I have searched the forum for information on the rudder blade repair and replacement but none of the threads seems to come to any kind of conclusion.

What is the thickness of the original rudder blade? 8mm was suggested and it looks about right but it was never confirmed and mine is too corroded for accurate measurement.

I have drawn the blade in CAD ready for laser cutting so getting a price for any thickness in any material costs nothing. Did anyone actually make one in marine grade dural and was it any good?

Could the standard blade shape be improved upon or is it plenty good enough as it is?

I have removed the two plates from the sides of the rudder stock and found two square dowels. Am I correct in thinking these are to control the sideways play in the blade?

I have applied to join the PSSA and at the same time ordered a manual but it is yet to arrive.

The original blade was 5/16th inch "boiler plate" so 8mm would be close. People have made copies in Dural or similar and we have heard of them failing due to fatigue along the line of the bottom of the stock so be sure the alloy is not one that could have that problem.

The standard blade shape is fine IF it is fitted the right way round! I have seen many fitted backwards. The leading edge should be nearly vertical and in line with the pintles well forward of the stock.

I'm not sure about the dowels - there should be a plastic block at the foot of the forward edge of the stock to locate the step aft of the downhaul hole to get the right blade angle.

Geoff

Thank you Geoff.
I have just received the manual and membership information so that should shut me up for a while! The manual is excellent and easily worth the joining fee and cost; and that's just from a quick browse.

Back to the rudder:
I have found two small nylon blocks in the foot of the stock and a metal bracket at the leading edge where I presume the blade seats.
Which is the correct way round for the blade? The large radius at the top comes down to a small step which looks like it should seat on the aforementioned bracket - so the radius faces forward?

Sorry about the basic question but there are precious few pictures of seal rudders on the net and my experience of them is limited to this one. :-)
And as one of the up/down haul holes is broken, this one may well have been reversed for reasons of economy.

http://s144.photobucket....jpg.html?sort=3&o=10 

Thanks again Geoff, a fine figure of a man but are you sure it's not Prince Harry? :-)

That photo confirms that my blade was the wrong way round; I suspected so as it is the uphaul hole which has broken through. Reversing the blade may have made it easier to lift as I notice the downhaul hole is further from the pivot point.
Weakened by corrosion, the blade has bent just below the stock so is therefore, heading for the bin. The anti fouling on Alea is aproximately 4 inches higher than that shown on the photo.

I'll now fully digest the manual before returning.

Floyd
Welcome
It's some years since I sold my 22 but when I bought Tulena No 154 the rudder blade had had plywood added to both sides and shaped to a traditional aerofoil shape which made it more efficient and lighter in the water. Later the blade cracked near the stock so I replaced the metal part with stainless steel (probably 8mm)but only half the length and with 3 or 4 2" dia holes. I made the remainder of the blade in layers of plywood (2" rounds filling the holes in the metal), gluing and screwing the layers together. The blade I shaped to the foil section and glassed the whole blade. It worked very well and is still in use probably 15-20 years later.
Philip

Philip
Thank you for the welcome, and the information which gives me confidence with my own idea:

I have previous experience of producing drawings as .dxf files for laser cutting and I have already traced the original blade for this purpose. I have also just discovered that a friend of a friend operates a laser cutting machine so a straight replacement in 8mm steel plate comes in at the right price! But on the drawing I have left enough steel below the stock to maintain strength and hollowed out the main part of the blade, leaving around 30mm to keep the overall shape. I would then fill the void with 8mm foam to form the filling of a ply/glass sandwich.
Any opinions on the above would be welcomed.

In my ownership the boat will probably only ever see the fresh waters of Rutland or Her Majesty's Lake District; none of this crashing through waves business for me! 🙂 So a standard blade would probably be plenty good enough for me but for a little effort I could end up with something a tad lighter if nothing else.

Floyd

Floyd
I like your idea, but I think I would leave a narrow, say 20-25mm wide strip of steel across the middle for strength.
I had (I hope I've aged out of it) a tendency not to reef soon enough so sometimes had to use a lot of rudder to keep control, at this time there is a lot of load on the blade.
When applying any degree of rudder the flat blade soon stalls, but a shaped blade is much more efficient and keeps working. I used the internet to get the right shape.
Good luck
Philip

Philip

Thanks again, I will do that. I am also taking photographs and keeping records so if it works they may will be seen.

Floyd

I was hoping to get this back by April 1st and post it as a revolutionary new rudder blade for high speed use.

Here is the laser cut blank with score marks to show the locations of the holes. I have added a "nose" to the design for easier lifting but if it doesn't prove successful it can be hacked off and a hole drilled in the original location. The score mark is there.

Floyd,
I have access to laser cutter which can take instructions from ACAD files. Would it be possible to get a copy ?
If the blade were cut in mild steel and galvanized would this work in sea conditions ?

Pat

Well it's been a long time coming but it's finally finished. It is a little crude, rather like myself, but it could easily have been improved with a little more attention to the shaping. If I did it again (and I have no plans to!) I would get myself a belt sander.

For the laser cutting I was quoted around £100.00 inc VAT (March 2015) by a good specialist company in Wigston, Leicestershire.
The ply is 5MM Exterior from B&Q. The 2 viods are filled with foam filler. Over the ply are 2 layers of regular glass matting topped with a layer of "tissue" and self coloured epoxy. The black is an excellent classic car chassis paint.

In the old pic you can just see the old blade fitted in reverse due to the uphaul corroding through.

The new blade is 7kg lighter than the old.

I have pictures of the build and I am prepared to write up the exercise into an article if there is any interest.

I should also add that the rudder is untested and there is a chance it may never be, by me anyway; I have decided to sell the boat and start again next year.

I've just noticed the two pictures look like they've been doctored for use on QVC! The "before" picture being deliberately poor quality to emphasise the difference.

The old picture was taken before I bought it, and all the timber has been epoxied and varnished since then.

Floyd,
I have access to laser cutter which can take instructions from ACAD files. Would it be possible to get a copy ?
If the blade were cut in mild steel and galvanized would this work in sea conditions ?

Pat

Sorry Pat, I saw this a while ago and completely forgot about it.
The blade I have made is 8mm mild steel but I am not qualified to say how well it will perform. I have just copied the original shape and size as far as possible. As for giving out copies I think the best forward is for me to let the PSSA have a copy for them to issue to members as they see fit. This keeps me clear of any possible copyright/design problems.

HELLO!
If there is anyone still alive out there, my boat is now for sale from the place I bought it from, Andy Seedhouse Boatsales.

I have seen a better boat, that's all.