Replace glassed in chainplates

[BenBowSirocco]

Another opinion:
It has always been a bit baffling to me that "cruising" boat builders puts chainplates through the deck. I have never been able to point that high offshore where the extra 6-8" mattered- at least not on any boat I have sailed (not many really in the scheme of things though). When your at sea and in a seaway, or even coastal cruising, pointing is done by assessing the best average SOG balanced to your angle on the wind for current conditions- not drawing the sheet in to the shroud.

Anyway, my point is, putting chainplates outboard is a very simple and reliable method of putting a critical piece of gear in plain sight where it can be easily inspected and cared for.
Your stainless price is about the same as what I paid to have my laser cut and electropolished from 316L .375" (4.3mm). If its at all possible to have them laser cut- its worth it because drilling stainless is a process that requires great patients to avoid work hardening the metal and the last thing you want to do is work harden a chainplate.

Exterior bolting of the plates is very simply executed. Try to leave all nuts/washers/backing plates visible for periodic inspection. When mine were done by the owner/builder and he used high quality Butyl and they never leaked for 39 years. So when I did them last year- I did the same. What you choose to use is up to. I like the idea that butyl never hardens and is forever sticky/mastic because chainplates will always receive pumping and variable loading/unloading.

Great cruising boat designers like the Dashews and experienced world sailors like Hal Roth have switch to external bolted chainplates for good reason.

[medvinden]

OK, that sounds encouraging! My price actually includes drilled holes and electropolishing, so it should save some time. I "only" need to drill through the existin chainplates... And I need to figure out how to do the connection to the turnbuckles. I have the idea to cut through the toe rail in order to get them on the same level as the existing ones, but am not sure how that could be done in a strong and proper looking way.

[S/V Adeline]

Originally Posted by medvinden

OK, that sounds encouraging! My price actually includes drilled holes and electropolishing, so it should save some time. I "only" need to drill through the existin chainplates... And I need to figure out how to do the connection to the turnbuckles. I have the idea to cut through the toe rail in order to get them on the same level as the existing ones, but am not sure how that could be done in a strong and proper looking way.

If there is any practical way to avoid cutting the toe rail, I would avoid it. For drilling the stainless, I strongly recommend using appropriate cutting oil and keeping the bit wet. Drilling slow revolutions with moderate to heavy pressure. Because of the angle, it will be easier if someone can apply oil as you drill. Keep it wet, if it gets hot enough to smoke, it's dulling the bit.
We installed custom stainless floor pans in US Navy surface combatants, only 2mm thick stainless, but keeping the bit wet, not allowing it to "smoke", will allow 10-12 or more holes before a bit is dull, compared to 3-4 from a bit that gets too hot. We had an unlimited supply of bits and a schedule to maintain.

[Breaking Waves]

I will comment . . . .if I were doing chainplates today, I would 100% do carbon ones. They are completely totally leakproof and will last 'forever'. They are not hard to retrofit but would be more work than bolting metal ones on.

[BenBowSirocco]

S/V Adeline is correct.

According the Machinist Handbook, proper speeds and feeds for .375" or 4.3mm is 30rpm, my drill press only does 50rpm, but it worked well. Keep it oiled. If you are doing this by hand held drill- you may need to rent/borrow a low speed high torque drill. I have seen drilled burned up by running them at to low a speed.

If I may suggest: I can see that removing the old chainplates is a lot of work- but drilling them accurately enough to make them useful may be more work. An oscillating tool with a carbide cutting bit is a very accurate and low dust method of cutting fiberglass. The hole in the deck is easily filled with an epoxy putty.
The holes will most likely need to be drilled from the outside-in as you need the hole to be 90 degrees to the new plate. Pilot drilling is required and accuracy can be improved using a drill guide: LINK

Breaking waves brings up a great point! You can see the well marketed "Carbon Cutter" for examples of this method. They do not really need to be carbon fiber- although it sames quite a bit of weight/bulk. You can have them made by a third party and then simply bond them into place with methacrylate (Plexus) or epoxy to your properly prepped hull.
Most reputable boat builders can provide a lamination schedule to exceed the strength of your Stainless Plates.