J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment Rudder CAD

does anyone have a cad file for the rudder?

no, but I went here (http://www.profili2.com/eng/default.htm - and downloaded/installed the "light version")and made my own drawing and template in about 1/2 hour.

When you have installed the program, open it up. The initial Database of wings will open. Go to Management and choose New Airfoil. Enter the data points from the excel sheet in this post. Negative Y's will complete the full foil profile for the "lower" section.

Then go to "Ribs/Templates" and change the chord length to be 411 mm.

Print. Cut out and make template.

It may not be perfect, but it will follow the rules of the given data from the excel file and is far easier and more accurate than doing it by hand.

Jon
Margay

Thank you Jon, any plans to build a rudder?

No, I am rebuilding mine this spring as the core is soaked, the weight is almost 80 lbs and the structure is worrisomely weak.

a rudder engineered 30+ years ago ... when paper and pencil was the way to go.

23 years ago when I decided that I didn't have time to OD race Vee Jay and would use it mostly for day sailing ... the built in weather helm became tiring. So I added a little blip to the leading edge to provide a bit more balance ... took this photo yesterday of work from 23 years ago.

Bill thinks this may be a bit too much, when he sailed Vee Jay this winter and felt he needed more feedback [weather helm]. I think after a few weeks he would have become addicted to it.

When I sailed Rhapsody last summer I thought his OD rudder steered like a barge. Red head, when she sailed Vee Jay this winter, instantly related it to another J30 she had sailed on with a re-engineered balanced rudder.

I will leave Vee Jay 2 OD for the NA ... and see if I can get used to a OD rudder again. I may have to start lifting weights to build up my arms.

Vic, I'm curious as to the extent of the difference? I sail for pleasure and don't enjoy fighting an unbalanced rudder. It looks like the blip is approximately 4"? I intend modifying the rudder by cutting the stock to move it forward 4". Or build a new balanced rudder but would like to know if it will be worth the effort.

I did comment on Vic's rudder when I sailed on Vee Jay last November. Too me, the helm had no feel with the balanced rudder. I've become quite used to the stock J/30 helm pressure. If I were modifying a rudder for cruising, I wouldn't make it quite as "neutral" feel that Vic has on Vee Jay.

Vic - can you measure how far forward your rudder extends past the normal leading edge position?

Since I now have a "spare" rudder that is patched from my Block Island storm damage last year, I may consider playing with it another year. Too much other stuff to do now.

it was a pretty simple add on of a extra dry piece of 2x3. Obsolutely without engineering ... more of a pure art form from looking at a few other rudders and comparing how gross the j30 rudder was. I will measure it once they finish the painting, put a tape on it and do a front view. the experiment 23 years ago was just to add it on, and if it was a problem to sawzall off however much. weight was not a consideration.

Nearly all my sailing was off beavertail where the wind is stronger and only in the bay if it was too rough to go out.

I have to admit in light wind when you would normally not mind a bit more of weather helm it may be a touch too neutral, but as the wind kicks up and sail trim doesn't seem to do as much as you would like ... it does help. We haven't been getting a lot of light wind days for the last couple of years here, but when we do i have to concentrate on the woolies, and not so much on feel, on tight haul.

I cut a set of keel templates and will see if any of those precut radius's come close to the leading edge. one of the lower ones might be close.

My keel templates did ok on 505 ... and gave the bottom guy a good idea of how to fair the dent at the bottom from hitting a rock when in Newport. other than that no real need to make changes to the keel for phrf competition down here. this was the first time we templated it since it was new.

Naples is a social racing circuit where low budget programs keep the retired guys active.

gave the Vee Jay 505 rudder a quick look this morning ... the V keel template appears to have the same radius at the leading edge. photo shows the V template in position ... on the rudder. Whether we are looking for a similar lift foil for a keel as a rudder I haven't got a hint.

original part of rudder is ~15.5 in. leading to trailing edge.
mod is 19 in. leading edge to trailing edge
Leading edge is ~26 in. deep before taper.

doing it again I probably would bring it out to the V foil line and perhaps shorten the leading edge depth of the mod to 20 in.

but I am used to this rudder and it does make a difference ... but of course OD VIOLATION.

That's the nice thing about OD ... we sort of get to stay in a time warp where some things stay the same but other things move on.

If marine engineering was a science we wouldn't have to have AC boats.

Now racing 526 against 348 in JYC tues nights ... so OK maybe going out in 20 with gusts to 25 not the best way to break in new and short-handed crew.

BUT a note on recovery from knock downs re design of rudder: I noticed that it seemed to take a bit longer and I had to work harder with the OD rudder on 526 than the rudder on 505 ...

I am thinking that because the modified rudder on 505 has more bite in the bottom 15 inches it reacts faster to near knockdown conditions than the OD rudder.

This input for yous that is looking to add a little balance ... but also as another + for rudder mod. more bite in hard heel conditions.