Making a bigger rudder for a Klepper AE2

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Romainpek

Making a bigger rudder for a Klepper AE2

Post by Romainpek »

Now that I have stability (thanks to my new outriggers) I want to ameliorate the rudder of my Klepper. I hope to get something that will allow me to tack more often than now.

I would say that with light winds, I can tack properly 4 times out of 5 (using the jib on the wrong side to help me turn) with both lee-boards down. A couple of friends reported that using only one lee-board helped tacking but I still saw them using the paddle to help turning.

In heavy winds, it's a different story and the existing rudder seems totally inadequate for tacking. When in irons and the boat starts to go backwards, counter-steering doesn't seem to work at all (while this works great on a catamaran).

My idea is to keep the existing Klepper blade and build a bigger wooden rudder foil around it, that could be installed or removed just like you would wear or remove a shoe.

This is the concept:

Image

Romainpek

Re: Making a bigger rudder for a Klepper AE2

Post by Romainpek »

The core is of approximately the same thickness as the original blade (around 3mm). The blade shape has been cut-out in it and I'm gluing all the wooden slats across it on the first layer...

Image

and then down for the 2nd layer.

Image

The glue is PU, it makes a lot of foam.
Last edited by Romainpek on Sat May 16, 2009 9:34 am, edited 1 time in total.

Romainpek

Re: Making a bigger rudder for a Klepper AE2

Post by Romainpek »

See the cutout for the original blade :

Image

As for the foil shape, I read that NACA0012 works well for rudders so that's what I'm trying to get.

Image

The chord of my new rudder is 20cm, its total thickness should reach 12% which gives 2.4 cm. Much much more than the original blade. See the first side:

Image

Romainpek

Re: Making a bigger rudder for a Klepper AE2

Post by Romainpek »

Here I am now, one half is about done

from inside:
Image

from outside:
Image

The interest of using 2 layers of 6mm instead of one 12 mm are:
-the aft down plank is placed only where the thickness of the foil will be greater than 6mm. Less wood to rasp.
-The lines (front and back) between 2 layers give me a free visual indication to see if I'm rasping correctly or not. If the line starts waving, it means that there are some bumps or dips.
-also I hope to get a more resistant blade and less warp with this "home made plywood" than with a solid piece.

Romainpek

Re: Making a bigger rudder for a Klepper AE2

Post by Romainpek »

Yesterday, I glued the 2 halves on each other with the Klepper blade inside.

Today, a moment of panic when I could not remove the blade... Slowly, delicately, carefully (I hammered the hell of the assembly) I managed to remove it. Quick sanding of the glue traces, a bit of oiling the blade and now it gets in and out nicely.

I shaped the second half and now the rudder is drying its first layer of varnish.

Image

Image

Alm

Re: Making a bigger rudder for a Klepper AE2

Post by Alm »

Romainpek wrote:Yesterday, I glued the 2 halves on each other with the Klepper blade inside.

Today, a moment of panic when I could not remove the blade...
Perhaps I missed something. Why did you have to remove it? Will you make another "neck" to hang it onto the existing Klepper molding?
(My interest is based on inevitable modification of FC rudder for sailing, don't know yet where even to start from :-) )

Romainpek

Re: Making a bigger rudder for a Klepper AE2

Post by Romainpek »

Perhaps I missed something. Why did you have to remove it?
I'm never sure of doing things right, so I want to be able to try both ways: with or/or without my wooden foil on top of my original rudder blade. I guess a bigger rudder will mean extra drag and I don't know yet if the expected benefit (better steering) will compensate it.

Also, If I want to paddle instead of sailing, the original rudder does its job fine. I must then be able to remove the foil.

About the attachment of the foil to the original blade, I don't know if I need to add anything yet. It's quite tight as it is, I don't think it will disengage easily. If necessary, I can drill a little hole higher in the blade and install a little rope or bungee that would be tied to one or both sides of the foil.

My main interrogation now is whether the blade + wood foil will stay down while sailing... Maybe I will need to add something (a bungee?) to hold the rudder down. In fact I don't even now if the original blade alone stays down when sailing fast.

Alm

Re: Making a bigger rudder for a Klepper AE2

Post by Alm »

Romainpek wrote: My main interrogation now is whether the blade + wood foil will stay down while sailing... Maybe I will need to add something (a bungee?) to hold the rudder down. In fact I don't even now if the original blade alone stays down when sailing fast.
Yes, a downhaul bungee line. I have some photos somewhere (homemade foil for Folbot schooner), and you may google up Sunfish rudder - the idea is the same. It won't stay down at sailing speeds 4 knots and up without this added line.

Romainpek

Re: Making a bigger rudder for a Klepper AE2

Post by Romainpek »

I added a bungee line by fitting 2 metal holders in a bolt that was there, plus drilling a hole at the back of the blade.

In the down position:

Image

And when it's up, the hole with the bungee disappears between the jaws...

Image

I'm not sure it will work very well. In order to be still able to raise and lower the rudder, you can't put too much tension in the bungee when it's at the proper sailing position...

Alm

Re: Making a bigger rudder for a Klepper AE2

Post by Alm »

Bungee has to be a) adjustable, and b) brought close to the rudder pin axis.
a) I used a short nylon line with loop at the end (white on the photo), connected to 4 or 5 ft long black bungee via small metal clip
Image. The photo was made to show tiller arrangement on MK1, but incidentally shows the bungee as well. The bungee goes all the way to the perimeter loop near cockpit, where it ends in the barrel lock, to adjust the tension.

b) White nylon line is passed through the D-ring sitting on the lower lip of the rudder molding, to avoid interference of the bungee when rudder is deflected to the opposite side.

Romainpek

Re: Making a bigger rudder for a Klepper AE2

Post by Romainpek »

b) White nylon line is passed through the D-ring sitting on the lower lip of the rudder molding, to avoid interference of the bungee when rudder is deflected to the opposite side.
if you could show this, that would help...

Alm

Re: Making a bigger rudder for a Klepper AE2

Post by Alm »

Can't show - don't have MK1 anymore. Regular stainless D-ring. Could be a round ring, I just happened to have a spare D, - probably 1" size. Put it on the lower lip of the stern molding (or, perhaps, on the lower lip of the rudder head) before putting the pin through. White line is tied to the hole in the blade approximately at the level with this D.

Btw, I didn't notice too much resistance when lifting the blade, so this adjustability of the bungee might be not important for lifting the blade, but it is important to keep the blade down.

John Monroe

Re: Making a bigger rudder for a Klepper AE2

Post by John Monroe »

Romainpec when I switched to the NACA 12 rudder and the NACA 9 leeboard I had a big difference in my boats sailing ability. I don't know which made the biggest difference but maybe they were both equally responsible for the good results. I do have to have a bungee on the rudder to keep mind down.

One easy way to come about is to Gibe with the wind at you back as you cross the wind but you have to practice this on calm days to get the feel for it. As you cross the wind you pull your sail in tight just as you cross you let it out gently or fast depending on the force of the wind as you turn to the other tack. If this isn't done correctly in high winds you can turn you boat over but you get a feel for it.

John

Image

Romainpek

Re: Making a bigger rudder for a Klepper AE2

Post by Romainpek »

Nice rudder John! Did you experience much more drag than with a flat metal blade?

Your bungee must be the diagonal black line on the rudder itself, isn't it? As you added a strong lever on top to pull the rudder up, you should not have too much problems to raise it.

Regarding gibing, it's no problem with the Klepper as long as the wind is limited. Even with the old rudder blade.

John Monroe

Re: Making a bigger rudder for a Klepper AE2

Post by John Monroe »

My flat small rudder and leeboard were so terrible that I couldn't sail upwind so I really can't compare it for drag. The boat now seems to be everything I want my setup to do. I may be lucky in that all the combinations of leeboard, rudder, sail and balance are close to being about right. What is so excellent about this boat is it sails 40 degrees to the wind and that is at full sail and not just sputtering along. If I have a worry, it is that my pontoons have drag in high winds as they are shoved deeper into the water. That is why I was interested in your more streamlined pontoons that you made.

John

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