bed hardware? I'm preparing to attach bow eye, pintles & gudgeons, store-bought hatches, gunwhales, cleats, etc. My best guess is that holes should be painted with epoxy for insurance, then a little non-adhesive caulk (like the silicone I use on the tub?) should be applied around the screws and bolts before(?) they're tightened. Can anyone give me some straightforward techniques?

[Barry Pyeatt]

Yes to epoxy coating the screw holes. For parts that are going to be load bearing or structural in nature, I would seriously consider drilling over sized holes and then using small spacers insert the screws/bolts into the holes and then filling the hole with epoxy. The spacers keep the bolt centered in the hole and let the epoxy seal completely around it. This prevents any wicking of moisture along threads and prevents any rot from beginning around the screw/bolt holes in the material. Little extra work, but if you are serious about doing a long lasting job of it, then it is worth the effort. Once the bolts are bedded in epoxy this way, they are stronger than the material around them.

3M 101 is a bedding compound with only a little stickum. Apply it to the parts being bedded and just tighten them enough that they contact. Let the bedding compound setup a bit, (kick off) and then tighten them down the rest of the way. That way you won't be squeezing the material out from beneath the parts.

You can also use dolphinite which is available from a lot of marine supply houses.

3M 4300 is also a bedding compound but has a bit more of an adhesieve quality to it. Things will be bedded well but difficult to remove when needed.

3M 5200 is calk/adhesieve and only used where it is going to be permanently in place.

I would use the 101 and not silicone or modified house caulk personally. It is designed for this use and works extreemly well.

[Frank Hagan]

Barry, that's an interesting method ... slightly oversize holes with spacers, and epoxy filled in around the fastener. I think that would work well, as the epoxy would then seal well against the threads.

For critical areas, where water may pool like on decks, etc., I've used a slightly different technique. I drill an oversized hole and then use plastic tape on the underside and fill the hole with unthickened epoxy. Once cured, I drill through the epoxy for the fastener. Then I bed the hardware with one of the available bedding compounds (3M 4300, Sikaflex or BoatLife Caulk). Any water that penetrates under the hardware and wicks down along the threads of the fastener doesn't cause rot to the wood. This has worked well, even though the hole in the epoxy could let water drip inside, I haven't had a problem with that. I think the bedding compound does very well along the threads of the fastener and doesn't deteriorate as quickly as it does up on top.

[Tim Diebert]

I will jump in on this one and plop my opinion and method down.

I have bedded down hundreds of below and above the waterline fittings.

I learned from an old cogger that was beyond fussy.

If on new work...wood. Seal the hole edges always a good thing....but we never did it in new construction or on new holes in old construction. Either in glass or wood. Not to say this is right or wrong.

I have only a little experience with the 3M products, what I have used worked great. But my main experience has been with Boatlife Caulk and various sikaflex products. The cure time and set time works for me. And I can usually find these products around.

Use enough bedding compound so that you get squeeze out. Torque it down, scrape off access and clean up tight to joint with a rag and paint thinners.

If you are using bolts, run the bolts through, then 'wick them' with good fluffy cotton string. build up a good sized lump right under your plate on the bolt, break it off. You can also first wick under the washer of the bolt head. When tightening, try to move only the nut. Get lots of goop right around the wicking and the fitting and bed her down, clean up. I do the same with through hulls. Trick is to use plenty of bedding so it is totally covered down there.

I like Barry's pre-torque and post-torque method, never done it myself, but it sounds like a good plan.

[JeffM]

Thank you, Gentlemen! Barry's method seems clear enough. Thanks also for the recommendations on compounds. I wonder how difficult it might be to loosen a bolt that is epoxied in place? Frank's method is familiar -- my rudder and cb pivot on epoxy bushings. Tim, I don't know what you mean by "wicking." Please explain.

[PAR]

I don't use Dolfinite for anything other then wood to wood beds. As has been said, 3M 5200 is a very aggressive adhesive/sealant and will stick like nobodies business. Parts joined with this goo will be damaged, come removal time. 3M 4200 is almost as aggressive, but with a little jaw clenching and talking kindly to the pieces, it can be asked to separate. 3M 101 is at the bottom of the stick-em-to-it-ness scale, a real bedding compound. BoatLife caulk has more adhesive qualities then 3M 101, but is still a good bedding compound.

I bond all weather deck fasteners and below LWL fasteners. I don't bother with the hole centering tricks, though I may use a tooth pick on the over size hole after the epoxy has kicked, but is still quite soft, to provide a center punch for the re-drilling operation. I wet out the oversize hole (about 40 - 50% bigger then shank of the fastener) with unthickened epoxy (to prevent glue starvation), then fill the hole with thickened epoxy. The filler is typically colloidal silica or milled 'glass fibers (usually a mixture of both) this makes a very strong bond with the substrate. Then I drill out the hole the exact size of the threads. I fill this new hole about half way with unthickened epoxy and insert the bolt/screw. If the bolt/screw is to be removed often for maintenance, then I coat the screw with paste wax before shoving it in the hole. This technique provides a "keyed" hole, with epoxy completely surrounding the threads and mechanically bonded to the oversize hole, which is laminated to the substrate. The wax permits easy screw/bolt removal, but the mechanical "keying" remains in place for a much stronger fastener to substrate lock. A soldering iron held to the end of the screw or bolt will soften the epoxy enough for removal on fasteners not waxed.

Fastener holes done like this can have the fastener removed and re-installed many times without the hole or threads stripping out. On things like deck cleats, fair leads, bow lights or anything that may need to be moved, changed, upgraded or damaged by dropping an anchor on it or something, I wax the threads and use a less aggressive caulk like BoatLife or 3M 101. These are pieces that will require re-bedding from time to time. Parts that will not likely see removal for a decade or so, unless you get rammed by a destroyer, like bow eyes, chain plates, thru hulls, headsail tracks, rub rails and the like I use an aggressive caulk like 3M 4200 or 5200. Generally these will be heavy load, maybe structural members.

A little trick I use to seal the top of the re-drilled hole is to stick clear plastic box tape on the underside of the part getting fastened down, then insert the waxed fastener in the part's hold down holes. I usually place a weight on top until the glue sets, then I remove the fastener, bed with goo and re-fasten.

Log onto WWW.WestSystem.com for a very well shown description of this technique. They also will show you several other cool tricks to help with these sort of things, using epoxy.

[BobSmalser]

In hard-use applications like this tiller yoke and thwart, I bed the entire hardware mortise in epoxy, to include the screw holes as has been described. Use paste wax as a release agent on the metal.

When fastening hardware plywood I double drill all the holes using epoxy as Frank describes...then use a bedding compound, too. I believe it a big mistake to rely on mild putty like common bedding compounds alone to seal something as critical as those absorbant and fragile lams.

Otherwise I use an industrial poly sealant similar to 4200. It's adhesive, but it lasts forever and doesn't leak. When applied between two painted surfaces it comes right off with a length of piano wire and no damage can occur beyond your layer of paint. Followup with a heat gun and a scraper and it comes right off with the paint. Course you gotta repaint....but I was gonna do that anyways.

Special applications like this CB pin get both a neoprene gasket and a tad of poly sealant.

And nail and drift holes should be swabbed with red lead paste before driving. Acts as a good lube, too, for those tight bronze drifts.

Here you see poly sealant and red lead used together to rivet a CB trunk.

Finally, some hardware I simply glue on in addition its fasteners using epoxy, if the installation is fragile and I want max strength. Heating the part up with a large soldering iron or torch easily releases the epoxy. Ever had a stem too sharp to make a brass nose strip for? Simply rasp a small flat and install narrow bronze flat stock using large brass box nails and epoxy.

[Stump]

I'm serious Bob, have you ever thought about getting your pic's together and publiching a book on all this stuff you give us for free?

It always blows me away when I see the stuff you post.

[Russ Sylvester]

How is it that I learn more from just ONE of Bob's posts than from an entire book that I purchase on a subject. I agree with Stump there Bob. You truly should put all of this priceless information into a book of some type. Kind of a "Boatbuilder's Apprentice" or something. I know I would be first in line to buy one.

Russ

[BobSmalser]

5200 is interesting stuff. It's certainly a glue when you assemble bare wood with it...but saturate that wood with water, and that 5200 pulls off like rope.

I had to make a specialized work punt in a hurry several years ago and nailed the lengthwise cedar planking to the frames under clamping pressure with no caulking seams and 5200 between. Tar on the bottom and linseed on the top was the only protection.

That punt stayed in the water like that for 6 straight years before I got around to pulling it out to saw in proper caulking seams and paint it. The 5200 was still fully functional but no longer had any adherence to the wood at all below the waterline....and not all that much above the waterline.

I don't trust the stuff or its construction-adhesive ilk for anything other than sealants.

[Tim Diebert]

Jeff, sorry man, I missed this.

Tim, I don't know what you mean by "wicking." Please explain.

The wicking is the cotton string. I use it under any under water fastener that has a washer. ie: a pan head screw and washer or a washer under a bolt head...or even under a carriage bolt head.

The string has to be fine enough to be able to break with your hand.

I wind it clockwise around the bolt shaft just up against the washer. Build up a 1/8" kind of gasket. Snap it off...run a bead of polysulphide around there, bed the sucker down. If you wind it clockwise (whilst holding the bolt upside down, head down, threads towards you) it will not unravel if you manage to turn the washer when tightening.

I have no idea why it is called a 'wicking', sounds like the last thing you would want to call something that is supposed to prevent wicking....

This old shipwright I worked for at the time was third generation shipwright and he was in his 70's when I worked for him. Some of the terms he came up with were old world british. Spent most of my time with him being yelled at, learning to understand his lingo and peeling him off boat owners he wanted to toss off the work float.

[JeffM]

Thanks, Tim. Sounds like the point of the string is to prevent the tightening of the fastener from squeezing all the bedding compound out.