Wind Vane conundrum

[Cardo]

So we're working on our boat to get her all ready to depart these fair waters in 2013.

We're intending to do some long passages, including the Atlantic at some point and I've been having a look at wind vanes for self steering. The boat has a very hefty mechanical autopilot that works wonders in pretty much any sea, however sucks down about 5A when it's turning the wheel. Unfortunately, I fear this would eat up the batteries in no time on a long sailing passage.
So my attention has turned to those fancy wind vanes, which seem to be rather popular.

The problem comes in the boat itself. She was modified by the previous owner and now has twin transom hung rudders with a small boarding platform over the top. I have attached a picture to make this layout somewhat more clear.

Would a "traditional" commercial wind vane work with this set up? Where would it go? Ideally, it would need to be removable so it doesn't obstruct the platform/boarding ladder when not in use.

My alternative thought was constructing something myself. I am intending to add a backup steering mechanism so an emergency tiller can be connected via a hole in the platform that will link directly to the rudders. My initial thought had been to construct some kind of wind vane that would "plug in" to the emergency tiller socket and act directly upon the rudders. However, reading http://www.faymarine.com/plansite/fay_marine_yacht_pl.htm it would appear having the wind vane act directly on the rudders would be over the top? Unfortunately, I don't see how I could practically add trim tabs to the twin rudder setup.

So this is my conundrum. I would appreciate it if anyone could provide any advice or direction!

 

[macd]

You might struggle to fit a Hydrovane to that stern, but I daresay some of the servo-pendulum systems would fit. Since most of them steer the ship's rudder rather than their own rudder, the mounting to the hull needs be far less substantial (though still pretty strong). You could do worse than to e-mail the photo to Peter Forthmann at Windpilot for his advice: peter@windpilot.com

The Windpilot site has heaps of photos of installations on all mannr of boats. It might offer a few pointers: http://windpilot.com/n/wind/en

 

[Kelpie]

Was this boat, the the twin rudder conversion, recently featured in ST?

Hard to see an elegant solution to your problem. Perhaps you could remove the boarding ladder and mount a windvane system there, maybe one that steers using its own rudder, and just lock off or raise the normal rudders.

Alternatively rebuild the existing rudders to make them balanced, and that would reduce the worload on your autopilot?

 

[Cardo]

Was this boat, the the twin rudder conversion, recently featured in ST?

Hard to see an elegant solution to your problem. Perhaps you could remove the boarding ladder and mount a windvane system there, maybe one that steers using its own rudder, and just lock off or raise the normal rudders.

Alternatively rebuild the existing rudders to make them balanced, and that would reduce the worload on your autopilot?

The conversion was recently featured in PBO. The previous owner submitted the article back in 2005 and they only recently decided to print it!

I feel the reason the autopilot uses quite so much power is that is uses an old, massive motor that drives a chain attached to the helm, that is then connected via hydraulics to the rudders. Whilst I'd imagine it could cope with just about any weather conditions, it does mean it's not particularly light on consumption.

The idea of a wind vane seemed good as it would work even if all the power cut out. Wouldn't want to start manually steering half way across the Atlantic!

I see there is mention of the wind vane driving the existing rudders. I believe I could have such a system manufactured (and should tie in nicely with my thoughts for the emergency steerage). Is having a wind vane driving the rudders directly a sensible idea? Most things I've read seem to suggest either a trim tab on the end of the existing rudder or a separate, auxiliary rudder?

 

[Poignard]

Scanmar Corp., the makers of the Monitor windvane, have supplied systems for all types of yachts and could probably come up with a solution for your yacht.

http://www.selfsteer.com/products/monitor/index.php

Wealth warning! Cheap they are not. But they do work very well. I am very happy with mine.

 

[oldvarnish]

I've had both Monitor and Hydrovane and both are excellent and versatile. Also, both companies are hugely inventive when it comes to mountings. Send them your picture and they'll tell you straight away if they think theirs will work - and in case you are thinking they are both bound to say 'yes', I know of occasions where they have talked owners out of buying their gear because they didn't think they would work well.

 

[KellysEye]

I would also recommend sending a photo to Hydrovane, the vanes can be offset from the centre line and they should have a fitting solution.

 

[MASH]

I think you'll find that with hydraulic steering the resistance will rule out a servo pendulum system meaning you'll have to resort to the heavier, rather more cumbersome and harder to mount auxilliary rudder type. Harder to mount due to the strength of the mounting required as it is the unit itself that will be imposing the entire steering loads onto the transom instead of using the existing rudder/s to steer as in a servo pendulum system. This will involve something akin to a section of a box-girder railway bridge sticking out from the transom to give clearance to that overhang and must avoid fouling the sweep of the rudders. That mounting may not be easy or cheap and won't be easily demountable but as said above manufacturers seem good at solutions.

I doubt if it is possible to mount an AR system assymetrically - it will have to be on the centreline which would mean moving the ladder (some SPs can be mounted assymetrically, eg Sailomat) but no doubt others will confirm/deny this.

A servo-tab system might - just might work but it's going to be an absolute sod to design and build the linkages on a twin rudder setup. I don't know how much expertise there is on those out there - not much would be my guess, they're seldom seen.

My guess is that you'd be better to either live with the existing system and spend a third of the cost of the windvane on an aquagen (or two) or similar (power is no problem when motoring) or heavily modify the existing steering/autopilot.

 

[michael_w]

Another vote for Scanmar. I'd much rather have my old boat's Monitor, than the crappy Hydrovane that I've got at the moment.

There is no comparison in steering efficency.

 

[macd]

I see there is mention of the wind vane driving the existing rudders.....Is having a wind vane driving the rudders directly a sensible idea? Most things I've read seem to suggest either a trim tab on the end of the existing rudder or a separate, auxiliary rudder?

"Most things you've read" suggests more reading required

Almost all modern wind vane systems drive the ship's rudder. You'll find few, if any, commercial trim-tab systems. The Hydrovane (plus one model of Windpilot, but not most) drive a dedicated wind-vane rudder.

For a comprehensive round-up of all self-steering systems, visit the Windpilot site (address above) where you can download Peter Forthmann's book for free as a pdf. As proprietor of Windpilot he obviously has his leanings, but the book is fairly even-handed. A 'must-read' for someone in your position, perhaps?

 

[Cardo]

Thanks for the various replies, all.

I definitely need to do some more reading. I have only just started looking into this matter.

It would appear the fact the steering system is hydraulic is going to make life somewhat more difficult.

I will send the photo of Tinkerbell's lovely bum to the various manufacturers and see what they come up with, if anything!

Do keep the thoughts and suggestions coming, though.

 

[Tranona]

You may well find it possible to fit a Hydrovane through your platform on the centreline. Quite common to fit through sugarscoops - there are (or were) photos on their site showing that type of installation. You could also then link it up a tiller type autopilot and reduce your dependence on your current system - for example when motoring in light weather.

 

[Blueboatman]

Having owned and used both Hydrovane and Monitot I would second what Old Varnish has written in full.

BTW I have fitted Hydrovane off centre too-You have a boarding ladder, I had a walk through transom with a long shaft o/board there. Hydrovane wasn't the least bit bothered though you will get 'some' disturbed water flow from a rudder.

I have also seen Hydrovane fitted centrally through a slot in your aft addition. You would then need a fold out-and-over boarding ladder to one side. ( And fitting or removing the vane rudder will be less easy but perfectly do-able.

There, that should keep you busy in research

 

[Poignard]

Just a point but was the previous owner's modification worthwhile? What do other owners of that type of yacht think of it?

If it's not worthwhile it might make life simpler to reinstate the single rudder she was designed with.

I remember talking to a Dutchman who had a very nice yacht with twin rudders and he said her only fault was the lack of propwash over the rudders making her difficult handle at low speeds. Certainly on my boat a kick ahead with the rudder over is the only way I can make the tight turns sometimes needed in marinas.

 

[Cardo]

Just a point but was the previous owner's modification worthwhile? What do other owners of that type of yacht think of it?

If it's not worthwhile it might make life simpler to reinstate the single rudder she was designed with.

I remember talking to a Dutchman who had a very nice yacht with twin rudders and he said her only fault was the lack of propwash over the rudders making her difficult handle at low speeds. Certainly on my boat a kick ahead with the rudder over is the only way I can make the tight turns sometimes needed in marinas.

This generation of Southerly's (and more so the 115 that evolved from my 105) suffered serious weather helm as the rudders needed to be short to allow for drying out. New Southerly's have twin rudders (though not transom hung) to get around this issue. The previous owner converted this girl to twin rudders after gleaning inspiration from the new, twin rudder models. Whilst obviously not as elegant as the new models, it follows the same principle.
I personally can't compare to how she handled with the original, single rudder, but the previous owner felt it was a big improvement.

As for prop wash, this is the same as with the new models. She has a bow thruster to assist with the tight turns.

 

[Poignard]

Fair enough. It was just a thought.

 

[rogerthebodger]

This is how I fitted mine self steering gear

 

[Cardo]

This is how I fitted mine self steering gear

Wow, that's quite a substantial piece of kit. :O