Who Owns IDA Sailor Rudders?

delevi · Post by **delevi** » Tue Aug 15, 2006 1:14 am

Calling all Mac Sailors with IDA rudders installed on their boats. I'm wondering where your rudder pull-down line is connected. Mine is almost directly off the leading edge. This is several inches forward of where the stock rudders connect, though after careful measuring, the distances and angles are the same due to differen foil shape. The center of effort, I believe, is still more forward. The result, at least on my boat, is that the rudders trail aft when the boat moves forward, even though the downhaul line is super tight and cleated. My only solution was to drill extra holes and pin them into the brackets so they wouldn't move when deployed. There must be a better way, though. I have considered drilling aft of the existing attachment hole, but that would cause extra drag, since I would have to run the line around the leading edge, not to mention even more holes which aren't being used, causing turbulance. Joel told me that nothing sticks to these things, not even epoxy. I know there aren't many of us with these rudders, but I would appreciate some input from those who have them, and of course anyone else who doesn't. Thanks.

Leon

Chip Hindes · Post by **Chip Hindes** » Tue Aug 15, 2006 4:04 pm

It looks from the photo like the hole for the tiedown line is way further forward on the new compared to the stock rudder. Not familiar with the M; what is the angle of the holdown rope when the rudder is down and the line tight?

delevi · Post by **delevi** » Tue Aug 15, 2006 5:08 pm

Chip,

Yes, it is forward, adjacent to the leading edge vs. stock rudder which is a few inches aft. The leading edge of the stock rudder, however goes far under the transom while with the IDA rudder, barely so. With the IDA rudder in the down position, vertical, the line pulls straight up vertically, same as with stock. The effort, however is applied to the front 1/3 of the stock rudder vs at the front (leading edge) of the IDA rudder. Not sure if this accounts for the trailing effect. Hopefully you can answer this. If this is the case, one solution would be to drill through the rudder several incehs aft of the current hole. The problem I see here is added drag from the line. I can't create a nice entry point through the edge and exiting at the side for a stop knot as they have done at the factory. I would have to loop the line around the new hole and would have it pull forward in front of the leading edge and dragging through the water the whole time.

Leon

Frank C · Post by **Frank C** » Tue Aug 15, 2006 5:51 pm

delevi wrote: ,,, I can't create a nice entry point through the edge and exiting at the side for a stop knot as they have done at the factory.

Hmmm - why not?

I have a 3/8" drill bit that is 12 inches long, if that's the dilemma ...

delevi · Post by **delevi** » Tue Aug 15, 2006 6:49 pm

Hmmm - why not?
I have a 3/8" drill bit that is 12 inches long, if that's the dilemma ...

probably need 1/4" and I'm not sure about creating the side (larger) opening and having it line up with the entry. Frank, perhaps I may need to borrow you for an hour. I can offer beer, sandwiches and a brisk day on the bay, so we can demo these puppies.

Richard O'Brien · Post by **Richard O'Brien** » Tue Aug 15, 2006 9:32 pm

delevi wrote: probably need 1/4" and I'm not sure about creating the side (larger) opening

I used a step drill bit that I got cheap from Harbor freight to enlarge the holes and create a pocket for the knots. Mine are considerably shorter than yours Leon. I think the increase of blade pressure fore was increased adequately to help the aft section rotate on the apparent "fulcrum" for mine. They do trail more than the originals .but they are wider so that's expected. I still haven't had them out in higher winds, so i don't know if they'll be any problem yet?? maybe tomorrow?

Frank C · Post by **Frank C** » Tue Aug 15, 2006 9:47 pm

I'll bring the cordless drill;
(with two batteries);
I know where to buy a long 1/4" bit;
I have a complete set of Forstner bits for the side pocket.

See ya Fri???
P.S. the winds were rippin' today!

Chip Hindes · Post by **Chip Hindes** » Wed Aug 16, 2006 2:05 pm

Yes, it is forward, adjacent to the leading edge vs. stock rudder which is a few inches aft

Don't see that from the photo. It looks to me like both are within an inch or so of the leading edge. It's not that important, in any case.

When you say the line is "vertical" when the rudders are down, vertical in relation to what? Compared to gravity, or to the forward edge of the rudders or what? Sorry to be so dense, but from what you're describing I see no reason to explain your problem, so I must be missing something.

What really matters when it comes to holddown force is the perpendicular distance from the holddown line to the rudder pivot. It's the same principle as any lever arm, the longer the arm the more force created.

delevi · Post by **delevi** » Thu Aug 17, 2006 12:23 am

When you say the line is "vertical" when the rudders are down, vertical in relation to what? Compared to gravity, or to the forward edge of the rudders or what?

Vertical as in a right angle to the water. May not be a perfect 90 deg, since I have no way of measuring but visually looks pretty close.

I see no reason to explain your problem, so I must be missing something.

I can't explain it either. It is baffling to me, but looks like Richard O'Brien is having the same issue with his IDA rudders.

What really matters when it comes to holddown force is the perpendicular distance from the holddown line to the rudder pivot. It's the same principle as any lever arm, the longer the arm the more force created.

Would that mean the attachment of the line to the rudder should be longer? It seems to be about the same as stock. The only real difference is that there is more leading edge going under the transom in the stock rudder, with the same point of attacment, therefore, force is being applied to about 1/3 of the way from the leading edge straight up on the stock rudder, compared to right to the leading edge, straight up on the IDA rudder.

Richard,

They do trail more than the originals .but they are wider so that's expected.

I don't think they're supposed to trail at all. The stock rudders don't trail. When they trail, the helm gets excess loads, and I believe the rudders' efficiency is reduced. Correct me if I'm wrong on this one Chip. I know for sure about the loads, but not certain about diminished holding/steering power with rudders trailing.

Frank,

Friday sounds good. I need to make sure that I can tie up all loose ends with work and take the day off. Let's get in touch late in the day tomorrow.

Leon

Catigale · Post by **Catigale** » Thu Aug 17, 2006 3:55 am

I sailed my

for a whole season with a heavy helm just pulling my rudder lines up and cleating, without making sure the rudders were both firm up against the transom.

The effort and steering response changes drastically if the rudders trail...the forces on the brackets also goes up of course.

Make sure your rudders dont trail....

Richard O'Brien · Post by **Richard O'Brien** » Thu Aug 17, 2006 9:09 am

I finally got to try mine, but it was dead calm again

I added two cam cleats outside the original cleats because I wasn't getting them snug enough, and now they are perpendicular. Unfortunately I'm still waiting for some decent wind. I did find out I can sure stall the boat if I try to steer too severely. I'm optimistic, but still need a good puff or two two judge the difference? I couldn't get to the backing screws so I just embedded some sheet metal screws to mount the new cleats. 'Sure hope they hold

Frank C · Post by **Frank C** » Thu Aug 17, 2006 10:16 am

Sounds as if the stock design has a bit of the rudder's "toe" under the transom ... if so, this might improve the angle applied by the hold down line? ... thereby improving its leverage.

"Toe-under" of the rudder has the same effect discussed earlier. It places some rudder area ahead of the rudder's vertical axis (the vertical pin for steering rotation). This adds some "power steering" effect to the rudders. If Ida's larger rudder completely fills the top space near the transom, then it would obviously constrain the degree of toe-under.

baldbaby2000 · Post by **baldbaby2000** » Thu Aug 17, 2006 4:32 pm

I added two cam cleats outside the original cleats because I wasn't getting them snug enough, and now they are perpendicular.

I added a pulley on the down haul line (inside the boat) and on the up haul line (outside the boat). These double the purchase and ensure that the rudders are all the way up or down.

baldbaby2000 · Post by **baldbaby2000** » Thu Aug 17, 2006 4:38 pm

I used a step drill bit that I got cheap from Harbor freight to enlarge the holes and create a pocket for the knots. Mine are considerably shorter than yours Leon.

Richard, you're saying your rudders are different than Leon's. So are there 2 kinds of IDA rudders for the 26M!?

Richard O'Brien · Post by **Richard O'Brien** » Thu Aug 17, 2006 7:22 pm

baldbaby2000 wrote: Richard, you're saying your rudders are different than Leon's. So are there 2 kinds of IDA rudders for the 26M!?

Yup! I talked to Joel at Idasailor, and he built some extra big ones for Leon. He said he doubted if he'd do it again. I think Leon and San Francisco Bay weather is the proving ground for M innovations

I like your idea of adding blocks for leverage. It would make the extra weight easer to handle, and take strain off my "screw-attached" cam-cleats.

MacGregorSailors.com

MacGregorSailors.com

Who Owns IDA Sailor Rudders?

Who Owns IDA Sailor Rudders?