The manual for my 30 indicates the rake should be 9in measured at the
gooseneck. I have a 1973 vintage.
I've sailed in 15kt with gusts and the 160 up and a bubble in half the main,
traveler down, with no problems with weather helm until the puffs hit. Granted
the rail was almost kissing the water.
Something sounds wrong if you're suffering weather helm and I don't believe
it's the mast rake.
Ron
Wild Cheri
On Wednesday, November 27, 2013 6:32 PM, Dennis C. <capt...@yahoo.com> wrote:
Aaron,
It's not a 10" rake, it's a 1 degree rake. Conventional wisdom for C&C's seems
to be that a 1 inch rake is optimum.
However, that's dependent on lots of factors, namely the condition of the
sails. Flat sails result in less weather helm. Note that it's not just the
main but can include the genoa as well. A larger genoa, 150-170% overlap, with
a deep draft aft or a cupped leech can increase the propensity for weather
helm.
Yes, it's a balance between center of effort (CE) and center of resistance
(CR). The draft of the sails affects CE. The further aft the draft is, the
more CE moves aft. The deeper the draft, the more effect it has.
So, 1 degree of rake is probably about 7 inches for your boat. I run
about 11 inches on Touche' and am contemplating another inch or two more.
Multiply your boat's P dimension by the sine of 1 degree or 0.01745. Your P is
34 feet. That gives you 0.5933 feet or 7 inches aft. Drop a plumb from the
masthead to the gooseneck.
Increasing the length of your forestay will move the masthead aft and increase
rake. I seem to believe 1 inch of forestay will move the masthead about 3-4
inches. You can approximate it closely it with the Pythagorean theorem. Go
here:
http://www.basic-mathematics.com/pythagorean-theorem-calculator.html
Assuming the technical info on the C&C website is a plumb mast, we do a bit of
math. "C" = your I dimension or 39 feet. "A" will be your J dimension, 13.5
feet. This yields a "B" of 36.6. This will be the new B in our next
calculation. Let's add the desired rake, 7 inches to the "old" J to yield a
new A of
14.08. Plug that in with the calculated "B" of 36.6 and you get a new C of
39.2. So, you need to increase your I dimension by .2 feet or about 2.5 inches
to move the masthead 7 inches.
Of course, your mast may not be plumb but you can use the tool above to see
where you need to be.
Good luck,
Dennis C.
Touche' 35-1 #83
Mandeville, LA
>________________________________
> From: Aaron Rouhi <admiralmag...@outlook.com>
>To: "cnc-list@cnc-list.com" <cnc-list@cnc-list.com>
>Sent: Wednesday, November 27, 2013 2:14 PM
>Subject: Re: Stus-List 30 MKI weather helm
>
>
>
>I never tried a 10" rake. I'll give it shot. I think I have enough tread in my
>forestay turnbuckle... Thanks guys!
>
>
>
>Cheers,
>Aaron R.
>Admiral Maggie,
>1979 C&C 30 MK1 #540
>Annapolis, MD
>
>
>
>________________________________
>From: dwight...@gmail.com
>To: cnc-list@cnc-list.com
>Date: Wed, 27 Nov 2013 16:08:37 -0400
>Subject: Re: Stus-List 30 MKI weather helm
>
>
>Your thinking seems fine: I just have no
experience with forward rake that I can share. I have never tried that but I
don’t think it would work good upwind…6-10 inches should be good, something
else might be the problem
>
>
>________________________________
>
>From:CnC-List
[mailto:cnc-list-boun...@cnc-list.com] On
Behalf Of Aaron Rouhi
>Sent: November 27, 2013 3:55 PM
>To: cnc-list@cnc-list.com
>Subject: Re: Stus-List 30 MKI
weather helm
>
>Hmmm.... I always thought with
more mast rake the Center Of Effort moves further
aft which means wind pushing the boat from behind the CLR and as a result
weather helm increases so using that logic I raked it forward to move COE
forward. Am I wrong?
>
>Cheers,
>Aaron R.
>Admiral Maggie,
>1979 C&C 30 MK1 #540
>Annapolis, MD
>
>
>________________________________
>
>From: f...@postaudio.net
>Date: Wed, 27 Nov 2013 13:43:13 -0600
>To: cnc-list@cnc-list.com
>Subject: Re: Stus-List 30 MKI weather helm
>
>Aaron — Dwight’s right, you’re going the wrong way! Rake aft about
six to eight inches and see what happens.
>
>Fred Street-- Minneapolis
>S/V Oceanis (1979
C&C Landfall 38) -- on the hard in Bayfield, WI :^(
>
>On Nov 27, 2013, at 12:52 PM,
dwight <dwight...@gmail.com>
wrote:
>
>>What
is she like after that change? I am not sure how that would work on a
beat…seems unconventional to me…I would try 6 to 10 inches aft
>>
>>Are
you talking 10 kts true or apparent wind…is it usual for you have a reef in
when most other boats around you don’t
>>
>>
>>________________________________
>>
>>From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On
Behalf Of Aaron
Rouhi
>>Sent: November 27, 2013 2:20 PM
>>To: cnc-list@cnc-list.com
>>Subject: Re: Stus-List 30 MKI weather helm
>>
>>It's raked about an inch
forward... It's a recent change I made in an attempt to reduce the weather
helm...
>
>
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