Understanding Windvane Capabilities and Limitations

[Andrew Troup]

Originally Posted by Terra Nova

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

Some windvanes (and most commercial ones) are, for sure. I guess you're reverting there to talking about off-the-shelf systems, and comparing their vulnerabilities to those of autopilots?

Shouldn't be a huge concern to the target market, namely those who spend most of their time crossing oceans, in the hope of finding empty anchorages

I misunderstood it as a comment to my proposal, and my only excuse for being so self absorbed is that you made it in the same breath as the apposite comment about twin rudders.

[Terra Nova]

Sorry I wasn't clear. Just some random thoughts more or less related to windvane/steering. Hope you'll post a sketch of the mechanism you described.

Doesn't it seem that boats with transom-hung rudders are naturals for trim-tab self-steering?

When I was shopping for TN, high on my list of must-haves was tiller steering. TN has a wheel, a compromise I accepted because the rest of the deal was a good fit. And because 24,000 lbs may be more than I could handle with a tiller. But the idea of having a tiller still haunts me.

A tiller could be made to be simply easily removable, to clear the cockpit, in port. Long ago I built one out of stainless and oak, a collapsible tiller.

[robert sailor]

If more boats today had tillers many more sailors would be aware of proper sail trim, nothing like a lot of helm sailing upwind on a larger boat with a tiller.

[Jon Eisberg]

Originally Posted by Delancey

Doesn't seem right to me either, the unit came with poor documentation. Not even a decent drawing. The casting at the top of the tube has a set screw which would also allow for trimming but a set screw seems like a dumber idea than a thumb screw you can't safely reach. Also the set screw seems like it would be difficult to access with the counter weight flopping around.

As previously noted, that vane looks very much like a copy of one of the Sailomats previous to the 601 model of about a dozen years ago, a superb vane...

Seems to me whoever assembled his vane might have gotten the positioning of the set screw the top of the tube, and the thumb screw at the base of the tube, backwards? The course adjustment on the Sailomat is definitely done by spinning the air blade carrier at the top of the tube.

There is also a way to configure a sort of 'remote control' of the course adjustment, by using control lines fixed to the stern rail or similar to rotate/adjust the air blade. Similar to the way most Monitors are adjusted, actually. This seems a less desirable solution than locking it in place with this particular vane, and Sailomat only recommends it if the tube really is dangerously out of reach, but it could definitely be an option in this case...

Also, it may be a bit of wide angle distortion or perspective, but that tube in your pic makes it appear that tube is canted forward slightly, probably to bring it within easier reach of the stern rail. Not sure whether it matters especially with that vane, but as per the installation of my Sailomat, you want to have that tube set in as close to a vertical position as possible...

But I'd first compare the threads on that set screw, and the thumb screw. If they're identical, I'd bet someone simply got them reversed...

[robert sailor]

Actually these S Atlantic vanes are part knock off's of the Wind pilot vanes.

[robert sailor]

Another nice looking vane made in Canada is the Voyager Vane. For those of you with stronger currencies they might make some sense. Cape Horn is also Canadian as well.

[Capt Rottnest]

Originally Posted by robert sailor

If more boats today had tillers many more sailors would be aware of proper sail trim, nothing like a lot of helm sailing upwind on a larger boat with a tiller.

While sorting out the homebuilt windvane, it only seemed to work to windward, but not on other points of sail - at that early stage. But then I discovered our boat can sail herself upwind without the vane but with the tiller lashed (she can do it without lashed too, but I think sails a straighter course lashed). Then talking to several others all with tillers, I found out many sail boats can do this (including the Hiscocks' on their video). I have no idea if boats with a wheel can.

But its very handy to know.
(like when the vane breaks and the batteries go flat..)

[robert sailor]

Capt Rottnest,
Any mono hull with properly trimmed sails will sail its self upwind, just add a little helm and lock the wheel. I've sailed for hours offshore like this and the boat will simply follow the wind.

[hpeer]

Originally Posted by leightonyachts

My issue with a Wind Vane is I have a 24 ton full keel schooner, and my aft deck freeboard is about 6 feet high. Not sure if it would do me any good.

I have a AP installed to work with my hydraulic steering which works good but just concerned about battery life. I have three Grp 31 AGM batteries onboard. I plan on 400 watts of solar panels and one 600 watt wind machine. I do not really want to depend on my diesel to keep the batteries charged if all possible, although I have 200 gal on board.

Any Advice?

Our big boat is about 20 tons with fairly high freeboard aft. Full keel, keel hung rudder, moderately cut away forefoot. She was originally designed by Alan Pape as a ketch, but was redrawn at builders request as a cutter.

She is 44' with a 5' bow sprit.

She was built to have wheel steering but also has a tiller. The tiller is there because she intended from scratch to have an Aeries vane. I even have letters to and from the Aries company owner discussing the mount. I modified the tiller to make it more useful, but maintained the geometry. I also added a radar arch. I recently added solar panels, but have no experience with them using the vane. I further fitted a Raymarine tiller pilot to the vane.

The boat does well with the vane. My first few hours were difficult but once I got it working it did well. The adjustment lines run all the way to the companionway, so I can make adjustments without coming on deck. The tiller pilot also does well but can hunt a bit and at times is fussy. The tiller pilot is really not a robust piece of kit, experience.

Getting the tiller connections sufficiently tight is important. ( thanks to Atoll for that advice.) I ripped out the original turning blocks and had to fit more sturdy ones. I also had to fuss with and change the chain connection to make those adjustments easier. Also the tiller lines were under siEd and wore through quickly. So, even though the boat was nearly 30 years old and had three transatlantics, thee were issues with the vane hat had never been sorted out.

It takes some fussing to sort it out but is surely worthwhile. The tiller pilot attachment is also worthwhile. But that said, I've a CPT waiting to be fitted for those times when I'm struggling with the sails solo and I have no way on.


Our small boat has a very well done home made aux rudder vane. She has long fin keel and as keg hung rudder. This I think is a little more fussy, but I need some more time with it. I will almost certainly fit a tiller pilot to it. I also had an old Autohelm 3000, but parts seem to be getting dear.

Both boats do well in the right conditions.

[Andrew Troup]

Originally Posted by Terra Nova

Doesn't it seem that boats with transom-hung rudders are naturals for trim-tab self-steering?

In the case of traditional transom-hung rudders (single, centrally located, NOT kickup or dagger, let alone both!) I quite agree there's a natural fit.

Originally Posted by Terra Nova

A tiller could be made to be simply easily removable, to clear the cockpit, in port. Long ago I built one out of stainless and oak, a collapsible tiller.

I agree, eminently possible, if well engineered (given the bending loads at the joint) ... but I suppose I would feel a bit reluctant to remove such a beast, except in the most sheltered anchorage, in case of a 'five alarm alert', such as needing to avoid a dragging yacht...

... that is, unless it was a real 'quick connect', and there was stowage provision right there (such as a recess in the cockpit sole)

I had a formative experience with a removable bridge deck once on an offshore yacht, stowed 'offsite' in the owner's cabin, and I guess that colours my feelings ...

Originally Posted by Terra Nova

Hope you'll post a sketch of the mechanism you described.

I'm not sure which part of the mechanism you would like to see ?

The sketch I posted above showed (albeit sketchily) what I thought was the least obvious part of the mechanism I described.

I haven't yet designed the details of the servo oar 'power head', or the input side of my vane gear.

I have a Targa arch level with the transom, so it slopes forwards, protecting a vane mounted on it from the collision risk you mentioned.

In some ways, either corner would be the natural place to mount the vane. Tricky though, getting the action from there to the servo oar.

It probably makes more sense to have the vane on centre, and have a pair of tierods to transfer the waggle down to the oar (both in tension, but only one at a time.) Removable, so that in harbour, they could be stowed across the underside of the arch and free up the boarding area.

I'm torn between going with the tried and true geometry as refined by Monitor and Cap Horn, and trying an upside down vane, as designed and tested and described by Jan Alkema (a Google search should throw up his paper, "an Innovative Windvane System")

The chief advantage he promotes from that geometry is an automatic tendency to apply more helm with increasing heel angle, and that appeals, because my boat will be reasonably tender in some circumstances.

[Andrew Troup]

Originally Posted by robert sailor

Capt Rottnest,
Any mono hull with properly trimmed sails will sail its self upwind, just add a little helm and lock the wheel. I've sailed for hours offshore like this and the boat will simply follow the wind.

I agree (with minor reservations, for instance, major variations in wind strength).

I've had owners check the battery levels in the morning and say to me something like "did you hand steer all night or something? I never heard the autopilot come on"

(in reply to Capt R, and in confirmation of rs reply):
It makes no diff whether wheel or tiller.


There is variation between hulls, though, IME; some make this very easy to achieve, and at least a few make it impossible, even with well cut and well trimmed sails.

In cases where it's not easy, it helps greatly if you slightly overtrim the headsail and undertrim the main.

If the sails are in reasonable shape, this almost always does the trick, I've found.

[Terra Nova]

A rough diagram of the main shaft showing each input and output?

[Cheechako]

Originally Posted by cwyckham

I can't tell from your post if this is theoretical or if you've used one in these conditions.

I also don't feel that your typical monohull has any issue with heavy weather use of a windvane. They don't surf too quickly, and if the wind is blowing 35 knots and get a surf up to about 9 or 10 knots, it isn't going to bring the apparent wind too far forward.

Also, remember that a servo-pendulum will tend to act against any gybe, quite independent of wind angle. The stern slewing around pushes the paddle hard over and spins the wheel in the opposite direction.

I've had two Monitors (on 3 boats!) and an Aries. There's no wind in the trough.

[Andrew Troup]

Originally Posted by Terra Nova

A rough diagram of the main shaft showing each input and output?

Thanks again for your interest. Here's a diagram...

One other thing I like about the whipstaff is the way the top end of it lends itself to tiller lines, including sheet-to-tiller jury steering.

I plan to run an endless tiller line around the coaming, (which has a 3" overhanging lip, except at the very stern), which will run right around the forrard hatch, a bit like the breakwater on the foredeck of a naval destroyer.

I've worked out an idea for the steering brake, which I plan to locate immediately inboard of the Y quadrant (note to self: but readily accessible!).

This keeps the forces arising when (say) hove to, and perhaps thrown backwards against the rudders, local and isolated from the remainder of the steering system.

This brake will be 'normally on', (unless the servo oar is steering) but be defeated anytime the whipstaff or pedals are 'energised'. That way, grabbing a tiller line from the foredeck would override the brake, but any correction to the helm would 'stay put' until a further input was made.

This whipstaff implementation works like a 'one spoke wheel', rather than a tiller, in terms of which way it is moved for a course alteration.

I think this is potentially quite useful, once again, in broaching situations, because the weight of the helmer thrown to leeward by the sudden heel will help in bearing the boat away.

I plan to use heavy braid for at least the first sector of the tiller lines, around the turning blocks embedded in the coaming athwarthsips of the whipstaff, before it is led forward

This large diameter braid will serve a bit like the 'rim' of a wheel.

ON EDIT:
This setup would also permit ‘helping’ the servo oar from anywhere on deck, particularly in light going. However the friction of the tiller line could be an issue in the same conditions. I visualise the endless line terminating in a 'hood' for the whipstaff, so it could easily be decoupled in such situations.

[Terra Nova]

To be able to adjust steering from the foredeck would be wonderful. I'm afraid the hysteresis in the system might be too great, because of the line.