Masthead Sheave--what's a good diameter?

Bought this hobie used... (haven't we all?)... and I'm not sure of the masthead story. It looks as if someone replaced the sheave at some point (or maybe the masthead altogether) with a smaller sheave: The halyard line doesn't seem to cleanly come off the sheave to the cable stopper (the forked piece)... it looks like it rubs against the mast as seen by the wear in the pictures. (I've put 2 photos in the post. Check them out.) This to me says the sheave is too small (in diameter). And honestly, it looks like it's too small.

I've seen pictures of halyards coming straight down off the sheave and connecting to the forked piece -- and the line was beautifully parallel to the mast. But that's not the case for mine.

What are your thoughts? Do I need to replace the sheave, and if so, what's the correct diameter?

Apparently it's a 4-inch sheave in there now (or something close to that).

I think the correct size is a hair over 5 inches.

We took off the masthead today and for sure, we've got a 4" little sheave in there. Definitely not the optimal size.

Looking to order/make a new one.

Get Wet Sailing made a good video on repairing a single sheeve masthead.

http://www.facebook.com/video/video.php?v=410821706293

_________________
Tim
84 H16
82 H16
87 H14T
Tortola Sails: 115222
Blue Prism Sails: 88863
Clearwater, FL

In the video (Get Wet sailing) why do they go to all the trouble of mounting the mast head on a peg prior to drilling out the retainer?

_________________
1980 18 foot class A Unicorn catamaran
1977 Super Sunfish (sold)
1979 Hobie (sold)
1983 Hobie 16 Hawiian Sunset (sold)
1981 Hobie 16 Tequilla Sunrise (sold)
2008 Hobie 16 (sold)
2023 Hobie 16
Founding member of the "San Dimas Yacht Club"
John

I had a similar problem last year (my sheave was worn out). Take a look at my old post.

viewtopic.php?f=14&t=28129&p=117139&hilit=sheave#p117139

Good luck!
Don