Wind vane on Multihull

[Cavalier MK2]

Vane development for multihulls hasn't gotten much attention since auto pilots took off. I've seen a picture of Mike McMullen's 46' Newick tri 3 Cheers where 2 vanes were mounted, one on each aka with the windward one always being used. A similar approach to a cat would work or having the vane on a extension tall enough to clear the cabin. Bike style control cables are reported to work well for the linkage.

The easy answer is to just slow down when using the vane, towing a warp or small drogue to get the speed in the right range. Not really a bad idea at night anyway, plus you wouldn't have the autopilot noise when sleeping. During the day you could go back to an auto pilot and speed things up.

Sailing to windward and directly down wind there wouldn't be the huge apparent wind change of the other courses so a fast boat vane needs some kind of differential to cope with the changes. I plan on tinkering with one eventually but it is a ways down the list. The Haig's Nicol 40, a similar boat to mine, did well with a Searunner style vertical vane working on a auxiliary transom mounted rudder and tab. Like the Searunner, it is a cruising design so acceleration and apparent wind changes were more moderate, so again, slowing down might be the place to start.

[colemj]

What autopilots are you guys using that make that much noise? We sleep directly over our below deck drive, with just the mattress between it and our ears, and can't hear it at all. I can hear it at anchor if I remove the bedding and open the hatch to the quadrant area.

To put both transoms out of use and drag warps to keep boat speed within range sounds nuts to me - I would be looking at quieter drive units instead.

But to each his own!

Mark

[robert sailor]

From what I hear about the newer cruising cats the performance is such that vane will probably work with no need for slowing down as they do not go that fast to begin with.

[Cavalier MK2]

Originally Posted by colemj

What autopilots are you guys using that make that much noise? We sleep directly over our below deck drive, with just the mattress between it and our ears, and can't hear it at all. I can hear it at anchor if I remove the bedding and open the hatch to the quadrant area.

To put both transoms out of use and drag warps to keep boat speed within range sounds nuts to me - I would be looking at quieter drive units instead.

But to each his own!

Mark

Nuts to having to tie up your transoms, a cable linkage can allow many placements of the vane. I agree that many cruising cats aren't going to have to worry about apparent wind differences. On the other forum we can't name though was an account of crossing the Atlantic by somebody sailing a Woods Sagitta, a higher performance cat. After surfing past 18 knots and into the backs of waves he found he maintained a higher average speed towing warps in a "Abbot drogue" configuration to eliminate the surges. This also allowed his autopilot to work better as it wasn't able to keep up with the speed variations. The same thing would work for a vane.

Getting a vane working is an interesting puzzle probably not for those who need in the box solutions, some ingenuity is required. I like the idea doing without the electricity use and having a system that can be repaired without sending units back to the factory.

[markd456]

I have logged quite few ocean miles with a windvane self steerer on Crowther 33' Buccaneer trip a few years ago. It was a simple horizontal pivot vane with thin cord and some small chain to attach it to a pin on the tiller. The rudder was a balanced spade. The van was mounter on the stern of the main hull with the pivot about at the same height as the boom. The design was from the NZer Bob Belcher, and it cost me some spares and scrap plywood and epoxy to build.

The vane worked exceptionally well to windward and around to a broad reach in wind speeds from 5 to 35kts and boat speeds of 3 to 18 kts. Over 18 on a reach you really needed to be on the tiller to make the best of the 20+ bursts down waves.

The vane also worked well downwind....it was my only helmsman from Tonga to Fiji to Noumea to Coffs Harbour NSW. But you had to have at least 1 reef in the mainsail (to be frank for much of those passages I was happy with just the headsail and to jog along between 5 and 8kts) and accept that the boat would make a very pretty 3 wakes in a wavy S pattern with the course varying +/-15 to 20 degrees (who cares if the sailing is downwind and it is bare tops and shorts weather day and night?). The only problem I had was in VERY steep waves along the NSW coast downwind with the main hoisted. We would surf a wave, the boat would jibe then accelerate on a broach/reach....the only time I have been worried about capsize. Problem fixed by dropping the main.

I now have an 11m Simpson cat with wheel steering with an Surgeon tiller pilot driving a pin on the wheel (1 turn lock to lock). The wheel is attached to string (spectra braid if you are a wanker) which via blocks go to a tiller bar on each rudder post, providing a pull-pull system. So far this has worked great, though it has difficulty in following seas as much as the old wind vane. I am currently trying to figure out how to install the same windvane I had on the Buc33, but driving the wheel via a telefax cable also to the same pin on the wheel. I don't trust tillerpilot.

In all of this I have assumed the boat is easily steered....not the white-nuckled feats of strength I have experienced on keel boat tillers and wheels, but the two fingered touches needed on a good multi. I can highly recommend Belcher's book on self steering gear.

Cheers, Mark