Rudders...

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DickB

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Reading YW this month about the ARC, I was a bit perturbed about the critisism of modern rudders. One of the statements was to carry a spare! For my own part, at the boat shows, looking at the array of modern yachts the rudder seems very vulnerable. The leverage at the base it tremendous and even if the rudder stock is substantial the lower bearing housing in the yacht hull could be torn out if enough pressure were applied, (as in that recent incident with the Hanse I believe)... I guess what I am saying is that the semi or full skeg rudders of the older boats seems to be intrinsically stronger.

As it happens I have a AWB which has a typical modern spade rudder, and it is fine, it works, but I do think from a simple mechanical advantage point of view, it looks weak!

I guess as always, you get what you pay for, and most of the yachts are really built to a price!!! Of course in the long run, that price might be the cost of calling out the RNLI in the event of a rudder failure...
 
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(as in that recent incident with the Hanse I believe)...

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That Hanse report is both detailed and salutary and is essential reading for all cruising boats IMHO ( MCIB Report )
 
It has always surprised me how boats getting ready for ocean crossings, will inspect the rigging in great detail, and yet few will drop the rudder by a few inches to inspect the shaft / bearing / and hull surrounding the bearing. Rig failure is a problem but not as serious as rudder failure.

How many boats check their steering thoroughly before setting off across an ocean? That means removing the cable, close up inspection of pulleys and joints, drop it out, get inside the aft locker, take the steering apart...I do, but then I've had the steering fail on a Sweden 38.
 
There are some performance reasons why a spade rudder is preferred over a skeg hung one, especially a full skeg version. A full skeg doesn't allow for balancing (adding some area ahead of the pivot) to reduce the weight on the helm and the angle at which the rudder stalls is lower. I'm not sure either why a spade rudder would be cheaper to make than a skeg hung one, indeed some have very sophisticated (read pricey) bearing systems compared to the simpler skeg hung ones and certainly they need substantial added support inside the hull.

Skeg hung rudders are not always stronger either than spades, witness the failure of the skegs in big Moodys back in the late 80's from memory (one sank when the skeg broke off). I think one of YMs editors had to return to repair his Sadler 34 skeg that was cracked and leaking at the start of the ARC and certainly he added a LOT of reinforcing to it if I remember the articles correctly. I think the 'best' skegs would be ones added on the outside of the hull rather than moulded into it, that way they might not leave a big hole if the broke away!

Our 1988 Jeanneau has a half skeg with the bottom bearing on that and the shaft heavily supported inside, far better than a similar looking arrangement on our earlier Westerly 33 which had a small skeg but it didn't actually carry the bottom bearing. We had to reinforce the rudder shaft supports substantially on the W33 to stop the top moving around in its cross brace.

There are however many succesful designs sailing the world's oceans with modern rudders so it must be possible if the design and build is done correctly.
 
I think at the very least though, the rudder bearing should be between bulkheads, such that if it fails, the boat doesn't fill up.
 
Did you notice that the Hanse had covered 14,000 miles before the incident.

How many seasons of "average" use for an AWB is that? 28??
 
Even more reason for having a Hydrovane self steering system on the transom!
They work brilliantly, and they also fill the role of emergency rudder, as they are completely independent of the main rudder.

If those ARC boats who lost their rudders had had Hydrovanes, perhaps instead of expensive autopilots, they would most probably have been able to sail their vessels to St Lucia without incident, assuming of course that the Hydrovane was not also damaged when the main rudder failure occured.

This comment by a satisfied Hydrovane customer, who has no connection with the manufacturers.
 
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I think at the very least though, the rudder bearing should be between bulkheads, such that if it fails, the boat doesn't fill up.

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I think that would be a good idea too either with or without a skeg. It could have been done easily enough on our current boat during building but our previous centre cockpit one had the rudder bearings/quadrant etc below stern cabin bunks and that one would have been difficult to seal I suspect.
 
Nowhere near as much as I would like.........see bio /forums/images/graemlins/frown.gif /forums/images/graemlins/frown.gif
 
I like the sound of the bulkhead to keep the are around the rudder bearings outside of the main yacht insides.

When I bought my 3 yr old Bav42cc little did I know how bad the corrision was at the bottom of the lower bearing, just where the blade of the rudder is attached. Had to be replaced at £2500 plus VAT of course...

The brokerage picked up the labour costs since I had only had the yacht for a few months. I now check the rudder bearing surface each year by dropping the runnder about 1/2 inch to see if there is more corrosion.

I now have a galvanic insulator and I have an anode on a wire attached as well.. The Rudder is FINE!!!.
 
I doublt very much if you'll find a better arrangement than that found on Vancouvers (semi-balanced but with the bottom of the rudder attached to a extended keel - protects the prop from ropes too!) But then I'm biased...
 
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