[MHml] mast rake
lforgy at coursemark.com
Wed Nov 15 10:05:38 EST 2006
Thanks for all the responses. I gather that it is mostly important for
boat balance, and that I am probably best off with very little, if any,
I have to learn to make my questions short and to the point, without
preface. There were lots of other comments, so I guess I owe a bit of
The Macgregor 36 is indeed an older design: masthead rig with a
traditional pin head main with little roach and no full length battens.
One set of spreaders, forestay and inner forestay (or baby stay), upper
shrouds, lower shrouds, and two backstays going to the sterns. With
solid fiberglass hulls, it is not particularly light, but with very
little built in it or on it, it is definitely not a heavyweight.
Macgregor claims it weighs 3,000 pounds, which is probably an
underestimate. The first owner replaced the tramp between main and
stern beam with a solid deck, and I am guessing that the boat weighs
between 3,500 and 4,000 pounds.
The sail area to displacement is pretty modest by today's standards, and
the Chesapeake Bay, where I sail, is by all accounts a light wind
venue. I bought the boat last year and brought it up from Florida, and
have been tinkering with it ever since. First, I stripped of probably
500 pounds of cruising stuff (anyone want to buy a windlass with remote
control, thermal circuit breaker, etc.). This winter I am working on
1. Rotating mast. An Reynolds 33 capsized last year in 20 feet of water
and broke his mast. There is enough left that I am having the break
sleeved and I will come out with a mast about 2 feet longer than my
current mast. And yes, we have done the calculations and it is strong
enough to work on a wider and heavier cat than the R33.
2. Main. I got a used F31 main that will work with the new mast. Mike
Leneman tells me that F31 mast and the R33 mast have the same outside
dimensions, though the R33 mast is stronger. That flat head and all
that roach is going to add about 100 square feet to the mainsail.
3. Rigging. I am converting to a modern three point rig, which will
require beefing up the hulls where the new shrouds will be. An
alternative, which I have seen on some Macgregors, is to attach the
shrouds to a yoke that runs from the main and stern beams, rather than
the hulls themselves. I'll have to decide on this soon. I may try to
convert the fixed backstays to running backstays, though I really hated
these on monohulls. I am overjoyed to get rid of the damn inner
forestay. Also, I am added a bow sprit for flying my newly acquired
asymmetrical spinnaker. I'm working on a way to set the genoa flying
from the sprit, a la a screecher. In light to moderate winds, this
should help balance the bigger main.
4. Foils. I don't want to move the daggerboards, which are just forward
of the main beam, if I can avoid it. The rudders, however, have got to
go. They were thick, heavy, and poorly shaped to begin with, and in
poor shape when I bought the boat. Currently, they are spade rudders on
posts, are the deepest part of the boat and can't be retracted. I'm
going to take them out and build some nice transom hung rudders in
cassettes. This will move the rudders about two feet aft, which
hopefully will help with the increase in weather helm I will probably
get from the bigger main.
All this will increase my rating, but that's okay. The Chesapeake
Multihulls Assoc. (CMA) tries hard to develop appropriate ratings for
our boats, and I just want to go faster. By the way, CMA does rate the
area of a rotating mast. I think I remember the rater telling me that
is something like the side area of the mast times 1.5. Still, I would
think it is worth it. I can remember on my old Hobie 16 when
occasionally the mast would not flip over on a tack. We would feel dead
in the water until someone noticed and kicked the mast over.
Also, Dan, I do scrub the bottom before each race, and I think the new
mast is going to weigh about the same as the old one (which is a large
oval with about 40 pounds of wires attached).
All suggestions and comments welcome.
Larry Forgy wrote:
>I'm replacing the rig on my Macgregor 36, as I have the opportunity to
>change from my fixed mast to a rotating one, and found a used but
>reasonably good fully battened main to replace the piece of junk I have now.
>The old mast was vertical with no mast rake, but there is a suggestion
>to include some (4 to 8 degrees) of rake with the new mast, which is
>what it had on the boat where it was previously used.
>What exactly is the point of mast rake anyway? If it is just to balance
>the boat, rake is going to make my boat more unbalanced. Is there some
>aerodynamic reason for rake? I'm inclined (no pun intended) to just
>make the stick vertical unless there is a compelling reason not to.
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