Chain Plate Slot Cutting

[barnakiel]

Originally Posted by ShipShape

see: Re-Bedding Deck Hardware Photo Gallery by Compass Marine at pbase.com

Very nice indeed!

Not sure I would be able to apply this into a very narrow slot like with a a chain plate. But otherwise brilliant idea - I will use it for our genoa tracks!

THX for sharing.

b.

[barnakiel]

From that source:

" ... #2 TIGHTEN ONCE - Whether you use butyl or a tube type sealant Please don't listen to that old wives tale about letting sealant cure and then tightening it a second time. ..."

Well, technically, one can tighten, but NOT by turning the bolt - only by turning (and not too much) the nut.

Or at least this is how it is done with a setting sealant like sika. IMHO the butyl tape road looks much neater, faster and safer!

Cheers,
b

[zeehag]

mine were placed with a hole way too large for the chain plate--i had to use wedges and liquid caulk to remove the niagra falls leakage in rain...so, just dont do the too large hole thing-- good luck. i want to externalize mine....

[ShipShape]

Originally Posted by barnakiel

Very nice indeed! Not sure I would be able to apply this into a very narrow slot like with a a chain plate. But otherwise brilliant idea - I will use it for our genoa tracks! THX for sharing.b.

That's Main Sail's web link - very helpful info for many DIY projects. BRT softens with heat, I'm going to give it a try with my IFS chain plate by stuffing the slot with it, heating it with a heat gun to soften it, and poking it in. Sounds like really bad sex, but if you don't try you'll never know.

DO NOT underestimate the tenacity of the butyl tape! I had a cleat 90% bolted down when I remembered it was in the way of something else I needed to do first ... OMG it was hard to remove the cleat! Easy to clean up the BRT, just rolled off in a ball - but the initial difficulty of getting everything apart was a 5200 type of surprise.

Originally Posted by barnakiel

IMHO the butyl tape road looks much neater, faster and safer!

Go for it, I highly recommend safe sealant.

[ShipShape]

My slot came out so perfect I am posting pictures with commentary to help other people in the same boat. This is what the bulkhead looked like after I peeled off the delaminated wood, filled in the original holes with thickened epoxy, and built up the bulkhead with fiberglass to its original thickness. (Half the fiberglass strips go up and over (under the plywood reinforcement) onto the underside of the deck. I also reinforced the other side of the bulkhead with fiberglass.) It was relatively easy to find center and perpendicular - the green lines.



The surface needs to be flat and smooth so I covered a board with waxed paper, smeared a shot of epoxy on it, and bolted it to the bulkhead until it hardened.



You can see how uneven the fiberglassed surface was - darker red is thicker epoxy. BTW, that is the same batch of resin and hardener that I used for the fiberglass - the hardener changes color quickly.



I started with the biggest, stiffest blade I have - it has the maximum amount of bearing surface and is easy to control.



I went as deep as I could, then switched to a short, stiff blade, 1.5", which performed very well, and went as deep as I could with that, then changed to the extended reach blade to finish the cut. OMG, size matters! I quickly discovered why the long blades are not common. For those of you who haven't used one of these tools yet, the blade oscillates back and forth very quickly, it looks like the attachment is vibrating. So the longer the blade the longer the travel path for the tip of the blade - it quickly got smoking hot! Burnt the epoxy inside the cut!! I bought three blades so I changed blades once a minute to keep things cool. In the picture below you can see the heat stains on the blades - given the position where the burn marks start it looks like 1.5 inches is the max optimum length, but that wasn't enough to finish the job. Also, the tips came square - the action wore the side teeth down to nubs so they look rounded.



Here is the first cut - this angle of the photo shows the importance of having a smooth, flat bearing surface for the blades to slide on. The green ticks on the sides are the width of my new chain plate - three inches.



The two holes are test holes I drilled before making my initial post - one hole I drilled trying to use a square as a guide, and the other hole my neighbor eyeballed the drill bit to help me get it aimed straight down. Like the original slot, both are too far aft, and, for most people, it's not good to go there.

Here it is on deck, the cut, the two test holes, and the scar from the original slot. (The bubbles are because the epoxy got too hot.)



To make the second cut I used a 3/8" piece of aluminum for a spacer. I was a lazy @ss and just taped it to the bulkead, you can just see the tape along the bottom of the picture. The buzzy marks all over it are from it vibrating under the saw blade. Shoulda drilled some holes in it and bolted it to the bulkhead.



I made the second cut the same way as the first, here it is on deck, thank goodness it was too far forward instead of too far aft.



The green lines are marks to finish the cuts - they show how bad the second cut was. I marked center by inserting a long, thin, stiff straight-edge piece of plastic up the slot, using my center marks on the bulkhead as a guide. Then measured out the rest of the slot from there. Using my 20/20 hindsight I'm not sure it was necessary to make the second cut from below since I also used the piece of plastic through the first slot to orient my drill bit. Drilled a 3/8" hole on each end. (Practiced some language when the drill bit walked on the starboard side.)



Finished the cut from the deck side, and the chain plate penetrated the slot perfectly.



On deck - that's a perfect fit!



Thanks to everybody - especially Vamonos.

[Vamonos]

Beautiful job! Are you going to use 4200 or butyl tape or ???? to seal it? I have recently become a member of the butyl camp. It's amazing stuff.

[ShipShape]

When I'm ready to mount the chain plate I'll run my router's 1/8" roundover bit around the hole so there is plenty of room for a ring of sealant. First I will try the butyl rubber tape - heat softens it so I'll pack it around the chain plate, heat it with a heat gun and poke it into the slot (sounds like really bad sex, but if you don't try you'll never know. ). If that doesn't work it's relatively easy to remove, just roll it up in a ball, and I'll use polysulfide for the seal.

[brankin]

Nice job...now you can come and work on my boat : 0)