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Old 06-21-2012
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Centerboard position - keel/centerboard Tartan 37 upwind

I recently returned to sailing after a rather long hiatus. I am sailing on a friend's Tartan 37. We have had some discussion about the proper position of the centerboard while sailing upwind in relatively light wind. The boat has a shallow keel along with the centerboard. Should it be all the way down on the beat, up slightly, or up all the way to reduce drag?
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Old 06-21-2012
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in light winds I don't bother with it, seems to add more drag than its worth anything over 10 apparent and I will lower it
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Old 06-22-2012
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Re: Centerboard position - keel/centerboard Tartan 37 upwind

We have an Irwin Citation 39 CB, similar to the Tartan, that we race.
Under 10 knots apparent we leave it full up.
We start lowering it as the apparent winds build. By 20 knots apparent it is full down.

I used a Sharpe and marked the line, placing marks at full up, quarter down, half down, three quarter down, and full down. Gives a quick visual reference of where that CB is.
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Old 06-22-2012
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Quote:
Originally Posted by Tweegs:887944
I used a Sharpe and marked the line, placing marks at full up, quarter down, half down, three quarter down, and full down. Gives a quick visual reference of where that CB is.
good tip...we do the same
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Old 06-22-2012
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Re: Centerboard position - keel/centerboard Tartan 37 upwind

I find in chopy sloppy light winds it settles the boat a tad at half down, but no breeze and light seas she stays up.
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Old 06-25-2012
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Re: Centerboard position - keel/centerboard Tartan 37 upwind

Thank you all for the advice.
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Old 06-29-2012
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Re: Centerboard position - keel/centerboard Tartan 37 upwind

I have no experience racing such a creature, but I am surprised that you would get better performance with your centerboard up when beating. I would think the added lift you get from the board would outweigh the drag. Are you able to point with the rest of the fleet with your board up? Looking at images of the keel design it appears that what is left when the board is up is a far from ideal upwind shape.
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Old 07-02-2012
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Re: Centerboard position - keel/centerboard Tartan 37 upwind

On my boat in particular, yes, we can point OK in about 5 knots true with the board up. We can come up a little closer with the board down, or partially down, but we can lose up to half a knot of boat speed. Itís more advantageous for us to leave the board up, fall off the extra 2 or 3 degrees and make it up with speed, especially on the 1 or 2 mile legs that we run.

For us, that crossover point between drag vs. lift was right around 10 knots apparent.

Thereís nothing that says my CB is in the best condition though, probably could use some work. Went down for a look a couple of weeks back and found no damage, everything felt smooth enough, but that means nothing. I wear glasses and underwater, even with a mask in clear water, things are still a bit fuzzy.

Iíd like to get that board out of there when we come out this fall. Give it all the attention it needs.
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Old 07-02-2012
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Re: Centerboard position - keel/centerboard Tartan 37 upwind

Another question that comes to mind: As I understand it, moving the centerboard up and down does change the position of the draft (perhaps this is the wrong term, I meant the balance) of the boat, doesn't it? Moving that back and forth depending on the position of the centerboard can affect the boat's ability to point, right? Is this offset by the decreased drag?
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Old 07-02-2012
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Re: Centerboard position - keel/centerboard Tartan 37 upwind

I think you are referring to moving the center of lateral resistance (CLR) to help balance the helm (usually to tame weather helm).

Here is a good article on the subject:

Helm Balance Ė Center of Effort, Lateral Resistance, Centerboard, Mast Rake - Waves ę Jordan Yacht Brokerage

We havenít found a condition yet that moving the centerboard was the best answer. Adjusting the vang, Cunningham, outhaul and/or reducing sail are our first choices. Since the backstay on my boat is on a turnbuckle and not easily adjustable underway, we might put a couple of turns on it before we leave the slip in heavy air, and have to live with the results. If you have an adjustable backstay, throw that in the mix.
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