Wind Vane Steering on a Cat

[2Hulls]

Hi Rezzy - I wish you luck in this project. One thing I wonder about is the size of the wind vane rudder - is it big enough? Cats tend to want to go in a straight line more than monos and it may take more rudder to result in the same turn angle.

Dave

[colemj]

Originally Posted by Rezzy

Hi All,



To answer your points Colemj I don't expect the vane to clear the rigid bimini but the Hydrovane will be way back on the end of the pontoon giving clean air on all points of sail except going to windward on one tack. I accept that limitation as a minor downside.

At best, it will work this way on one tack only. With the wind over the opposite hull, I doubt it will correctly sense the wind on anything forward of a broad reach. It won't go to windward on any tack.

There is a huge windage and superstructure difference between that Nautitech and your L440.

Hey go for it. I don't care at all - just trying to help you see rationally.

Mark

[Rezzy]

Hi All,

The reason I am pursuing this is there will be others coming behind me and they can make their own minds up.

The aft view of the Nautitech 47 shows that on the starboard tack at least there is completely clean air. Colemj states that the boat won't go to windward on this tack - why not?

Colemj states that at best on port tack a broad reach only is possible. I maintain that you will get clean air up to a beam reach and accept that there will be disturbed air going to windward on port tack.

Upon further research there are Hydrovanes fitted to a Lagoon 380, Lagoon 400, Lagoon 410 and a St Francis 50 amongst others.

Hydrovane have addressed the problem of bulky superstructures on cats by doing two things. One, the gear has to be on the extreme end of one of the pontoons and two, specify the fitting of an "extended heading tube" which jacks up the height of the vane by another couple of feet or so. Note that the Nautitech 47 in the picture does not have this fitted and could be added if needed.

A direct comparison between the height above waterline of a Nautitech 47 and a Lagoon 440 cannot be found on the internet. By inference, if it's okay for a Lagoon 400 and 410 then it's okay for a 440. I'm only trying to be rational here.

[colemj]

To be clear, my comments have been directed toward installing one on a L440.

There is not much of an "extreme back end" on that boat, and the super structure must be 15' off the water. Additionally, there is no dodger to the front of the superstructure to pass air, which creates a large venturi off the back of it. The wind will be swirling in varying strengths and directions off the back.

Do yourself a favor first - get a cheap weather station with wind instrument and mount it on a pole on your stern where the vane would be. Log wind direction and speed from it through various points of sail in various conditions.

In the US, you can get these devices with PC logging capability for <$100.

Mark

[Rezzy]

Hi Mark (colemj)

Thanks for the advice about some sort of wind direction instrument to test the conditions at the end of the pontoon. This is a good cheap way of getting crude information about the various forces, venturi effects etc. Assuming this checks out okay I'll update this thread in a few months and give you all the low down.

Fair winds

[805gregg]

With all the room for solar, no need for windvane just use autopilot like everyone else

[Sailmonkey]

Why are you so narrowly pursuing the hydro vane?
The Cape Horn vane I posted can be centrally mounted and custom built to allow the wind vane to be above the coach roof.
So much cleaner than something mounted on the swim step.


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[Paul L]

Originally Posted by Rezzy

.....
Upon further research there are Hydrovanes fitted to a Lagoon 380, Lagoon 400, Lagoon 410 and a St Francis 50 amongst others.
......

And how many of them use the windvane as their primary means of offshore self-steering? Installing a windvane is only the first part -- does it get used is the second part.

[44'cruisingcat]

Originally Posted by Rezzy

Hi, thanks for the replies.

I've found at last an image of a Nautitech 47 cruising the South Pacific with the Hydrovane on the extreme end of the pontoon which is very similar to how I will fit mine on the Lagoon. They reported to Hydrovane excellent performance after 6000 miles and counting.

For me, having a rock solid energy free source of self-steering is pure gold. A close runner up would be to have another complete autopilot system ready to swap out in case of failure. I suppose the more miles you are planning on putting under the keel the more sense it makes in my opinion.

But does it work?

[colemj]

Originally Posted by Sailmonkey

The Cape Horn vane I posted can be centrally mounted and custom built to allow the wind vane to be above the coach roof.
So much cleaner than something mounted on the swim step.

There isn't any practical way to centrally mount one on a L440, let alone most catamarans, and it would have to be extended 20' to get a hope of clear air on that boat. Then I can't even begin to understand how, and to what, you would be connecting the steering control lines.

Here is a pic of the boat in question:
http://www.regisguillemot.com/sites/...sition=elastic

Mark

[Sailmonkey]

Originally Posted by colemj

There isn't any practical way to centrally mount one on a L440, let alone most catamarans, and it would have to be extended 20' to get a hope of clear air on that boat. Then I can't even begin to understand how, and to what, you would be connecting the steering control lines.

Here is a pic of the boat in question:
http://www.regisguillemot.com/sites/...sition=elastic

Mark

I retract all my previous statements.....that is not the lagoon I've chartered before. That's a barge!! I don't see a windvane working to steer that on any point of sail. I still think the Cape Horn could be centrally mounted an have the control lines led internally to one of the quadrants, but I don't think it would create desirable results.

The amount of disturbed air around that boat would be like mounting a wind gen on a post in the backyard and expecting it to work when the wind is blowing towards the house. Sure it feels windy, but it's also fluky.


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[Rezzy]

Well Sailmonkey,

As I said in an earlier post, I'll update this post with real experience of a Hydrovane on my own 440 in future months. Something tells me however that if I report back fantastic results there will be those who will dredge up some reason as to why I am wrong. We shall see. We shall see.

[Rezzy]

Originally Posted by 44'cruisingcat

But does it work?

Just got an email from the skipper in Fiji. He is very pleased with how it works. Now just maybe there is something wrong with the skipper!

[double u]

would have a windvane on any boat & if it's just as a backup in case of ailing autopilot(s)
Aries steered our 34' Wharram alright during our circumnavigation in the 80ies, & this included 4 consecutive days in the pacific-se-trades with runs >190nm/day (albeit bearing away sharply with each surf...) & lightwind performance was outstanding: until there was hardly any headway any more (then the servo-paddle seemed to steer the boat, as boatspeed was insufficient to make it swing to the side)