I've always heard how inaccurate these things are, typically on the high side, with members saying discrepancies can be as high as 15mph. Well, not mine. I was out playing a couple weeks ago and and decided to check them against each other.

My Gaffrig pitot tube speedometer from 1997 is within 1-2mph from 35mph to 72 mph, the highest speed I saw that day. The batteries were dead in my Garmin so i had to use a speedo app on my Galaxy S4 and couldn't get any pics. I can see why the Gaffrig is accurate, the scale isn't linear but has a decreasing rate.

That saved me like $500.

With my last boat, I was always hitting chit in the water and bending the pitot tubes. When the tube was brand new and straight, It would read high. Then it would end up getting bent a little and read right on with my GPS. Then it would get bent more, and start reading low. Bought a GPS speedo and never looked back.

My current boat does not even have a speedo. I just use the GPS.

My old Norskog was usually within a MPH across the board, but as Dave said, bent tubes and messed up brackets made GPS the best choice in the long run. I haven't run a manual speedo in years.

Mine just uses the pitot built into the Bravo

I had a liquid filled gaffrig in my boat when I bought it, with transom mount pee tote. Metal gaffrig one.

Speed readings were close to GPS, very close.

Another buddy has same setup, speedo readings way off. Low actually. He probably has some chit clogged in his pee tote though.

I agree no speedo just a GPS. I think we are in a minority but I think the GPS is easier to read then a guage and it gives more room on the dash for things like oil temp and water pressure.

Padraig

I used to have a paddle wheel speedo with a trolling mode switch. From 0 (and I mean zero, if we were anchored and the current was moving in troll mode you could see it) to 55 mph it was dead on. But like others have said a couple debris whacks and it was never the same. Nowadays the only time I use gps is prop testing besides that it rpm's are all that matter to me.

Without a speedo, you cut down significantly on gawkers looking at the speedo and debating from the dock whether the boat can reach the big number....

I didn't hook my speedo back up after I did the transom in my scarab. It's a liquid filled gaffrig it was fairly off. I played with the pilot tube but could never make it better.