Rudders and Irons (not chains)

[Dimitri-2000X-Tampa]

I left work a few hours early today to go sailing by myself for once. Normally, I have the whole family on board and am limited with how much exciting sailing I can do. The offshore winds were nice and gusty today, 10-12 mph sustained with gusts up around 20-22. With full sails, I did some fun wing-on-wing running at around 5.5-6 knots, switched to a broad reach and got up close to 7 kn or so, then dropped the CB all the way to beat back to my starting point. Singlehanding is the only time I get to experiment some so I wanted to see how well I could point..even though my outhaul could have been tighter and I had some wrinkles in the main.

Anyway, contrary to the naysayers, I was able to get about 35 degrees off the wind (windex blade right next to 30 degree mark) with just the main up and a tad of genoa out..too much heel (35 degrees or so) in the gusts with the full genoa. Pointing this high, I could only get 3-4 kn of speed which I guess is why I never beat much with the family aboard. Falling off about another 5 degrees picked up the speed about another knot to a more reasonable pace. I think I'm definitely going to have to get a new shorter forestay cause it took about 2/3 deflection of the rudders to keep the boat from rounding up.

I got back to my starting point which happens to be a bridge pass where there is a bit of a current. I rolled up the rest of the headsail, stopped paying attention for a few minutes and the boat rounded up completely and went into irons...and it was stuck good...drifting backwards and sideways no matter what I did to the mainsail or the rudders. The CB was stuck mostly down in the current and I didn't want to let out the genoa since I was getting ready to go in...so, I lowered the motor. Right when I lowered the motor, the boat started sailing foward again...so, whats up with that, there is not enough rudder for these boats?

[mike]

Hmmmm... your post reminded me of a 26x I saw for sale locally a few weeks ago. It was fitted with rudders that looked much different than the stock rudders. They were "deeper" (from front to back). I wonder how they made these? And, perhaps more importantly, WHY did they make them? Was it simply to replace broken rudders, or did they install these larger rudders to increase the steering force?

--Mike

[amnesia]

I believe the "deeper" rudders you saw were from and earlier 26x. My buddy has a 1998 with that stylle rudder.

[Duane Dunn, Allegro]

The earlier rudders did have more fore/aft distance than the late ones. They are also more rounded. The ones on the M are even smaller. My '96 has the larger rudders.

By the way Dimitri, I think you mean you were in "Irons", not "Chains"

[craiglaforce]

I was somewhat amazed when I saw them change to the smaller rudders. I have the big oval rudders on mine and they are none to big in my opinion. They work fine until you turn them past the stall angle. They need a good flow across them and you have to be careful not to stall them out. Supposely they are more efficient having a large aspect ratio, but at low speed you have to be much more careful not to stall them.

You may not have to buy a new forestay to take the sting out of the weatherhelm. My forestay turnbuckle under the black furler drum had enough adjustment in it to remove the weatherhelm completely. I had to reverse my adjustment a tad to get the small amount of weather helm desired. Just remember to let out a little on the side shrouds to let the mast tilt forward that little bit. (I collapsed the forestay turnbuckle about an inch on mine and that made a huge difference). I used to feel like I had been wrestling a bear for 6 hours after sailing in hard winds. Now the boat is almost perfectly balanced and even in the high gusts the boat heels, but the helm feel is still light and under control. It makes a big improvement in boat speed, course keeping and pointing ability.

The other problem with the new rudders which looks really underdesigned is the head of the rudder that fits into the metal brackets. It looks like they are just being held by the very tip. Kinda Spookey to me.

Don't forget that 35 degrees of pointing you saw was to the apparent wind and not the true wind. THe true wind pointing is obtained by sailing close to the wind, taking a compass heading, then tacking and sailing as high as poissble on the new tack and taking another compass heading. Find the angle through which you have tacked and divide by 2. THat is roughly the angle that is usually referenced for pointing ability.

90 degree tacks or45 degrees to true wind is about the best I have seen on my boat with the 100% jib. With the big genoa which I only used a few times due to the high winds where I sail, the pointing suffered quite a bit. Probably could have gotten it better, but I didn't use the sail much.

[mike]

This boat (with the bigger rudders) was a '97... mine's a '98. I guess that's when they made the change!

--Mike

[Dimitri-2000X-Tampa]

Thanks for the corrections guys, brain fart on the chains versus irons

I wonder how much the apparent wind differs from true wind at a slow forward speed though, you wouldn't think all that much. But, it sure wouldn't point worth a darn with any more than a tiny bit of the genoa out.

The rudders were definitely stalled. I suppose since I just had the main up, if I had been able to pull up the CB some it would have moved the center of lateral resistance further back and allowed the bow to fall off the wind some more to start sailing again. I guess dropping the bigfoot back into the water must have accomplished the same thing...there was no doubt that the extra surface area from the motor caused the boat to start sailing again. No doubt this has been the most difficult transition from a keel boat to a CB boat. I know the bottom is getting pretty fouled and I'm getting ready to pull the boat out for 6-8 weeks (partly for an extended family vacation and partly to do the bottom job). This probably made it even harder to pull the CB up...but once you are caught in a sideways drift, seems to be too much lateral pressure on the board to pull it up.

Makes you wonder why MacGregor reduced the size of the rudders though! Must have been for that 17 mph speed

[craiglaforce]

Interesting question.

I tried to calculate the impact on pointing angle with an example.


Lets say the boat is pointed 45 degrees off a 10 knot (or mph) true wind but not moving. This can be shown as the sum of 2 wind vectors each having length 10/sqrt2 or 7.07

Now lets say the boat is moving forward at 4 knots (or mph) along this same 45 degree directional orientation. The wind vector that is perpendicualr to the boat is unaffected, but the other vector is now
4 + 7.07= 11.07

The apparent wind is then

tan (theta) = 7.07/11.07 or theta = 32.56 degrees of apparent wind pointing angle.

[mike]

Today I passed by the 26x for sale that I mentioned above, and hopped out to snap a few photos. Is this the factory rudder for a '97?




Also, the brackets look quite a bit different than mine...



--Mike

[Duane Dunn, Allegro]

No, the stock early rudders have about a 3" notch where they get wider and then they taper back some to a narrower tip. Those have quite a bit more surface area.

Here are mine


Those are the early stock aluminum brackets but the diamond plate has been added.

[Erik Hardtle]

I got the chance to single hand the boat today as well... the rest of the family went on a girl scout camp.... I had 15 - 20 winds with gusts at 23-25.. I have a 99 Mac with the newer rudders... they definately stalled out at about 30-35 degree heel and went right into the wind... handy for the family... I did find that small rudder changes kept the speed up and kept it from stalling out... but not always. I had full genoa and main out.. .. kept the main pretty loose.. kept me on my toes... hit about 6-7 kts today... fun.

[Dimitri-2000X-Tampa]

I hauled my boat out yesterday and spent a couple hours scraping about 1/2-3/4 of an inch of barnacle growth from a pretty fair part of hull (all around the CB slot). Although it had been in the water for almost 3 months, the last few weeks of fouling were especially bad ever since I dragged the boat through the sand inadvertently...combined with rising water temps. I could see where the bottom paint had been scraped off sideways when we had to push the boat broadside to get it floating again.

You should be able to squeeze some better upwind boatspeed than that.

I'm pretty sure I was losing 1-2 kn of speed due to the fouling. Probably 1 kn at low sailing speed and about 2 kn at high motoring speed.

I need to get some micro blocks or something to help tension the outhaul as the stock method is not so great. Also planning to do something about the backstay so I can get a bit more bend at the top of the mast. I have to decide what to do about my forestay though.

I have the forestay turnbuckle virtually all the way tight and I still have a pretty good amount of mast rake and weather helm. I know the mast would stand up straighter if I loosened the shrouds some, but I think the rig would be too loose then. Right now, the slot adjusters are around half way..with 3-5 holes showing over the top. I've heard that the folks that shortened their forestays have the shrouds close to the end of the adjusters. I would still be interested in some data from those who have shortened the forestays...how close are the rudders to neutral when you are beating along in say 12-15 mph winds?

A partially furled genoa will hurt pointing as well, due to the turbulence off the luff

I found this to be true with 1/2 or more of the genoa out, but when I rolled it up very small (like 1/3 to 1/4 of full size), it seemed to point pretty well still. Of course, with that little of it out, the sail shape tends to be much flatter also.

I need to try this again with a freshly painted bottom. Even with my former keel boat, I remember it was a 3 hour sail on the way to the boatyard to haul and paint it, but only a 2 hour sail back in virtually the same winds I didn't have a GPS back then, so that was my poor man's way of comparing the speed. I'm gonna start a different thread about bottom painting.