Following is a review of wrote:
Review Cape Horn Windvane Self-Steering System
Posted by: IDUNA (IP Logged)
Date: February 16, 2006 03:32PM
Tom Harrer, BCC White Wings II, asked for a review of the Cape Horn Windvane Self-Steering System fitted to our BCC, IDUNA. There are several good self-steering windvane systems on the market. The one that obviously comes to mind is Scanmar’s Monitor (http://www.selfsteer.com/), as well as the Australian Fleming system (http://www.flemingselfsteering.com.au/) and the German made Windpilot unit (http://www.windpilot.com/en/Ra/rawelen.html). I also need to mention the Aries windvane. The original Aries system was developed and produced by Nick Franklin and set the standard in the 1970’s for the modern horizontal axis windvane connected to a servo-pendulum rudder (Aries - Providing Vane Gear Spares and information). The Aries is now produced under license in Denmark (http://www.selfsteer.dk/) but parts for the Franklin unit are still available. Links to eleven windvane self-steering systems may be found at [www.onpassage.com].
The windvanes listed above are all horizontal axis servo-pendulum rudder systems. If you are interested in a Pardey type windvane then please visit www.freehandsteering.com. Mike Anderson builds a backstay “vertical” axis windvane coupled to a balanced trim tab which is attached to the boat’s outboard rudder. Perhaps one of our readers who owns one of these systems would be kind enough to review it for us. Regardless Mike Anderson runs a cool website and is the owner of Anderson Boatworks in Newport Beach, CA.
Our first purchase of a Cape Horn Self-steering system was for our Nor’star custom built aft-cabin Flicka in 1995. We needed a system that would fit under a bumpkin (boomkin) and of lightweight. In a our initial conversation with Yves Ge’linas, the developer and founder of Cape Horn, he said, “No Problem.” The Cape Horn fitted to our Flicka weighed about 32 lb. with teak servo-rudder attached, steered the boat in light air and heavy air conditions. We soon discovered the key to using a windvane was balancing the boat. The only time the windvane did not steer the boat was while broad reaching up the Houston Ship channel. Winds were light, so we set a tri-radial spinnaker that was original built for an Evelyn 26 racing boat. As the day wore on, we were unaware the wind was increasing. The boat was running fine, maintaining her course and the bow wave was a mass of “boiling white water.” This should have been a hint. About mid-afternoon the boat started to yaw to port and starboard along her course. I tried to adjust the windvane then started to think bad thoughts about this piece of “junk” until I released the windvane control lines connected to the tiller. I was sitting to starboard. With the tiller control lines released, the weather helm pulled me out of my seat and introduced me to the boat’s port cockpit seat. After recovering my pride and apologizing for my bad thoughts, our lesson about balancing the boat was learned. We also began to sense when the wind is increasing. When using a windvane self-steering system, one learns to watch the input into the tiller. If the windvane is constantly correcting for weather helm, the boat is not balanced. Most windvane systems handle some degree of weather helm but at some point, the system will start to yaw around her course. This is caused when the weather helm becomes greater than the power available in the servo-pendulum rudder. Some may wonder how we could set a spinnaker from an Evelyn 26 on a 20 LOD boat. Our little custom build Flicka had a 33 ft stick, 12 boom and set 410 sq.ft. of working sail area - LOA was 27 ft. She was based on the original Bruce Bingham design not the Pacific Seacraft version.
Our criteria for selecting the Cape Horn for our BCC was as follows: cost, “clean” looking installation, could be fitted under the boomkin, light weight, strongly build and previous experience. The unit weighs less than 40 lb. fits inside the bumpkin, is strongly built and well supported by four 1" O.D. electro-polished SS tubes. All strut end-brackets are bolted through the bumpkin. Installation requires some thought to ensure the unit is as vertical as is possible on a boat, the support struts are well triangulated to ensure a strong mounting and the servo-rudder clears the main rudder. One has to cut and fit the support struts. Each strut is manufactured with an adjustable end fitting to make fitting easier. Fitting the unit is not difficult but does require some time. We fitted and mounted our unit from a floating dock. It would be easier and faster if the boat was on the hard. Images of our Cape Horn are available in the BCC Gallery under Projects.
We are pleased with the unit’s performance under choppy, heavy air conditions as well as light air conditions. I need to improve the lead for the control lines that run from the servo-rudder to the tiller. At present, the lead angle from the turning block to the tiller is too acute. Because this angle is close to 45 degrees, we are not taking full advantage of the power and sensitive available in the Cape Horn. Still the unit works but once I change this lead angle to closer to 90 degrees to the tiller, servo-rudder power and sensitivity will be significantly increased. Nothing is perfect, so let’s list and discuss some of the Cape Horn’s pros and cons as related to the BCC.
Lightweight and strong
Manufactured to a high standard - clean welds, electro-polished stainless steel, Delrin bushings, adjustable strut end fittings
Excellent performance in light air conditions and heavy air conditions both upwind and downwind,
Simple design that can be repaired by a machine shop and/or welder,
Excellent factory support,
Servo-rudder swings sideways when stored in place,
Uses bunges cords to hold the break-away servo-rudder to the its rudder stock, the rudder has a safety lanyard should you hit something,
Easy to inspect and maintain,
Priced lower than most other windvanes
No reduction gearing for the windvane course change control line, hence practice is required to make small course changes without over correcting,
Difficult to connect and disconnect the servo-rudder from the boat because of the bumpkin, we normally do this operation from the dink,
Swinging the servo-rudder into its storage position can only be done at very low speeds or when the boat is stopped,
Not NEMA compatible.
As with some other brands, two windvanes are provided for light air (<15 kt) and heavy air (>15 kt.), hence one has to step part way out on the bumpkin to make the changes. Because the windvane control tower is mounted inside the bumpkin, one can brace themself against the backstay, still, as with some other windvane brands, this is not the best arrangement when the seas are rough (this issue is a result of the bumpkin mounting required for the BCC.).
The Cape Horn is a good unit that is noted for its excellent light air performance downwind. It has its pros and cons and as with the other brands, the boat’s sail plan must be balanced to achieve the best performance. This is the key to making any good windvane self-steering system work. I can not emphasis this key point enough. A general rule we follow is to balance the sail plan such that we can steer the boat with two fingers. Sometimes we give up a little speed to reduce weather helm and achieve optimum performance from the self-steering system.
A word of warning:
If you fit a windvane system to your boat, it is important to understand, unlike an autopilot that steers a compass course, the windvane steers to the wind. If you are single-handing and running along a coast, a change in wind direction could run you onto the beach or rocks if you are asleep. This has happened.
If you have any questions about using a windvane, please post them in this thread and I will attempt to answer them.