Wheatstrong has a Hydrovane windvane which steered for over 15,000nm during our Pacific voyages. The Hydrovane is an auxiliary rudder type windvane, rather than a servo-pendulum, so it has no lines to the wheel. The idea is that you trim the sails and adjust the boat's rudder so that the boat is on the point of sail that you want, then use the wheel-brake to lock the boat's rudder. Then you turn the leading edge of the vane into the wind and engage the mechanism and it steers using its own small rudder (about 36x10x2 inches, nylon).
I ordered a hydrovane with a longer shaft so that the gearbox and head are above my sternbox. The install was very easy. All you have to do is mount the Hydrovane vertically with the bottom of the shaft two inches above the water. It can be mounted off center if you need to. I drilled only four holes in the transom for the bolts for the two mounting brackets: two holes above the deck just below the caprail and two about a foot above the waterline. I made teak pads to fit between the mounting brackets and and the hull and had stainless steel backing plates fabricated to distribute the load on the inboard side of the hull. I faired the lower teak pad with epoxy to keep it from getting too thin on the upper edge.
The vane's angle of attack, and therefore the heading, are adjusted from the cockpit using a small (1/4") continuous line that turns the hydrovane head. I ran the line through a sheave with a bungee cord on the end of it; I attached the bungee to the port cleat on the cockpit coaming so you just reach back and to the left from the helm in order to adjust the vane. Course corrections essentially involve steering to the new point of sail, balancing and trimming the sailplan, setting the main rudder trim, and setting the windvane angle of attack. It takes a few iterations to settle down but then you're good until the wind changes or you need to change course.
The Hydrovane worked very well when sailing to windward, pretty well when broad reaching or running and not so well when beam reaching.
The KP44 sails easily to weather and can be balanced to maintain a beat even without a windvane. It was easy to get the boat balanced and the windvane steering on a close reach or close hauled.
The hydrovane steered well with the wind on the aft quarter or from astern. Even running DDW was no problem for it as long as the sail plan was balanced and the seas were not confused.
I found our KP44 difficult to balance well enough to sail consistently on a beam reach without some main rudder movement. The boat would end up heading up or falling off in gusts or lulls and over-power the hydrovane's smaller rudder. I think this probably would not have happened with a servo-pendulum type, since they can steer with much more force by moving the ship's rudder. Hydrovane has since come up with a six-inch longer rudder as an option.
The Hydrovane can be locked with its rudder amidships by inserting a pin in the shaft at the gearbox/head. This is easily done from the deck. Once locked down the Hydrovane rudder exerts no influence. You can motor all you want with the Hydrovane locked down like this but I think it must generate a little drag and is probably needless wear on the Hydrovane as it tends to vibrate from the prop turbulence.
For motoring long distances in calm seas we remove the vane, lock the main rudder 'midships, and use a Simrad TP30 tiller autopilot to drive the Hydrovane's tiller. I had a mount and tiller extension built for a tiller autopilot on the pushpit and used that to drive the hydrovane while motoring. This worked very well in fairly calm conditions. But it would get in a feedback loop and spiral off course if seas were big. But then you remove the TP30, fold up the bracket, and sail in those conditions.
In cases where we are not going to use the Hydrovane for extended periods of sailing or motoring we take the hydrovane rudder off. This involves pulling a pin from the base of the shaft where it goes through the top of the rudder. You have to be at water level to do this so being in a dinghy or stern-to at a dock or quay is helpful. But if you're agile you can climb over the transom and squat on the hydrovane support; hang on with one hand and use the other to pull the pin. The rudder is heavier than water so I have it secured with a length of line as a precaution at all times. Once the pin is pulled I just pull the rudder up using the line. Putting the rudder back on is the reverse process and is a little trickier when hanging on with one hand because you need to hold the rudder at the right orientation to line up the holes for the pin.Pros:
We had to handsteer on only one passage, to the Va'vau Group, Tonga, when it was 35-40 knots from astern with 25 foot following seas. The boat would surf down the waves and spin out at the bottom in the windshadow of the wave if the helmsman didn't take corrective action. So we had probably 20 hours of hand steering over the course of a year. Not bad.
Our passage from Hawaii to San Francisco included a heavy gale in the last 600 nm with winds up to 50kts true (according to B&G). "Irene" stayed on the same point of sail, with a triple-reefed main and a storm stays'l, while we stayed below, only popping up every 15 minutes to scan the horizon and marvel at the size of the waves.
KP44s are well known for weather helm - in San Francisco bay we often sail with too much canvas up in 'the slot' and end up having to wrestle the wheel to leeward to maintain course. Reefing and trimming properly eliminates this problem, and saves the arm muscles. A servo-pendulum rig will turn the wheel against a large force in a strong wind so you may get away with an over-powered rig for longer than you will with the Hydrovane. In that same wind the Hydrovane will be overpowered by the weather helm. The vane will go all the way over and turn the Hydrovane rudder until it is stalled and the boat will head up anyways. Once you reef and trim, the Hydrovane does fine in pretty much any wind.
I think having the Hydrovane made me much more aware of helm trim and sailplan balance simply because it was essential to the proper operation of the device. In fact, we had a crew member on for our passage through Mexico to the Galapagos and he never did get the hang of adjusting the Hydrovane.
Hydrovane is now producing the bigger rudder (six inches longer with the same profile). If I start another refit to go cruising again the bigger rudder will be on my 'buy' list ($625 ugh). Also on my list would be the new 'stubby' vane (12 inches shorter and 8 inches wider) because the standard vane collides with my wind generator mast/outboard crane on certain points of sail.
One important thing that I really like about the Hydrovane is the simplicity of the system and its heavy-duty, bullet proof constuction. It's just really well built and not a lot can go wrong with it. It requires no maintenance other than to wash it with fresh water and detergent, let dry, and spray with WD40 - ONCE A YEAR. Nice.