Using Garmin Forerunner for boatspeed

[mark_swart]

I live in salt water and my knotmeter transducer fouls due to growth. Cleaning it is a pain and I'm sick of cleaning water out of the boat every time I pull it.
I'm considering buying a Garmin Forerunner 305 or 205 (looks like a wristwatch but it's a multifunction GPS) for my boatspeed when racing. I don't really want to buy a full on GPS system and I think it would be handy to just look down at my wrist as I normally don't sit behind the wheel anyway. I understand the difference between speed in the water and speed over ground, but in my case I'm mostly looking to see if what I'm tweaking on sails/course is helping or hurting me.
Just curious if anyone has tried this system on a boat and what they think of it, and if it is sensitive enough to speed changes at the low speeds we deal with on sailboats. The only thing I have seen close in a marine variant is the Speedpuck, but that costs over twice as much as the Garmin.

 

[kenn]

I'd worry about the wristwatch-style GPS not holding the satellites reliably enough for moment-to-moment accuracy, but I guess you can only try.

For about a third of the price of the new watch-based unit, you could probably get an older handheld hiker's GPS that would do the job.

My friend has an old beater pickup, and when his speedometer went, he just stuck his old GPS on the dash.

 

[dscribner]

Th Forerunner can pick up satellies thru trees on a hand that's swinging back and forth three feet about every second. It will have no trouble getting a fix on open water. We used one. Keep in mind that it will give your speed in MPH so deduct 10% ish to correct. Also, it doesn't give your position. We used ours for a couple of years, then bought a Garmin 76C on Ebay for $100 and the BlueChart for New England for $89. Not too expensive and it will give you everything including depth (within 6 meters).

 

[Joe]

Get a handheld Garmin 76 GPS.... no chart plotter... It's light enough to strap on your wrist, heh, heh.. but you can velcro it anywhere. If all you want is speed, vmg, course headings, compass... etc. that's the ticket... you can set up the display to show TWO LARGE data sets... speed and VMG , for iinstance.. you don't need charts for your purpost. You can find them pretty cheap.. I've had one for 5 years or more... never a problem, only uses 2 AAA batteries....