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To milk or not to milk
- Thread starter jamottep
- Start date
solosailor
New member
The real question most will ask is why are you going with a polyester halyard when most guides do not spec it for halyard applications. Most wouldn't use poly on a small keelboat.
Because I made a mistake. I need to go back to my old signature, newbie open to advice. I'm not stupid. I know I don't know what's ahead of me and that I don't have the knowledge nor experience to deal with it. I do want to go. I've put my foot down so to say.
I'm not sure a polyester halyard is a mistake in PJ's application. Apparently an old, hi-tech halyard has chafed on CHANGABANG. If I were planning on sailing 25,000 odd miles, I would want means to run external halyards when an internal halyard failed. Internal halyards can and do fail, sometimes being led on the wrong side of a spreader bar or other sharp, unseen projection inside the mast, or too small a turning radius of a sheave.
Yes, an external, 1/2" poly halyard, has stretch and windage factors. But on a course that is 75% off the wind, stretch and windage are non-factors. Upwind, PJ wants to get to windward safely. It could be argued stretch is a benefit on such an extended passage, reducing load when pounding.
And of course the cost of a poly spare halyard is less by a significant factor, more important to PJ than a minute fraction increase in speed with a hi-tech halyard than stretches (creeps) and weighs less.
And no, I've never "milked" a poly halyard. And yes, I did have all rope, dacron halyards on WILDFLOWER that lasted over 50,000 miles...same as jib, main, and spinny sheets that were furry and easy to handle.
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A 1/2" polyester core halyard has a breaking strength around 10,000 lbs. A Class 40 with a 400 sq ft jib in 25 knots upwind can see 2,000 lb of load. This chart from Yale Cordage shows that this line will stretch about 2%. Assuming his jib sheave is 50' off the deck and then it runs 20' back to a clutch for a total of 70', then he will see a stretch of 1.4'. Heading upwind, the load on the halyard will increase and decrease off each wave, effectively "sawing" the line at the top sheave. Yes, he can stitch chafe patches over this portion of the line to ameliorate the problem. The other issue though is the jib will sag as the wind comes up, and just when he needs an efficient foil going upwind in heavy air, the jib will sag the boat will heel more, and go sideways more not to mention slower. Will he get to where he's going with a polyester cored halyard? Yes if he somehow manages the increase in chafing. (unless he runs out of food because he's slower.) Sounds like someone should look into the cause of the original halyard's chafe problem.
You can make an argument that a polyester core on a spinnaker halyard is less of a concern and could even be beneficial, but you will still have the "sawing" issue with chafe, exacerbated by the changing angle of the halyard into the sheave.
Polyester cored sheets are less of a concern because there is far less distance to cause stretch, there is less chafe, and they are at deck level so they can be dealt with. Polyester Spin sheets with a little stretch may be advantageous to reduce shock loading when the chute refills.
I assume milking just works out any twisting and wouldn't hurt. May also be a waste of time unless you are into that sort of thing.
An external sheave up the mast with a mouse line is a good idea as a back up.
Now let's discuss whether shorthanders should knot the end of sheets and halyards...
You can make an argument that a polyester core on a spinnaker halyard is less of a concern and could even be beneficial, but you will still have the "sawing" issue with chafe, exacerbated by the changing angle of the halyard into the sheave.
Polyester cored sheets are less of a concern because there is far less distance to cause stretch, there is less chafe, and they are at deck level so they can be dealt with. Polyester Spin sheets with a little stretch may be advantageous to reduce shock loading when the chute refills.
I assume milking just works out any twisting and wouldn't hurt. May also be a waste of time unless you are into that sort of thing.
An external sheave up the mast with a mouse line is a good idea as a back up.
Now let's discuss whether shorthanders should knot the end of sheets and halyards...
Two halyards are 2:1: the mainsail and (I think) the gennaker.
I've been thinking about Ragnar's explanation. I'm not sure I fully understand. The jib will be hanked on. As the wind pipes up, increased pressure on the sail is parallel to the ground, i.e. almost perpendicular to the headstay. It seems to me that more pressure would translate into more pressure in the hanks, not the halyard, except maybe near the head, but there's not much sail area there. Isn't it so that if you let go of the halyard completely with the sail under pressure, it's barely going to move?
Maybe I'm missing something.
I though the concern for stretch is more of the "set and forget" nature (i.e. one doesn't have to constantly watch the stretch and take some more halyard in for 100% performance). Also, to put things in context, the stretch is only related to the increase in pressure, should there be any, i.e. it's not a couple of feet.
I do agree that I need to check what caused the chafing.
Maybe I'm missing something.
I though the concern for stretch is more of the "set and forget" nature (i.e. one doesn't have to constantly watch the stretch and take some more halyard in for 100% performance). Also, to put things in context, the stretch is only related to the increase in pressure, should there be any, i.e. it's not a couple of feet.
I do agree that I need to check what caused the chafing.