mast bending

[CaptK]

Looking at those videos from a riggers standpoint, that setup gives me the heebie-jeebies.



Look how sloppy that leeward shroud is, how much it moves around. That is stainless steel, and when it is doing what you see there, it is "work hardening" the wire, which will cause premature failure of the wire, usually/probably right at the top end of a pressed swedge on the lower end of the shroud.

You know what 'work hardening' is; take a piece of metal, bend it first one way, then the other... Repeat this over and over, and sooner or later, it WILL fail.

This is happening to those shrouds. The 1x19 is held very rigid at the swage fitting (like in a vise), and the whole part above that is moving back and forth, back and forth - I would bet you at least several hundred cycles of this during the course of a 1-2 hour sail, based on what I saw in that video. Each back and forth is a 'bending' - slight, for sure, but a bending nonetheless. And that will be work hardening the wire right there at the swedge...

So if your boat looks like that, something needs fixing. Maybe setup needs to take longer, for you to tighten those shroud turnbuckles down a bit more. Maybe you could set up some sort of Hyfield lever (1) (2) (3), or if that isn't needed, just a proper tuning to remove that slack once underway...

But it is not good for the wire to be flopping around *that* much. It should go a bit loose, but not floppy, on the leeward side, when you are under sail.

[CaptRon28]

I've been rigging boats for years, mostly much larger ones. Do anything like this with the standing rigging on a 30 / 40 foot or larger sloop and you're going to lose the rig. Besides the wire flexing, the mast head will be whipping around like a wrecking ball  as the pressure or direction changes in heavier air or seas. Everthing up there is magnified. Climb up there in 10 foot seas and you'll see what I mean. The forces on a much smaller boat are, of course, much lower - but the top of the rig will still be swaying in the breeze. Any violent movement could easily cause major damage.

That said, take a look at the Horizon demo sail on the Hutchins web site. The shrouds are as loose as the above two videos. Are cat boats that different? It's the same physical forces as any other sail boat - from a small sloop up to a 400 foot clipper. You really cant let uncontrollrd spars move around like this.

I have a hunch that they are coming from the factory like this to make it easier to raise the mast. The shrouds are swept back a few feet and under tension would cause difficulty in raising the stick the last few degrees. There's got to be a better way of doing it. Maybe a quick release or a knurled adjusting wheel in place of the standard turnbuckle on each shroud. I'll look into it before next year. With my shoulder damaged I can't really do much about it now anyway. I'd want something easy to adjust and that would guarentee some sort of repeatability in day to day tuning.

[newt]

Thats interesting Bob. I wonder what advantage there in in keeping the shrouds that loose??

[Bob23]

Newt:
   The only thing I can think of is concerning the gaff rig. Maybe when the sail swings way out as on a run, the shroud needs to be loose so as not to impeed the position of the sail. But it looks so wrong to me. Many small catboats that I see up here on the Barnegat Bay in NJ have free standing masts with maybe a small forestay.
   Perhaps an email to Gerry or Rich would clear this up. They are the Masters, after all. If I see 'em at Annapolis, I'll ask them.
Bob23

[Rahn]

My stays are tight when the mast is raised, just like all of my sloop-rigged boats I've owned. I know that the owner of the second boat video I linked actually added spreaders to his boat. I am in no way an expert but don't we have to trust the builder/designer of our boats? I have owned Com-Pac Catboats for four years now and they all have been that way and I haven't noticed any ill effects. My point is that before I change the rig I would want to hear what the builder has to say.

[brackish]

Bob23 said:

   Newt: I do exactly the opposite when raising/lowering my mast. The only shroud I detach is the forward lower- I've found I can leave the others alone- the forward lower is the only one that impedes mast lowering. And of course I loosen the bobstay.

Bob23, does that work?  Does loosening the bobstay get enough slack to get the clevis pin out of the forestay?  I disconnect the forward lowers completely and have been loosening the backstay just to get the pin out and back in on the forestay.  Would be easier to loosen the bobstay, but that doesn't harm the sprit does it?  Hey, if that will work, another four or five minutes off my ramp time.

[Rahn]

I was searching for a picture of the HC with the spreaders and came across this post from Carl on the trailer sailors board:

"No less than Gerry Hutchins himself advised me to not worry about shroud tension. He said he figured the rigging was there to keep the mast up, not really to tune the boat, and that doesn't require any tension at all on the lee shroud. Mine hangs loose when sheeted in and heeling, and Gerry said that was fine.

The best indicator for rig tension on our boats is probably the effort it takes to set the quick release forestay lever. It should take a firm push, but without much muscle.

You may be able to affect your weather helm with mast rake, but that is definitely not the primary way to take care of that. The helm's balance is controlled by the centerboard. As you pull up, the board rotates aft, and that makes the weather helm go away. That bit in the brochure about the 'light balanced helm' is actually true."

[Bob23]

Brack:
   It does work and I ain't pullin' yer leg either.  I never touch the backstay at all. Keep in mind, when I lower my mast I relieve some of the tension on the forestay but pulling forward on the tied off jib halyard. I then loosen the bob stay until I can remove the clevis pin from the forestay and then lower the whole shebang, hopefully without the bang. The CDI furler and forestay are laid alongside the mast and all is well. This scientifically tested and proven procedure does not affect the bowsprit at all.
   If I had to do this repeatedly a season, I'd build a ginpole so I could winch the mast up and down. Kinda like the way the Horizon cat mast is raised in the Compac video.
Bob23

[Rahn]

Here's a thread concerning why Carl added spreaders to his HC

http://bbs.trailersailor.com/forums/catboatarchives/index.cgi/read/7964

I'm trying to find his site but I'm not being very successful.

[CaptK]

It may be OK/designed to sail with slack shrouds and a whippy spar, but if it was my rig, then I would run a bungee, perhaps from one shroud to the other in front of the spar, to stop the wear and tear on the shrouds due to that crazy flopping when they are to leeward...

[CaptRon28]

"No less than Gerry Hutchins himself advised me to not worry about shroud tension. He said he figured the rigging was there to keep the mast up, not really to tune the boat, and that doesn't require any tension at all on the lee shroud. Mine hangs loose when sheeted in and heeling, and Gerry said that was fine.

Not sure if the loose leeward shroud would even effect the tune. I'm more concerned about the top of the mast moving around as conditions change. Change in tack, heavier seas, chop, etc. With both sides loose when leeward, the masthead has got to be moving around. That would put a lot more stress on the rig. The moving mast creates momentum up there which must be stopped on the other side. Over and over again.

This is my first cat boat, so I'm not convinced that this is wrong yet. It wouldn't work on anything else though.

[harrys]

I find the discussion on shroud tension interesting.  I just bought a used HC this spring so am very new to sailing a cat boat and looking to learn more.  I had it out on the weekend in 20 kt winds with a reef and it looked just like the videos.  I was also concerned about the slack on the leeward shroud.  However, listening to you guys and seeing the videos makes me feel a little more comfortable.  At least now I know we are all in the same boat, so to speak.

Here is something interesting.  When I went to pick up my HC this spring, the dealer informed me of a delay because he had to replace the mast.  When I got there, the old mast was in his garage and it definitely had some significant curvature.  When I asked what was the cause, he told me that the previous owner had over tightened the shrouds.  He said that over tightening put the mast into too much compression which weakened its lateral strength and hence the bend.  I believe the bend was below the hound assemblies so he may have something there.  I checked the tension out with him on the replaced mast and they felt very loose compared to my old CS27.   Of course the CS27 mast was much bigger and stronger.

Does the manufacturer have any specs on proper shroud tension?  It would be comforting to know. I used a stay tension gauge on my CS which took the guess work out of the setup.