Replace 'em. I agree with (1). The chainplate with both shrouds attached
represents a single point of failure for all support against side loads.
Blowing out a chainplate on the bay could ruin your entire day. While it's
true that a 1/4" x 2" chainplate cross-section is way overkill for the size
of the rig, you can't tell by looking at the surface how deep and pervasive
the damage really is.

If the $200 is outside your budget, find a metals supplier and buy a piece
of stainless strap of the right dimensions and make them yourself. You can
cut it with a hacksaw with some difficulty, but if you can find a friend
with a metal-cutting bandsaw and a drill press and a bench grinder it'll go
a lot faster and better. Or perhaps you can do some of the fabrication and
have a machine shop do just the drilling and bending, at less expense to
you. The $200 quote seems in line with what a boatyard machine shop would
want for the job, but it seems a little high to me for the actual amount of
work that needs to be done. I doubt if there's an hour of work in the job,
and even at $75/hour (my local boatyard shop's rate) that's a little high.
Probably you got the quote from a shop that caters to the marine trades. If
you supply the materials, just about any auto parts store with a machine
shop in the back could probably do the fabrication for you at a lower price.

Get 316L stainless while you're at it, instead of the cheaper 304 or 18-8 -
the 316L is relatively immune to the crevice corrosion problem you're
experiencing. You can probably buy the metal for twenty dollars or less -
they sell it by the pound.

Before you reinstall the chainplates, look very carefully at the condition
of the bulkhead where the chainplates are fastened. If water has been
getting in for a long time, it's possible that there's localized
deterioration of the plywood. If there is, do whatever is necessary to
restore the strength of that area. It doesn't make much difference how new
and strong your chainplate is, if it pulls out of the bulkhead.

When you're done, caulk the hell out of the openings where the chain plates
pass through the deck. If you can make a slotted cover plate that slides
down over the chain plate and covers the opening and is separately fastened
to the deck, you can protect the caulking from UV degradation and it will
last longer.

Good luck,
Tom Dacon


"joe anglim" wrote in message
om...
I am in the process of refitting a santana 22 that will be used on the
san francisco bay, and will be replacing the standing rigging. The
upper and lower shrouds on each side attach to one chainplate. This
chainplate is located about 18" inboard of the beam, passes through
the cabintop, and is throughbolted to the main bulkhead.

That's all the background, now the problem. I have the chainplates
out, and have found an area of pitting in the stainless (grade
unknown) that is about 1" wide and 2 1/2" tall, with a few small
isolated pits outside of this area. The pits range from barely a
pinhole with almost no depth, to nearly 1/16" diam by nearly 1/16"
deep. All of the pitting is in the area where the plate passes
through the deck, and there is evidence on the bulkhead of water
getting through the deck seal.
The plate is 2" wide, 1/4" thick, and about 18" long. the shrouds
attached are 5/32" upper and 3/16" lower. The boat is about 35 years
old, but the original chainplates from Schock were 1/4" aluminum
plate, and I don't know how far back the stainless plates were put in.

I have gotten three opinions on whether the pitting is a big deal or
not:

1. YES, it's a big deal, the pitting will continue and likely extends
beyond what is visible now. Replace the plates immediately.

2. No, it's insignificant, the plate is way, way, way oversized and a
little pitting won't hurt a bit. You could lift the boat (2600 lbs
unloaded) with a plate half that size.

3. Probably not. Just paint the area of the plate that will be
sealed off from the atmosphere before reinstalling to prevent further
pitting.

The machine shop offering the third opinion also said that they could
fabricate two new chainplates for $200 us.

Relative to the cost of things on this boat, $200 is a large sum and I
don't want to throw it away on servicable parts, but I also don't want
to suffer a dramatic failure out on the bay.

In the realm of peace of mind, my wife / co-owner was present to hear
the first and most troubling opinion, but not the other more calming
opinions.

any thoughts?

thanks,
Joe