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Any Wisdom on Re-bedding Stations?

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joegeiger
1st Mate

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USA
63 Posts

Initially Posted - 06/24/2005 : 11:07:08

I've noticed a little rust around the base of the most aft starboard stantion. I think it's time to rebed all of them and the bow and stern pulpits. How big a job is this? What is the best bedding compound to use? Any tricks or advice you can give me would be greatly appreciated.

Also I've noticed a few stress cracks in the gelcoat around the forward stern pulpit stantions. Is it important to fix those or is it alright to leave them as is?

My boat is an "86 FK/SR Hull#5401.

Thanks for your help.

Joe

Edited by - on

Dave Laux
Captain

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318 Posts

Response Posted - 06/25/2005 : 07:30:58

The cracks will allow water to get into the plywood core material so should be repaired after drying them out. Loose fasteners or decayed bedding compound will also allow water in. If you have seriously wet core you have a major problem cause its hard to get the water back out.
When you get the cracks and water sorted out rebedding is fairly simple. Draw around the base of the fitting. Tape (masking) to about 1/16 outside the lines. Put down a generous amount of caulk. Set the fitting and bolts and snug the bolts until you squeeze the caulk to a uniform 1/32 thickness. Let set for as long as you can. At least a couple of days. Tighten the bolts to normal (firm but not too tight). Take a knife and cut the caulk around the base. Lift the tape and the excess caulk. Dave

Edited by - on

ronrryan
Admiral

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USA
561 Posts

Response Posted - 06/25/2005 : 11:51:35

What Dave said, except if possible, when tightening after the goop sets, carefully hold the outside of the fasstener to prevent turning, and tighten only from the bottom, so as not to break the caulking seal of the goop.(Obviously, this works only on thrubolted items) Good luck, ron srsk Orion SW FL

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Leon Sisson
Master Marine Consultant

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USA
1893 Posts

Response Posted - 06/25/2005 : 15:36:25

In my opinion, stanchions bolted through cored deck is a real good place to use cast in epoxy bushings to prevent leaks into the core, or fastener loads crushing the core and crazing the deck and/or headliner.

-- Leon Sisson

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ddlyle
Captain

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302 Posts

Response Posted - 06/26/2005 : 22:23:50

Okay Leon ... you got me.

How does one acquire these cast in epoxy bushings?
They sound delightful.
Thanks

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Frank Hopper
Past Commodore

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Pitcairn Island
6776 Posts

Response Posted - 06/26/2005 : 23:30:20

You know Leon, one of these days I am going to through bolt something that way, maybe soon.

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lcharlot
Master Marine Consultant

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Antigua and Barbuda
1301 Posts

Response Posted - 06/27/2005 : 01:27:00

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by joegeiger
 I think it's time to rebed all of them and the bow and stern pulpits. How big a job is this? What is the best bedding compound to use?
My boat is an "86 FK/SR Hull#5401.

<hr height="1" noshade id="quote"></blockquote id="quote">

The stanchions aren't too hard to re-bed, since you can get at the nuts from inside the cabin. The stern pulpit is another story - the nuts are just about impossible to get at. Pulpits are attached to the deck at the factory while the deck and hull are still separated; once they are joined, the bow and stern pulpit nuts and backing washers are a nightmare to get at from down inside the boat. You will need mirrors and a set of ratchet extentions in various lengths, plus a set of deep sockets to do the job, and some of the nuts may prove to be impossible to get at. For those, you will have to grind the bolt heads off from the outside to remove the pulpit, then use wedge anchors or some other kind of one-side-access-only fasteners during the reinstallation. For the bedding compound, I would use 3M-4200 Polyurethane, SikaFlex, or BoatLife. 3M-5200 will also work, but it's adhesion is very strong, making it difficult to disassemble those parts again if you ever need to.

Edited by - on

thaind
Navigator

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Canada
145 Posts

Response Posted - 06/27/2005 : 08:15:47

I had to weld the broken port aft stantion and found some leftover Gitrot epoxy ideal for sealing the bolt hole without creating a bushing. Mask the inside with duct tape and fill the holes with gitrot until flush, may take two or three applications. Then redrill bolt hole and continue. Gitrot has a realy low viscosity and penetrated from the upper to the lower holes. I don't think that it is therefore neccessary to bore oversize in the begining and risk reboring off-centred.

Edited by - thaind on 06/27/2005 09:30:52

Frank Hopper
Past Commodore

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Pitcairn Island
6776 Posts

Response Posted - 06/27/2005 : 11:04:31

Leon, your cast comment I assume means where you coat the bolt in wax and have it in the epoxy while it sets and then you unscrew it out leaving the thread casting behind.

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Leon Sisson
Master Marine Consultant

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USA
1893 Posts

Response Posted - 06/27/2005 : 18:54:12

<blockquote id="quote">quote:<hr height="1" noshade id="quote">originally posted by Cap'n Dave:
How does one acquire these cast in epoxy bushings?<hr height="1" noshade id="quote"></blockquote id="quote">You cook up your own at home. There's more than one technique for doing this. I'll try to describe a couple of the ones more frequently mentioned here.

Here's the method I use most often (a.k.a. the fool proof lazy method): Drill the cored thru-deck hole out to twice its original diameter. Tape over the bottom opening. Paint the walls of the hole with unthickened epoxy until saturated. Mix up some more epoxy thickened with milled fiberglass or other fiber. Pour the holes full with that. I try to very slightly over fill them to allow for the core to continue absorbing resin before it cures. After the epoxy & fiber plug has hardened (next day), I use a drum sander in a slow turning drill motor to carefully level off any remaining over fill. I then use the part being attached as a drilling jig to establish the new hole in the original location and diameter. Finally, I very slightly countersink the top edge of the hole to help form an O-ring of sealant when the part is installed.

Here's my understanding of a variation described by Dave Laux: Using an L-shaped cutter chucked in a spinning drill, carefully reach down in the original hole, and remove a cylinder shaped portion of the core material in the immediate vacinity of the hole (leaving the skins intact). Depending on the core material and hole diameter, I've used bent nails, cut off motorcycle wire wheel spokes (fistfulls for free at your local bike shop), cheap allen wrenches, etc., all sharpened to act as a flycutter. Expect to tear up whatever improvised cutter you use. Blow out the debris with a vacuum or compressed air. Then proceed as described above with tape, saturate, fill, cure, level off, redrill, slightly countersink.

With either of these methods, do about half of the holes for a piece of hardware at a time, so that bolts dropped through the remaining holes can help maintain the original location and orientation of the part. If doing only one part, this can be tedious. If you do a whole lot of deck hardware at once, it goes real fast. I did almost all of my deck mounted hardware at once in about two or three evenings after work.
<blockquote id="quote">quote:<hr height="1" noshade id="quote">originally posted by Frank and Martha:

...where you coat the bolt in wax and have it in the epoxy while it sets and then you unscrew it out leaving the thread casting behind.<hr height="1" noshade id="quote"></blockquote id="quote">That's yet another variation which can be combined with either of the methods above, or can be used to produce a threaded blind hole. (as in no nut, or even a visible hole sticking through on the other side.) If using this method, stick with course machine threads, get the wax very thin and even, and go at least two or three bolt diameters deep. Of course the cast hole needs to be at least slightly deeper than the final installed length of the fastener. If the final install involves washers, leave them off when casting. Or use a slightly longer fastener for the casting phase. Whatever - just don't forget to do something to prevent the threads from bottoming out before the part is down tight. Be carefull when thickening the filler resin not to get it so stiff it won't completely flow into the bolt threads, leaving them shallow and weak. I'd suggest practicing with this method on something lightly loaded before taking on winches, halyard clutches, or other heavily stressed parts.

-- Leon Sisson

Edited by - on

thaind
Navigator

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Canada
145 Posts

Response Posted - 06/27/2005 : 23:05:29

Leon, why would you not simply drill and tap the hole rather than attempting to cast it threaded?

Edited by - on

Leon Sisson
Master Marine Consultant

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USA
1893 Posts

Response Posted - 06/27/2005 : 23:38:46

Derek,<blockquote id="quote">quote:<hr height="1" noshade id="quote">why would you not simply drill and tap the hole rather than attempting to cast it threaded?<hr height="1" noshade id="quote"></blockquote id="quote">That's a very good question! Has anyone here tried tapping epoxy? I read the cast threads method in "The Gougeon Brothers On Boat Construction" (and if they don't know epoxy, no one does), and just assumed there was some really good reason not to cut threads in epoxy. In fact, they go on for 20 pages or so on the topic of cast threads and bonded fasteners with technical explanations, quantitative lab data, incredibly detailed techniques, etc. I just now skimmed back over it, and saw no mention of tapped threads at all.

Come to think of it, I have tapped epoxy, but only for small very lightly loaded fasteners. And by the way, the Gougeon/WEST folks are very forthcoming with technical data and consultation. They have sort of an epoxy users' hotline. If anyone among us were to take the initiative (he said without actually volunteering

), I'm sure they'd have a detailed technical but understandable answer.

-- Leon Sisson

Edited by - Leon Sisson on 06/28/2005 00:01:15

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