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Author Topic: Sail Control Methods  (Read 2816 times)

clegg

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Sail Control Methods
« on: November 05, 2013, 10:56:47 AM »




I have recently ordered one of Alan Horne's beautiful J Class hulls.
I would welcome any input on the methods and merits of closed loop
Vs open loop sail control systems.

I want to do justice to this hull. I will not be racing her.

I have built a pair of Comtesse models and a Thunder Tiger and I own a Kyosho Seawind so I have a basic knowledge of sailing but please please, I am NOT any sort of expert so please keep the phrase "idiot's guide" in mind.


I intend employing a ketch rig with twin headsails but, Following Alan's advice I will not be using a bowsprit.

Thank you
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Netleyned

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Re: Sail Control Methods
« Reply #1 on: November 05, 2013, 12:37:50 PM »

Are you using two masts?
Be a bit different on a J Class hull.
Don't forget that to be a ketch, the
mizzen mast must be forward of the
rudder post.

Ned
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clegg

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Re: Sail Control Methods
« Reply #2 on: November 06, 2013, 12:57:48 AM »

My apologies. That should read Gaff Rig.
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Netleyned

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Re: Sail Control Methods
« Reply #3 on: November 06, 2013, 07:52:43 AM »

Your best bet is to get in touch with John Dowd
Username on the forum Jaydee.
He is the guy for all aspects of J class Yachts
and a very nice guy to boot  :-))

Ned.
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JayDee

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Re: Sail Control Methods
« Reply #4 on: November 06, 2013, 10:02:47 AM »

Hello Ned,

I am sure I MUST owe you Money !!!.

John.  :-))
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mrpenguin

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Re: Sail Control Methods
« Reply #5 on: November 06, 2013, 09:46:52 PM »

Further to Clegg's original question, my personal preference is a closed loop winch system, with sheets taken off in appropriate places. You may be able to do the loop on deck with the winch below depending on the boat and your needs.
 
The video below shows a modified winch setup for an 800mm Surmount (a cheap Chinese boat but it sails Ok), this has the winch below deck and loop above deck. This boat had endless issues with the sheets getting caught up below deck or binding in the through-deck fairleads. The modification brings everything on deck except the actual winch; the loop comes up though a couple of fairleads near the stern in this case.
 
You may be able to adapt the idea to your J class perhaps...?
http://www.youtube.com/watch?feature=player_detailpage&v=JWhI3F_MY74
 
 
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alanh

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Re: Sail Control Methods
« Reply #6 on: November 11, 2013, 09:21:56 PM »

Hello Clegg.  Thanks for your kind words! I'm sure that you will have already seen the website, but for the benefit of others who may be interested, the pictures of the gaff rigged J with twin headsails are now posted, more detail to follow.
The gaff rigger carries a bit more sail area but the centre of effort is lower than the Bermuda rig allowing for a better scale look and predictable sailing manners. The centre of effort is on the same vertical line as the B rig of the Nottingham J so the mast position is the same and the Bermuda rig, and the gaff rig can be carried on the same hull provided that the sheeting is thought through at the build stage.
I've only just fitted the new, professionally made sails, but with my home made sails (looking a bit like Nora Batties tights!) the boat sailed very well indeed.
Peter Wiles at PJ Sails now has the templates for this rig.
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Twister

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Re: Sail Control Methods
« Reply #7 on: November 20, 2013, 09:40:58 PM »

Responding to the original question, I've come across what appears to be a very good solution to the winch drum open/closed loop question - have a look at this site for more info:


                 http://www.sailservo.co.uk/captive.html


I've not used the products but am giving them serious consideration. I'll also state 'for the record' that I don't know the chap who runs it but having read his research & opinions he certainly makes an awful lot of sense. I reckon I'd go as far to say it's recommended reading for anyone new to the 'black art' of sheeting arrangements!


Row
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rmaddock

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Re: Sail Control Methods
« Reply #8 on: November 21, 2013, 03:45:58 PM »

I've seen and considered those captive servos.
Think about how much sheet travel you're going to need though.  Ie, if you're going for a scale look with the mainsheet attached to the outer end of the boom then you'll need less torque but much more travel.
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Yogibear

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Re: Sail Control Methods
« Reply #9 on: December 10, 2013, 10:19:34 PM »

Whilst closed with loop systems I've found create more drag on the servo but are more reliable.

Several times I've had the main sail line come off the drum and spent a long time trying to get the model in on just the jib.

I'm currently working on a TopCat which is a closed loop system and the system appears to work very well but you can feel the friction on the lines when they are drawn through all of the tubing.


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Twister

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Re: Sail Control Methods
« Reply #10 on: December 15, 2013, 08:51:06 AM »

Surely when you make reference to the main sheet coming off you're referring to an open loop system?


In terms of friction I've noticed quite a few models utilising tubes to guide the sheets when they double back on themselves which will add dramatically to friction once any load is applied. Ideally we should use ball raced turning blocks (unfortunately very expensive) although plain bearing blocks will still give vastly superior performance over tubes.


Row
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