1990 C&C 30 MkII halyard replacement, ISSUES!

[sheardc]

Has anyone replaced their wire/rope halyards with Dyneema rope? Having issues with halyards getting jammed at mast head. Halyards ran free when halyards were installed.
Using the old V shaped wire sheaves and 10mm 2 part Dyneema core with a polyester braid cover line. The sheaves looked fine. We pulled them out looked for sharp edges. Just lubed them up and reinstalled them.

 

[Leeward Rail]

Using the old V shaped wire sheaves and 10mm 2 part Dyneema core with a polyester braid cover line.

When you say v shaped, do you mean step grooved ? My C&C mk1 wire/rope halyard sheeves are stepped.
Effectively a lower spot for the wire and a area above for the rope.
Swapping to rope only was just a matter of running the new halyard and using the original sheeves. Works fine. (I assume you know this, just clarifying it so any other replies will take that into account)

I suspect that the dyneema +sheath is decreasing in diameter when stretched and dropping into the bottom wire groove when tight and it then expands as the load decreases, and that is causing it to jam or increase friction. My experience is that dyneema type rope is less stable in its diameter than traditional halyard rope when under various loads.
(Using dyneema with an outer sheath can cause jams on a trailer or atv winch for that reason)

Personally I wouldnt reinvent the wheel and just use normal rope halyards since it is known to work fine with the original sheeves. Or get new sheeves.

 

[jssailem]

When I refit my mast, I changed from wire/line halyard to all line. To prevent the line from deforming into the wire groove of the sheave there are two options. 1. Buy new sheaves that are U-Grooved for line, or 2. Sand the V-Groove into a U shape. For two of my sheaves plan 2 worked. The other two needed to be replaced.

It was all about the material and condition of the sheaves. To do the sanding we spun the sheaves against the sand paper. Time consuming but results were spot on.

 

[Apex]

replaced mine last year with dyneema core. No issues with jamming. Could it be the taper of a splice at full hoist? When is it jamming?

 

[Leeward Rail]

To do the sanding we spun the sheaves against the sand paper. Time consuming but results were spot on.

That would definitely work but be a bit of an imprecise hassle with aluminium.

Best option IMO if you want to keep the original c&c aluminium sheeves ,is to take them to a machine shop and have the groove recut.

That assumes they are a in perfect shape. Which mine are after 45 years in a freshwater environment.

My c&C mark 1 manual says the main halyard was 5/32" stainless wire with 3/8" yacht braid.. assuming the Mark 2 is the same, using 10mm/38 "should" be ok, but since you are using spectra or whatever brand, and it has different properties than traditional polyester braid I can't say it would work. All the c&c around here that kept their original dual groove sheeves, are using polyester.

I would be tempted to climb the mast and have someone inspect the sheeves while the halyard is moving under load.

Is there any chance the halyard is rubbing on wiring or ? Does the mark 2 have cable conduit ? Obviously if you connected old to new and pulled it though that wouldn't be a problem.

 

[jssailem]

Machining would generate a more precise result. My sheaves were made of Delrin.

 

[sheardc]

Looks like I did not update what I found at the masthead!! DOH

Both jib & spinnaker halyards were getting "pinched" between the outside of the wire cage and the top forestay connection / clevis pin. One could raise the sails with a some interference, but trying to drop sails/lower the halyards back thru the cage forestay interference was NOT happening. The big issue is the smaller wire moved fine thru this area, but the 1/2" / 10mm Dyneema is too fat to fit thru the same space.

The fix was to route both halyards underneath the cage. HUZZAH both halyards work fine. But the cage is not doing it's job. At some point, I would like to remove the cage and have a horizontal SS bar welded across the cage at the midpoint of it's vertical length. This should route the halyards up and away from the forestay connection. One point is how much force know would be applied to the cage and halyards as they would be pushing down on the cage?
Wear on the halyards?
Also considering getting smaller halyards; switching down to 3/8" Dyneema.

There was no issue with the sheaves; they seem to work fine.

 

[Apex]

3/8 or 10mm should be more than up to the task at hand. = more room around the cage?

 

[sheardc]

Well 10mm is what I have and it's jamming up. I looked at 8mm / 5/16. It works in the clutch but feels too small in my hand to hoist.

 

[Leeward Rail]

1/2" / 10mm Dyneema is too fat to fit thru the same space.

In assume you mean 3/8" / 10mm ?

1/2" = 12.7mm. Which I would assume would jam.

 

[sheardc]

Considering keeping 10mm and fixing cage. Having the halyards under the cage instead of thru is not a good situation. Can you say spinnaker halyard jam!!
Thinking of having a SS crossbar welded to tie the 2 side rails of cage together, above clevis pin and lift halyards over forestay clevis pin.

 

[jssailem]

switching down to 3/8" Dyneema.

That sounds like a smart idea. Not sure why you considered the need for 1/2 dyneema.

1/4” would be more than strong enough. Not to easy on the hands. Some choose to add a polyester sleeve to the dyneema to give the line a better handling feel.

 

[Apex]

That sounds like a smart idea. Not sure why you considered the need for 1/2 dyneema.

1/4” would be more than strong enough. Not to easy on the hands. Some choose to add a polyester sleeve to the dyneema to give the line a better handling feel.

i think there was some confusion on conversion. OP has 3/8 (~13/32 or 10mm).
@sheardc are you talking about straight Dyneema, or Dyneema core? I am using Sampson MLX3, which is a Dyneema core, with Polyester cover.

MLX3 - Samson Rope

MLX3 is a lightweight, core-dependent line that has excellent strength and moderate stretch.

samsonrope.com

..I will have to take a picture of my cage in the next month. Yours looks off, though it may simply be angle of the forestay in those pictures as I recall a similar proximity of jib and spin halyard to the cotter pin. I don't recall the cage being so far away from the mast extrusion.

 

[sheardc]

i think there was some confusion on conversion. OP has 3/8 (~13/32 or 10mm).
@sheardc are you talking about straight Dyneema, or Dyneema core? I am using Sampson MLX3, which is a Dyneema core, with Polyester cover.

MLX3 - Samson Rope

MLX3 is a lightweight, core-dependent line that has excellent strength and moderate stretch.

samsonrope.com

..I will have to take a picture of my cage in the next month. Yours looks off, though it may simply be angle of the forestay in those pictures as I recall a similar proximity of jib and spin halyard to the cotter pin. I don't recall the cage being so far away from the mast extrusion.

Sorry for confusion.
What I have now is 10mm Dyneema with a polyester cover. I have the option to go to 5/16 inch but I feel it's too small on the hands.
Where the cage is mounted now left enough room to fit the new 10mm halyards UNDERNEATH the cage, which fixes the issue. Note I had to coax the cage onto the mast head with a hammer. BUT still can get a nasty jam with the spin halyard flying upward and to side, to jam between cage & mast. The fix would be to add a small crossbar on the cage to lift halyards away from forestay clevis pin. then reroute halyards back thru cage.

 

[Apex]

@sheardc I am thinking of a way to make the forestay pin smoother, so I don't worry about proximity and catching. Under the cage, I can see that is not much clearance. I am over the cage currently, and will share pics in a couple of weeks. But 2yrs in, no problems to date with potential chafe and over position.