What material for a spare wind vane for self steering?

I have a Monitor and it specifies two sizes both are in 4 mm x 4 ply birch plywood. The larger size is 8" taller and 60% more area designed for light wind but tested up to 40 knots. This demonstrates that 4 mm ply is more than up to the job.
 
PuffTheMagicDragon said:
Surely there is a counterweight that can be adjusted?
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The OP's told us it's a Seafeather. I've not used one so can't say whether it's adjustable or not. On the servo-pendulum systems I'm familiar with, it isn't.

On the Windpilot Pacific, for which I still happen to have the handbook, the vane must be no more than 50g lighter than the counterweight and never heavier. Of course it's always possible to adjust the weight, but clearly less inertia in the vane assembly is desirable, especially in light airs.
 
On my Aeries I found that using thin plywood with some GRP each side for the bottom half ( tapering off) not only made it much stiffer but improved its performance. I have experimented with a number of vanes & found that the stiffer versions are definitely better than flexible ones. I also replaced the bolts holding the weight with lengths of studding & can add further weight which can be moved in & out as I require to change balance & response
 
PuffTheMagicDragon said:
You don't "adjust the weight". You alter its position by moving it up or down as necessary until the required 'balance' is reached.
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Well thankyou, but you do adjust the weight, whether you move it (which is not practicable on some windvane systems), or change its mass. As well as English, I'm familiar with moments and you've just had a small one ;)
 
The counterweight is adjustable by slackening a holding screw (grub screw) and moving the weight along the shaft that it mounts on. The weight is about middle position now, so some room for adjustment either way. I think I'll try some ply wood, and maybe make an aluminium one too. I seem to carry several spares for everything else aboard (with all that weigh no wonder I never win any races), so several vanes seems to fit the pattern. Thanks for all suggestions.
 
Geoff

I would use "Foamex". Widely available in many colours, light, rigid, waterproof, easy to cut to size, available in different thicknesses, cheap, UV stable. The list goes on.
If you are near a sign writer or shop fitter they will almost definitely have scrap pieces lying around for a couple of £s.

Second bet would be multiwalled polycarbonate.

Donald
 
Have never tried it but may I suggest Tufnol. This can be obtained from "Direct Plastics Online" & can be supplied 3mm th. Their website gives a full description of 3 types of Tufnol, plus lots of other plastic sheet. However, I see that a 1200 * 300 sheet of IP3 can be obtained for £16-00. If you can make the vane tapered in its length & cut the sheet slightly diagonally you should get 2 vanes for that & it is easy enough to cut. Their website describes it as rigid & half the weight of aluminium.
 
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macd said:
Well thankyou, but you do adjust the weight, whether you move it (which is not practicable on some windvane systems), or change its mass. As well as English, I'm familiar with moments and you've just had a small one ;)
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Well, if you are "familiar with moments" you would have appreciated that the vane/counterweight assembly is a lever system - think 'see-saw' -that is (intentionally) slightly off balance so that the whole assembly can rotate freely around the fulcrum with the vane just managing to be vertical when the wind pressure is equally balanced on both sides, its resistance to movement sideways being controlled by shifting the counterweight mass, up or down, as necessary.

BTW, a system where the counterweight position cannot be readily altered is either silly or is there intentionally to keep most customers captive when it comes to buying spare vanes. At the prices that are charged for pendulum wind vane systems I find this practice to be dishonest and not just bad engineering.
 
I have a sea feather and have made numerous feathers out of ply. I would not recommend playing about too much with the weight. I have used cheap ply and have painted them and personalised them. I have two shapes. If you google seafeather you will see the two different shapes. The seafeather is is a very simple system that I have always found to be a great little unit. I have attached a photo of the vane that I made myself. I have kept the originals to use as my templates. I have also made spare paddles. Happy to discuss if you want any further information?
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Thanks BB. I was planning to use the existing (original) as a template too. I don't have a spare paddle, but that's a bit easier in teak or oak or similar. Did you use other than 3mm thick material? (as the original is 3mm.) I suspect the holder might take 4 or 5mm ?
 
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