I took my maiden voyage this past Sunday on my 5.0 and ended up twice nearly dumping the boat when the tiller crossbar "locked" itself by rotating. I have ready several post about the options for upgrading. I can get hobie ends, buy the Murrays welded joint for $48, or buy Nacra's urethane rubber tendons for $52. I kinda liked the autohelm nature of the locking joints. I'd bet the urethane joints would do the same. What do I go with? Thanks!

--
FYC, Nacra 5.2 "Chris's Flyer" & Nacra Playcat & Farrier Tramp
Previously owned: Trac 14, H14, H16, H18, N5.0, G-cat 5.0
--

can you post links to the choices?

Option 1 https://westcoastsailing.…bie-rudder-adjuster-kit/
https://www.ebay.com/i/132036647734?chn=ps
Option 2 Nacra upgradehttps://www.murrays.com/product/56-5516/
Option 3 Urethane Rubber https://www.murrays.com/product/56-4536/

--
FYC, Nacra 5.2 "Chris's Flyer" & Nacra Playcat & Farrier Tramp
Previously owned: Trac 14, H14, H16, H18, N5.0, G-cat 5.0
--

The urethane doesn't really auto lock and needs replacement every 2-3 years as it breaks down. They do work pretty well other than those limits.

The Murrays solution looks like it would develop slop over time.

Adjust-ability is nice but I'm not sure the hobie setup fits your boat.

What I have done on my latest setup is copy the Goodall system with McMaster-Carr eyes and machined delrin end fittings for the crossbar.

thanks for the links
i wasn't sure what you meant "rotated"

http://owners.aquarius-sa…ller+crossbar+connection

There's a pic about half way down that shows a method. With only one yolk there in no slop in the connection.
Yeah, I know it means putting SuperCat parts on your Nacra but hey you were thinking about Hobie parts.
This kit is stock from Aquarius.

http://www.aquarius-sail.com/



Edited by gahamby on Feb 22, 2019 - 12:59 PM.

--
'82 Super Cat 15
Hull #315
Virginia
Previously owned: '70 H14, '79 H16, '68 Sailmaster 26, '85 H14T
--

Yeah no. Those yolks (these bits here: https://www.murrays.com/product/01-0062/) inherently have slop. I machine custom bushing for those to ride on so you can tighten down all the way on the bolt and still allow the yolk to pivot.

The Nacra urethane parts are 100% slop free but have limited adjust-ability. The other system that is pretty good is the eXploder setup which has machined delrin ends inserted into the end of the crossbar that ride on pintails on the tillers. One side of the crossbar gets slotted for adjustment.

rch701

Option 1 https://westcoastsailing.…bie-rudder-adjuster-kit/
https://www.ebay.com/i/132036647734?chn=ps
Option 2 Nacra upgradehttps://www.murrays.com/product/56-5516/
Option 3 Urethane Rubber https://www.murrays.com/product/56-4536/

Option 1 may not work with your crossbar length and just complicates a very simple system.

Option 3 is for boats with tiller tubes bent at 90 degrees that line up with the crossbar.

Option 2 is what I did years ago on a 5.5 SL, it requires drilling new holes in your tiller tubes and may require adjusting the length of your crossbar

A temp and cheap fix is to use 2 zip ties in a cross on each end to stop the spinning of the connection.
What has happened is that the weld has broken where the bolt is welded to the U shaped piece.
Another option is to get that re-welded.

--
Ron
Nacra F18
Reservoir Sailing Assn.
Brandon, Mississippi
--

There is a good thread somewhere on this forum about that problem. I’ll try to dig it up. In the meantime...
You’re sailing a 5.0. Be honest, it’s a great heavy wind, old school boat. Do what we do on the 5.0 & 5.7
Take a piece of SS wire, & wrap it around one side of the connection, so it can’t rotate.
Time involved, around 5 minutes. Cost, almost zero. Lifespan...I couldn’t find my roll of SS aviation lockwire, so I temporarily used a piece of galvanized “farm wire”.
That was about 5 years ago. I keep putting it on my to-do list each spring.

--
Hobie 18 Magnum
Dart 15
Mystere 6.0XL Sold Was a handful solo
Nacra 5.7
Nacra 5.0
Bombardier Invitation (Now officially DEAD)
Various other Dock cluttering WaterCrap
--

only one my joints is welded and does the job for both. Just in case you want to go step by step..
The crossbar adjuster, if you have one, has to be locked tight with the counter nut



Edited by Andinista on Feb 23, 2019 - 05:22 AM.

rch701

Option 1 https://westcoastsailing.…bie-rudder-adjuster-kit/
https://www.ebay.com/i/132036647734?chn=ps
Option 2 Nacra upgradehttps://www.murrays.com/product/56-5516/
Option 3 Urethane Rubber https://www.murrays.com/product/56-4536/

I run Option 2 with the addition of the adjustable end cap, Nacra 5508 which I no longer find on Murrays??? Does anyone know if the 5508 has been discontinued? 3-1/2 seasons on this setup with no issues.

nacra55

Option 2 is what I did years ago on a 5.5 SL, it requires drilling new holes in your tiller tubes and may require adjusting the length of your crossbar

You do not have to re-drill your tiller tubes to use the Murrays Tie Bar Kit, 56-5516. Simply attach it through the hole where the two welded halves meet (see pic above).

Relative to the various comments on "slop," there must be some in this system or it will bind at the extremes of movement. The ends (top to bottom) of the tiller tubes DO NOT swing in a plane thus the geometry of the assembly changes from the nominal (steering straight) position to the extreme (hard turn) position. The trick is to occasionally check the amount of "slop" and keep it to a minimum.

--
Hobie 16 (3 formerly)
MacGregor 25 (formerly)
Chrysler Dagger 14 (formerly)
NACRA 5.0 (currently)
High Point, NC
--

The Nacra Urethane system doesn't bind and has no slop (or very very little). The eXploder setup can bind at the extremes of tiller movement so you learn to avoid that.

Thanks all.
Edchriss177, I'll take you suggestion for the next trip out.
Nacra55, I'll weld them up if possible. To my recollection this can't be fixed with a welder.

--
FYC, Nacra 5.2 "Chris's Flyer" & Nacra Playcat & Farrier Tramp
Previously owned: Trac 14, H14, H16, H18, N5.0, G-cat 5.0
--

The slop is between the rudder and the casting. Adjust the casting bolt and shim where necessary. Very little slop should exist in the crossbar. If there is, the holes are excessively enlarged.

Later model legacy Nacras had Ackermann rudder tiller arms (what leeboweffect touched on) from the factory. It is easy to put this bend in the arm of the older boats and it makes a noticeable improvement to tacking.

--
Philip
--

Is there anyway to make a adjustment to the urethane NACRA system.
Is there an aftermarket fix?
Something like this? https://westcoastsailing.net/hobie-rudder-adjuster-kit/

Or a way to make the whole urethane tendon adjustable?

upwindhacker

Something like this? https://westcoastsailing.net/hobie-rudder-adjuster-kit/

If you want to use that part simply purchase tubing the same size OD/ID as the Hobie 16 tie bar and cut it to the correct length depending on your tiller arms etc.. IMHO the Ackermann idea is worthless.

--
Hobie 16 (3 formerly)
MacGregor 25 (formerly)
Chrysler Dagger 14 (formerly)
NACRA 5.0 (currently)
High Point, NC
--

Quote

IMHO the Ackermann idea is worthless.

why is that?

MN3

Quote

IMHO the Ackermann idea is worthless.

why is that?

We've already had part of this discussion.

https://www.thebeachcats.…nc=viewtopic&topic=15766

Here is a decent explanation of the theory relative to a typical vehicle with 4 wheels on land/pavement where slip is the primary concern and to be minimized/eliminated.

https://www.youtube.com/watch?v=oYMMdjbmQXc

I spend 99.9 % of my time sailing moving in a straight line and when the wind is sufficient with one hull out of the water and/or with the windward rudder up. Why, even if you buy in to the theory, would you concentrate on optimizing 0.1% and sacrificing performance when both rudders are in the water during the other 99.9%.

Next, does anyone always sail the same radius when turning? A fixed Ackermann angle is only "right" when you're sailing the radius it is set for, the rest of the time it's a hindrance. I set my rudders square at the centered (steering straight ahead) position, no toe in and minimal slop in the steering. Note that if you explore the steering geometry throughout it's envelop the amount of toe in/out changes as the tiller handle ends do not move in a plane.

--
Hobie 16 (3 formerly)
MacGregor 25 (formerly)
Chrysler Dagger 14 (formerly)
NACRA 5.0 (currently)
High Point, NC
--

leeboweffect

MN3

Quote

IMHO the Ackermann idea is worthless.

why is that?

I spend 99.9 % of my time sailing moving in a straight line and when the wind is sufficient with one hull out of the water and/or with the windward rudder up. Why, even if you buy in to the theory, would you concentrate on optimizing 0.1% and sacrificing performance when both rudders are in the water during the other 99.9%.

Sounds like you are thinking of toe in. Ackerman steering does not add toe in or any extra drag to the rudder system when it's going straight....

Beyond that and any other technical discussion, lets just go look at the top level A class boat, the DNA F1, and we notice that it has ackerman bend in their rudder arms... so I'll trust the class still throwing seeming unlimited money every year at trying to gain 0.0001% on the competition.

leeboweffect

Next, does anyone always sail the same radius when turning? A fixed Ackermann angle is only "right" when you're sailing the radius it is set for, the rest of the time it's a hindrance.

This is all in reference to the most important "radius" and that's the one the boat takes when tacking. Since the boat mostly rotates around one hull due to the boat slowing down, there is a formula for each beam width to add in the ackerman angle so that when it matters most you have minimal rudder drag. I think you'll find that speeding up a tack and minimizing the time you are head to wind will gain you far more than the half a second you spent at speed making a minor steering correction with different turning radius' present.

So for the newer NACRA's with the Urethane tendons, there is no official NACRA solution to the lack of adjustment?. Once you set that screw in the urethane you are stuck at that amount of toe in or tow out. I can adjust the rake of the rudder very easily , but I can't adjust the rudder toe in . That seems like a bad design.

upwindhacker, that is absolutely 100% correct, and I agree its not the best design. The plus side is once you have it locked in its solid, but the downside is you have to drill that hole dead nuts on the first time!

What I did to one of my Infusion crossbars that I kept, figuring somebody else would like adjustable down the road and my standard one was setup correctly, is take one of the Nacra 5508's mentioned above and shown in this photo here



and pin that to the crossbar then insert the urethane tiller on the other side. It took a bit of fidgeting to get the diameters sorted and its heavy but it does work well.

The right thing to do is probably install one of the Hobie 20 threaded crossbar endcaps into the aluminum crossbar (would need to double check the size) then machine a fitting with the correct threads for that endcap on one side and a hole for the urethane piece with its plastic housing on the other (this is where the pin goes through to remove the setup from the boat). Optionally, and probably smarter, is to effectively bond or screw a threaded stud into one end of the tiller crossbar and machine that same fitting but with a threaded hole for the stud. I say that as I could machine that fitting in a few hours on a lathe and use a 316 stainless fastener in the end of the tiller, where as machining external threads is painful. See the Hobie 20 kit here: https://www.murrays.com/product/07-1953/

The alternative is to run the complete Hobie 20 style setup, which is similar to the Exploder setup. You would have to cut down the Nacra tillers and install pins, which isn't a trivial job but do-able. The big issue I see is the length of the tillers, there is a sort of minimum there in terms of force required to turn the rudders. On some of the boats you could order Nacra 20 tillers but its gets tricky as the ackerman angle is built into the tiller bars on a modern Nacra.

And I have no clue how much that matters but I will say that if you can lower drag in a turn on a race boat it absolutely does matter. Keep in mind on an F18 in breeze tacking upwind you are looking at boat speeds from the top teams in the 12.5-13.5 kt range for an upwind VMG of 9.5 kts assuming a tacking angle of 90 degrees (we run tighter than that but only in flat water). In a tack you are probably down to half that in terms of VMG, and a very good tack is still a 20 second operation before you are coming back up to speed; we can take a minute to accelerate back to max speed. Lets call it 45 seconds at an average vmg of 4.5 kts during the tack. That translates into 360 feet or 20 boat lengths lost in what I would call an average tack. A top team can probably get it down to 5 or 6 boat lengths, but if you have additional drag from the rudder system that could impact that further with less ability to turn the boat easily. Add in some waves and any additional drag from +20 deg to -20deg head to wind could have you stopped dead which would spell disaster.

This math also shows why tacking on high performance boats must be done smoothly and quickly, and why it should also be avoided whenever possible! The problem gets worse at higher speeds, if you watched Glenn Ashby at the last A-Cat Worlds fully airborne upwind he would go right for the layline and one tack it to the market at a boat speed in excess of 21 kts.

All of this probably doesn't mean much to the OP's original issue or long term plans, or most folks sailing recreation ally though having a proper rudder system setup tends to be more enjoyable with less force on the tiller during long outings!

Thank you samc99us. That is what I was afraid of - no adjustment. I am going to have to make something up. I like being able to make adjustments if I don't get it right the first time (which is usual). I can't believe that the NACRA 17s use the same system. If anyone needs fine adjustments, they do.

The Hobie 20 system looks good. I think I can make something like that.

upwindhacker

Thank you samc99us. That is what I was afraid of - no adjustment. I am going to have to make something up. I like being able to make adjustments if I don't get it right the first time (which is usual). I can't believe that the NACRA 17s use the same system. If anyone needs fine adjustments, they do.

The Hobie 20 system looks good. I think I can make something like that.

When you are dealing with boats off the showroom floor they can be pretty confident in the fit/alignment of parts. The rudder alignment isn’t really something anyone adjusts once it’s set so if it’s built correct then it’s one less thing to check. Also I’ve had my alignment screw come loose in a race so had to tighten it back down while underway. So them making it non adjustable also means it can’t mess up your day at the same time.

But on our old beaters with half the rudder system replaced and bent up it’s nice to be able to fine tune things.

Haha you must be joking right? The build quality has come up on newer boats sure (Hobie is pretty high, Nacra is good as are others) but there is still enough mis-alignment in the beam bolts between boats and slop in the system that if you take your boat apart and store it or ship it then re-assemble it there is no guarantee you will be back to zero, and you could have 1mm of toe-in/toe-out which is impossible to fix with a standard tiller crossbar from Nacra.

The other note is the N17's (c-board boats) played with toe-in/out on the rudders plus boards to get to an optimal foiling configuration. It is also an important thing to dial in for proper helm balance, and it would be nice to tune it on the water to get a clean exit angle off your rudders.

tamumpower1

Sounds like you are thinking of toe in.

Toe in as a general steering setup has nothing to do with the Ackermann theory/concept. However, Ackermann does add/subtract differential toe in when the steering is at any position other than centered (steering straight ahead).

tamumpower1

Ackerman steering does not add toe in or any extra drag to the rudder system when it's going straight....

(SP, Ackernmann NOT Ackerman) True, but it does add/subtract differential toe in at any other position and as previously stated it is only at the theoretically correct amount of differential for one predetermined turning radius, all other positions are off.

tamumpower1

Beyond that and any other technical discussion, lets just go look at the top level A class boat, the DNA F1, and we notice that it has ackerman bend in their rudder arms... so I'll trust the class still throwing seeming unlimited money every year at trying to gain 0.0001% on the competition.

I personally couldn't care less about what other folks do. No one has ever gained an advantage at anything being a me too. Further, before I buy in to any theory (and that's all it really is relative to boats) show me the tank testing with strain gauges etc. where it has been proven. My experience is that perhaps 90% of everything you will ever be told about how to make a boat "fast" is nothing more than theory and opinion based on nothing more than what an individual "thinks is right" urban mythesk.

tamumpower1

This is all in reference to the most important "radius" and that's the one the boat takes when tacking.

Why is the turning radius at tacking the most important? Steering to climb the wind and change gears etc. is equally important to the turning radius during tacking and generally a much more gentle turn, larger radius. Further, my turning rate/radius in a tack varies substantially depending on wind speed, waves, weight, trapping and the part of the tack I'm in beginning/end.

tamumpower1

Since the boat mostly rotates around one hull due to the boat slowing down, there is a formula for each beam width to add in the ackerman angle so that when it matters most you have minimal rudder drag.

The boat does indeed not "rotate." With two hulls in the water it's being shoved sideways through a very non-circular arc, think French curve.

tamumpower1

I think you'll find that speeding up a tack and minimizing the time you are head to wind will gain you far more than the half a second you spent at speed making a minor steering correction with different turning radius' present.

Not exactly sure what the last half of this comment is about? I roll tack my boat when possible with all weight in the old side rear corner until through the eye.

--
Hobie 16 (3 formerly)
MacGregor 25 (formerly)
Chrysler Dagger 14 (formerly)
NACRA 5.0 (currently)
High Point, NC
--

Then run parallel rudder arms and don’t complain about it...? You remind me of a guy I heard going off about how “that stuff about lift is all bull, the sail just redirects the wind”

I suggest removing all copy cat items on your boat since they must not work. Bendy mast, high aspect sail, actually the sail all together, dagger boards, smooth hulls in general. Actually all that stuff about saving weight must be bs too since everyone does it.

Just because you don’t understand the theory behind something doesn’t mean you should go fake news on it.

I think you are in the camp of “if my boat still sails without it then clearly it’s not needed”. Reality is small changes add up. I have no doubt it’s not a massive change to the rudder drag so if it makes you feel smart to buck the trend then be my guest. But my guess is if that’s your mind set then you’ll probably be admiring everyone else’s copy cat improvements quite well from behind them as they pull away

If Hobie can make adjustable till crossbar fittings, why can't NACRA? The fact that if I don't get it right the first time on a NACRA (that screw in the urethane tendon), I am stuck buying new tendons. I should be able to fine tune my rudders in and out. NACRA designs are good, but this part of the system on new NACRAs is poorly designed.

upwind, no argument from me that it isn't the best (or lowest cost) system; they would be better to make the tiller arms straight or with only one bend for the ackerman (cheaper than multiple bent tubes) and going to a Hobie or Goodall style setup. Of course the Goodall and Scorpion setup can bind, I don't think Hobie has that problem.

Anyway, if you mess up on a Nacra urethane install you can flip it 180 degrees and try again. Its a two person plus lots of e-tape job for sure.

I have this on one of my tillers
i like it (mine is black which is much faster)


https://www.ebay.com/i/151045562707?chn=ps

MN3

I have this on one of my tillers
i like it (mine is black which is much faster)


https://www.ebay.com/i/151045562707?chn=ps

I think that would work quite well. Off to the machine shop.

That is a prindle end

--
Captain Chris Holley
Fulshear, TX
'87 Prindle 19 "¡Hijole!"
'74 sunfish "1fish"
--

I find it a touch ironic that Nacra developed solutions for both the Prindle and older Nacra 5.2/5.5/5.8 line back in the day but neglected to implement one on their new boats. I guess the reality there is they have probably sold 1000+ new gen Nacra's since 1997 when the i20 arrived and I'm guessing they haven't had enough customer complaints to warrant a factory solution.

MN3

I have this on one of my tillers
i like it (mine is black which is much faster)


https://www.ebay.com/i/151045562707?chn=ps

Well you may have the preferred black one, but just shut it down buddy. I've got the Ackermann version which is the ultimate "go fast" part to have.



How do I know it's fast, well because I said so, nuff said.

I'm selling these for $10,000 each and don't delay as demand will instantly outrun supply. PM me to place your order. I lamented for years as to whether or not to share this with everyone, but here it is alas...

--
Hobie 16 (3 formerly)
MacGregor 25 (formerly)
Chrysler Dagger 14 (formerly)
NACRA 5.0 (currently)
High Point, NC
--

The previous owner of my boat replaced one of the bent tiller arms with a straight one, i sailed like that for years until i broke the other one, which i replaced with a straight one, as well as replacing the cross bar with a longer one. I was too lazy to find a workshop to bend the tubes. My impression is that it is harder to turn the boat now, particularly at the first half of the turn, at higher speed. I’m tempted to fiix it but i’m still too lazy. Perhaps i could add 90 deg. elbows each side with a short length of tube, instead of bending the tubes, but i doubt the end result will be elegant enough.



Edited by Andinista on Mar 03, 2019 - 04:33 PM.

Quote

Well you may have the preferred black one, but just shut it down buddy. I've got the Ackermann version which is the ultimate "go fast" part to have.

SWEEET!