DRAGONFLY Trimarans User Forum

A little while ago our 920 had a coming together with the bottom. We weren't going particularly fast, and the centreboard cleat tripped OK. However, the rudder cleat didn't, and the stainless steel eye bolt in the front of the rudder blade that takes the downhaul tackle sheared off. We sorted things out and rigged a temporary downhaul to get home but now want to make a permanent repair.

The front of the rudder blade was left with the stainless washer and the trace of a weld where the eye had sheared off. We briefly contemplated getting an engineering firm to weld another eye in place but decided that the temperature needed to do a stainless weld would probably destroy the rudder. I ground off the weld and drilled out the stem of the eyebolt. As soon as I had gone through the remains of the weld the washer dropped off. I drilled the shank of the bolt out to a depth of about 2.5 cm and then hit something very hard. The drill that had easily removed the stainless shank just would not go any further.

So my question is twofold -
1. What is inside the head of a 920 rudder?
2. What should I do next to fix a new eyebolt in place?

Or is this a lost cause and a new blade the only answer?

(There is also the question of whether the rudder release system is adequate. The cleat holds the end of a four to one purchase, so only sees a quarter of the force exerted at the eyebolt. In our case, the cleat stayed put while the stainless steel sheared. Any comments?)

Greg I don't know what is inside (you should ask Quorning) but I have had the 920 rudder release properly several times: Twice when contacting a shallow bottom, and once when we snagged a lobster trap float.

Maybe you should compare the way your rudder down-haul is rigged with another 920.

Greg Lamb wrote:
Or is this a lost cause and a new blade the only answer?

(There is also the question of whether the rudder release system is adequate. The cleat holds the end of a four to one purchase, so only sees a quarter of the force exerted at the eye bolt. In our case, the cleat stayed put while the stainless steel sheared. Any comments?)

How about replacing the existing eye bolt with a Dyneema rope by drilling an extra traverse hole for it somewhere near the leading edge of the rudder. Use gelcoat to get the surfaces watertight.
I have noticed the downhaul 4:1 tackle needs to be cleaned once a year because of salt. The ball bearings of the sheaves does not work properly and the tackle is jammed.

i made a pin on a metal bar. I put the metal bar inside into the blade and ifixed it with two wire and some epoxy. If you want to weld the pin, you can do but you need to rebuild a little of the blade with new carbon. i did it but after one month i broke the pin. The most important thing is to check if under the blade you still have a bronze busching. I lost mine and probably i had several problem.
I made a hole into the upper part of the blade as emergency, so if i 'll broke the pin and i need to use the rudder immediatly, i push down the blade and fix ii with a scredriver.

Why is there a wire that holds down the rudder? On a DF800 there is a regular rope.

Any known reason?

Christian wrote:Why is there a wire that holds down the rudder? On a DF800 there is a regular rope.

Any known reason?

Old construction, I have replaced it with dyneema rope nowadays.

There is a very good reason to have a wire: barnacles that grow around and inside the tube where the rudder down haul goes are very sharp and can chafe a line. (This is one of the very few areas of the boat where I am unsuccessful in preventing growth.)

I do carry a dyneema line as a spare...

That explains why the rope on DF800 is over the water line.

Had some problems in getting the rudder down in position. Checked the wire and found that it is bent and 2 of the strands are broken. Think that the long metal cover for the eye is the problem. Think it gets stuck in some way.
So my idea is to replace the wire with a chain. It will handle barnacles too.

Any ideas?

This happened to me also. The wire gets jammed between the blade and the rudder housing if there is slack in downhaul. I learned to keep tension on both uphaul and downhaul lines when putting the rudder down. It prevents broken wire.

I replaced mine with an identical wire. I kept the old one as a spare.

I don't see any reason why a light chain would not work. Certainly a lot cheaper than a wire with 2 fittings!

Could not find a stainless chain in right dimension, so I'm in the dyneema club now.

why not get cheap galvanized chain? The whole thing is above water most of the time. And even if you get corrosion, it is the cheap chain that will get it, not the stainless fittings on the blade or block. So you will replace it in 2-3 years!