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Expert needed on Inter 18 rudder system... #258482
03/22/13 10:27 AM
03/22/13 10:27 AM
Joined: Jun 2012
Posts: 97
The Netherlands
Arjan13 Offline OP
journeyman
Arjan13  Offline OP
journeyman

Joined: Jun 2012
Posts: 97
The Netherlands
After starting the season this year, we stranded 20 meters further with a big bang, and two broken ruthers. (both broke out the top end corner)

After getting two new rudder blades, I've mounted them, and wanted to test them. Closing the system is possible with a little force (then they are in "sailing mode") but when I want to test the capability of opening when running on the ground (putting force on the blades) they do not open, even with extreme force. (and now the force is again on the weak part in the top end corner)

Looking at the rudder system, I have the impression that either the springs are too strong, or the wheels are not the right size. Most probably it is the last option, because we changed some broken wheels last year. We inserted the black one, and have taken out smaller wheels. But according to the dealer the black wheels are standard.

In this picture the situation which does not work ok.

[Linked Image]

and this is how it was before (you can see the broken wheels which got out:

[Linked Image]

And this is the result of the system not working:

[Linked Image]

can anybody help me out, and tell from experience how the system originally looks like on the Nacra Inter 18?

-- Have You Seen This? --
Re: Expert needed on Inter 18 rudder system... [Re: Arjan13] #258497
03/22/13 02:30 PM
03/22/13 02:30 PM
Joined: Jul 2009
Posts: 53
Y
yurdle Offline
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yurdle  Offline
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Y

Joined: Jul 2009
Posts: 53
In my limited experience with them, I've found that the key for me is to 'pop' them open.

I've broken a tiller arm while trying to open one back up while not on the boat. Likewise with a top casting. However, I knew they worked fine on the boat...

So, when they're off the boat, if I need to open them, I whack the arm with a rubber mallet and they open fine. On the boat I don't have issues, but after breaking the arm I make sure to open them with a quick jerk.

I've seen castings much more used than mine, and the hook on the lower one seems to wear down a bit, making them take less force to pop open and closed.

I've also got 4 used inter rudders -- all of them have some amount of cracking around the hole that broke all the way through on yours. I *think* it's likely common, and happens from trying to steer a bit after raising them.

Re: Expert needed on Inter 18 rudder system... [Re: Arjan13] #258500
03/22/13 03:34 PM
03/22/13 03:34 PM
Joined: Jun 2001
Posts: 12,310
South Carolina
Jake Offline
Carpal Tunnel
Jake  Offline
Carpal Tunnel

Joined: Jun 2001
Posts: 12,310
South Carolina
that is a common problem. I've reinforced every I 20 rudder head I've ever owned to strengthen it and prevent that.

The springs are pretty standard - I wouldn't change much with that...however, the geometry is pretty complex on that rudder system and it's tricky to change/adjust. My Nacra Infusion (same rudder system) was bought second hand and the previous owner had carved out the lower casting where the roller engages...presumably to make it engage harder in the down position - they require a LOT of force to release and kick the rudders up.

If you are happy with the amount of force to lift/release the rudders and with the force required for a rudder to automatically release, I would only reinforce the top of the rudder.

I have some photos of my reinforcement method and will upload tonight.


Jake Kohl
Re: Expert needed on Inter 18 rudder system... [Re: Jake] #258504
03/22/13 07:42 PM
03/22/13 07:42 PM
Joined: Jul 2009
Posts: 53
Y
yurdle Offline
journeyman
yurdle  Offline
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Y

Joined: Jul 2009
Posts: 53
Originally Posted by Jake
I have some photos of my reinforcement method and will upload tonight.


And my new composite supplies just showed up on my porch today...this clearly isn't a coincidence. I look forward to seeing pics of the next project I'll make a complete mess of.

Re: Expert needed on Inter 18 rudder system... [Re: yurdle] #258505
03/22/13 08:13 PM
03/22/13 08:13 PM
Joined: Jun 2001
Posts: 12,310
South Carolina
Jake Offline
Carpal Tunnel
Jake  Offline
Carpal Tunnel

Joined: Jun 2001
Posts: 12,310
South Carolina
OK...you can go see the set where there are several other photos here:

http://www.flickr.com/photos/teamseacats/sets/72057594056084945/


I tried two different techniques to repair the rudder. First I made some white opaque plastic spacers to fill the hole and keep resin from accumulating. They were later visible with a bright light so I could redrill through the repair fiberglass and extract the spacers. They popped right out.

1) electrical tape compression. I tightly wrapped electrical tape around the rudder head after placing a couple of layers relatively heavy weave knytex fiberglass around the area and then clamped some pieces of wood on the wide flat areas to get compression on the fiberglass repair. It worked very well and I was impressed.

2) I vacuum bagged the repair - I expected this to work well and it did...but you couldn't tell the difference between the electrical tape compression and the vacuum bag compression. The vacuum bag setup required a lot more equipment.

Both rudders held up very well - three Tybee 500s and a bunch of sailing between with no sign of stress.

[Linked Image]
DSC06828 by Team Seacats, on Flickr

[Linked Image]
DSC06829 by Team Seacats, on Flickr

[Linked Image]
DSC06830 by Team Seacats, on Flickr

[Linked Image]
DSC06858 by Team Seacats, on Flickr

[Linked Image]
DSC06855 by Team Seacats, on Flickr

[img]http://farm1.staticflickr.com/38/101854093_9accebea1d.jpg[/img]
DSC06862 by Team Seacats, on Flickr


Jake Kohl
Re: Expert needed on Inter 18 rudder system... [Re: Jake] #258508
03/23/13 03:29 AM
03/23/13 03:29 AM
Joined: Jun 2012
Posts: 97
The Netherlands
Arjan13 Offline OP
journeyman
Arjan13  Offline OP
journeyman

Joined: Jun 2012
Posts: 97
The Netherlands
Hi Jake,

Thanks a lot for these photo's !! It looks like you are not born with two left hands! I most certainly will try to to (or ask somebody to do) the same thing.

Basically I extract from the messages that this is a common "failure" on this type of blades. It was not the answer I was looking for (you always hope for the easy answer), but I have to live with that.

Could you also make a commend on the wheels/rollers or what ever name they have? Are they original / common size for these rudders?

Re: Expert needed on Inter 18 rudder system... [Re: Arjan13] #258509
03/23/13 07:36 AM
03/23/13 07:36 AM
Joined: Apr 2002
Posts: 602
Wilmington,NC
Dlennard Offline
addict
Dlennard  Offline
addict

Joined: Apr 2002
Posts: 602
Wilmington,NC
The rollers in the new boats are black and two different sizes in each rudder. The rollers are also longer than the ones you have in the photos and take up the space in the rudder arm. You can also adjust the bolt with the roller on it with the rudder in the down position by pulling it back and down.

Re: Expert needed on Inter 18 rudder system... [Re: Dlennard] #258513
03/24/13 04:15 AM
03/24/13 04:15 AM
Joined: Jun 2012
Posts: 97
The Netherlands
Arjan13 Offline OP
journeyman
Arjan13  Offline OP
journeyman

Joined: Jun 2012
Posts: 97
The Netherlands
Ok, yesterday we've been testing some different set ups with different types of rollers. The conclusion in the end was that it doesn't make any difference for the force needed to kick up the rudders. It only makes a difference for the space for motion when they are fixed in the down position. In the end we've made it original (found a drawing on the web) with rollers we appeared to have in our box :-)

Nevertheless I think it's at least remarkeble that when you fix the rudders to the boat it is not possible to release the rudders when putting force on the top of the blades. We have put quit a bit force on it, but they didn't release. We also were afraid to put more force on them, so they would break again.

After that conclusion we decided to spend our time wisely and started repairing the broken rudders, so we will have some spares (which are reinforced)

If nobody has the experience that these rudders should kick up easily when putting force on the blades, we have to accept that apparently it works this way....

Last edited by Arjan13; 03/24/13 04:17 AM.
Re: Expert needed on Inter 18 rudder system... [Re: Arjan13] #258517
03/24/13 09:47 AM
03/24/13 09:47 AM
Joined: Jun 2001
Posts: 12,310
South Carolina
Jake Offline
Carpal Tunnel
Jake  Offline
Carpal Tunnel

Joined: Jun 2001
Posts: 12,310
South Carolina
It is a pretty good system when it's right. And yes, it is surprising how much force is required when you are manually making a rudder release (from the tip). However, you really need a good bit of resistance for them to remain down and when encountering minor annoyances (like jelly fish impact at speed, etc.). During the Tybee 500, we sometimes encounter large numbers of jelly balls (relatively harmless jelly fish). We've affixed additional bunjis to help keep the rudders down because of the frequency the rudders would release in these conditions.


Jake Kohl
Re: Expert needed on Inter 18 rudder system... [Re: Arjan13] #258519
03/24/13 10:20 AM
03/24/13 10:20 AM
Joined: Nov 2011
Posts: 382
SE MI / NE IN
rehmbo Offline
enthusiast
rehmbo  Offline
enthusiast

Joined: Nov 2011
Posts: 382
SE MI / NE IN
Sailed my buddies NacraF18 several times last summer. Also noted the very high release torque. Those transoms must be really strong. Amazed that the pintles don't get torn out.


Jeff R

H18, C2 USA1193
cramsailing.com
crescentsail.com

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