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Infusion rudder tuning

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Gabe Silverman
(@uogecko)
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[#26912]

I've been setting up my Infusion according to the online assembly manual. I've measured the distance between the 2 rudders and set the trailing edge to be about 2mm further out than the leading edge (exactly as the manual states). The manual shows the measurements taken directly below the rudder castings (about even with the bottom of the hull).

As you can see from the attached photos there is about a 1/4 of an inch gap between each rudder arm and the tiller connector. That means that when I turn the rudders the little rubber piece that bends doesn't have much space to stretch and resists the turning quite a bit. In fact, if I let go over the tiller the rudders will auto-center pretty quickly.

Anyone have experience with this? Did I take measurements from the wrong part of the rudders?

[Linked Image]
[Linked Image]


 
Posted : June 8, 2010 6:58 pm
(@Dan_DeLave)
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What does the other side look like?

It sounds as though you are measuring right but that is not enough gap.


 
Posted : June 8, 2010 7:40 pm
Gabe Silverman
(@uogecko)
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The other side is exactly the same!


 
Posted : June 8, 2010 8:03 pm
(@Anonymous 13274)
Posts: 3111
 
Originally Posted by uogecko
The other side is exactly the same!

Well there's your problem... you have two starboard rudders.


 
Posted : June 8, 2010 8:44 pm
Gabe Silverman
(@uogecko)
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Okay, the other side is the mirror image of the rudder shown in the picture.


 
Posted : June 8, 2010 8:52 pm
 Karl
(@sogncab)
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Can you cut the tube down?

Don't mind JW either, he's under the impression that he's funny.


 
Posted : June 8, 2010 9:06 pm
Gabe Silverman
(@uogecko)
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I could cut it down but I'm surprised that needs to be done? How long is the tiller connector supposed to be? How much of a gap is normal?


 
Posted : June 8, 2010 9:09 pm
(@Anonymous 335)
Posts: 566
 

I had the same problem with mine and cut about 7/16 off each rudder arm and drilled a new hole for the screw. It seems that one of my hulls is canted more than the other. With the boat upside down I put a 8' straight edge on the hulls right behind the dagger boards with the boards in down position. I then took a framing square 2' up and 1' out and lined up the bottom of the square with the dagger board and measured the difference between the board and the square at the top. I had about a 3/8 difference you could really see the difference looking from the back of the boat. I did mount the rudders and they lined up with the daggers, but you could really see the extra cant in the starboard hull. Since the rudder and dagger line up it looks like the hull must have the beam pockets off a little.


 
Posted : June 8, 2010 9:49 pm
Gabe Silverman
(@uogecko)
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David, why did you cut the rudder arms down instead of cutting the tiller connector?


 
Posted : June 8, 2010 9:52 pm
(@Anonymous 39709)
Posts: 913
 

That's that nice Nacra quality. I got some new rudder arms for my Nacra 20 and one was 4 inches longer than the other one! 4 inches! Christ, that's not just a little mistake. I measured them with my existing ones and luckily the longer one was the wrong size and just a simple cut was all that was needed.
Do like Dave said and cut your tiller arms a little and re-drill.


 
Posted : June 9, 2010 1:35 am
(@Anonymous 335)
Posts: 566
 

I cut the rudder arms because the amount I cut off was real close to the existing hole in the arm that way when I drilled a new hole you could not tell they had been cut. If you cut the tiller connector you have to cut both ends to keep the tiller centered that leaves you with extra holes in the ends of the tiller connector. The existing clevis pin holes will be close to the new ones you will have to drill in the tiller connector and the rubber connector. I was worried about the strength of both having the holes so close together.


 
Posted : June 9, 2010 5:39 am
(@alexvb)
Posts: 71
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It might be easier to just bend the the rudder arm. It was probably bent in shipping to cause the problem in the first place.


 
Posted : June 9, 2010 10:10 am
Gabe Silverman
(@uogecko)
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Well I measured the rudder arms and they are the same. I guess I'm going to have to cut something. Really surprised that this is necessary with a new boat!


 
Posted : June 9, 2010 11:52 am
(@Anonymous 335)
Posts: 566
 

I have had 3 new Infusions and two I had to cut the rudder arms and one the tiller was too short. As far as I know Nacra does not pre assemble their boats before shipment so you get what you get. The way I look at it you just bought a kit with outdated instructions and have to guess on the way it is supposed to be rigged and you always have parts left over but are always missing some. Get the hacksaw out and start cutting on you new 15,000 boat.


 
Posted : June 9, 2010 7:20 pm
Gabe Silverman
(@uogecko)
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Thanks David, I'll do some cutting. I'm not happy about it, but it sounds like that's the solution.


 
Posted : June 9, 2010 11:33 pm
TEAMVMG
(@TEAMVMG)
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Just a thought before you get the hacksaw out.....

Check that you are measuring the toe of the rudders at points front and back of the blades that are parallel to the water line because the rudders are canted


 
Posted : June 10, 2010 1:54 pm
Gabe Silverman
(@uogecko)
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Yeah, I am doing that - I saw in the manual photos of the measurements taken just below the castings.


 
Posted : June 10, 2010 2:00 pm
CatSailingHu
(@catsailinghu)
Posts: 96
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check the dolphin striker tension before measuring the toe of the rudders. I think the pre-bend of the front crossbeam will modify the geometry a bit.


 
Posted : June 10, 2010 3:27 pm
Gabe Silverman
(@uogecko)
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What should the tension be?


 
Posted : June 10, 2010 3:30 pm
CatSailingHu
(@catsailinghu)
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I'm not sure it is the right method, but:

I'm usually strain a small rope or bungee under the crossbeam, and at the middle the distance between the line and crossbeam should be 5-10 mm (the half of the height of the nut)


 
Posted : June 10, 2010 3:46 pm
(@wyndsurf2000)
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Originally Posted by CatSailingHu
I'm not sure it is the right method, but:

I'm usually strain a small rope or bungee under the crossbeam, and at the middle the distance between the line and crossbeam should be 5-10 mm (the half of the height of the nut)

Is this measurement taken with the mast up and rig tensioned or with the mast down?


 
Posted : June 11, 2010 7:26 am
(@Anonymous 13274)
Posts: 3111
 

Mast off.


 
Posted : June 11, 2010 9:29 am
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