[Public-List] Blown out sails OK for crusing
Bill Spires
spiresac at yahoo.com
Sun Jan 9 09:33:35 PST 2011
I agree, Unfortunately, speed goes up at the square root of money. Some
classes I have raced in limit how many sails you can buy. Or you can figure out
a handicap for sails and other factors. It seems to me that the Albergs manage
to have some fun, enjoy a little friendly racing and there will no doubt be
those who will put in the time and money to win. I have seen class after class
destroyed by becoming more concerned with who won than the enjoyment of the
sport. Please don't let that happen to the Albergs.
Capt. Bill
________________________________
From: Don Campbell <dk.campbell at sympatico.ca>
To: Alberg 30 Public List -- open to all <public-list at lists.alberg30.org>
Sent: Sun, January 9, 2011 11:33:44 AM
Subject: Re: [Public-List] Blown out sails OK for crusing
All I can say is amen! The biggest problem for the converted is to convince
those who like "good" old sails to get that new sail in the first place in
order to actually feel the difference and become a convert to enjoying some
power to drive their boat and therefore enjoy some fun while sailing.
The one thing you must remember regarding a transfer from a racing sail to a
cruising sail (at least in my sail inventory) is the slight degree of loss of
shape (competitiveness) to effect the transfer.
It takes very little loss of shape to take the edge off a good sail, when
the difference of a few boat lengths over a race makes the difference between
winning and losing. When this loss of power happens, a change of sail (to new)
is necessary. This often depends upon those against whom you compete and how
often they get new sails too.
If you want to look at the math of this, it gets to be very small numbers.
For example in a mid wind range race, with an average speed of 5.0000 knots over
a 5.0 mile race, that race will have a time duration of 1 hour. Let us assume
two boats are in the race with good crews and no one makes a mistake throughout
the race so both boats are able to run at a constant average speed for the hour.
(This rarely happens, but for the math it is easier.) Say the second boat
finished in the 1 hour. If the first boat finished ahead by exactly one Alberg
30 boat length, then its distance travelled in the same time would be 30 feet
more than the second place boat. Since s = d / T, where d is distance, s is
speed, and T is time, then the difference in speed of the two boats is s1-s2 =
(d1/T1) - (d2/T2) = (d1-d2)/T, since both boats are timed in 1 hour or 3600
seconds. Distance 2 is the full racecourse so 5.0 miles or 5.0 x 6076.1 feet.
Distance 1 is 30 feet more than distance 2. Thus the difference in speed is
(30410.5 - 30380.5 ) / 3600 = 0.0083 feet per second or about 1/10 of an inch
difference in average speed per second. This amounts to us being able to say
that this difference is valid per second per boat length as well. Therefore if
you are getting 10 boat lengths behind at the finish, (which many would say was
a comfortable win for the winner and a definite loss for the second boat), then
you are a huge 1 inch per second different in speed! Most cruisers would say
that is negligible, - but there is no gold for the racers in the second boat
who are 10 lengths behind per hour! However, over the time period of a day
cruising for 8 hours, that small difference amounts to almost 4/10 of a mile.
Just a brief comment about Michaels' two sails: Excessive luffing of a 110
for only a minute in a bit of a blow will finish that sail's shape, regardless
of how new it is, because it will lengthen the leech from the whipping action
and make that sail untrimable. The 150 is far less likely to undergo excessive
luffing because it is never flown in those big breezes. Chronological age is
not the only criteria for ending the useful life of a sail.
Don #528
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