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Plugging leaks in Gudgeon Through-bolt holes

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bbriner
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349 Posts

Initially Posted - 06/26/2006 : 17:04:51

It's my turn finally with the whole lower gudgeon replacement thing. That's under control (thanks to all the notes about this in the archives). The fact that one of the bolts sheared off - in the hole - did make it a little more interesting. Thankfully I didn't lose the rudder, especially while under sail. (As an aside, I've ordered the CD HD Gudgeon as a replacement).

However, in taking the rudder off and cleaning it up I noticed the lower pintle was very loose. After 22 years of wear, the holes are now too big for the bolts. So, it seems that the best thing to do is to drill out the holes, fill them with epoxy then drill new bolt holes through the epoxy filler.

My question for those who have done this is - how big do I have to drill the holes for the epoxy filler?

Any other suggestions are welcome too. TIA!

Bill B
Wind Dancer
#4036 84 SR/FK
San Francisco Bay

Edited by - bbriner on 07/05/2006 14:12:40

Leon Sisson
Master Marine Consultant

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Response Posted - 06/26/2006 : 20:57:32

Re: "My question for those who have done this is - how big do I have to drill the holes for the epoxy filler?"

I'd say a good guideline would be at least twice the fastener diameter, more if the fastener is to be shear loaded within an inch of its life, or if the core and skin materials are uncomfortably soft and/or thin. I assume you already know about mixing reinforcing additives with the epoxy filler, such as milled fiberglass, cotton microfibers, aluminum powder, coloidial silica, etc.

-- Leon Sisson

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bbriner
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Response Posted - 06/27/2006 : 00:54:23

Leon
Thank you! I was just thinking that the epoxy plug would be like a compression tube between the two sides of the pintle so the thought never even crossed my mind. It's certainly a good idea to add some more strength to the whole contraption - especially with these kinds of stresses. In some book (don't remember which) the author suggested that when doing this (using the epoxy plug) you should drill out the insides of the hole with something like an inverted allen wrench, making a 'tongue in groove' like fitting for more strength. Is that recommended too? Has anyone done that?

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Leon Sisson
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Response Posted - 06/27/2006 : 09:49:47

You're welcome, Bill!

Yes, I also like the technique of hollowing out the space for the cast bushing, leaving the fiberglass skins intact. My quick and dirty compromise is to only enlarge the hole in one skin (the 'top' one), and stop when the drill bit just touches the second skin. I think the hollow out the core method is particularly appropriate where the core is very soft and/or damaged (honeycomb, foam, balsa, rotted wood).

In addition to a modified cheap allen wrench, I've also used a bent nail. I think a cut off and sharpened motocycle wire wheel spoke would work too. They're made of very good steel, and already have a heavy hook formed on one end. Most any bike shop is likely to have fist fulls of those lying around, or they may direct you and your light duty bolt cutters to a particularly forlorn corner of their graveyard out back.

Another tool I think would work well is a small circular saw bit chucked in a die grinder (a.k.a. Dremel tool), although it can never reach 2x diameter without enlarging the hole in one skin by 1/8".

-- Leon Sisson

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Heartbeat
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Response Posted - 06/27/2006 : 21:24:21

Well, I once ripped the whole lower pintle out of the rudder. As it turned out, the previous owner had 'helped' with a prior grounding. I had about a 5" x 3" hole in the lower section of my rudder where the lower pintle should have been. I am not kidding - I though the whole rudder was toast... Luckily I had some friends that "had seen worse." I still owe those guys a beer every time I see them!

Under direction, I used the West/Gugeon system with silica (cut glass threads) to fill in the colossal lost area. Then I glassed the whole thing in with new fabric. I put a layer of gel coat (using the spray 'mold release' to get it to set) to finish the whole thing. I had to spread the pintles a bit, but the rudder was solid.

Since the repair, I have raced the boat with a kite up on a beam reach at 8+ knots with the rudder throwing a bit of a rooster tail. It held up just fine.

I would suggest that you grind/dremel out the area until you reach clean (and dry) foam core. Next, mix yourself up a batch of silica/epoxy to fill in the lost area. Then wrap the thing with epoxy/cloth and paint or gel coat. It will be stronger than the original, although slightly heavier.

-Matt Q.

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bbriner
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Response Posted - 06/28/2006 : 10:49:51

Matt - great advice. Thanks!

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Heartbeat
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Response Posted - 06/28/2006 : 21:55:47

Bill,

Glad I could help. Seal that rudder up - I continue to be amazed how strong glass repairs are.

I should also add that the repair gurus I worked with had a tip for me on every hole I drilled on the boat. Overdrill with the next drill size up. Fill with the epoxy/silica, then re-drill with the right sized drill. Seal with 4200 and put baking plates and oversize washers.

This has probably been covered many times, though. Shall I start an oil thread next? *lol*

Matt Q.

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bbriner
Captain

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Response Posted - 07/02/2006 : 12:01:59

This was my first time doing the overdrilling and filling with expoy bit. I had duct tape on the bottom which I thought I had covered really tightly. I poured the epoxy in when still quite liquid so it would fill in all the spaces in the foam core. After several hours I removed the tape and found that some of the epoxy had leaked out of the hole between the tape and the indentation where the pintle goes - so I have a thin layer of epoxy in there. I'm a little concerned about doing this in more sensitive places now. Is there some trick to it?

Edited by - bbriner on 07/03/2006 10:54:06

Frank Hopper
Past Commodore

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Pitcairn Island
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Response Posted - 07/03/2006 : 11:24:36

"Fill with the epoxy/silica, " or some other thickened epoxy. I save all of the teak dust from my orbital for this purpose but am not out of micro balloons yet so I have not used any dust yet.

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bbriner
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Response Posted - 07/05/2006 : 14:12:08

This weekend I completed this project: mounting the new CD Gudgeons, through-bolting the lower gudgeon (I did the upper one 2 yrs ago), drilling out the lower pintle holes on the rudder, epoxying them, drilling them out and reinstalling the pintle.

On Sunday, all was good until I checked the lower gudgeon after a nice sail. I crawled into the aft quarter berth and checked them out and they were damp!! They weren't dripping but they were damp - and they shouldn't be.

So, what to do now? I put quite a bit of 4200 on the gudgeon but in hindsight I realize that I neglected the through bolt itself. So I will have to take out the bolts and seal the entrance hole to stop the water from seaping into the hole.

What do I do about bolt holes though? How do I get them dry before sealing them up again? Suggestions?

Thanks again... I thought I was done but not quite yet.

Edited by - on

Leon Sisson
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Response Posted - 07/05/2006 : 16:39:16

Bill B, <blockquote id="quote">quote:<hr height="1" noshade id="quote"> ...to stop the water from seaping into the hole... What do I do about bolt holes though? How do I get them dry before sealing them up again? Suggestions? <hr height="1" noshade id="quote"></blockquote id="quote"> When using the drill 2x, fill, redrill technique for protecting cored laminate where one of the surfaces are exposed to water (including rain), I suggest countersinking the exposed end of the hole slightly. Don't get carried away with the countersink bit, or you might break out through the edge of the poured bushing, eliminating its compression sleeve support function, and exposing core. If the over drill was 200% original diameter, only countersink to maybe 125% original diameter. Then when the sealant is applied, it will form sort of an O-ring in the countersink around the fastener, helping to seal it.

I have a couple of suggestions regarding: <blockquote id="quote">quote:<hr height="1" noshade id="quote"> I had duct tape on the bottom which I thought I had covered really tightly. I poured the epoxy in when still quite liquid so it would fill in all the spaces in the foam core. After several hours I removed the tape and found that some of the epoxy had leaked out of the hole between the tape ... Is there some trick to it? <hr height="1" noshade id="quote"></blockquote id="quote"> Using unthickened epoxy to improve penetration and saturation is a good idea. However, I usually paint the inside of the hole with a couple coats of unthickened epoxy in rapid succession (two or more applications from the same batch). for the more fanatical, try briefly heating the work piece with a hairdryer or heat lamp just before coating the core and adding filler. The heat causes air trapped in pockets (cells of wood or foam) to expand. As the work cools, the remaining air contracts, creating a vacuum, and pulling resin deeper into the pores of the core material. Having thus assured a good boundary bond, I fill the rest of the hole with reinforced epoxy so thick it will just barely allow air to escape, perhaps aided by some gentle poking and stirring with a toothpick. On small jobs, with good timing and temperature, this can all be done with the same batch of epoxy by painting the sides of the hole after thorough mixing, but before adding fillers. Using fibers to thicken and reinforce the resin doesn't really stop the liquid from penetrating, as it can flow out from among the fibers into tiny details of the surrounding void. However, adding finely powdered thickeners will impede wicking into the surrounding porous materials. Regardless of what filler is used, check for sinkholes while there's still time to establish a strong primary chemical bond with the added filler.

To reduce the likelihood of resin escaping the dam on the bottom of the hole, first carefully inspect the edge of the hole and surrounding surface for chips, cracks, and other imperfections. If it looks smooth, then try using a larger patch of tape, and mashing the tape down harder. If you can see there are potential resin leaks tape won't fix, then consider using a putty type filler, such as the modeling clay like caulk sold to seal around RV window frames. Obviously you don't want to get the putty up into the hole (unless it's on the side you want to countersink

). Maybe just force a small amount of putty into the imperfections before applying tape.

-- Leon Sisson

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dlucier
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Virgin Islands (United Kingdom)
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Response Posted - 07/05/2006 : 17:23:15

Bill,

If water is leaking past the bolts on the lower gudgeon, you could try using neoprene washers to keep the water out.

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bbriner
Captain

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Response Posted - 07/05/2006 : 18:22:02

Leon,
I can see how what you describe - and thank you for the great detail! - is great for a vertical hole, like that for stanchions or deck hardware. I'm guessing though that this isn't recommended for horizontal holes like the holes for the gudgeon bolts. I'm kinda stuck on that now... (#1) drying the now-wet core around the hole, and (#2) sealing them so they don't leak anymore. I think I can do #2 by making sure the hole is sealed on the outside with 4200 (or other?).. but #1? Does this make sense?

A question WRT the neoprene washers, does anyone have any experience with using those? I hope to not have to do this too many times :)

Edited by - on

Leon Sisson
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Response Posted - 07/05/2006 : 20:18:34

Bill B,<blockquote id="quote">quote:<hr height="1" noshade id="quote">I can see [now?] what you describe ... for a vertical hole, ... guessing ... isn't recommended for horizontal holes like the holes for the gudgeon bolts.<hr height="1" noshade id="quote"></blockquote id="quote">I used the same general procedure I described above on the gudgeon bolt holes and motor mount holes in the transom. Think of the outboard surface as the 'lower' (to be sealed flat with tape), and the inboard surface as the 'upper' (through which you will apply the filler). About the only differences are that after swabbing the over-drilled holes with unthickened epoxy, I used duct tape to form a sort of scoop shaped pouring funnel stuck over and around the hole inside the transom. It's hard to describe -- the bottom edge of tape is taught and slightly curved. The top edge of the tape bulges out over the width of the hole, forming a tapering passage leading down to the hole. I then mix the filler to a pourable consistency, and fill the scoop to its top edge. (In tight locations, a disposable plastic syringe can be helpful in adding the thickened epoxy without getting it all over the place.) As trapped air finds its way to the surface, and filler soaks into the core, I continue adding thickened filler to keep the scoop full. After the plug has hardened, before redrilling the original size hole (or 5/16" hole in the case of C-25 replacement gudgeons), I remove the tape, and grind or sand the scoop-shaped lump of epoxy flush with the inner surface of the transom. I hope that's not too muddled. It's easier from me to do than to describe.

-- Leon Sisson

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ct95949
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Aruba
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Response Posted - 07/06/2006 : 10:31:15

When I replaced the gudgeons,installed a swim ladder and fabricated a scupper in the transom I used the tape and epoxy method Leon describes above-works great.I poured the epoxy from the outside of the transom being easier to access but I also had to replace more gelcoat after sanding the epoxy down.
You will find some parts of the transom have layers and cavitys which can be stuffed with newspaper away from the hole to keep the epoxy from running into the bilge.
I backed up all transom fasteners with epoxy coated 3/8" plywood (the transom seems a little thin and weak to me).
I always bevel all fastener holes with a countersink bit so the hole will accept a bead of 4200.Don't tighten the bolt until the sealant is cured and you will have a nice 'washer' to seal the hole.
I found syringes at a hobby shop that were perfect for the epoxy work.
I've gotten most of these ideas from posts by Leon Sisson-he should really write a book-thanks Leon!

Edited by - on

bbriner
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Response Posted - 07/06/2006 : 11:51:19

Thanks guys... sounds like a plan.

Leon - Do I have to 'dry out' the hole before I do this? If so, how do you recommend doing that? (tia)

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