So I have most of the parts to do the conversion but I need to know if anyone has done this or not. I am sure it can be done but would prefer not to reinvent the wheel if I do not have to. Things like spacers replacing hardware etc. I have the lower castings and the uppers and the arms. No cross bar yet but that will come when I need it. Any good pictures would help also. Thanks in advance. Ricardo.

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Lake Perry KS
H-18
N-5.5 UNI +spin
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If I'm reading your subject line correctly, you will have a problem with excessive cavitation and balance by using the the higher aspect rudders. You will completely loose the ability to steer with the spin up when it cavitates. You can also experience excessive cavitation (rudder stall) when reaching.

There are 3 generations of newer style rudders. The third generation is you least painful mod. If you use the first generation "pin" rudders you are going to hate yourself for doing the retrofit.

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Philip
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So does the 5.5 have the old "piv-matic (tm)" design? I have first gen inter-rudders on my inter-18. the are "touchy" and it does take some practice to get in/out from the wire w/o tacking/jibing the boat. A shorter boat is going to exacerbate (triple bonus word) this. There was a guy selling some 5.7 rudders off a boat that got crunched as inter rudders. They where not inter rudders, but fatter (prob like your 5.5), but had the inter/F-18 kick-up (no-piv-matic). These would work on any Nacra I would think. These might be better. They were like longer H-18 rudder blades.

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nacra inter-18
CNBP
--

The Inter 18 has higher aspect foils than the 5.5. Think short/wide vs. long/narrow.

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Philip
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I got most of the parts from a 2000 Nacra 570 (I think). Sorry for the terminology mix up, I was more concerned about making it clear old vs new. I am still new to this Nacra stuff, been (still am) a Hobie guy. I am more interested in the system than the blades, the blades look very much the same as my 5.5. My whole goal is to get rid of the pivmatic system (sorry but I hate it). My concerns were more about the install on the hull than the blades. If necessary I will swap the 5.5 blades onto the new system. Some Epoxy and a drill should fix that.

My plan is to do one side and use the other original side to duplicate rake and toe in.

My question was to will I need to space the pintles off the stern, if so how much? things like that. My plan is to assemble the new and match it up to the old as close as possible. I am short one lower casting and I should have that when the guy gets back in town.

Thanks for the replies. Richard.

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Lake Perry KS
H-18
N-5.5 UNI +spin
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AS someone who hates the Nacra system, I am waiting with baited breath. I got some H-18 blades and castings so I could change the 5.2 to a different system..I want one that that did not require a action when you hit a small obstruction AND one could lock blades in place with out depending on bungi to old them up on the road or when beaching. NOt sure about the mounting at this point cuz I just found them but a bud from the far away coast sold the H18 set he had rather than make the change.. I would pass on the 5.2 but I love the boat.. Hal

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Hal Liske
Livermore CA
H 16 (6+ 1.. Friends) H 3.2 N 5.2 (2) H 17 (2) H-18
Nacra 5.8 (son's) H 20 (Friends)
It's a Sickness

I Need a A Cat Please
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You are using rudders from a boat with no center board vs one the has them.. You may want to look at using the rudders from a Inter 20 or Inter 18 as this may be a better match up...

The NACRA 580 is using this system and the boards are very similar to the Gen II rudders for the Inter/NACRA 20Here's a pic of a 580 with the system



Having come from a NACRA 5.8 system to the newer system it is night and day and most the guess work is taken out. I prefer the new system much better...

Regarding the rudder rake I personally I don't think you're going to have an issue... I would set i t up give it a sail. If you need to adjust you can do so with washers in the gudgeon bolts... Just be sure to silicone the snot out of it.

I have a bunch of extra parts...shoot me a PM if you need anything...

mummp

If I'm reading your subject line correctly, you will have a problem with excessive cavitation and balance by using the the higher aspect rudders. You will completely loose the ability to steer with the spin up when it cavitates. You can also experience excessive cavitation (rudder stall) when reaching.

There are 3 generations of newer style rudders. The third generation is you least painful mod. If you use the first generation "pin" rudders you are going to hate yourself for doing the retrofit.

Having just looked at acquiring either the Gen II or the Gen III new style rudders for my Inter/NACRA 20 I went with the Gen II... As it was explained the Gen III is more for course racing and way more expensive.

Having a spin on the 5.5 I believe anything will be an improvement over what he has. Having a spin on my 5.8 was issue with the stock rudders...

I say I say I say pull the tiller boy!!!!! And once you got the windward rudder out of the water....yeiks!!! IMPO, a good set of Gen I will work for fine for this application...



Edited by JohnES on Feb 11, 2012 - 09:32 AM.

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John Schwartz
Ventura, CA
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Thanks John, I may contact you as I am peiceing the thing together. I have a hooter on the boat now and no issues with the rudders except the pivmatic fiasco. So I am pretty sure the blades will be fine whether I use the 5.5 or the 570s.

I Got most of the parts from one guy, then got another arm and lower casting from another. So far i am lacking one lower casting and the cross bar. But I may be able to use some other parts I have for the cross bar. I will not know for sure of what else I am missing but will let you know when I get to that point. AND when it warms up, 8 degrees this morning and that is Degrees F for you metric guys, dang cold. Doing a soft spin and rudder swap on a boat I have only had a year and am not familiar with is a steep learning curve.

Thanks to all, Ricardo.

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Lake Perry KS
H-18
N-5.5 UNI +spin
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Good luck, I have Gen 1 rudders on my 20 and I really like them. I will say I liked the Hobie 18 rudder system more than my inter rudders.

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Greenville SC

Offering sails and other go fast parts for A-class catamarans
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Anyone have a big diagram of what everything is and where it goes so I know what I am missing? Thanks in advance, Richard.

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Lake Perry KS
H-18
N-5.5 UNI +spin
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http://www.nacra.ca/image…acra2007partscatalog.pdf

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Ron
Nacra F18
Reservoir Sailing Assn.
Brandon, Mississippi
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Great stuff now I know what to call everything. Adjuster VS rake eye bolt. Thanks again, Ricardo.

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Lake Perry KS
H-18
N-5.5 UNI +spin
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John ES I sent you a PM about parts. Ricardo.

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Lake Perry KS
H-18
N-5.5 UNI +spin
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I have been following along oben , just faired and re-gelcoated rudders dont think 5.5 system is up to the task.wondering which system i have ?There are no pivmatic release there is hole in rudder arm ,i think there was one at some point.The system there is has a continuous line that runs through cam cleats on top of rear beam does any of
sound familiar?schock cords pull rudders up.Does this sound like a inter system,80's nacra,custom ? i know a picture would have simplified this..

will learn to take photos and up load
89 5.5sl

If it is an 89 it is the older pivmatic system. The pivots may have been removed in place of an up/down line and a single cleat on either side. The newer system does not use shock cords. My expeience is the rudders must be able to kick up on their own or they will break or break something. I kicked on last year and the pivmatic system worked on letting the rudder kick up. That part of the system is fine, it is the rest of it that blows chunks. Do a search and you will find pix of the old system and likely the new system as well.

I plan to take pix of the install when the time comes, still gathering parts at this point. HTH, Ricardo.

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Lake Perry KS
H-18
N-5.5 UNI +spin
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Quote

.The system there is has a continuous line that runs through cam cleats on top of rear beam does any of
sound familiar?

No.

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Rob
OKC
Pile of Nacra parts..
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Ricardo,
You shouldn't hate the pivmatic system. Yeah, it's an older system but when they are tuned right and every thing works, it is a great system. Chances are something ain't right with what you got. There are several threads here that address proper set up, tuning, and upgrades to the original system. The newer system is nice and has it's advantages, but they have issues themselves, like bent cam pins, broken eye bolts, deformed cams, springs needing replacing, broken castings and the dreaded broken rudder pintle (make sure you get the double welded pintles). When all is said and done you will probably like the new set up.

"Now, I say, I say, I say pay attention boy." As for the 1st Gen Inter rudders, they will stall. They will stall on any boat you put them on. You could put them on a rubber boat in the bathtub and they will stall. Not necessarily a bad thing in it's self, 'cause it teaches you when you load them up and cavitate how to trim/sail better to correct. The reason Nacra developed the 2nd and 3rd generation rudders is because the originals stalled so easily, so they addressed the problem. Looks like you are sailing a modified platform already (spin added) so you will be shifting your COE and loading up the rudders already.

JohnES

Having a spin on my 5.8 was issue with the stock rudders...

That's because he shifted the COE and was loading up the rudders with the spin up. It would be more helpful to have a larger wider rudder, not a narrower smaller one.
Got It?

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Philip
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The ones I have are tuned right, when down they are fine, they work, they kick up. The BS bungee up is a pain, the no good way to keep them up when on the trailer is BS and yes I know about the line up as opposed to the bungee. But WTF 4 lines on the back of the boat vs one flick of the rudder. The do not really come up when up, they just pivot to horizontal. Getting them on the beach (we use PVC pipe to protect the hulls and these rudders get hung up all the time. The whole thing is just poorly designed IMO.

I have a local with I 17 and he loves the rudder set up on it. He is hard on stuff, so far a couple of the couplers have failed, not spring failure and no real issues. He sails 200 days a year and for hours a day and so far no problems. I know the blades may be different but they look very close to my 5.5 blades so I am willing to give it a gamble. I will however remember your concerns and sail accordingly. Thanks for all the help it has been a learning experience already. Cheers Ricardo.

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Lake Perry KS
H-18
N-5.5 UNI +spin
--

Quote

As for the 1st Gen Inter rudders, they will stall. They will stall on any boat you put them on. You could put them on a rubber boat in the bathtub and they will stall. Not necessarily a bad thing in it's self, 'cause it teaches you when you load them up and cavitate how to trim/sail better to correct. The reason Nacra developed the 2nd and 3rd generation rudders is because the originals stalled so easily, so they addressed the problem.

Anyone have pics of the different generations to compare?

Quote

The ones I have are tuned right, when down they are fine, they work, they kick up. The BS bungee up is a pain, the no good way to keep them up when on the trailer is BS and yes I know about the line up as opposed to the bungee. But WTF 4 lines on the back of the boat vs one flick of the rudder. The do not really come up when up, they just pivot to horizontal. Getting them on the beach (we use PVC pipe to protect the hulls and these rudders get hung up all the time. The whole thing is just poorly designed IMO.

IMO you're doing it wrong. You should just have a doubled up shock cord and one line. You can get the shock cord tight enough to raise the rudders with no ill effects -- just keep pulling more shock cord out of the top and cinching it with hog rings -- but you have to use the pivmatics with this setup.



I didn't use the standard cleat and eyelet with this setup, but IMO it works slightly better as the rudder won't accidentally re-cleat itself.

Just use a spare piece of 3/16 line or similar and tie them up when on the trailer. You don't need to use the same system that operates them in the water for trailering.

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Rob
OKC
Pile of Nacra parts..
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I have double shock cord, I have them tuned right, I have the extra line for trailering. The system is just poor and always has been IMO, Ricardo.

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Lake Perry KS
H-18
N-5.5 UNI +spin
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Fair enough..

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Rob
OKC
Pile of Nacra parts..
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launched my 5.5sl for the first time maiden ,its been months of work and research to bring this one back my other
(first )boat 5.2 compared to 5.5 ...two up first time out,i know rookie but remember the first time ,the 5.2 had single wire .so well balanced the 5.5 was .Anyways replaced everything as i found it,inc rudders ,schock cord runs through arm pulls up.Line runs around middle tramp cam cleats on rear beam line pulls rudders down sound familiar?Is this inter style? custom?1989 nacra? side note-Photos have made all the differance!!!lets all start posting more photos !!

Here's a pic of an inter rudder, casting and arm.



I assume it's a 1st gen but I honestly don't know as I've never seen pics of all 3.

I still don't follow you on your setup. I can't think of any cam cleats on the rear of a 5.5 other than the traveler and lower main block....I also can't think of any cleats on the rear beam. The 5.2 can have a couple cleats on the rear beam for adjusting the jib blocks along the wires.

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Rob
OKC
Pile of Nacra parts..
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I'll enlist the help of wife to post photo

walls619

I'll enlist the help of wife to post photo

If you haven't found them, instructions for posting photos are in the FAQ, links in my signature below.

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Damon Linkous
1992 Hobie 18
Memphis, TN

How To Create Your Signature

How To Create Your Own Cool Avatar

How To Display Pictures In The Forums.
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Ok I finally got around to doing the swap. I got about 1/2 the parts from Dan Berger (cat reaper) on this forum. I got one arm and one lower casting from someone else on the forum. I got the rest of the parts including some new stuff from Rick Bliss of New England Catamarans.

THIS IS IMPORTANT. I can not say enough good about Rick. I knew who he was from the old Worell 1000 coverage in Cat Sailor magazine as well as many other races he has participated in and won over the years. He was always reponsive on email, and by phone. I knew very little about what I was doing and he was SUPER Helpful. When I need parts I am calling Rick every time PERIOD. THe knowledge he has is amazing.

On with the story:

I started with the stock 5.5 rudder on one side.


I then put one bolt in the old hole with the new style on the other hull. They came from a Nacra inter 570. I was after the casting style more than the blade.


The next problem was the arms. On the 5.5 they never move and wer up high enough. The inter arms were striaght on the 570 and needed to be bent. I borrow a Harbor Freight tubing bender and did the bending, it was easy, getting them the same was not as easy.




They fit and are on but they are very tight, the rudder is almost touching the hull and the casting is almost touching the top of the hull.


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Lake Perry KS
H-18
N-5.5 UNI +spin
--

To follow up more, I used the 5.5 cross bar, just got rid of the adjuster and put the new ends in the tubing. No mods to the tubing but drilling one hole. The adjuster hole lined up with the roll pin so I had to move it inboard about 1/2 inch.

I have not sailed the boat yet but they work nice and have to be better than the rope thing. I have several hundred bucks in the swap so I hope it works good. I will have some old parts for sale soon. If there are any questions let me know. Richard.

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Lake Perry KS
H-18
N-5.5 UNI +spin
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I like it. What did you use for the rubber connections between the arms and xbar?

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Rob
OKC
Pile of Nacra parts..
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got pics of a 5.5 rudder next to a 570 rudder? Is the 570 a skeg boat?

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Rob
OKC
Pile of Nacra parts..
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I used the Inter style rubber connections, the set up I bought came with one used one and I got two new ones so I can have a spare. The first two pics are of the 5.5 and the 570 on opposite sides of the boat. The 570 is about an inch longer and has about 1/2 inch more chord. They are so close it is amazing. I will have to sail it to see if I have the rake right or not.

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Lake Perry KS
H-18
N-5.5 UNI +spin
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Those are first gen inter rudders. I don't want to be a debbie downer, but the 5.5 (no dagger boards) might be a bit touchy with those. there are a bunch of 5.7 blades on the classifieds here right now. But don't let me stop you. If it works ... do it.

my bad .. they are on ebay ... http://www.ebay.com/itm/N…fd&vxp=mtr#ht_500wt_1289



Edited by nhanson on Apr 02, 2012 - 05:38 PM.

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nacra inter-18
CNBP
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those look to me like they'll work great for his 5.5. It looks like they're a touch longer (makes sense w/ skegs from the 570) but I doubt that's an issue. Maybe you're looking at my pic of the Inter rudder? I'm not planning on using it for anything other than my Inter. =)

Here's a pic of the 5.2/5.5's next to the inter (not to scale, just for quick comparison):



Also, the 5.5 most def. has daggers, not sure what you meant there.

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Rob
OKC
Pile of Nacra parts..
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N hanson, I have a 5.5 Uni and it has pretty big dagger boards, see my Avatar the up board is as tall as I am. The rudders from the 570 are longer and will help with the fact I have a hooter or soft spin set up on the boat. My only question at this point is rake, do I have it close enough or not. The first pix make me think it will be very close, I will know when I sail it. My plan is to sail it with one rudder down at a time and feel the helm, make adjustments and then do the other side. I can do that without the spin right off of the beach.

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Lake Perry KS
H-18
N-5.5 UNI +spin
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I don't think that the rudders and rake will affect each other at all in this case. The rudders may feel a little heavy but I don't think your rake will negate that (without drastically moving it forward, which isn't an option)

The 5.5 is balanced enough that I doubt the slightly larger rudders present any issue at all. You'll know soon enough. (hopefully the rest of us will too)

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Rob
OKC
Pile of Nacra parts..
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I agree with you Yurdle, I think they could even be better, a longer blade will give more stability. Also the rake adjustment is very easy on the Inter style castings. I will not know for sure for several weeks. Richard.

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Lake Perry KS
H-18
N-5.5 UNI +spin
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