CAUTION: Montauk 17 Drilling out RPS Deck Fastener Holes

Repair or modification of Boston Whaler boats, their engines, trailers, and gear
Crusty the Clam
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Location: Austin, Texas

CAUTION: Montauk 17 Drilling out RPS Deck Fastener Holes

Postby Crusty the Clam » Sat Jul 06, 2019 1:37 pm

My first original post here describing a temporary solution for one problem and seeking advice on creating another problem. Perfectionists, experienced old salts, and newbies, please grab your favorite beverage and pull up a chair. The perfectionists will be horrified with my temporary solution, the old salts will quickly know where this story is headed, and the newbies will hopefully be forewarned.

My recently acquired 1983 Montauk 17 had a number of loose screws on the bow rail (two pulled completely free on the port side) and loose deck screws on the RPS seat base on the port side that were clearly not biting into much of anything. This post relates to the "attempted" repair of the deck below the RPS where its screws locate.

After removing the RPS from the deck, it was clear that water had intruded into the plywood below the fiberglass over some longer period of time. As I drilled out the holes on the port side with a 1/2" brad point drill bit, the "wood dust" was a bit moist, very black, and rotted. Close to being compost. The starboard side was in pretty good condition. However, again on the port side, the deck was soft for close to 3 feet fore and aft - starting a few inches in front of the forward deck screw holes for the RPS and going aft for the three feet. Athwart, the soft area extends about a foot or more beginning on the port side about 8" from the inside hull inboard to the rigging tunnel. The rest of the deck seemed solid.

My proposed solution was a temporary repair: drill out wider holes where the RPS screws were, angling the drill bit through the rotted plywood in a circular pattern to open up a void in the foam below, let it dry, and fill it with West System Six10 epoxy. The point being to simply seal the deck up from further water intrusion pending a more permanent fix down the road. On top of the now sealed deck, I would lay a 4x4 foot sheet of plywood and screw down the perimeter into "good" plywood. The screw holes will be potted - i.e. over drilled and filled with epoxy so as to exclude water and make them stronger. The edges of the plywood will be sealed with epoxy but the plywood itself simply painted a light tan with porch paint. Seal the plywood edge to the deck with caulk. Finally each of the RPS legs will be screwed to a plywood strip (3/4" x 3' x 6") and those strips glued and screwed to the new, temporary deck. Voila. Good enough for Caribbean fisherman, good enough for me - at least as a stop gap measure.

Here's the caution. If you look at the transom of a classic whaler, you will notice that each of the inboard chines forms a "V" and that the inboard upper tip of the V lines up closely (looking from astern toward the bow) with the location of the RPS leg screws. And if you put one hand on the deck and the other on the tip of the V on the hull bottom, you'll be able to feel that the distance from the deck to the bottom of the hull along that line is not very much.

And, yes, if you are not thinking too deeply about it, you can very easily drill too deeply into it when hogging out the holes especially with a brad point bit. But you won't notice that error until you are waiting for the epoxy to set and decide that, yes, you will go ahead and tackle replacing the trailer lights and, while you're doing that, you will decide to inspect the trailer wires. And while you're down there on your back looking around you'll notice a curious thing: a small area on the port side of the hull bottom where near dry streaks apparently caused by tea-stained water have appeared and that the streaks appear to emanate from the very highest crease in the hull at the uppermost tip of the V that forms the chine and that that point looks like a tiny, pimple-sized pinhead blister. You'll wonder what the heck is going on. Why is the hull blistering at that location? And you'll cogitate on that for a day or so, until you are inspecting old repairs in the transom and notice a curious thing: that the deck to bottom thickness of the hull is pretty narrow in one location...

Note to self: stop drilling holes in boats if you are not positively certain that either a) you know the hull thickness and won't drill all the way through, or b) you don't care because want to drill all the way through.

That's a long way to getting to my question: what would be a good (right) way to permanently repair the pin hole? Sand out a dished area around the hole and patch? Drill it out further and plug? Take it to a competent professional because you have proved yourself unqualified to touch a boat?

Thanks in advance.
Crusty

jimh
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Location: Michigan, Lower Peninsula
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Re: Caution 1983 Montauk 17 Drilling out RPS deck screw holes

Postby jimh » Sat Jul 06, 2019 1:58 pm

The cross-section of a classic 13-foot hull may be illustrative of the problem described above in the 17-foot hull:


Image
Approximate cross-section of a classic 13-foot Boston Whaler hull

Crusty the Clam
Posts: 33
Joined: Mon May 06, 2019 12:00 pm
Location: Austin, Texas

Re: Caution 1983 Montauk 17 Drilling out RPS deck screw holes

Postby Crusty the Clam » Sat Jul 06, 2019 2:02 pm

Thank you, Jim, that cross section shows exactly what I was trying to describe. Also, please excuse my lack of manners - I meant to thank you for creating and hosting this forum and for doing a GREAT job editing posts and subject lines to make the information shared accessible and understandable.

biggiefl
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Re: Caution 1983 Montauk 17 Drilling out RPS deck screw holes

Postby biggiefl » Mon Jul 15, 2019 12:15 pm

I would epoxy and sand and keep an eye on it.
On my 24th Whaler. Currently in the stable: 86 18' Outrage, 81 13' Sport(original owner), 87 11' Sport, 69 Squall(for sale cheap).

Crusty the Clam
Posts: 33
Joined: Mon May 06, 2019 12:00 pm
Location: Austin, Texas

Re: CAUTION: Montauk 17 Drilling out RPS Deck Fastener Holes

Postby Crusty the Clam » Sat Jul 20, 2019 1:19 pm

Thanks, biggie. Took your advice and also found the CW FAQ on hull repairs.

A little hole expansion (3/16”), a bit of dishing of the area around the hole and roughing it up, and then created a void in the foam area on the inside... then Marine-Tex... voila. Fingers crossed and an offering to Neptune. It’s in dry storage so plenty opportunity to check it periodically.