New dyneema halyards to replace wire to rope

[tchierici]

This has probably come up a million times before but I just wanted to check again.

I have some old wire to rope jib and main halyards that need replacing on my IOR type cruiser/racer (Verl Hustler SJ 33 foot) which has about 55 sq. m. of sail area (main and genoa). I am looking at Dyneema ropes which would allow me to reduce the size of the ropes without sacrificing strength.
I went up the mast to check the width, shape and condition of the old sheaves and they seem to be still good. The max width is about 10mm and they're V shaped, a bit like the one on the left hand side in this picture .

Given the shape of the sheaves, would dyneema ropes be fine? And what diameter should the new halyards be? 10mm ropes would be nice to handle but they might be a bit too large for the width of the sheaves, I am trending towards 8mm but it might be a bit too thin to handle.
Has anyone else done a similar replacement?
Thanks
Tomar

 

[Don107]

Hi Tomar

I replaced the wire and rope halyards on my 28 footer a couple of years ago with 8mm dyneema and it thick enough to be easy to handle and works well

I never looked at the sheeves at the top of the mast but the dyneema runs freely around them and it is not being marked by them

The only consideration might be that if you have self tailing winches for the halyards is the 8mm going to work ok with the self tailers if they were designed to hold a larger diameter double braid

Regards Don

 

[tchierici]

Sounds good. I don't have self tailing winches anyway.

 

[PuffTheMagicDragon]

My boat is a Centurion 32 from 1973 so, possibly, similar to yours. I replaced the wire/rope main halyard last year with 8mm Liros Regatta 2000. No problems with strength, nor with the plain (not self-tailing) winch on the mast. Did not bother with replacing the Genoa halyard as this is only used once per season (roller furling). Don't see the point of wire/rope on a furler anyway because the luff should not be under too much tension; maybe one day I'll get round to replacing it.