I am thinking about replacing the cable halyards on our O’DAY25 with rope. People have advised me to use anywhere from ½ to ¼ inch rope. I realize that I will have to change the sheaves, but I need to select a rope dia. first. Also what style sheave should I use? We do all of our sailing on inland lakes and reservoirs.
If I had an O'Day 25 with wire/rope halyard, I'd replace it too. What I would do is take the mast down and lay it on something that will provide good working height. 5/16" STA SET X is what I would go with along with a metal sheave that will take it.
A friend of mine had a 1975 O'Day 25 with a wire/rope main and the rope came down and through a cheek block near the foot of the mast. That means you have to pull up on the halyard to raise the Mainsail and I don't like that. The Jib sheet on my mast came through this way and I hated it. I have internal halyards on my O'Day 222 and the Jib halyard came out the bottom of the tabernacle through a built in sheave.
I don't know how your mast is set up, but my Z-Spar mast has a mast winch that can be used to take up on both halyards.
When my a new mast set up with a Kenyon stainless steel hinge plate, the rigger cut an exit hole in the mast for the Jib Halyard and he installed a clam cleat below the new exit plate and a little to one side.
This worked out great for me and even though I no longer use the Jib Halyard much except for raising my mast, My Main Halyard is set up the same way and it works great.
I just raise the Mainsail and take about three wraps around the mast winch and snub the halyard off in the clam cleat above the winch after getting it up tight. The open clam cleat allows me to hold what I've got, pull the wraps off the winch, and cleat the halyard off on a horn cleat below the winch.
I think that this is a great system that can work on external or internal halyards and it really worth looking into. 5/16" halyard is big enough for my mast and it's probably large enough for yours. Whatever thickness you decide on, you need to take into consideration the thickness of the eye splice for the halyard shackle in relation to the width of mast head sheave opening. This also applies to the Jib block sheave.
The sheave pin in my mast head was pressed in at the factory and I couldn't use it when I replaced my sheave so I re-drilled the mast head for a stainless steel bolt and nut. I also had to use a stainless steel bushing for the sheave to ride on. I would have liked to have got a metal sheave but Rudy at D & R Marine didn't have one in the size needed for my mast head.
http://www.drmarine.com/ He may have one that will fit your mast head. He could also answer any questions you my have concerning the length and thickness and supply it to you.
Joe
