Knotmeter or GPS?

[ira]

I bought a Catalina 25 and want to be able to read boat speed; are installing knotmeters a thing of the past, now, and people just mount a GPS somewhere in the cockpit instead? Mounting a GPS, if that's what you do, would seem much less convenient than bulkhead mounting of the old-fashioned traditional knotmeter.
- I am aware that, unlike a GPS, a knotmeter shows speed relative to the water, not the ground. What do sailors these days prefer?

 

[Stu Jackson]

Both

since they show two completely different values and important information which are important if you sail where there are currents.

 

[Ray Bowles]

If you are trying to measure the effect of changes to your sail trim or other improvements in real time for performance then a knot meter is a must. If you want to know speed over ground then a GPS is the answer. If you want the difference between speed over ground and actual boat speed then you need both. This allows you to know the effect of current.
I love performance and want to know the effect of my sail trim and boat handlling so a knot meter is my main instrument.
I also us a GPS for course ploting and directions to steer to the next point.
Heck, boost the economy and buy both because you can use both all the time.
Ray

 

[Bilbo]

I use a GPS here but I have no currents. From what I hear the knotmeter is more accurate (if working correctly) because the GPS can give false readings. I've had some top-speed readings that aren't possible with the boat. I think that this is because the unit doesn't always get the signal and that when it does, it tries to "catch up". So, as a speed meter for a discerning one that is uisng it for honing sail trim, it's not quite accurate enough.
On the other hand my little GPS can provide other information such as course tracking that is good to have. I have used my handheld gps following past course tracks and waypoints to find our way home through the pitch darkness to an accuracy of within ~5 yds of an unlighted dockage.

 

[Banooma]

Ira, there's no right or wrong answer. As with most discussions on this site, the answer depends on how, and where you expect to use your boat. If you are performance-oriented, or destination-centric, measurement of speed and course are absolutely essential. If you bought your sailboat because you simply love being out on the water, have easy access to open sailing water, and do not intend to ever be more than an hour or two of where you launch your boat- you may have no real need to know how fast you're moving relative to land or the current. It's ok to simply enjoy daytripping, as well. I'm still new to the instrumentation on my boat, and it's cool to have it, but all I had on my previous boat - a Hunter 23 - was a handheld GPS, and that was was more than I needed.

 

[Maine Sail]

If you

If you are racing, or "sail tweaker" then you'll want a knot log. If you are simply cruising and don't really care about that extra .02 knot of speed then a GPS is fine.

 

[delliottg]

We have both on our C-250. In fact I generally have two GPS units on the boat, one's a chartplotter (Garmin GPSMap C-276), and the other is an older Garmin GPS 12 XL. I use the C276 to connect to my VHF radio for DSC capability, and the 12 is there generally just for back up. We sail on the Puget Sound, so there are currents & tides to deal with as well as the river we have our slip on, so I like having the GPS there for that, but as stated above, having a knotmeter (ours is dual readout speed & depth) is good for judging sail trim for your speed over water.

 

[PCP777]

I have a knotmeter and to me it's my report card in terms of sail trimming. I have no current where i sail, so I presume it's fairly accurate. I've also had a partner who owns a different C-25 who brought his GPS along and was able to determine that our boats point about the same compared to his previous tacks (He thought he was taking a hit for his wing keel) and that my knotmeter is more or less accurate.