Chainplate popped out when sailing - what's next?

[shanegeard]

I have a different boat (Slocum 43) and the chainplate sheared through just below the deck. It was caused by a stress fracture that oxidized and broke catastrophically when we ran aground a year ago.
I designed and had manufactured a full set of chainplates out of 2105 stainless, all exterior mounted and fixed through the hull and through the existing plates.
The hardest part was drilling through the old chain plates... it took many hours, lots of lube and many broken drill bits. But it works beautifully and is visible for inspection.

[shanegeard]

*2205 stainless. Don't use less than 316.

[phorvati]

Originally Posted by shanegeard

I have a different boat (Slocum 43) and the chainplate sheared through just below the deck. It was caused by a stress fracture that oxidized and broke catastrophically when we ran aground a year ago.
I designed and had manufactured a full set of chainplates out of 2105 stainless, all exterior mounted and fixed through the hull and through the existing plates.
The hardest part was drilling through the old chain plates... it took many hours, lots of lube and many broken drill bits. But it works beautifully and is visible for inspection.Attachment 189673

This is what I had to go through

[skenn_ie]

Drilling stainless: Use cobalt drills, very carefully. They break very easily if they are bent. The ones with a cross-tip don't need pilot holes, but are impossible to sharpen while maintaining the X tip. HSS is OK, but you need to keep sharpening them, and you MUST use cutting compound. . Use a good cutting compound. Rocol (liquid or paste) is good, but I am allergic to the stuff, I suggest using gloves in case you get sensitised. Keep the drill very sharp, and use a lot of pressure. If the cutting edges slide, the stainless hardens in an instant and then you are screwed. Titanium coated are OK, but if they blunt, chuck then away.

Even in Carbide milling/turning tips, the ones for stainless are sharp, for mild steel - slightly dull, cast iron - negative rake.