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Old 07-09-2014, 18:23   #1
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Convert "discontinuous" to "continuous" shrouds?

I'm looking at re-rigging my '86 Beneteau First 405. This boat has the tall, triple spreader rig, and the shrouds are discontinuous (four shrouds are reduced to 3 at the lower spreader). I'm considering changing this so that all 4 shrouds terminate to turnbuckles on deck. The biggest modification I'll need to make is to modify or fabricate a new set of chain plates, which doesn't look too difficult to do. Anyone else take on a project like this before? The boat was a race boat that we will only use for cruising.
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Old 07-09-2014, 18:55   #2
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Re: Convert "discontinuous" to "continuous" shrouds?

Expensive , and can i ask why? grouping 4 turnbuckles in the chainplate sounds insane to me, another point to consider its you need for a longer wire lenght more turns in the screw to keep the right tensión, if the mast its a Sparcraft prepare the wallet, you need to modify spreader end tips the first spreader to acomódate 3 wires in fact ,also keep in mind that with the original setup, when you slack the uppers , the inner lowers get loose to and when you tight the uppers the inners get tight to , this happen because the inners rest in the spreader tip for a reason, the spreaders are designed to get some flexion down when you tight the rigging and the inners counteract this flexion, dificult to explain in one post sorry, are your upper turnbuckles seized??
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Old 07-09-2014, 20:08   #3
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Re: Convert "discontinuous" to "continuous" shrouds?

The mast is an old Isomat with some really unusual fittings connected to the lower spreader tips (see my other thread here: Isomat discontinuous spreader fitting? ).

I've not found any info on those fittings and am afraid they may be frozen solid. Add to that all the rigging is metric and I'm in a non-metric country, so some modifications will likely be needed.

You make some good points, I'm just trying to weigh my options.
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Old 13-09-2014, 09:46   #4
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Re: Convert "discontinuous" to "continuous" shrouds?

Prof,
It would be wise to contact a professional rigger for final advice. However, how many chainplates do you have on deck? And, what is your setup: how many lowers? Intermediates? It may not be as complicated as it sounds. Can you describe your standing rigging? As I said in another post, it is my opinion your current setup is not desirable for cruising.
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Old 13-09-2014, 10:09   #5
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Re: Convert "discontinuous" to "continuous" shrouds?

I'm going over my options with a couple riggers here and so far have come up with a couple of ways to work around those weird stainless barrel fittings on the end of the lowers. Biggest part of the decision will be what parts I'm able to locate. So far costs to re-rig as continuous seems to be about the same as discontinuous. Will depend on whether I can modify my existing chainplates.
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Old 13-09-2014, 14:49   #6
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Re: Convert "discontinuous" to "continuous" shrouds?

Another consideration is the additional stretch afforded by running the D's down to the deck level. You might have to go up a size in the wire to compensate for that, and it would complicate tuning, I should think.

Oh... are the spreaders in line or swept, and is it masthead or fractional? Both of those factors are important in thinking this through.

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Old 13-09-2014, 20:28   #7
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Re: Convert "discontinuous" to "continuous" shrouds?

Masthead rig, spreaders swept by only a few degrees, baby stay and running backs were removed by previous owner, but I will be replacing them. The shrouds are currently rigged kind of weird. Shrouds are continuous from masthead to the bottom spreader, where two shrouds end in turnbuckles and then only three shrouds to the deck. I've never seen anything rigged like this before (and I've been on lots of race boats with discontinuous rod rigging). Only reason I can think of that caused them to rig this boat this way was so that they could use the same chainplates for the standard short mast (two spreader) and optional tall rig (triple spreaders).

I'm looking at multiple options and am working with riggers whose experience I am pretty confident in.
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Old 13-09-2014, 20:46   #8
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Re: Convert "discontinuous" to "continuous" shrouds?

Hmm... that is a kinda strange arrangement! I guess the conventional approach would be to convert to a normal discontinuous rig, where the D3 has a rigging screw at the 2nd spreader, the D2 has a RS at the 1st spreader, the cap shroud terminates at the first spreader and then a heroic V1 takes the full load to a single RS at the chainplate. But I guess that you are trying to simplify things and be able to tune the rig from on deck... and that ain't gonna be easy!

I think that I would rely upon your professionals who doubtless know far more than I do about complicated rigs. All the free advice garnered from the CF would look bad if your mast fell down!

Good luck with a difficult problem.

Jim
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Old 13-09-2014, 21:47   #9
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Re: Convert "discontinuous" to "continuous" shrouds?

Quote:
Originally Posted by Jim Cate View Post
Hmm... that is a kinda strange arrangement! I guess the conventional approach would be to convert to a normal discontinuous rig, where the D3 has a rigging screw at the 2nd spreader, the D2 has a RS at the 1st spreader, the cap shroud terminates at the first spreader and then a heroic V1 takes the full load to a single RS at the chainplate.
Yup, that is one option but it will require that I replace the spreader tips for 2 pairs of spreaders. Another option is to re-rig it as is but replace the bottom spreader tips. And the last option is to re-rig as continuous which would require replacing the bottom spreader tips and the chainplates. We're going to discuss costs next week which should help me decide which way to go.
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Old 14-09-2014, 06:54   #10
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Re: Convert "discontinuous" to "continuous" shrouds?

Also the spreader tips will be different. Make sure the ones you will need are available. Maybe you will have to have them designed and machined.

Talk to your rigger. Going continuous may render your rig more difficult to tune.

A well designed discontinuous system is as good as any other so I am not clear why you would change it.

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Old 15-09-2014, 09:58   #11
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Re: Convert "discontinuous" to "continuous" shrouds?

Prof,
Keep us informed of your decision. Remember, whatever choice you make . . . . K.I.S.S. should be your ultimate design and maintenance criteria. Good luck and good sailing.
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