Atkin's Thistle needs wind steering

Design, Construction and Use of Self-Steering Gear

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Atkin's Thistle needs wind steering

Postby danblu » Thu Oct 15, 2009 3:36 am

Hi folks,
I'm interested in Jan Alkema's system for homemade self steering. I have a 32 foot Thistle that would suit Jan's design I hope. At this stage I would like to build the RHM and try to control it with an electric auto pilot, the Simrad TP 32. I imagine the auto pilot could be placed alongside the tiller and attached to it at the forward end. A control arm at 90 degrees to the yacht centre line off the RHM would be the attachment point at the other end of the pilot.

I'm going to cruise about New Zealand, where I live. At this stage I'm only cruising by the coast so I'll try to get the upside down vane operating while cruising with the intention of going offshore later.

If someone here could advise me of the feasibility of this system for self steering I would be most grateful.
Kind regards
Pete.
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Re: Atkin's Thistle needs wind steering

Postby jan alkema » Thu Oct 15, 2009 10:26 am

Hi Pete,

I certainly can advise you about using the RHM oar for your (beautiful) sailing yacht. Double enders are not the most suitable yachts for the RHM solution, because of the narrowing end of the hull. But with the boomkin there must be possibilities to have the restraint lines fixed on that.
I have an description of the system available. If you are interested please give me your e-mail address or contact me via the administrator .

Jan
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Re: Atkin's Thistle needs wind steering

Postby danblu » Thu Oct 15, 2009 4:31 pm

Hi Jan,
Mine is a Sayer's built ferro version that is a little different as there is not a boomkin. She has the same hull and rudder but different cabin. I would like to post a photo but can't see how to do so. I built a model of the RHM to get my head around how it works and I love the design! I see what you mean about giving the rhm a pivot point. May have to build something aft to provide it. Please feel free to email me. I'm ..... @xtra.co.nz and the name is danblu. Then I can send a photo.
cheers
Pete.
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Re: Atkin's Thistle needs wind steering

Postby jan alkema » Thu Oct 29, 2009 3:36 pm

In the post regarding "double enders" it is shown via a sketch that the RHM pendulum in some cases will not work. For Pete I made a sketch which may be a solution to the problem.
The rudder head has to be extended, so that an arm X is available of about 0,4 m. That extension incorporates the horizontal pendulum axis, which is now lower than the rudder head. The linkage can be designed over the rudder head.
To make the angles of the restraint lines more favourable, for each side a strut will be used, which will be attached via a hinge to the side of the stern. When the restraint lines are loose, the the struts hang down. When the lines are tightened the struts will find its own position, which results in a better angle for pulling forces via the restraint lines.
It is an idea and more engineering has to be done, but it looks viable.

Jan[attachment=0]rhm2.jpg[/attachment]
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Re: Atkin's Thistle needs wind steering

Postby JoernHeinrich » Fri Dec 18, 2009 6:07 pm

Great Idea
To use struts on narrow-ended boats.

They could be mounted in standardized hinges.

Joern
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