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Spot check - internal halyard conversion

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JimGo
Admiral

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USA
962 Posts

Initially Posted - 03/08/2012 : 10:02:34

I'm getting ready to convert over to internal halyards which lead back to the cockpit, and wanted to get some feedback on my plan, please.

I am going back and forth about whether to install the PVC conduit inside, or to go with pipe insulation (the foam stuff for your hot water pipe). I'm screwing up the courage to install mast exit blocks (which I'll touch on in a moment), but the idea of drilling many holes and adding pop rivets to the mast has me a little concerned, so that's why I was thinking the foam might be a good alternative. Any feedback? Since I have the mast down and will be doing all this work, the thought is to just go ahead and check out all the wiring anyway, just to be certain it's all working properly. If I'm doing that, I may as well go ahead and put the insulation/PVC in place, too.

Here's my current configuration:

My plan is change this to the following configuration:
On the starboard side, running the spinnaker halyard and main halyard down to mast exit blocks (I am getting ready to order the EB2 mast exit blocks from Garhauer (https://garhauermarine.com/catalog_process.cfm?cid=69)), then out to a deck organizer and back to a double clutch that's installed on the cabin top next to the grab rail. I'm also considering relocating the winch that is currently on my mast, and putting that behind the clutch, thus letting me use the winch for both the spinnaker and main halyards.

I have replacement sheaves for the mast head on order; they should be here any day. Can I install the mast exit blocks low on the mast to keep the halyards from becoming trip hazards as they lead over to the organizer? Or am I better off putting the exit blocks higher up on the mast (above the gooseneck) for strength purposes? My thought was that the housing for the exit blocks should help reinforce the hole that's being cut, so I wasn't sure in the end whether the exit blocks were weakening or strengthening the mast.

If I wind up using free-standing blocks below the mast exit blocks, what size/kind of blocks should be used? My thought was to use something like 30-13UAB's from Garhauer (https://garhauermarine.com/catalog_process.cfm?cid=14), but it doesn't look like those have a swivel, and in this application I think a swivel might make sense.

I also have a spinnaker crane on order, which I'll be adding to the mast head for the asymetrical spinnaker. I'll probably hang a block from that, too, and hang the spinnaker from that block. Will the 30--13UAB's (or the swivel equivalent) work at the spinnaker crane, too?

On the port side, I'll lead the jib halyard down to the mast exit blocks, then tie off the halyard at the mast on the cleat that's already there, since I have a jib furler and won't be hoisting the jib very often. I'll have one unused sheave at the stern side of the mast, and one unused mast exit block location on the port side, but I don't think that should be a big problem (room for expansion later, if needed, and I may wind up adding a "halyard" to hoist a hammock). I'm planning on adding a double-block system (sorry, not sure the proper term) to the end of the fixed-length topping lift that's already in place, this way I can adjust the topping lift tension at the stern end of the boom (since that's where I normally sit).

- Jim
Formerly of 1984 C25 named Dragon Wing

NOTE: In my case, PLEASE don't confuse stars/number of posts with actual knowledge. On any topic.

Edited by - JimGo on 03/08/2012 10:08:00

dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 03/08/2012 : 12:44:51

Jim,

When planning your spinnaker rigging, try to envision how you'll be deploying and retrieving the sail. When I'm lowering my spinnaker, I'm on the foredeck with the halyard in hand so I can lower the sail while simultaneously gathering/guiding it for stowage so it doesn't go in the drink. Will you using a chute scoop/spin sock? Also, I don't think you'll be putting the spinnaker halyard to a winch.

Edited by - on

JimGo
Admiral

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USA
962 Posts

Response Posted - 03/08/2012 : 13:51:29

Don,
Thanks for the reply. My thought was to use a spinnaker sock to douse it, with the hope that I wouldn't have to go to the foredeck most of the time. Thanks also for the feedback on the need (or lack thereof) for a winch for the spinnaker halyard. If that's the case, then I may want to look at alternative arrangements, or possibly look at leaving the winch on the mast since the only thing I can really see needing it for would be the main halyard.

Edited by - on

Lee Panza
Captain

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USA
468 Posts

Response Posted - 03/10/2012 : 17:37:14

Jim;

For whatever it might be worth to you, I've put up on my website a few more of the CAD drawings I did in laying out my arrangement of lines. It's pretty complicated, so it was nice to be able to model everything in CAD before I did too much irreparable damage to the mast by cutting holes in the wrong places. It's still a work-in-progress, but I'll post pictures when I'm done this Spring (and, after sailing this summer points out to me what I SHOULD have done, I'll post that, too). In the meantime, I hope it helps stimulate your own thinking.

http://panza.smugmug.com/MYSAILBOAT/The-Boat-Renovation/Mast-Modifications/21650162_bHQXBG#!i=1744085334&k=zFS4cVX

Whatever you do, think it all the way through first before you start butchering your expensive mast. To paraphrase the old saying, "Think twice, cut once."

Edited by - on

Joe Diver
Master Marine Consultant

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USA
1218 Posts

Response Posted - 03/11/2012 : 08:01:01

I think Eddie is doing this, or did this, to his rig. Maybe he'll pop in here or you can ping him with an email. "eguevara"

Edited by - on

JimGo
Admiral

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USA
962 Posts

Response Posted - 03/12/2012 : 08:22:22

Lee, thanks for the feedback. "butchering your expensive mast" is exactly the way I see it! In my opinion, it's much easier to replace the mast head than the mast itself. That's why I'd rather not add rivets to the mast if I don't have to (and why I'm having second thoughts about the internal halyards!). What I may wind up doing is just checking out the wires inside the mast and add some pipe foam (or pool noodles) around the wires.

By the way, I read several of the threads on which you commented about your experience - thanks for all the excellent write-ups!

Lee, have you actually implemented the plans on your boat? Do you have any photos? The CAD drawings are very helpful, but I'd still love to see how everything looks.

I also note that you've spec'ed the exit blocks at the bottom of the mast to be pretty low compared to what others have suggested, and that you have one exit block almost exactly opposite the gooseneck. Any safety/mast strength issues there?

Edited by - JimGo on 03/12/2012 09:09:09

eguevara
Navigator

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USA
111 Posts

Response Posted - 03/12/2012 : 16:08:06

What makes my setup different that what most people are doing is that I'm not taking the halyards back to the cockpit.
I'll put pics when I'm all done.

-eddy

Edited by - on

Lee Panza
Captain

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USA
468 Posts

Response Posted - 03/12/2012 : 19:00:40

Jim;

Although my job has been pretty demanding lately, forcing me to slow down work on my boat, I've been trying to contribute when I can. I've learned a great deal from reading this forum over the past few years (in fact, the availability of such an active and generous users' group was a big factor in my choosing a Cat-25) that I want to be able to give back. We frequently see new Cat-25 owners talking about what they've picked up from the archives of this forum, and with the number of boats still in use - and the number that are being renovated over time - there will continue to be a need for the collective information we've been assembling here for many years to come.

As for photos of my project, they'll be posted in a month or so, when it's far enough along that I can actually field-test everything.

Your observation about the exit plates near the bottom is very perceptive, so I'd like to share my thinking with you. The plates are designed such that the line passes through them at a specific angle relative to the surface of the mast. If the line continues out at that, or a greater, angle, the line only rubs on the upper edge of the opening. If it continues on down closer to the mast it will also rub on the lower edge, forcing the line into a shallow s-curve and contributing significantly more friction. That minimum angle relative to the mast is about 20 degrees for 5/16" line passing through the Ronstan RF6031 plates that I used. When I laid it out in CAD it became evident that the slots had to be low to minimize the friction.

The upper pair of exit plates is higher than I would have liked. I had the same concern that you raised about the horizontal load from the boom. That's why there's a gap between the two lower pairs and the upper pair. During light to moderate conditions that horizontal load is relatively mild, but when I go to a second reef I'll also be lowering the boom into that gap (to just above the cheekblock for the 2nd reef line) to get the whole rig lower. Bringing the boom too far down, however, seriously impairs the vang's effectiveness by reducing the angle between it and the boom.

Your concern about cutting the slots in the vicinity of the boom is natural, and in an offshore boat with a higher aspect mast (a greater ratio of height to section) this would have to be more rigorously engineered. However, with our boats the structural section of the mast is relatively beefy. With only one set of spreaders, it's sized more for the bending moment at it's mid-height than for the shear loading near its base. The horizontal loads near the base are on the order of a few hundred pounds in the kinds of winds that a Cat-25 would be capable of sailing in. The most extreme case would be an accidental gybe, when the boom slams home. The weak link in the entire system, however, is the gooseneck fitting, and there have been cases of them breaking. I've left a lot more metal between the gooseneck and those exit slots than there is around the hinge pin of the gooseneck. Still, I would have put all of the slots closer to the forward side of the mast except for the friction between lines (or between the individual lines and the sides of the slots, especially if they had been moved forward around the radiussed portion of the mast).

By the way, you mentioned using pop rivets: I'd strongly urge you to use machine screws tapped into the mast. Tapping is not that difficult if you're careful. I use a tapping guide:

www.use-enco.com/CGI/INSRIT?PMAKA=325-4924

(there's a substantially less expensive "imported" model available elsewhere, but my experience with Chinese-made knock-offs has convinced me to pay the premium for anything I expect to get much use out of, and I expect to be doing various "projects" on this boat for the rest of my life).

Most guides for drill sizing are based on 75% thread depth, but with stainless screws into thin aluminum extrusion (and the slight irregularity from hand-tapping) I go a couple of drill sizes smaller. And, of course, Tef-Gel (although it really is a bit unpleasant to use).

I've been buying short screws (as short as 3/16" in 1/4-20) from Bolt Depot (and just gritting my teeth over the shipping and handling charges for small orders). With internal wiring, whether the control lines are internal or not, one should avoid sheetmetal screws, and pop rivets make it very difficult to change anything if you later decide that it's not right the first time (or if you decide to rearrange things so you can add something you hadn't considered the first time). Besides, machine screws are a lot stronger in shear, and I believe the sizes commonly needed for what we're doing (generally #10-24 or 1/4-20) are also stronger against straight withdrawl than aluminum pop rivets. I'll admit, however, that pop-rivits are easier and less expensive.

Anyway, good luck with your project, Jim. I'd encourage you to continue, even if you just take another season to get up the courage to begin cutting holes in your mast ("butchering" was perhaps an unnecessarily strong word; we DIY'ers can do reasonably good work if we're careful).

Now back to bed to try to shake this cold that one of the guys brought into the office last week - I spent most of the weekend in and out of bed (didn't even get downstairs to try unscrewing those winch caps, although I'm dying to know if that'll work). But this has given me a chance to share a little of the thinking I've been doing lately. I hope it's helpful.

Edited by - on

Lee Panza
Captain

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USA
468 Posts

Response Posted - 03/12/2012 : 19:20:24

Jim:

One more thing, in answer to one of your Q's: I'm using the Garhauer 30-13's at my mast base organizer, and yes, they do swivel (they can also be fixed by tightening a setscrew). They're a bit large for the spinnaker lines, though. It's wise to minimize the weight that far aloft, and the lightweight composites like the ones Lewmar makes are probably a better choice.

Edited by - on

JimGo
Admiral

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USA
962 Posts

Response Posted - 03/13/2012 : 07:09:11

Lee,
Thanks for the replies!!! VERY helpful. I especially appreciate you taking the time to write them up while under the weather - I hope you're feeling better soon!

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