rdubuque
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« on: February 03, 2008, 08:25:37 pm » |
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As some of you know I am going to attempt to build a vane for my boat this winter. There is an incredible amount of information out there and I feel the boat is well suited for this. I have a tiller in the cockpit and feel that the ability to raise it up and out of the way while under sail would be a huge benefit to sailing with a family of five. I also just get tired on longer passages and sail often single handed. I also plan to add a tillerpilot that can be attached directly to the van with a remote back to the cockpit. I have posted some pictures of my ideas and would welcome any comments. Bob http://picasaweb.google.com/rdubuque/ParkerDawsonWindvane |
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rdubuque
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« Reply #1 on: February 05, 2008, 04:21:17 am » |
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I am having a great time with Picasa loading up my photos and being able to share them online. It also becomes a work in progress. I would love to see some other projects / ideas come to life in pictures.
More design features have been added.
Bob
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sfisher
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« Reply #2 on: February 05, 2008, 05:49:57 am » |
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Now I am confused.
I've been giving light thought to the same problem, but had assumed that self steering would require a seperate rudder, not atached to the primary rudder. But as I was writing that sentence, I began to think that attaching it to the primary rudder or rudder cage might be the answer.
My first impression was that the auxillary rudder was essentially a trim tab that would move the primary rudder. But then, I began to see the possibility that the primary rudder would not move at all and simply be a mount for the only moving rudder when on wind vane mode.
I'd certainly like to have osmethink like you describe. I'll give it more thought tomorrow night. Off to bed right now.
Steve in San Jose
Dawson 26, "Banana Split"
Hull 270
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Steve in San Jose
Dawson 26, "Banana Split"
Hull 270
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sfisher
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« Reply #3 on: February 05, 2008, 05:54:31 am » |
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Missed one item. Look under boats for sale at the last item, the 26Ft Parker Dawson. See the unit on that. I identified it the other day, but can't recall. Thought it used a seperate rudder ?
Steve in San Jose
Dawson 26, "Banana Split"
Hull 270
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Steve in San Jose
Dawson 26, "Banana Split"
Hull 270
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rdubuque
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« Reply #4 on: February 05, 2008, 07:10:10 pm » |
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I am pretty sure it is a Cape Horn on the green Dawson.
From what I have read a trim tab moving the main rudder works quite well with an almost vertical transom hung rudder, like ours. The servo vanes work better(hold a steadier course) but require a huge and expensive apparatus on the transom that I would like to avoid.
I figure if Bob Lengyl could sail across the Atlantic 4 times with one, it would be good enough for me.
Bob
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sfisher
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« Reply #5 on: February 06, 2008, 04:14:05 am » |
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I think that what I'm missing here is the movement of the rudder. If the wheel or tiller is connected to the rudder through the usual cable, can an autopilot provide enough steering force?
As I write that, I again start to understand something. You have a tiller. I'll bet that the only friction is the cable itself. On the boats with wheel steering, there is no feedback from the rudder. The wheel mechanism provides for no movement other than that provided by the wheel. As an example, with my boat on the trailer, I cannot move the rudder by hand while standing behind the boat.
If that is all correct, you can make a windvane work, and I can't. Darn......
Steve in San Jose
Dawson 26, "Banana Split"
Hull 270
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Steve in San Jose
Dawson 26, "Banana Split"
Hull 270
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rdubuque
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« Reply #6 on: February 07, 2008, 04:49:37 am » |
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From what I understand the extra friction caused by the wheel or in my case a cable to the tiller can be overcome by a larger tab. Also the farther aft the tab is set on the rudder the more force it exerts.
If you cannot move your rudder by hand, I would think something might be amiss in your cable connection to the rudder.
Bob
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sfisher
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« Reply #7 on: February 09, 2008, 05:37:32 am » |
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Had a few minutes at the boat today and ran a test. I had a precision force gauge available from the inspection lab at work.
I hooked it to the arms of the Wheel, at the edge of the rim. This is about where your hands would be.
With the boat on the trailer, it took about 20 pounds of force to start the movement of the Wheel. To continue moving it, took about 15 to 17 pounds of force.
That pretty much stinks . Don't know what a modern steering system with wire rope and pulleys would be, but I'd bet that it is less than 5 pounds under the same conditions.
Now, if I get brave enough to pull the steering cable out of the boat, I can test the cable in the same sort of way. After getting those numbers for pulling force, I'll try to lubricate the cable and then see where we go from there.
Steve in San Jose
Dawson 26, "Banana Split"
Hull 270
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Steve in San Jose
Dawson 26, "Banana Split"
Hull 270
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rdubuque
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« Reply #8 on: February 09, 2008, 04:22:19 pm » |
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On my boat there was a serial number on the side of the cable housing. I don't know how much access you have to yours but it would be nice to know if and how much a new one might cost.
Bob
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herby
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« Reply #9 on: February 09, 2008, 07:12:12 pm » |
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I did the same test on hull #237 using my fish scale and it took 12 lb to start movement and 10 lb to keep moving, I don't think it could get much better, considering your moving the rack ( as in rack and pinion) on the end of the cable through a chain and two sprockets.
The two sprockets by the way are same diameter, so theres no mechanical advantage either way.
Herb Owner of Hull # 237
In Astor Florida
Sail fast live slow
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Herb Owner of Hull # 237
In Astor Florida
Sail fast live slow
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josh_richard
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« Reply #10 on: February 09, 2008, 08:38:39 pm » |
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quote:
Originally posted by rdubuque
On my boat there was a serial number on the side of the cable housing. I don't know how much access you have to yours but it would be nice to know if and how much a new one might cost.
Bob
I have to pull out the steering pedestal and cable assembly. I am quite worried about munging the cable in the process. In preparation for the worst case, I started looking around for a replacement and found these folks: http://www.midwestcontrol.comNo ideas on cost, but they sell push-pull assemblies. Any metrics regarding the pulling force of a pull-pull setup? I have the DA wheel/cable setup. Any information about a pull-pull conversion for this assembly or modern day replacement? It is my intent to make what I have work as from what I can tell, the cable is fine, but a little research can save a bundle. The fishing scale is a great idea. I will take a measurement before pulling things out, oil and remeasure upon installation. It will be interesting to compare notes. Josh |
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sfisher
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« Reply #11 on: February 10, 2008, 06:48:17 pm » |
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I've sent two brief emails to TELEFLEX MARINE to see if they would custom build a cable for me. The gent that responded clearly had no idea what sort of cable I was asking about. ( I have visited the factory the extrudes the PTFE liner for Teleflex Marine)
For recent upgrades, Steve Johnson has mentioned that he changed his system to an EDSON system. He lives close to the factory and also found a source for surplus parts in his area.
The EDSON factory has all the info on the system that Parker Dawson installed and would be happy to sell you a system. Steve managed to save a good bit of money by using his surplus source. I have no idea what their system looks like, other than it is a pull-pull system.
OOPS, I do have their web page, just haven't studied the pages that would help.
My email conversation with EDSON told me that the DA system was in no way compatible with the EDSON system. That said, it would seem to be a worth a little imagineering to see if a cable system could be rigged to the DA Steering.
Steve in San Jose
Dawson 26, "Banana Split"
Hull 270
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Steve in San Jose
Dawson 26, "Banana Split"
Hull 270
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rdubuque
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« Reply #12 on: February 19, 2008, 03:22:33 am » |
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rdubuque
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« Reply #13 on: March 01, 2008, 03:36:04 am » |
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LBerg
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« Reply #14 on: March 26, 2008, 03:39:34 am » |
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Does anyone know details of the self steering on Bob Lengyel's boat. The photos in the brochure "Story of the windship'Prodigal'" appear to be of an auxiliary rudder mounted to the side and independant of the main rudder. It would be possible to use a balanced rudder in this configuration.
The force required to move the rudder will be much smaller than the force of the water on the rudder. I made a balanced rudder and horizontal axis vane for a Cal 20. This project was not very successful because the wind force is much less than the force of water on the rudder.
lberg in San Jose Skeena #253
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