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RE: SJ23 Hull Speed


Eliminate the "owner-" and send to

I would think you would have received an "undeliverable" message or
something, but maybe the server doesn't work that way on your e-mail
program. Anyway, I will forward it now.


-----Original Message-----
From:	Art Brown []
Sent:	Friday, October 02, 1998 8:14 PM
To:	Van de Wetering, Chuck
Cc:	Schimmel, Bob
Subject:	FW: SJ23 Hull Speed


I sent the following message to the majordomo list (I think I did it - the
right way - I hope)
and to-date the message has not come back to me.  I just sent it to
"owner-sanjuan23@PEAK.ORG" on Sept. 24.

Is this correct?  What do you think happened to the message?  Should I have
received a copy?

Good to get together with you and Bob last weekend.


Art Brown

Sent: 	Thursday, September 24, 1998 8:59 PM
To: 	owner-sanjuan23@PEAK.ORG
Subject: 	SJ23 Hull Speed

As Eric Johnson has said the Hull Speed for a displacement hull is:

		1.34 x sqrt(LWL)

where:     The speed is in knots and the LWL is in feet.

For those that might not understand what this is all about let me quote from
the U.S. Coast Guard Auxiliary's book "Sailing and Seamanship":

	"Displacement boats generally cannot go faster than a certain speed which
closely related to the boat's waterline length.  You can figure your boat's
maximum displacement speed - called its hull speed - quite easily:  take the
square root of the boat's length at the waterline (often known as its LWL)
feet, and multiply it by 1.34, to find the boat's approximate maximum speed
nautical miles per hour" (knots).

The LWL for a SJ23 is 20' 4".  So for a SJ23 the Hull Speed = 1.34 x 4.51 =
6.04 knots (or 6.96 mph).

One of the interesting things about this is that with my 5hp outboard motor
GPS tells me that I am getting about 5 knots speed.  Given the above limit
about 6 knots, I would not be able to get more than about 1 additional knot
speed even if I were to put a 50hp motor on my SJ23.  On the other hand, if
were fighting a head wind then more power would probably help.

Of course if you are racing my SJ23 it is at least several time faster than
this so you might as well give up before you even start!

Art Brown

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