Thursday 14 May 2009

A quiver of rudders

That new rudder blade that I made for OB is too small. It turns the boat fine and is lighter sailing off the breeze but is not big enough for going to windward.

At first I thought I’d just knock up a copy of the previous rudder, which I’d butchered to make the current one but the shape of the available ply off-cut got me thinking. It was a small piece of ply; barely big enough to create a rudder blade with sufficient surface area unless I changed the rudder shape. So I drew and cut a new blade with more surface area on the leading edge rather than the trailing edge where it had been before. I like the resulting shape. And I love the way that small boat building and owning allows you experiment in this fashion. I don’t know the exact optimum surface area for the Light Trow rudder and what I’ve made is only based on intuition.

Then I looked at another off-cut and found that I could cut something similar to the rudder that Gav originally drew. I had to lose one aft corner so it is slightly smaller than drawn but I’m keen to test it.


Gavin Atkin said...

That last rudder needs a bit of thought. First off, it can only hope to work if it's like and inverted 'T' - that is, it has a flat bit added to the bottom. I hope this is in the drawings somewhere.

Also, it'll only work if it isn't out of the water - go forward in your boat, and you may find it stops working altogether.

On the broader point, no-one knows what the size of a rudder will be.

Ben said...

It was that raising out of the water that originally put me off making this rudder.
The T piece is in the drawings, though its only now that you mention it that I remember it, and I hope to fit it soon.
As far as rudder size goes I think I'm getting nearer.

Anonymous said...

hi ben,my name is esteve.I arrived to your blog from the joan sol's one.I watched some photos and videos of OB, and tried to read your comments,I'm sorry but due to technical names and the english I miss a lot of things.the fact that you'r in tarragona made me write you this comment(well,it's more a message),I live in barcelona but I'm from a little town close to tarragona,and I use to visit it very often.I did some windsurf and now I become interested with the latin sail or traditional sailing,for the moment I did a three days navigation with the far barcelona and I become volunteer of vilassar de mar boat's Sant Ramon.well sorry for the long message,just ask you if is possible to make you a visit where you have the boat and see how is and how you work on it or how you enter to the sea from the beach.I really hope don't disturb you,I'don't know your mail adress,that's the reason I write you throug this comments inbox and I hope you'll be able to erase it and preserve people to see this stupid comment,I'm feel shy about it but is the only way I see for contact mail is,I'll be very glad if you drop me an email and you can receive me some day.thanks a lot and sorry for the intromission.esteve