The thing about line diameter is that it can vary between manufacturers for a given stated size. In other words, not al line identified as 5/16 will be the same diameter. I can't find the source right now but I read this somewhere in a faq about rope & line, including (maybe especially) double braid. It has something to do with weight per length, or volume...anyhow, some 5/16 will be a tiny bit thicker, or thinner, than others. Same for any other stated size. I have seen this myself with line from different manufacturers. So if you had slightly 'fat' 5/16 it might chafe on the sheaves whereas if you had slightly 'thin' 5/16 it might not. My halyards on my M17 are I am pretty certain 5/16" nominal size. But the sheaves appear to be sized for that. So maybe the OEM on my boat was all line. It's #38 from 1974 if Jerry or anyone else can speak to what the OEM halyards were then. cheers, John On 6/21/21 8:07 AM, Andrei Caldararu via montgomery_boats wrote:
Hello all, my 1987 M-17 came with rope/steel wire halyards when I bought it about 15 years. About 11 years ago I decided to replace the halyards, and I used StaSet 5/16" line going both up and down the mast. Unfortunately I did not replace the masthead blocks (sheaves?) that the old steel cable went through, and over time the halyards became frayed. Now one of them has become unusable. I need to replace the halyards, and was wondering if 5/16" line is not overkill. I was hoping to conduct an unscientific poll: what size halyard line is on your M-17? I was thinking of going down to 1/4" to make the line run smoother through the blocks. Also, does anyone know what size masthead blocks do I need to replace the existing ones that are intended for wire? Is there a good source for these? Thanks,Andrei.
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