what is this?

[davidpm]

Prefeeder?
Seems a little big for the catalina 25 it came off of.

[Liquorice]

It's an old style bail for the boom.
On second thoughts, maybe not - a bit small!

[centaursailor]

Looks like a boom vang for a roller reefing boom. Its tensoioned when all sail is up and allows the sail to roll round the boom when lossened. Mine looks bigger but same design.
Safe sailing.

[davidpm]

Originally Posted by centaursailor

Looks like a boom vang for a roller reefing boom. Its tensoioned when all sail is up and allows the sail to roll round the boom when lossened. Mine looks bigger but same design.
Safe sailing.

That sounds right but would be really hard on the sail when reefed.

[svHyLyte]

Originally Posted by Liquorice

It's an old style bail for the boom.
On second thoughts, maybe not - a bit small!

Correct--and it is a bit small for the yacht in question. Likely picked up at a Nautical flea-market at some point, stashed away and forgotten. Attached to the rail with a 3-part tackle, these actually worked pretty well.

[centaursailor]

Originally Posted by davidpm

That sounds right but would be really hard on the sail when reefed.

Exactly. I don,t use it when reefed, sail shape is so bad it wouldn,t help and could damage the sail.
Safe sailing