| 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 OP
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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. and this is how it was before (you can see the broken wheels which got out: And this is the result of the system not working: can anybody help me out, and tell from experience how the system originally looks like on the Nacra Inter 18? | | | 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
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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 yurdle
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Posts: 53 | 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
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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. DSC06828 by Team Seacats, on Flickr DSC06829 by Team Seacats, on Flickr DSC06830 by Team Seacats, on Flickr DSC06858 by Team Seacats, on Flickr 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: Dlennard]
#258513 03/24/13 04:15 AM 03/24/13 04:15 AM |
Joined: Jun 2012 Posts: 97 The Netherlands Arjan13 OP
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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
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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 | | |
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