Halyard strength - Why so much

[wingssail]

Originally Posted by donradcliffe

So you will gybe on the shifts and carry on with full canvas to a new anchorage when your ETA is 0400? I did that once and learned my lesson.

OTOH, I always left large piles on the dock and in the water when I raced my Beneteau First 456. What a huge difference taking a thousand pounds out of the ends makes.

Yes we will gybe on the shifts but we won't carry on with full canvas if it means arriving before dawn. There's been many a time when we find ourselves slowly tacking off shore waiting for sun up.

We never leave big piles on the dock, we race with what we have, however we do have a storage locker full of cruising gear which goes on at the end of racing season and its place in the locker is taken by the racing sails. When you race 25 ties in three months each year you can't be bothered with loading and unloading for each race.

When we went around the world we raced in many countries with the entire load on board, but we still kept weight out of the rig.

[CyKlop]

There is an additional factor that is not being considered - the geometry of the forces.

Imagine this configuration:

========================== Line
---------------> Force

At this point, the line is subject to 100% of the force. This is the case, for example, on halyards for a mainsail or staysail, but not a spinnaker.

Now imagine this:

========================== Line
|
|
V Force

At this point, the amount of tension on that line FAR exceeds the force being applied. What might be such a situation? Sheets on a close reach or close haul, as an example.

Then, of course, there's the working load versus breaking strength that others have previously pointed out.

[argonauta1]

Let me tell you how I broke my 3/8 nylon main halyard mid Pacific of course running down wind. You will be aware that a preventer is needed to protect against an inadvertent jibe all standing. I had rigged the preventer too tightly with insufficient play for the rear of the boom to move up and down as the leach billows causing the luff to increase and decrease tension on the main halyard. I was running too aggressively with too much tension on the preventer. After about a day in ENE 20K, the main halyard parted at the sheave. Since then I included an oil rig strength bungee in the preventer set up. Oh yes, we secured everything and ran on the genoa poled out and stay sail for about a 1000 Nm until we repaired everything with the help of other yachties in our first South Pacific anchorage.

[Bill_Giles]

There seem to be two main reasons to over specify halyards and sheets. One is ease of handling, while a 6mm or 1/4” modern rope may still be over-strength it is hard on the hands and not so easy to untangle. The other is wear as a thicker rope will accept more wear and incidental damage. Of course these points don’t seem to worry the racers.

[wingssail]

Originally Posted by Bill_Giles

There seem to be two main reasons to over specify halyards and sheets. One is ease of handling, while a 6mm or 1/4” modern rope may still be over-strength it is hard on the hands and not so easy to untangle. The other is wear as a thicker rope will accept more wear and incidental damage. Of course these points don’t seem to worry the racers.

Mr Bill Giles, You shouldn't let your disgust with racers show so transparently. Most of us are also cruisers.

Handling: Racers and knowledgeable cruisers who want to use 6mm dyneema will keep or add covers where the line may be handled or go through stoppers. The crew members will be handling 8-12mm line.

Wear acceptance: Nobody wants a halyard (or other lines) to break so wear is monitored very closely. Sheaves and sharp points in contact with halyards are repaired.

Racers spend a lot of time using their gear and want reliability, but not extra weight or windage. Dyneema running rigging generally offers both.

[Breaking Waves]

Originally Posted by Bill_Giles

There seem to be two main reasons to over specify halyards and sheets. ease of handling ..... accept more wear and incidental damage.

hmmm . . . actually I would suggest that one of the main reason to 'over specify' (by which I think we mean more working strength than expected loads) is that sailors (at least those who care about sailing well) want to minimize stretch in those lines, and sizing for low stretch tends to lead to 'over strength'.

[sailorboy1]

I have had a main halyard break on a bad gybe. So I don't feel they are oversized.

[Be Free]

Originally Posted by StuM

Or maybe because you used a sheet bend instead of a Zeppelin Bend

I was wondering the same. A sheet bend will come apart if there is not tension on it.

[Bill_Giles]

I really did not mean to demean the racing fraternity being a small boat racer myself. I know what it is like on a dinghy to handle 3mm ropes but then the loads are lighter. My friend gave me a line from a sports hang glider, it is 1.5mm and has a breaking strain of 500kg. Tempted as I was to get some use out of it it did occur to me that under load it might act as a cheese wire and slice through flesh.

[Cheechako]

For common ropes, bigger = less stretch. It's not about the ultimate strength. Also, anything below 7/16 or so is hard on the hands.

[StuM]

Originally Posted by Bill_Giles

I really did not mean to demean the racing fraternity being a small boat racer myself. I know what it is like on a dinghy to handle 3mm ropes but then the loads are lighter. My friend gave me a line from a sports hang glider, it is 1.5mm and has a breaking strain of 500kg. Tempted as I was to get some use out of it it did occur to me that under load it might act as a cheese wire and slice through flesh.

With a BS of 500kg in a critical environment such as a hang glider, I wouldn't use it anywhere that expected loads would exceed 100kg at most.