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Trapeze or hike

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    Posted: 19 Aug 10 at 9:49am

On a reach what do you think would be quicker in those medium conditions:

Dagger board down more and trapeze?

or

Dagger board up a bit more and hike?

My thinking is that dagger board downish and trapezing increases drag above and below the water. Although trapezing gives a more stable arrangement, dagger board further down also makes the boat more twitchy when planing (or seems to).

Am I overlooking anything?

 



Edited by GK.LaserII
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JimC View Drop Down
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Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 19 Aug 10 at 10:29am
Drag is a bit more complicated than just the wetted area of the daggerboard. There will be a point at which the foil area is so low that the dagggerboard is working very hard and drag increases as you pull the board up further.
I think I would consider in which configuration you can sail the boat most efficiantly and best respond to gusts and lulls, rather than worry about foil drag, which is probably a relatively minor factor...
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Post Options Post Options   Quote Guests Quote  Post ReplyReply Direct Link To This Post Posted: 19 Aug 10 at 11:29am

Thanks for that, what you say makes sense.

I've sailed with a couple of different crew recently, both using different plate hieghts on the fast reaches and it seems to make a lot of difference to how the boat behaves.

So I'm trying to get my head around the relationship between the rudder and plate.... When the plate is downish at speed the rudder gets hyper sensitive, I assume because the boat is pivoting around lots of efficiently working dagger board?

When the plate is upish, the rudder sensitivity feels less extreme, presumeably because the smaller, less efficient pivot (daggerboard) is now stalling slightly during minor direction changes. This stalling creates high drag?

Is this vastely over simplified or just plain wrong? 

As you can tell I'm no expert on hydrodynamics but I want to be able to understand the basics. Now I know the sharp end from the blunt end I reckon getting lots of small things right on a boat is the way forward gfor me at the mo.



Edited by GK.LaserII
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tim grasse View Drop Down
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Post Options Post Options   Quote tim grasse Quote  Post ReplyReply Direct Link To This Post Posted: 19 Aug 10 at 10:42pm
i would say that on a reach you should keep the board down and trapeze so you can handle more power and more speed.
When the board is up i think that the boat is less twichy because there is more sideways movement in the turns and you sort of drift round the corner which keeps a constant flow over the foils preventing them from staling.
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Post Options Post Options   Quote Guests Quote  Post ReplyReply Direct Link To This Post Posted: 20 Aug 10 at 8:16am

Absolutely, use the leverage when it's blowing.........I was thinking more about medium (say force 4) situations when you can be fully powered up in either position on a reach.

Some prefer the plate down a bit more so they can trapeze. I'm not sure it's quicker. Looks good though.

I want to understand what happens with the foils........Anyone recommend a good book on the suject.

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Post Options Post Options   Quote Hughph Quote  Post ReplyReply Direct Link To This Post Posted: 13 Oct 10 at 2:22pm
I would say board down and trapeze- unless the board has been designed slightly long for easy righting like 29ers where you raise it 150mm-From sailing 420's is that the boat definitely performs better with weight on the trapeze and is easier to plane- if the design had not had wires retrofitted then it was probably built like to perform better with a man on the wire- I might be wrong- feel free to point me out! 

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Post Options Post Options   Quote redback Quote  Post ReplyReply Direct Link To This Post Posted: 27 Dec 10 at 3:46pm
I sail a 4000.  Its not worth considering because 1. it gets in the way, 2. you'd have to stop to get the weight off the board to raise it, 3. it makes no difference to leeway anyway, and 4. the boat is so tippy without a deep board its very difficult to control.  

The trapeze or hike decision is all about downwind angle.  In medium winds you have a choice deep and slow and no trapeze or higher and faster in which case the crew will need to trapeze.  Which you choose is dependent on tides, other boats, waves and anticipated wind.
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