<<Personally, I wouldn't recommend much more than that unless you
either sail a boat small enough that a capsize is a mere nuisance,
or you are an adrenalin addict with exceptional skill and attention
span and you can afford the cost of the occasional salvage.>>
Or, if you frequently deal with light winds and need to be able to
cover some distance during those days.
We rarely cruise, but I can't begin to recite the number of summer
days we used to plod around while daysailing on our old monohull when
the wind gods weren't helping out. Granted, it wasn't a racing boat,
but on a lot of those days no one under 45 feet was doing much of
anything.
Our current catamaran has a Bruce number of 1.9 empty, 1.8 with my
wife and me on board, and I have to say that it's absolutely wonderful
to be able to sail on days when our old boat wouldn't even move, and
sail quickly when we would have been crawling. Not only is it more
fun, and cooler with more apparent wind in our faces, it allows us to
cover a lot more ground and see something besides the same old bay.
It's also nice if we need to cover some real distance in order to get
to another harbor before supper time, or perhaps get home before a
change in weather makes us miserable.
The flip side is that only a fool would carry full sail on a BN 1.7+
boat once the wind kicks up. 15 knots is about the top end of where we
can sail without a reef and still remain calm. We purchased our boat
with new sails, and the main came without any reef points. We had one
added before we used it, and are now adding two more based upon our
sailing experience.
So the price of a high Bruce number is the requirement of reefing
early and often. Not everyone is willing to do this, but that's true
for all sailboats. Some folks just don't want to reef. I can't say
why. I'm personally happy to pay the price of reefing if that means
I'll be able to sail in winds that are too light for others to bother
with.
Alternately, as Roger points out, the price of a high Bruce number is
white-knuckle sailing and the willingness to risk capsize when a gust
comes by. That's certainly a legitimate use of a boat, but it's a bit
too exciting for my tastes.
---
One thing to note with the Harryproas is that a higher Bruce number
will be a bit easier to handle than other boats. This is for two
reasons:
a) The majority of the weight is in the windward hull, creating a
greater righting moment than a standard cat or trimaran with the same
Bruce number.
b) The masts flex readily in gusts, making it much less finicky when
you're not dealing with perfect trade winds. Some have criticized the
masts for being too flexible, but the appear to be looking at the boat
from more of a pure racing perspective. While there's no substitute
for an overpowered stiff rig and an expert crew to man it, there's a
lot to be said about a rig that will help absorb some of the gusts.
This is especially true if you want to use a boat with such a high
Bruce number for something other than racing.
More Bruce number information on the larger Visionarry Harryproa at:
http://www.harryproa.com/blinddate.htm
- Mike
robertbiegler wrote:
--- In
harryproa@yahoogroups.com.au, "oceanplodder2003"
<dana-tenacity@u...> wrote:
> Just been reading an article on these, seems 1.9 and above is a
fast
> boat, do we know what the no. is for Harry?
The Bruce number is simply the square root of sail area divided by the
cube root of displacement. The numbers caclulated from metric or
imterial units differ by about a factor 4. For Harry, calculated from
sail area and displacement in metric units and racing trim (empty
weight plus two crew) it's 7.02, calculated from imperial units it's
1.76. At designed cruising displacement, the numbers are 6.12 from
metric units and 1.53 from imperial units.
As for a Bruce number of 1.9 or above, that's for pretty extreme
racers requiring a lot of attention and skill. Ellen Macarthur's
B&Q
comes in at 7.95 in mteric or 1.99 in imperial. Fujifilm, one of the
ORMA 60 trimarans is at 9.52 or 2.39. That's the kind of boat which
is fully powered up in 8 knots of wind. Most monohull cruisers come
in at 4 to 5 or 1 to 1.25, reasonably fast multihull cruisers at about
6 or 1.5. Personally, I wouldn't recommend much more than that unless
you either sail a boat small enough that a capsize is a mere nuisance,
or you are an adrenalin addict with exceptional skill and attention
span and you can afford the cost of the occasional salvage. Though if
you do crave that sort of excitement, I am sure Rob can provide it.
Regards
Robert Biegler
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