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Old 10-04-2016, 03:21   #1
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Converting to a Cat rig

Hi Everyone
I am thinking of purchasing a “36ft sailboat” that has been designed with the typical masthead Marconi rig. Does anyone know of a designer that can detail the changes required to convert to a Cat/wishbone rig? I have a full set of structural, layout and sail plans. Thanks.
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Old 10-04-2016, 10:22   #2
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Re: Converting to a Cat rig

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Originally Posted by Horseman View Post
Hi Everyone
I am thinking of purchasing a “36ft sailboat” that has been designed with the typical masthead Marconi rig. Does anyone know of a designer that can detail the changes required to convert to a Cat/wishbone rig? -----
Do you mean you want to convert the mainsail to a wishbone boom, or do you want to convert the entire rig to a catboat rig?

The latter involves having only one sail and relocating the mast forward.
That would be complicated and expensive, and you might not like the results.
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Old 10-04-2016, 11:44   #3
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Re: Converting to a Cat rig

If you intend to move the mast forward I suspect it would be about the same price to have a new hull made. Buying a boat set up like this already would be far cheaper.

Off hand the required changes would include

1) moving the structural support for the mast
2) new chainplates
3) reinforcing the hull to take the new chainplates
4) moving the keel
5) moving all the deck hardware, adding some, removing others.
6) buying a new mast, sails, and standing rigging

This would be a massive project. Buying any used Cat rigged boat would be cheaper by a long shot
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Old 10-04-2016, 17:14   #4
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Re: Converting to a Cat rig

A good first question is what are you trying to achieve with this conversion? Sticking an unstayed cat rig onto a narrow beam tippy boat may not give you that joy you see on the faces of people with a nonsuch.

On the other hand if you are looking to get rid of your standing rigging and move towards a simpler rig, or maybe you bought a great hull and engine with the rig missing, this is something you CAN do. Whether or not you should is up to you. You definitely won't need new chainplates. Or any chainplates for that matter
I suggest looking at a book by Derek van Loan, The Chinese Sailing Rig, Design and Build Your Own. It gives an idea of the considerations of what you have to do convert a boat originally meant for standing rigging to one with freestanding masts. Even if you have no interest in junk rig the book is still valuable for that.

But think long and hard about why you are considering this route. It might be easier to find a freedom 44 for sale somewhere. Or one of the later carbon rigged nonsuch.

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Old 11-04-2016, 09:21   #5
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Re: Converting to a Cat rig

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Originally Posted by Horseman View Post
Hi Everyone
I am thinking of purchasing a “36ft sailboat” that has been designed with the typical masthead Marconi rig. Does anyone know of a designer that can detail the changes required to convert to a Cat/wishbone rig? I have a full set of structural, layout and sail plans. Thanks.

What, precisely, is it you wish to achieve by such a conversion? What, precisely, is it you think the given hull could do better if it were cat-rigged, than it can with the present marconi rig? What, precisely, is it you think YOU can do better (or avoid having to do) after such a conversion?

The answer to your specific request to furnish the name of a designer who is competent to "detail the changes" of such a conversion is that any yacht designer of repute is COMPETENT to do it. A corollary is, IMO, that any competent yacht designer would REFUSE to do it.

If it's a cat-rigged, wishbone-boomed 36-footer you want, then just go buy an existing one. But make sure it was designed by a competent yacht designer!

TrentePieds
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Old 11-04-2016, 10:25   #6
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Re: Converting to a Cat rig

I see that the Loan Junk rig book has been suggested, and I would second that.

Also try the junk rig association web site which has much of its documentation open to non-members. You won't have to move the keel, as someone has suggested, just calculate the centre of lateral resistance and centre of effort of the existing rig. The reinforcement of the hull and deck to take the unstayed mast is not too big a task, as long as you can get enough bury where you want to place the new mast. Most junk rig boats are conversions and have repositioned the mast(s) forward of their bermudian position.
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Old 11-04-2016, 10:53   #7
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Re: Converting to a Cat rig

We sailed a cat-ketch for about 10 years. Interesting rig but I don't think there's any real benefit over any other rig. It's certainly not worth spending the money & time to change a boat to that rig when it was designed for something else. Not only would it be expensive but it would really hurt the boat's value, especially if done by an amateur. If that's a rig you really want buy a Nonsuch or a Freedom.
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Old 11-04-2016, 11:06   #8
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Re: Converting to a Cat rig

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Originally Posted by nuvaslacker View Post
I see that the Loan Junk rig book has been suggested, and I would second that.

Also try the junk rig association web site which has much of its documentation open to non-members. You won't have to move the keel, as someone has suggested, just calculate the centre of lateral resistance and centre of effort of the existing rig. The reinforcement of the hull and deck to take the unstayed mast is not too big a task, as long as you can get enough bury where you want to place the new mast. Most junk rig boats are conversions and have repositioned the mast(s) forward of their bermudian position.
You don't have to move the keel, but you should. Designed cat boats tend to have lots of weather healm that becomes even worse as the sail is reefed. By not moving the keel you make this even more problematic. Redesigning the rudder to be both larger and balanced (if it isn't already) will also help.
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Old 11-04-2016, 13:57   #9
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Re: Converting to a Cat rig

Waste of money

Waste of time

Waste of Flexibility.

Dont do it!
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Old 11-04-2016, 15:55   #10
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Re: Converting to a Cat rig

I think Tom Wylie would be the best person to advise you on this. His Wylie Cats and Wylie Cat-Ketches are very popular, and I suspect he as more experience with unstayed rigs than any other recent naval architect. Plus, he's a hell of a nice guy.

If I were you, I'd do a couple of things:

1. I would hire Tom for whatever his hourly rate is for a 2-3 hour consultation. Let's say he charges $175 an hour, and you are reluctant to spend $500 before you've even gotten started. That's the cheapest $500 you'll ever spend.

2. He may advise you that the boat is not a good candidate, or more importantly, it's just not a good boat. That, too, would be helpful.

www.wyliedesigngroup.com

Cheers,

Chuck
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Old 11-04-2016, 16:16   #11
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Re: Converting to a Cat rig

I assume most designers can do this. It's just a matter of where the center of effort is as far as balance.
Other construction issues are noted above. There are examples of boats sold both ways with the same hull.
A free standing spar is quite expensive though if that's where you are headed.
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Old 11-04-2016, 22:23   #12
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Re: Converting to a Cat rig

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Originally Posted by Chuck Hawley View Post
I think Tom Wylie would be the best person to advise you on this. His Wylie Cats and Wylie Cat-Ketches are very popular, and I suspect he as more experience with unstayed rigs than any other recent naval architect. Plus, he's a hell of a nice guy.

If I were you, I'd do a couple of things:

1. I would hire Tom for whatever his hourly rate is for a 2-3 hour consultation. Let's say he charges $175 an hour, and you are reluctant to spend $500 before you've even gotten started. That's the cheapest $500 you'll ever spend.

2. He may advise you that the boat is not a good candidate, or more importantly, it's just not a good boat. That, too, would be helpful.

www.wyliedesigngroup.com

Cheers,

Chuck
Thank you Chuck! I'd completely forgotten about Wyliecats!

I've sailed in several Nonsuches and once on one of the later carbon rigged ones. The carbon Nonsuch was like a completely different boat. It went from being so easy to sail that you sail more often to being so fun to sail! While not losing any of the easy.

Wyliecats are another magnitude in that same direction. Like a Laser that you could never capsize and with a dry bunk.

I think it is unlikely you could get that kind of performance from converting most sailboats you find used, but I agree with Chuck. If you want a designer for this project you really couldn't beat Tom Wylie. As cool as those Wyliecats are they aren't even the coolest boats he has designed.

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Old 12-04-2016, 23:45   #13
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Re: Converting to a Cat rig

Thank you all for your comments and in particular to Chuck Hawley for his referral to Wylie Cats.

Most of the other posts suggest I forget the whole thing or buy a ready-made cat rigged boat. This would be a good idea if I could find one that ticks these boxes:

A very good sea boat – (I want to go south of 40degS), aluminium construction, shoal draft, 36’, basic/robust systems and fit out and setup for single handed sailing (cat rig). The closest thing might be an Alubat Ovni 36, but they come with a hefty price attached and it would not be feasible to convert one for the reasons already posted.

So I have found the hull (not rigged) and hence the need for advice on the potential for a cat rig from a qualified yacht designer.
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Old 13-04-2016, 04:35   #14
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Re: Converting to a Cat rig

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(I want to go south of 40degS),
....snip....
So I have found the hull (not rigged) and hence the need for advice on the potential for a cat rig from a qualified yacht designer.


Quote:
Originally Posted by Cu Mor Glas View Post
or maybe you bought a great hull and engine with the rig missing, this is something you CAN do. Whether or not you should is up to you. You definitely won't need new chainplates. Or any chainplates for that matter
I suggest looking at a book by Derek van Loan, The Chinese Sailing Rig, Design and Build Your Own. It gives an idea of the considerations of what you have to do convert a boat originally meant for standing rigging to one with freestanding masts. Even if you have no interest in junk rig the book is still valuable for that.

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So you are in the position I described. Have a good hull with no rig. That wasn't clear from the first post. And sailing that far south wasn't mentioned the first time either. A single mast cat rig like a nonsuch would not be recommended for that sort of adventure. Their balance gets weird as you reef them. Cat ketch balances better.


The good news is that Tom Wylie is still a great recommendation. His back catalog includes a diverse selection of boats from sail powered scientific research vessels to the adorable Wylie Wabbits. I do strongly encourage you to leaf through the van Loan book though. And check out the Junk rig association as well. Reefing a junk mostly just brings your C.E closer to the deck. Not much movement forward or aft. If you are going somewhere that you are likely to be always reefed this is the difference between a comfortable neutral helm and dragging a barn door of weather or worse Lee helm.

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