If you're sailing in an area where current or tides aren't a concern IMHO the best GPS option is the Rockbox. It has all the same features of any of the other GPS solutions plus a back light and remote control.

http://rockcitymarine.com/

For speed through water we have a NavMan system. It was what was installed in the boat when we got it, it displays depth and speed. We've not removed it as it keeps on going. The NavMan and LED running lights / cabin lights are all we have working off the battery, which is cool because we can run off that small motor cycle style battery for a long time.

:: Im using the Tack Tick racemaster wireless- combo
:: sped/depth/ compass.

:: It is pretty slick but I find very tempermental-also
:: slow to react.(maybe due to wireless?) I wouldnt
:: recomend it myself. Also, theyve been bought by
:: Raymarine so they are in a bit of chaos.
::
::
::
:: :: There is one serious problem with installing only a gps
:: :: aided knot meter on a boat...You never know what the
:: :: boat is doing through the water. The GPS directed
:: :: systems only tell you your boat speed over the ground so
:: :: you can not compare the speed of the boat through the
:: :: water, thus you really don't know the affect of the
:: :: current on the boat....
:: ::
:: :: Dan I have a comnav which is now nexus marine, system on
:: :: the boat; boat speed, depth, and compass. I really like
:: :: the system as it has every feature I could ever imagine
:: :: using, and it is simple to install and operate. The
:: :: nexus system is easily expandable if you wanted a wind
:: :: instrument, which like tack tick is wireless, so no
:: :: wires in the mast. There are a lot of good reliable
:: :: systems out there, even the over the counter raymarine
:: :: sold at West Marine is a good option. But I can tell you
:: :: this I wouldn't sail a boat on SF bay without a actual
:: :: in the water knotmeter.
:: ::
:: :: Tom
:: ::
:: :: :: Hi Dan,
:: :: ::
:: :: :: We have been using the Velocitek Prostart. It works
:: :: :: quite well and updates fairly quickly. The features are
:: :: :: similar to the KVH unit.
:: :: ::
:: :: :: I believe it is also class legal as it is all integrated
:: :: :: to itself as for the GPS.
:: :: ::
:: :: :: Don
:: :: :: :: Does anyone have a recommendation for a knotmeter? We've
:: :: :: :: been using a Speedmate for a long time. It's a good
:: :: :: :: unit, but is incredibly unreliable (maybe that's why
:: :: :: :: they don't make them anymore). I tried the entry level
:: :: :: :: TackTick (T035), but found that it reacted too slowly
:: :: :: :: and there is no way to adjust the damping. What else is
:: :: :: :: good out there?
:: :: :: ::
:: :: :: :: Thanks
:: :: :: ::
:: :: :: :: Dan