Repaired my deck - how do I cut the hole for my chainplate?

kindofblue · Post by **kindofblue** » Mon Jun 15, 2009 2:34 pm

I just repaired by deck this weekend, which included making a 4x4 non-cored section for the chainplates. What is the best method and tools to re-cut the hole for the chainplate?

Oscar · Post by **Oscar** » Mon Jun 15, 2009 3:01 pm

If it was me it would be drilling with a bit the width of the required opening at the ends and as close together as possible in between. I would then remove the remaining material in between with a Dremmel on low RPM with a Zip bit in it. But I'm sure the pro's here will have the marine version of a mortising bit......

bcooke · Post by **bcooke** » Mon Jun 15, 2009 5:59 pm

If it was me it would be drilling with a bit the width of the required opening at the ends and as close together as possible in between. I would then remove the remaining material in between with a Dremmel on low RPM with a Zip bit in it.

I did the exact thing just last week.

Post by **Tim** » Tue Jun 16, 2009 6:18 am

That is basically how I have done it as well, though I use a jigsaw to connect the holes. Nothing fancy required.

Ric in Richmond · Post by **Ric in Richmond** » Tue Jun 16, 2009 7:53 am

Looks perfect for fein tool. Plunge cuts, very controllable.

kindofblue · Post by **kindofblue** » Tue Jun 16, 2009 1:49 pm

I do have a Fein Multimaster. I'll plan on drilling the ends and connect using the multimaster.

I would think that I want to be very careful so that I only make this only big enough for the chainplate to just pass through. Start small and slowly make larger as needed.

Once the hole is cut, I think that I want to bevel the top skin around the hole so that I can get a nice gasket of butyl tape around the chainplate. For a round hole, I would use a countersink bit, but what should I use for an oval hole? Maybe a dremel with a sanding barrel bit on an angle and just freehand it carefully.

bcooke · Post by **bcooke** » Tue Jun 16, 2009 5:41 pm

would think that I want to be very careful so that I only make this only big enough for the chainplate to just pass through.

That's why they make big chainplate covers ;-)

Ric in Richmond · Post by **Ric in Richmond** » Tue Jun 16, 2009 8:15 pm

Good old Boat in the last couple of months had an article where the author built up raised pads around the chainplate so that average water on deck never came close to entering the chainplate/ sealant area.

Basically he built molds in place on the deck and poured layers of epoxy then removed the molds and finish sanded and painted.

Simple idea that looks like it would keep 99% of water out.

Hirilondë · Post by **Hirilondë** » Tue Jun 16, 2009 8:48 pm

Ric in Richmond wrote:Simple idea that looks like it would keep 99% of water out.

I like keeping 100% of the water out.

Its an interesting idea, but the bottom line is how well the covers are bedded. If they are bedded well, it doesn't matter if you raise the top of the opening. If you don't bed them properly, even the raised top won't keep all of the water out. Repelling water only works on houses, boats require water proof.

Ric in Richmond · Post by **Ric in Richmond** » Tue Jun 16, 2009 9:37 pm

Didn't say you could skip bedding....Just that it was a neat idea.

For those of us with chainplates sitting in gutters it seems a simple, practical solution to the everyday dew and rain that no doubt will eventually get past the best bedded fittings as they age.

Triton 185 · Post by **Triton 185** » Tue Jun 16, 2009 10:01 pm

Basically he built molds in place on the deck and poured layers of epoxy then removed the molds and finish sanded and painted.

I had thought that it was ideal to use some glass as well. Could you use just epoxy and not have it fail in time?

Hirilondë · Post by **Hirilondë** » Wed Jun 17, 2009 1:29 am

Ric in Richmond wrote:.... it seems a simple, practical solution to the everyday dew and rain that no doubt will eventually get past the best bedded fittings as they age.

Why will it no doubt get past the bedding? I'm just saying it shouldn't. And if it ever does it is time to rebed. I like redundancy, but raising the top of the hole out of the gutter is only a partial measure. If the chain plate leaks at all, fix it, don't just reduce it. I see no point in efforts that don't resolve problems, but merely reduce them.

Post by **Tim** » Wed Jun 17, 2009 5:57 am

kindofblue wrote:I would think that I want to be very careful so that I only make this only big enough for the chainplate to just pass through. Start small and slowly make larger as needed.

I think a bit of extra space in the chainplate slots (in the deck) is actually a good thing, as it gives extra room for sealant beneath the covers. Within reason, of course; the slots shouldn't be much bigger, but neither should they be a "perfect", tight fit that you can barely slip the chainplates through. In any case, it's not a hard cut to make.

The bedding success of a chainplate comes mostly from the deck cover, as it's difficult to impossible to seal the slots effectively on their own, good deck covers, many of which have a formed, raised area that provides extra space for sealant right at the chainplate itself, make all the difference to the quality of the seal, as does ongoing maintenance.. Chainplates are dynamically loaded items and require frequent rebedding--I do mine every other season.

Sailordave · Post by **Sailordave** » Thu Aug 27, 2009 9:40 pm

This topic was discussed AD NAUSEUM over on Sailnet.... Basically the viewpoint was that you want a fairly loose slot for the chainplate b/c if it's tight what little sealant gets in there will only stretch a minimal amount when the chainplate is loaded. If you have a bit bigger gap and thus a bigger dimension of sealant, when it streches it won't exceed it's E value (elongation) and then fail. Don't have the time to find the thread but search Sailnet for rebedding...

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Repaired my deck - how do I cut the hole for my chainplate?

Repaired my deck - how do I cut the hole for my chainplate?

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