I have a new blog entry on rudders - SailNet Community
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post #1 of 49 Old 10-10-2011 Thread Starter
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I have a new blog entry on rudders

It's a bit different from your typical designer article on rudders but I think it's interesting.
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post #2 of 49 Old 10-10-2011
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Quote:
Originally Posted by bobperry View Post
It's a bit different from your typical designer article on rudders but I think it's interesting.
Bob,
You need to add link to your blog that auto appears each time you post.
Let me know if you want me to do it for you.
Cheers
Andrew

Yacht Design According to Perry

Andrew B

“Life is a trick, and you get one chance to learn it.”
― Terry Pratchett, Nation

Malo 39 Classic
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post #3 of 49 Old 10-10-2011 Thread Starter
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Andrew:
Yes please. I'd appreciate that.
I tried to do that but just could not find the right buttons.

I had James Judd from The Cone up for dinner last night. He's on his way back to Oz tomorrow for some CONE racing. He is renting the apartment that my son owns behind his house.
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post #4 of 49 Old 10-10-2011
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Interesting stuff indeed, Bob - keep them coming!

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"Honestly, I don't know why seamen persist in getting wrecked in some of the outlandish places they do, when they can do it in a nice place like Fiji." -- John Caldwell, "Desperate Voyage"
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post #5 of 49 Old 10-10-2011 Thread Starter
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Hart:
Thanks for that.

I have a little more fun with the blog than my other usual venues. I don't have to run things by an editor.
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post #6 of 49 Old 10-11-2011
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Rudder design from mother nature.

Reminds me of Ruffel's dorsal fin. He was a member of the southern resident Orca pod here in BC. Died last year of old age and PCB's .
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post #7 of 49 Old 10-11-2011 Thread Starter
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Len:
That's interesting. I don't recall seeing tubercles on any Orcas. Maybe I'm just not looking hard enough. You don't by chance have a pic of your old pal you could post do you?

Years ago designer Dave Pedrick tried to simulate the tip of a whale fin on some of his rudders but that effort did not catch on.
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post #8 of 49 Old 10-11-2011
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Borrowing from nature

Interesting post.

The swept back fin keels and rudders drawn by C&C and William Shaw at Pearson and others in the 70s also resembled natural fins of sharks or fish (no tuburcles, though).

The even older, traditional designs before computer assisted design showed similar natural looking curves and overhangs, producing some really beautiful boats (not the rule breakers).

It appears many yacht designers have now moved away from those more natural design features to the more modern, completely vertical keels and rudders, straight sheer, and very little overhang from racing boats.

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post #9 of 49 Old 10-11-2011 Thread Starter
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James:
I agree that the old shapes were more "organic" and sweet to the eye. But the newer shapes work better if you are after boat speed and control. The trend in production cruiser racers almost always follows what the racing classes are doing. I think its a bit like putting a spoiler on the back of your Toyota. They want to look racy.

Overhangs have dissapeared because production builders want max volume for a given LOA. I could argue that overhangs like you see in the old boats are not very effective but I'd step on toes and piss people off. Overhangs are pretty but dangling a lot of boat out in the air does not displace any water so I don't buy the argument that overhangs increase sailing length. Yes, they do when they are immersed and in many cases they can be immersed particularily in the stern. I think the argument for overhangs today has to be a subjective one. They just look great.

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post #10 of 49 Old 10-11-2011
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I love it when design and engineering take a cue from nature. Good stuff Bob!

I get the idea that short overhangs increase volume, speed and efficiency if done correctly, but I don't want to sail an ugly boat even if it is fast and roomy for her LOA. I need a bit of salty overhang so I have something stare back at when it's time to leave the boat and head off to work.

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