We have the same windvane self-steering system you had on Xiphias and the Pardey's used on Seraffyn. We plan to fit the vane's vertical shaft and its control arms with Delrin sleeve bearings to reduce friction. Before we commit ourselves to the expense of revamping this unit, I was wonder if you would be kind enough to discuss your experience with the unit on Xiphias, especial downwind and in light air conditions.
The attached image is of IDUNA and SIRIUS rafted together in Baltimore's beautiful Inner Harbor - 11/23/01. SIRIUS is equipped with a Ratcliff windvane self-steering system.
Fair Winds & Following Seas,
Hi Rod, I would be glad to discuss details of the vane but doubt other on this site would be interested. Email me you personal email address and I will get back to you... Roger firstname.lastname@example.org
Roger, I’d be interested as well.
Hmm… I’d be interested.
Hi Rod, I would be glad to discuss details of the vane but doubt
other on this site would be interested. Email me you personal email
address and I will get back to you… Roger
Rod, cancel my last email. Since I sent it a few minutes ago I have had several requests for the same information....so here it goes.
First, I added about 10 % to 15% of the trim tabs surface area to the leading edge to help balance it. Mike Anderson of Freehand Steering and I have worked this out pretty good. The older or original trim tabs had the leading edge go the full length of the trim tab. This caused severe vibration under power because of the erratic prop wash. If the additional area is added as low as possible will help reduce this problem..I don't know the actual numbers in my head but I guess it is about 1-1/2 to 2" deep and about 8" to 10'' long. First, I removed any leading edge that now exists. Then add the piece at the bottom by drilling and tapping into the shaft. If you do this make out of teak and a little more that 20% so if it is over balanced (oversteers) some can be planed off until you get exactly what you want. For more details on actual size email Mike at Freehand Steering. I just discovered I don't have the address but I think he subscribes to this group.
You used the term vertical shaft, I presume that you did not mean vertical because it has to go at quite an angle to the aft end of the rudder. The shaft axis must meet the rudder's pintle axis where the adjusting arm is located. I don't think this is an issue but if it is let me know and I will give you more detail.
To reduce friction on the trim tab I discovered that by making the bottom gudgeon a blind hole instead of a through hole really helps. Let me explain. I had the bottom gudgeon counterbored for a blind 1" hole. Inside the hole I place a 1/8" to 1/4" flat delrin or teflon disc followed by a 1" OD x 3/4" ID bushing. I cannot remember the type of bushing but if you have access to a McMaster-Carr catalogue you will find the ones with the minimum friction that is not effected by emersion in water . Delrin will work but not as well as this bushing..... I can't remember. I use the same bushing inside the middle and upper trim tab gudgeon. Now the problem is that the trim tab can come out of this bottom bushing when you don't want it to. Also at McMaster-Carr they have a 3/4" stainless steel split collar. I place this collar directly under the upper gudgeon so the shaft cannot be raised without removing this collar. It also makes it possible to remove the trim tab without getting wet. Just remove the collar, lift the trim tab shaft until it clears the bottom gudgeon then shove the shaft down until it slips out of the middle gudgeon. It does take a little effort to miss the bottom gudgeon but not a problem
The major problem with the windvane on a pedestal is to reduce friction and the ease of making adjustments. I don't feel it is necessary to discuss how to reduce friction but it must be free. Unlike what some people believe, a loose fit does not create less friction than a good fit. Personally, I like a clearance of about 2 to 5 thousands between shaft and bushing. However the bushing should not swell as delrin will. So if using delrin use .005 clearance.
I found the vane really worked well in most all conditions....if the sails are properly balanced and the friction is reduced. After I worked extensively to reduce friction and took out the major weather helm the vane would steer downwind in 5 knots of wind. Also, the friction in the trim tab is only as good as the friction on the rudder gudgeons and pintles. The trim tab steers the rudder so if it is not really free it will not work as well. Again I want to emphasize that a loose fit is not as good as a close fit.
I also found that there has to be some kind of locking device for the trim tab when motoring or backing. I also did not like the original clamping design because: It would slip in rough conditions and it had to be adjusted by climbing out on the boomkin. I designed a different method that I could adjust from the cockpit. I have drawings of it at work but it is a little complex unless you have access to silver solder or oxyacetylene. If you want me to try to explain it in writing let me know and I will try. Perhaps you are happy with what you have or may even have a better design.
Lastly, and again I am sure I am saying something you already know...I found that by using the cheapest autopilot on the trim tab works perfectly with the minimum of current draw. On my new boat, I hardly ever use the vane anymore because the autopilot is so effective and efficient.
The only limitations I found with this vane is:
It creates more of a load on the tiller when hand steering because of the additional surface area aft of the rudder. However it is this distance and surface area that gives the vane soooo much power to drive the rudder..
There is a real heavy load in reverse unless the trim tab can rotate 360 degrees freely. Something I cannot not do now so I have a lock
There will always be some vibrations when motoring at higher RPMs
It is susceptible to damage when going aground.
Don't hesitate to ask anymore questions, I have nothing but time right now.
Thank you for the information, we shall experiment this spring.