Portable Speed Indicator

[carry-on]

Would appreciate comments about the SpeedPuck or similar simple (read low cost) electronics to analyse boat speed.
I am a day sailer, familiar with the places I sail. So, chart plotting is not an important feature. Would like to know speed to evaluate the effect of sail trim, gear changes etc.
Thanks for you input. 

[Pacman]

I have had a Knotstick speed indicator for years.

It is just a calibrated clear plastic tube with a 90 degree inlet on the bottom.

Stick it in the water and the water level in the clear tube indicates speed through the water.

I checked it against my hand held GPS during a slack tide with no current running and found that it is very accurate at measuring speed through the water.

The only downside is that to use it you have to get it out, hang it over the side, and look at it.

Usually I just dip my hand in the water to tell when I am gaining boat speed by feel.

I get the Knotstick out every now and then just to play with it but my only real reason for being concerned with speed is to tell if a change in sail trim increases or decreases boat speed and I can do that by feel. 

A number is less important to me than knowing if it is faster or slower after a change in sail trim.

That said, I do recommend the Knotstick.  It is cheap, reliable, simple, and I think it is cool.

[NateD]

If you have a smartphone there are plenty of free GPS applications you can download that will tell you speed. Otherwise look around your local craigslist for OLD handheld GPS units (not chart plotters, these are just black and white screens with your coordinates/speed/heading/elevation). You should be able to pick one up for $20.