Parallax wrote:

A

Useless Idea #3729
s Y'all know, I dislike expensive gadgets and that extends to knotlogs
with their always fouling impellers but I would really like a
knotmeter that will help me really tell when my sail trimming is
helping (I admit, I really can't tell most of the time) and the
response time of even GPS is suspect. However, my little "KNotstik"
that drags a weighted drag behind with a spring in a cylinder has TOO
SHORT a response time and responds to every wave that passes. So, I
propose to give he Knotstik a longer response time by making the
indicator fit tighter in the cylinder and closing off the end through
the cord with the drag passes making it a sort of damper with air as
the damping fluid. This way, it doesnt respond to very fast
transients but only to longer increases in speed.

Any better ideas?


We have GPS and knotmeter. We remove the knotmeter and install the blank
plug while we're away from the boat, so it's usually clear. I can change
over without shipping more than a cup or two of water.

The knotmeter is probably the most effective measure of relative speed
when you tweak things. The GPS reads a bit faster, but measures speed
over ground, which is a good indication of whether you're pointing the
right direction, but isn't as important as speed through the water (in
my opinion.) Additionally, the GPS can sometimes go "wonky" for a few
minutes.

The problem with the knotstick is that you can't see it while you're
looking forward at the sails. The knotmeter and GPS are usually closer
to normal eyesight.

Frankly, the best indicators are the telltales on the sails. They give
instant feedback on your set, no matter what the wind's doing. When I am
trying to get speed, I look at the telltales first, the knotmeter
second, and the GPS last. [Somewhere in there is my wife's expression;
if distressed, we reef quickly.]

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/

Any better ideas?

I use a little self-powered portable knotmeter that is rather like an
electronic update on a Walker log. It's sold by Speedtech (
http://www.speedtech.com/asp/prodtype.asp?prodtype=35 ). Its life
isn't as long as I'd like (wore the first one out in four seasons) but
it works well, is portable and is only expensive (as opposed to REALLY
expensive). The big advantage for me is that it involves no
installation (other than throwing the trailing wire over the side) and
no holes in the boat.

Giles Morris