Drilling thru holes

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Yesyoucan4
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Drilling thru holes

Post by Yesyoucan4 »

Getting toward the end of my XF 20 build. Need to drill several holes for bilge pumps,jack plate,trim tabs,fuel vent,etc. what is the best method to be sure water does not penetrate
Thanks for the help

fallguy1000
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Re: Drilling thru holes

Post by fallguy1000 »

All holes should be oversized and replace with thickened epoxy.

How much to oversize depends on the hole and whether you can seal it. For an inch wide hole a quarter inch deep; sometimes you need to placehold a piece of dowel that is undersized, for example.

the general idea is no wood should show to the screw and the screw is sealed in sealant against a sealed wood
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fallguy1000
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Re: Drilling thru holes

Post by fallguy1000 »

Another method is to plate the surface with coosa or a waterproof core, for say like a transducer. Glue it on and then no overbore/decore, recoring is needed..
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TomW1
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Re: Drilling thru holes

Post by TomW1 »

Depending on the hole size it is best to drill it oversize and fill it with thickened epoxy and cabosil and wood fibers. Over drill by 1..25-1.5x the size of the bolt or thing going through the hole to give you plenty of room for error. You want to leave plenty of room for error so that anything you put in the hole is not against the wood.

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MrPaul
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Re: Drilling thru holes

Post by MrPaul »

I'm about to do the same with my xf20. What is cabosil...I have some stuff I ordered that came in a Styrofoam cup that BBC sent and for the life of me I can't remember if it is cabosil. Do you mix it with epoxy? Should I add woodflower to thicken it up. I'm waiting for my jackplate to arrive and will be installing it soon but I don't want the bolts touching the wood. Also...my transom is about 4" thick at the top with the clamping board. I haven't found any screws long enough where I ordered my atlas. Any recomendations on where I can get some longer jackplate bolts?

fallguy1000
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Re: Drilling thru holes

Post by fallguy1000 »

Jackplate bolts should be fine threaded to reduce the minor.

Mcmaster-Carr should have them.
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Dougster
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Re: Drilling thru holes

Post by Dougster »

Wood flour and epoxy works fine for filling holes before re-drilling them.

Dougster

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OrangeQuest
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Re: Drilling thru holes

Post by OrangeQuest »

I also like using wood flour mix to fill in for through holes since it seems to be harder and stronger than the other things used for fairing. My thinking was the wood flour sucks up the epoxy and helps waterproof everything that will have contact with water. My choice for waterproofing sealer was Loctite marine sealant. Fasteners need to be removed at times and because the sealant stays flexible enough you can turn fasteners without rounding them off or stripping them out if you do need to remove them and fairly easy clean up.

My method was to put the washer on the bolt, run a bead both sides of the washer while it is on the bolt, then a few beads of sealant down the length of the bolt to just a little past where the nut will bottom out. Insert the bolt and twist slowly as the bolt goes in making sure there is squeeze out from the edges of the washer both inside edge and outside edge, That assures no water enters from that side of the bolt. Then sealant on the nut side sliding washer on carefully looking for squeeze out again inside and outside the washer. Hold bolt from twisting as the nut is tighten to spec. For blind holes I run small bead of sealant down the length of the screw/bolt.

For a little easier cleanup of sealant like fixtures and mounted hardware, masking tape the mounting area, mount fixture without sealant. Trace the fixture with fine pen. Remove fixture and razor knife the inside area of where the fixture will be mounted. Do sealant method to mount fixture. After the fasteners are tighten...remove tape.
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BarraMan
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Re: Drilling thru holes

Post by BarraMan »

Dougster wrote: Mon Jun 05, 2023 9:47 am Wood flour and epoxy works fine for filling holes before re-drilling them.
Dougster
Ditto! :D

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Re: Drilling thru holes

Post by MrPaul »

Thanks for the input guys. I'll just use woodflower. I'm sure I'll have plenty of other questions in the near future.

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