thirdchildhood

iTrader: (6)

I plan to do a with and without comparison later when the water is warm enough for swimming but right now I'd like real world experience if anyone has experienced top speed loss from dragging a mechanical speedo pitot like this one on my boat. My average top speed is around 83 mph on gps.

MILD THUNDER

iTrader: (3)

I didnt even know people still used pitot speedos. Is 83mph from the pitot reading?

GPM

Just curious, is that speedometer or GPS speed ? MT, I guess we're wondering the same thing.

the deep

iTrader: (8)

You will see a speed loss when you go to GPS .

thirdchildhood

iTrader: (6)

No. I have gps on my chartplotter and also a handheld. 83 is average top gps speed. 85.8 is highest ever recorded speed. (no, not on the river!)


I want to keep the stock analog speedo and it only reads about 2 mph high on the top end. Looks more impressive to passengers too . If that pitot is scrubbing a couple mph though I will install a gps speedo in the dash. I've heard that a pitot can rob up to 5 mph. Has anyone seen that? I can't do the back to back runs until the water warms up.

dereknkathy

I was gonna say not if you asked the speedo. it is amazing how much drag a GPS signal induces. slows the boat down 5 mph sometimes...

Griff

I doubt you'll see more than a half mph, if that.

dereknkathy

that pitot is less area than a barnacle. pushing a hull thru water at speed is a whole crap load of drag. that's why 100 hp for 10 mph increase is optimistic. you will never measure a diff from something that small. but you will pick up 5 mph just by believing what that pitot has to say.

thirdchildhood

iTrader: (6)

OK, I have heard people claim to have seen a measurable loss from a pitot. Try to hold your finger in the water at 80+ mph! One person claims to have lost 4 mph which didn't seem possible to me. That's why I was looking for other input here. Here is a pic of my dash and the original speedo I'd like to keep working and a pic of my best recorded top speed.

Lee

iTrader: (4)

The issue with a Pitot is not the drag of the Pitot itself, it is the result of the water disturbance caused by the Pitot that can affect the prop.