In article .com,
wrote:
J Ganz said:
SS screws and nylon locknuts
Not sure that's so great an answer, they will have to be very skinny
to fit thru a cotter pin hole and very likely to have the threads
banged up. And the heads & nuts will need room to fit against the body
of the turnbuckle so it will be bulkier, likelier to trap salt water
in crevices too.
I tried one just for fun. The nuts don't touch the turnbuckles.
Dave wrote:
I assume you mean either machine screws or bolts.
yeah with Whitworth threads 
Frankly I don't see what the problem is with cotter pins, if you have
the right tool for installing/removign them, they are very easy to
work. It's not so difficult even with just a pair of cheap needle-nose
pliers.
One thing to be wary of is re-using cotter pins. They tend to break
from being bent/straightened and fall out.
Yeah, I don't reuse them. They're cheap.
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Capt. JG @@
www.sailnow.com