rudder derlyn screw size

am overhauling some H14 rudders, the threads in the casting are pretty rough, I want to run a tap over them to clean them up
anyone know the size and pitch?

They are 3/4"-10.

If you don't want to go thru the expense of buying a tap (and handle) that size, you can just go to your local hardware store and buy a 3/4" hex bolt. Use a flat file to cut two or three notches into the end of the bolt (parallel to the bolt centerline) and use the bolt to clear out the threads. The notches will provide space for any debris which works itself free. Be sure to use a little WD-40 or liquid wrench on the threads when you chase them out too. This is how I've cleaned out the threads on older castings.

sm

Second srm's bolt trick works perfectly! Grease new Delran screw well.

_________________
ADDICTION
1989 HOBIE 18 SE/sx wings
HOBIE ALTER SIGNATURE MODEL

Thanks I will do that.

May i suggest another tip.... learned from someone on this site... wrap the threads in plumbers teflon tape... (and grease them)
it has stopped my screws from locking up.. 5 years now...

_________________
•Present boat -1998 Hobie 16 Solana Sails furling jib[/size]