Brandon, Keith and Lee,
Thanks for the helpful advice and photo!
Tim
6254
I haven't set this up yet. If you go to Harkens site they have a tool
you can use were you can virtually set up what you want and they will
tell you the part numbers. I was going to go with a 6-1 but my local
sailing shop suggested 4-1 would be enough. He's set up a few of these
lately and I trust his advice. Here's the link
http://www.harkencompuspec.com/
Brandon
- -
That's what I did, and it makes a huge difference. I removed all the
turning blocks that route the sheet forward to the mast, then back
again, and just installed a fiddle block with cam right there at the
traveler. The sheet likes to hang down the companionway now, but
that's not a big deal. If I can figure out some sort of sheet bag
arrangement that snaps to the side of the companionway frame, that
would keep everything neat.
The only problem with this arrangement is if you have a dodger. I do,
but sailing on an inland lake means I only use it for the little bit
of shade it provides, not for keeping the spray out of my face. So, I
just removed the front panel.
I just uploaded a photo of my setup to the photos section, under 'Blown
Away'
Lee Scott
'87 C-27 #6350
- -
This all comes down to the physics. To trim your main, you have to
pull against a force (the lateral force on the main) through a
distance (the angle the boom moves). The product of force times
distance is work. When you pull on the end of the boom, you are
pulling the same angle to achieve proper flow, but the point you are
pulling on is moving a lot farther than if you have mid-boom sheeting.
To do the same amount of work, you don’t need to pull as hard. To put
some rough numbers to it, if you pull at the mid span of the boom, you
have to pull twice as hard for half the distance. To get back to a
reasonable pull force, you can add purchase (8:1 vs. 4:1 pulley setup,
for example) to trade back distance for force. Nothing is ever free,
however, and each layer of purchase adds drag, which hurts in both
directions (sheeting in and out). Big sheet tension hurts drag too, as
the frictional force is directly proportional to the sheet tension.
For this, and a bunch of other reasons, end boom sheeting is
mechanically more efficient, but Sailboat Design, like life, is a
series of compromises and imperfect solutions. There are a lot of
practical advantages to mid-boom sheeting.
Keith
#4760
