In outboats.com "dbraun" writes:

I prefer to drill and tap the cotter pin holes to accept small round head
machine screws. The screws (bolts actually) are only screwed in the depth
of the turnbuckle screw. Nothing protrudes except the round head of the
screw. No need for tape which can cause serious crevice corrosion.


I had the privilege of sailing with Rod Stevens years ago when he was
chairman of the ship committee for a sail training vessel I was
designing. He gave the whole lecture on cotter pins which I think was
basically, ends cut short and spread no more than 15 degrees, then
taped. The rational, which makes perfect sense to me, is that bending
long ends all the way around fatigues and changes the metal so that
the bends are susceptible to corrosion and breaking off. The pins then
fall out. Slight bends still keep the pins in and do not weaken the
cotters.

This approach creates sharp snags, thus the tape. The turnbuckles of
Rod’s day also had more room to hide the pin ends than the more
streamlined fittings found on many boats today. I’m using split rings
for the time being and keeping a close eye on them but they have ends
that can snag rope and lead to pulling out.

It seems to me that stainless steel seizing wire through the hole and
around the body with the ends tucked well in might be the best and
least snagging approach. I’d like not to depend on tape to protect
sails and fingers anymore than necessary. I also object to plastic
boots that hide critical components from pre-sail inspection.

Any experienced opinions?

The neatest way is to get locking nuts. After your rig is in trim,
thightten the nuts above and below the middle part of the rigging screw
or turbuckle as some like to call it. If you do not trust this, put a
drop of locktite under the nut. No taping no cotter pins. If you want a
checking point, use some water ressitant felt tim pen, and paint a
stripe ower the locking nut and both parts of the turnbuckle. If the
three pieces of the line are not aligned, you know that something works.

When I use cotter pins I follow Rod Stevens advice and if I have for
some reason rings, I tape them by a small piece tape, so that they hang
loose and the finla package looks like: |O|.

- Lauri Tarkkonen