Think about it a moment. You set mast rake with the boat in the water. By definition she is sitting on her lines and it doesn’t really matter if she is trimmed stern high or stern low.
Gravity points straight down, so the plumb bob (weight on the end of the main halyard) hangs straight down and if you measure 6” of rake, you have the mast slanted 6” aft of vertical. In the days of square riggers, and on more modern topsail schooners, it is common to trim the boat so it is down slightly at the stern. It is supposed to make the boat faster; I suppose that could be because the press of canvas when going downwind would push the bow down. I can’t think of a hydrodynamic reason a boat down at the stern would be faster than a boat sitting with the bottom level, but there may be one. Among the things I acquired when I bought my 38 was some of her ratings information from IOR racing in the 70s, and an article from a Canadian sailing magazine about the 38-1 race boats and how to optimize them for tonnage racing. Seems the 38-1 was designed to be slightly down at the bow – I presume so the weight of crew would bring her back to level in racing trim. And one of the tips in the magazine article was to add 100 pounds of ballast forward (I don’t recall the exact spot that was recommended) to accentuate the resting condition – and pick up a couple of tenths of rating points. Which is not really related to the discussion of mast rake. Just thought it might be interesting since the discussion is drifting toward hull trim. Rick Brass Imzadi C&C 38 mk 2 la Belle Aurore C&C 25 mk1 Washington, NC From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of William Hall via CnC-List Sent: Thursday, May 28, 2015 12:59 PM To: cnc-list Cc: William Hall Subject: Re: Stus-List Mast Rake on C&C 30 Seems to me that if the boat normally sails stern-low, it moves the center of effort aft and has the same effect as raking the mast on a level boat... On Thu, May 28, 2015 at 12:51 PM, Michael Brown via CnC-List <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com> > wrote: I think the initial tuning of about 8" of rake, usually done by hanging a weight on the main halyard, is a reference assuming the boat is sitting level in the water. At least a few of the C&C 30-1 I have looked at are stern heavy, some by a couple of inches. I suspect that will add some to the rake that would not be there if the boot strip and water surface were parallel. Under sail with crew on board the boat may sit properly. Given that people have reported noticing a change in weather helm from even a modest adjustment of rake the error in initial tuning by having the stern 2" low might be significant. A couple of weeks ago while out for practice starts we flew a heavy wind #1 ( a flatter cut ) and full main. Winds were 18 - 22 kts, gusts to 30. It was the wrong amount of sail to have up but the helm was fine. Eased the vang a bit and left some twist in the main, kept the #1 flat. With the boat level I have about 6" of rake. Michael Brown Windburn C&C 30-1 _______________________________________________ Email address: CnC-List@cnc-list.com <mailto:CnC-List@cnc-list.com> To change your list preferences, including unsubscribing -- go to the bottom of page at: http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com -- William D. Hall, Ph.D. 617 620 9078 (c) wh...@alum.mit.edu <mailto:wh...@alum.mit.edu>
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