Rudder lashing issues

[Thomas Nance]

Hi Wharramers

I have recently purchased a Simpson Woodwind 9.1 catamaran. The last owner/builder used a few Wharram ideas in the build. It has a tiki 30 rig, which is going very well, it also has lashed rudders. This weekend while sailing in some larger seas the rudders started moving from side to side. The lashings were creaking and the whole rudders were twisting. I have added a video of this happening on my page here. Can anyone help me? Are they too looses? Have they stretched?

I know a lot for people are switching from pintle style attachments to lashing, I don't want to go back the other way if I can get the lashings to work.

Any advice would be a big help.

Cheers

Thomas

[Roger]

From my blog:

In the above picture can be seen the industrial duty rudder hinges. When I first got the boat I wasn't that happy about them, wanting the standard Wharram lashing system. Several years later, however, I luv em. The hinges can be disconnected and both rudders unmounted in 30 secs, allowing proper sanding and painting on the hull stem and rudders - impossible to do with the lashing system. I feared that the hinges would also effect performance, but Little Cat has seen 14 knots several times, so it can't be too bad.

[Thomas Nance]

Hi again everyone.

Some news regarding the relashing. On Christmas day I beached the boat with my wife and relashed both the rudders with 8mm Dyneema then use a syringe to put thickened epoxy into the holes, glueing the lashings into their holes. 

On the 31st we left the Tamar river bound for Kettering, down near Hobart. About 4 hours into the trip in about 20knot following winds and 2.5 seas the starboard rudder case split in half! Not an experience I would recommend.

We had to sail on for another 12 hours to reach St Helens and a safe mooring.

My next question is..What do I do now???!!!

I am planning on making new tillers in the wharram style. Im also thinking about using SS gudgeons on both the rudder and transom with a heavy SS rod connecting them. However, do I just do away with the lifting rudder and attach the current rudder (both now removed from the boat) or do I remake ruder cases for vertical lifting of the rudders or, something new?

The boat has no skeg so Im worried about having fixed rudders protruding below at the mercy of groundings or collisions.

But I want a strong simple solution, in my mind any moving parts will begin to complicate things. Bearing in mind the only option for working on the boat would be beaching it in between tides as a suitable wide enough haul out is not available.  

Any and all ideas welcome.

The lashing seemed to work OK, no movement, Dyneema is bloody strong stuff, was almost entertaining watching the salesman trying to cut it in the shop. Also the boat sailed rather well considering it only had one rudder. Often surfing up to 10 knots and averaging 8knots for long periods with only a small jib up. (before the rudder broke) after that we spent most of our time trying to slow it down.

Cheers

[Andrés]

Yoy say the lashing work OK, so the problem seems to be that the cases are not strong enough. If this is the problem, then the solution is to make stronger cases.

Also you can attach the cases to the hull so they can pivot. There are interesting solutions in trimarans, see for instance a Farrier http://www.f-boat.com/f-33/f-33newfeatures.html 

Also you can google Seaclipper 20 or Seaclipper 24 where Jim Brown and John Marples has a more low-tech solution.

[Thomas Nance]

Yes Bao Ya, I often think about building or buying a Wharram, and if I can convince my wife that the stress to fun ratio is usually more biased to the fun side then after this boat a Wharram might be on the cards.

I do like those Farrier rudders, seems a very slick design. And the major components must be strong given their small sizing.

[boatsmith]

Looks like a few layers of glass tape to hold the rudder cassette together would do the trick.