Understanding Windvane Capabilities and Limitations

[ErBrown]

So is the general consensus that the Cape Horn is better or more reliable than something like the hydrovane and if so why?

I see the emergency tiller option for the Cape Horn but am dubious about the prospects of trying to attach that bracket while bouncing around rudderless. I don't want to give the impression that all I'm concerned about is the emergency steerage solution. Obviously, reliable self steering is the primary goal but to me, it seems emergency steerage is nice piece of mind.

[Andrew Troup]

Originally Posted by Ocean Girl

Gotta know how to trim the sails properly, or you definitely need an autopilot

The more you know, the less you need – Yvon Chouinard

[gordwedman]

Conventional wisdom says a servo pendulum unit like an Aries or Monitor works better as the wind get stronger since your boat tends to be going faster and the faster water flow against the servo pendulum gives it more power. I think this applies whether you are going upwind or down. Last September I crewed on a Valiant 40 from Victoria to San Diego and we sailed downwind in 30 to 40 knots for two days with the Monitor doing all the steering. Never had any real problems although I could only get the unit to steer us within 30 degrees or so of dead downwind. Probably due to our lack of experience using it and the fact we only had a triple reefed main set. I have since heard from the Valiant group that using just the staysail may have been a better option.
Our autopilot started acting up on day 3 and that is when we put the Monitor to use. I wouldn't go offshore without some type of windvane. Have an Aries on my boat and a below decks hydraulic AP to hopefully cover all bases.

[Andrew Troup]

I particularly like the Cap Horn's ability to mount the Tillerpilot inside the boat. They do hugely better under cover than under water.

I once helped build a boat small enough to use a Tillerpilot direct to the tiller, but knowing that they don't handle splashing very well over the long haul, let alone submersion, the crafty owner/builder came up with an endless rope system which meant the pilot could be enclosed in a cockpit coaming.

Quarter of a century later, that original Autohelm 1000 is still working perfectly.

The cord comes out of a plastic-bushed hole in the coaming, runs across the aft cockpit bulkhead under the tiller, round a springloaded takeup bullwheel, and back across to a second hole below the first. I built the pulleys, the mechanical connection, and the takeup system.

At the midpoint, one of the two runs of cord is interrupted (and joined endless) by a small piece of stainless flat with a notch in it. It's the work of a moment to pull that forward and hook it over a shoulder screw projecting from the underside of the tiller, which 'lashes' the tiller.

Then the pilot can be switched on and set, by removing a transparent inspection port in the inboard face of the coaming.

And the great thing about these pilots is that they are small enough, light enough and cheap enough that you can easily carry one or more complete spares. (With the pilot undercover, one should be heaps)

With the servo oar providing the 'heavy lifting' on bigger boats, it's a great partnership, I reckon.

[Terra Nova]

Originally Posted by Andrew Troup

...I'm going one stage further in the direction of total integration of the vane gear on my project yacht. The manual steering will be by vertical tiller (ie whipstaff) in the centre cockpit, hinged (so it can lay down into a slot in the cockpit floor, completely freeing up the cockpit) to a longitudinal shaft, which passes aft from the cockpit through the aft cabin (dividing around the watchkeeping seat, permitting inside steering with the feet, say if the windvane needs a helping hand to avert a broach, or to dodge a floating object)

The shaft carries on through the lazarette emerging just above the waterline, where a clevis detail (vertical thru slot and horizontal cross-hole) enables it to carry the servo oar directly.

A "quadrant" aft of the transom on the same shaft, is just a Y, with the shaft disappearing "into the page" at the bottom of the Y.

The top extremities of the Y have connecting rods across to spherical joints at the top aft corner of each transom-hung rudder. (Port arm of Y connects to starboard rudder, and vice versa, to provide Ackermann action)

The twin rudders are not strictly transom hung: while external, they're set forward into "notches" in the stern scoop, keeping the connecting rods in the plane of the transom. This also means the servo oar can swing past them.

So the quadrant and the servo oar head fitting are effectively one and the same.

When I started reading this I was thinking "Man! This guy sure comes up with some weird ideas!" But as the image continued to unfold I began to see the value in the shaft approach. Not convinced it benefits from dual rudder complications. Wondered why you aren't inclined to use a whipstaff below. A sketch would be illuminating.

Terra Nova has the Fleming auxiliary rudder system, not yet mounted. And a wheel pilot. A real pilot is on the list.

[Reefmagnet]

In defence of the autopilot, there is the need to differentiate between above deck and below deck units. Above deck systems are cheap and cheery and exposed to the elements. Underdeck systems are a lot more expensive, tend to be more heavy duty and are more protected. I wouldn't really rate an above deck system to a windvane, but underdeck systems are viable alternatives. Yet having said that, the 20 year old or so Autohelm 3000 above deck wheel pilot that came with my boat still works like a champ.

In the context of an underdeck system, I don't really buy into the "autopilots are electronic therefore unreliable" argument either. While yes, they do fail from time to time, there are also plenty of stories of windvane failures floating around as well. As the autopilot is a system built on components, failures of the complete system short of some major event should be near impossible. The individual components that make up the system are relatively (in boat buck terms!) cheap to replace.

A major con of the auto pilot is the fact it consumes power. Even in this thread, people mention that a windvane needs the boat to be balanced to function well. It always surprises me that this isn't assumed for an autopilot also. Balancing the boat when using an autopilot can result in significant power use reduction.

[SaltyMonkey]

So we've talked a good round about wind vane manufacturers and discussed successes and favorites. Does anyone have advice on electronic units along same lines?

[CarinaPDX]

With servo-pendulums the flow of the water is used to amplify the relatively light power of the wind on the vane. Trim tab systems also do this, in a slightly different way. The old independent systems, like the Hydrovane, that drive an auxiliary rudder directly with wind have less steering power but have served well on many boats. (Full disclosure: I have a Hydrovane, modified at the factory to drive in the opposite direction and attached to a trim tab - works a treat.)

The OP asked about a 40-50 foot monohull, and for that I would recommend the integrated servo/auxiliary rudder models from WindPilot and Fleming. They are very powerful and of course serve as emergency rudders, plus no lines strung to the wheel.

Cockpit autopilots, wheel or tiller, are notoriously unreliable. I lost count long ago on the number of drives I have had to buy or repair. With a wheel the first thing I would do is install a quality pilot that drives with a ram on the quadrant belowdecks. If the boat came with a cockpit model I would consider it as emergency backup only. For long passages I would definitely add a wind vane.

By putting a removable drive on the trim tab I save a lot of power over driving the tiller directly.

One does not just mount a windvane and sail away. It is necessary to understand how they work, and how to adjust them to the boat. When in Gibraltar I helped a Canadian boat fit a Sailomat on a Juneau; the folks that started the install didn't realize that the vane was designed for wheels that were at least 2 turns lock-to-lock, and the Juneau was a single turn. It was necessary to add additional blocks to increase the purchase and reduce the movement. Details really matter with a wind vane.

I made a set of smaller paddles for heavy wind; adjusting the rake of the vane only goes so far.

The Letcher book on self-steering is great for the technical minded but is a serious read. If you liked reading physics books then go for it (I did). The owner of Windpilot wrote a very accessible book explaining vanes and I recommend this to anyone interested.

Greg

[robert sailor]

I have owned a Cape Horn and Hydrovane as well as others. They are very different vanes. The Cape Horn operates on the servo pendulum system that first came out in the Aries vanes, most wind vanes use this system. Cape Horn uses a few different ideas on their vanes like bent push rods instead of gears, cute idea, cheaper and less friction. Others have mentioned the capability of hooking thru blocks directly to the quadrant. The emergency rudder is marginal at best in my mind, more of an after thought.
The vane works very well as do most of the others based on the same principle.
The Hydrovane is an old design that was bought by an acquaintance in Vancouver and marketed much more aggressively than in past years.
It is an auxiliary rudder design and unlike a servo pendulum which gets all its power from an oar in the water the Hydrovane uses air only and therefore has a large air vane. Because its an auxiliary rudder it has a very beefy system than can act as a spare/emergency rudder that is generally larger and stronger than those set up on servo pendulum vanes.
To recap, the Hydrovane has a superior emergency rudder system. The Servo pendulum vanes are more powerful. My personal view is that both vanes will do a decent job of steering the average 35-45 foot cruiser in normal conditions and like others have said good sail trim in essential with almost all helm taken out. Often striking the mainsail is necessary in stronger winds. Personally I really like windvanes for crossing oceans. If you are sailing in the Med or Caribbean or Mexico my recommendation would be to save your money and go with an autopilot as you'd be wasting it on a vane.

[Andrew Troup]

Originally Posted by Terra Nova

When I started reading this I was thinking "Man! This guy sure comes up with some weird ideas!" But as the image continued to unfold I began to see the value in the shaft approach. Not convinced it benefits from dual rudder complications. Wondered why you aren't inclined to use a whipstaff below. A sketch would be illuminating.
....

Not using a whipstaff below is an ergonomic choice, not greatly important.

When sitting facing forwards, pushing a whipstaff sideways, at arms length, does not seem a great option, bearing in mind what I'm talking about is (possibly waking suddenly and) coping with an overload the vane gear is struggling with, not routine steering.

You can exert a lot of force downwards with one foot by gripping both armrests and half standing, without undue strain on the back. Plus if you then have to go and attend to the boat, there's no impediment to leaving your station.

It works out that in a broach, it's the downhill (leeward) pedal which would be needing to be stood on, so the ergonomics probably work out quite well.

Twin rudders is a big topic, there are multiple benefits (given my objectives and the type of boat) which are irrelevant to a vane gear thread, but I'm happy to discuss in another thread if you want.

I'll mention just one: I would want a spare rudder in any event, but fitting them at sea is no easy task ... so why not have it prefitted?

The benefit which is relevant to vane gear is that otherwise, with shaft, servo pendulum oar and rudder all on the centreline, the heavily integrated approach does not fly, because of turf encroachment issues.

Each rudder can swing aft if they hit anything, as can the servo oar, so that's another potential encroachment, if they're all central...

The sketch shows only one dagger blade fitted, and only one connecting link, and the servo pendulum oar is not shown.

Both rudders are shown at full angle for a turn to starboard, but because of the Ackerman angles, the inside (starboard) rudder is angled a bit more than the port one.

The servo oar, when fitted, can be hinged upwards through 180 degrees when not in use.

I guess in this orientation, it could be used as an ad-hoc whipstaff for a stern-scoop steering station, handy (say) for backing up to a mooring or pontoon.

[Terra Nova]

The rudders pictured are identical to one I installed in a Columbia 22, with hull extension. Can't remember what stock boat it came off. But it was a cast aluminum scabbard with gudgeons and a very sleek fiberglass daggerboard-style rudder that you could run all the way down, for beating, or quite a way up, when running in light air, decreasing the wetted surface.

[Andrew Troup]

Good point, TN

When sailing on the wind, offshore (hence on one tack for extended periods - my personal record being ten days) I would expect to raise the windward blade altogether, so it would not create extra drag, nor would it be exposed to damage from hitting a floating object.

The leeward blade, being splayed, would of course be more effective when heeling than any single blade on the centreline can ever be.

When running in hard weather, which is when you really need a big rudder, I prefer to spread the load among two small rudders (each with deep draft, but minimal area, because of being skinny when viewed from the side).

The lack of area aft of the pivot axis should enable high gearing, in comparison with a wheel.

This high gearing is enforced by virtue of the whipstaff having a limited operating sector, being constrained within the cockpit coamings.

But the high aspect ratio means loads in all parts of the steering chain will be low, considering the power of the rudders available to change the boat's heading, and this will apply to the effort required on the whipstaff.

And, for that matter, it reduces the effort required from the servo oar, which in turn means it does not need to pivot through such a large angle, which is all to the good.


I've also found that boats with really deep rudders make if possible to counteract the occasional rhythmical rolling which can otherwise build up when running hard, to the point that a broach cannot be averted.

Counteracting rolling with a deep rudder is not a viable long-term proposition* but it can make a big difference if someone on board can do it reliably for as long as it takes (say) to get rid of some sail, or prevent a broach, if caught in a sudden squall.

It's much like the knack of steering a vehicle which has temporarily been allowed to drift above the critical swaying speed for towing a single axle heavy trailer. Unfortunately, as in the trailer example, it's fatally easy to make it worse rather than better, at least until the knack becomes second nature.


*(and in my experience this is not widely understood in the cruising fleet, partly because their rudders are generally shallow. It mainly seems to be the preserve of specialist downwind racing helmsmen)

[Terra Nova]

Playing devil's advocate, twin rudders are also more vulnerable than a single rudder protected by the keel. And the windvanes are vulnerable from behind.

[Andrew Troup]

Originally Posted by Terra Nova

Playing devil's advocate, twin rudders are also more vulnerable than a single rudder protected by the keel. And the windvanes are vulnerable from behind.

Indeed.

However my keel retracts flush with the bottom of the hull, so this protection could not be relied on. And that's why I plan to go to the trouble of making the rudders able to kick up.

Not sure of the windvane vulnerability you refer to. Do you perhaps mean the servo oar? In what way?

[Terra Nova]

Windvanes are vulnerable from being hit from behind, a collision with a dock or other boat.