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Grumpycat View Drop Down
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    Posted: 11 Apr 22 at 10:46pm
Originally posted by Rupert

A nice barn door rudder will turn a slow, heavy boat nicely where a narrow blade would simply not have enough bite.
Still doesn't explain why the Laser will happily change masts, sails and controls, but not the rudder. Should have done it 49 years ago.

The option of a larger/better rudder was put to a class vote sometime in the in late 80s/early 90s ( back when I was a class member ) . It failed and I don’t think this option has been put to the class since . 


Edited by Grumpycat - 11 Apr 22 at 10:49pm
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Grumpycat View Drop Down
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Posts: 497 		Post Options Post Options   Quote Grumpycat Quote  Post ReplyReply Direct Link To This Post Posted: 11 Apr 22 at 10:48pm
Originally posted by Sam.Spoons

Actually just allowing the blade angle to be free would be a virtually no cost mod that would improver the feel of the boat immeasurably.

So true . Smile
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Oatsandbeans View Drop Down
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Posts: 382 		Post Options Post Options   Quote Oatsandbeans Quote  Post ReplyReply Direct Link To This Post Posted: 12 Apr 22 at 6:07am
Originally posted by Rupert

A nice barn door rudder will turn a slow, heavy boat nicely where a narrow blade would simply not have enough bite.
Still doesn't explain why the Laser will happily change masts, sails and controls, but not the rudder. Should have done it 49 years ago.


I remember a story about the first IACC America’s Cup. Before race 1between America cubed, and Il Moro de Venezia they both had to remove the skirts to show the world the underwater appendages. When the US designers saw the size of the Italian rudder they realised that one of the designers had got it wrong. The Italian rudder was double the area of the US one. The larger rudder was slow and draggy. The US boat was faster but the sail trimmers had a big input into what the boat was doing-. It is the same for dinghies.
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Guests View Drop Down
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Post Options Post Options   Quote Guests Quote  Post ReplyReply Direct Link To This Post Posted: 12 Apr 22 at 6:15am
Originally posted by Oatsandbeans

There’s one reason why weather helm is good - having the rudder at a small angle of attack means that it is generating lift as well as the centre board -a bit like a gybing board .So a few degrees can be good. The reason why some sailors have weather helm as it gives them “feel “ this feel is often at the expense of boat speed as it adds drag-so if you develop better “feel “ by having a more balanced set up you can sail with a lighter helm (which is faster!)
I’ve done quite a bit of research and analysis on this.  As a first approximation, to minimise drag you want the lift to be shared between the daggerboard and rudder in proportion to the square of their spans.

For example if the daggerboard is 1m deep and the rudder is 0.7m deep: 1^2 = 1, 0.7^2 = 0.49, so ratio ~ 2:1 (i.e. the rudder should take one third of the total load). In reality the rudder is surface piercing and in the wash of the daggerboard so the relationship changes a little. 

In this example, if the rudder is less than one the total foil area then it can only provide one third the total force if angle of attack on the rudder is increased by pulling the tiller towards you. The boat therefore needs to be set up with some weather helm to keep it tracking straight. 
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Gordon 1430 View Drop Down
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Posts: 310 		Post Options Post Options   Quote Gordon 1430 Quote  Post ReplyReply Direct Link To This Post Posted: 12 Apr 22 at 7:41am
The angled rudder on the laser helps no end with rowing in the starting area.
Wink
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Oatsandbeans View Drop Down
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Posts: 382 		Post Options Post Options   Quote Oatsandbeans Quote  Post ReplyReply Direct Link To This Post Posted: 12 Apr 22 at 5:09pm
Yes -I am sure that’s why Bruce did it-(can’t think of any other good reason for it!)
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423zero View Drop Down
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Posts: 3420 		Post Options Post Options   Quote 423zero Quote  Post ReplyReply Direct Link To This Post Posted: 12 Apr 22 at 6:50pm
Probably already had the rudder from another boat. Not forgetting he didn't design it to be the racer it became, designed to carry two people and was going to be called the Weekender.

Edited by 423zero - 13 Apr 22 at 6:06am
Robert
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Sam.Spoons View Drop Down
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Posts: 3401 		Post Options Post Options   Quote Sam.Spoons Quote  Post ReplyReply Direct Link To This Post Posted: 13 Apr 22 at 11:13am
More likely that a 'swept back' rudder blade would look racier in the eyes of a non sailor.
Spice 346 "Flat Broke"
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423zero View Drop Down
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Posts: 3420 		Post Options Post Options   Quote 423zero Quote  Post ReplyReply Direct Link To This Post Posted: 13 Apr 22 at 12:20pm
Should have gone for stripes and a matt black foredeck
Painting a hood matte black - Technical - Antique Automobile Club of America - Discussion Forums


Edited by 423zero - 13 Apr 22 at 7:14pm
Robert
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