Chain plate replacement

When my wife and I recently purchased a Bristol-appearing Aloha 32, a thorough marine survey revealed that the stainless steel clevis pins used to connect the shrouds had worn the attachment holes in the aluminium chain plates. The survey required immediate replacement of the chain plates and recommended stainless steel as the material of choice.

The old chain plates, easily removed in about 60 minutes a side, had been made from aluminium bar stock. One-half inch thick below decks, they were milled to 3/8 inch thick above decks to accept the yokes for the rigging screws. Each chain plate also included a backing plate

I fabricated six chain plate assemblies for about $150 (Canadian) and about 8 hours work with a hand saw, grind wheel, belt sander, a drill press that was way too small and a Drill Doctor. Materials were purchased at The Metal Supermarket, a franchise chain that sells metal the way an old-fashioned butcher used to sell meat, cut the way you want it.

I used 3/8 inch thick material for the chain plates, together with a 1/16 inch spacer to maintain the original geometry. The old chain plates were used as templates for grinding and drilling.

If you have never worked stainless before, here are some tips: use a GOOD quality hacksaw blade that’s coarse enough (12 teeth per inch for 3/8 stainless) and keep it WELL lubricated with cutting oil, three-in-one oil, or whatever. For drilling, use a slow speed, lots of lubricant and lots of pressure, enough so that the bit is always cutting a good curl. (300-series stainless work hardens very quickly if you smear it around without actually cutting it, becoming impossible in the process.) Most important of all, make sure your drill bits are razor sharp. (This is where the Drill Doctor, a precision drill sharpening tool, comes in. I sharpened my drills after every chain plate.)

This photo shows one complete set (of the six). The new stainless chain plate is at the top, with the stainless spacer in the middle and the aluminium backing plate on the bottom.

If you attempt a similar project on your Aloha 32, note that the dimensions of the uppers and lowers are different.


Written by Treat Hull