If I can run 16 up river, and 21 DOWN* river....
Does that mean I go 18.5 in still water?


Sent from my iPhone using Tapatalk

Depends. The current may have more effect on your boat going one direction or the other. There's some math here I don't feel like doing right now, and the effect could have different results with more current or less, as the drag from your boat and drive/prop will hit a point where resistance won't be as linear.

It's not going to be as simple as saying 2.5 mph current, so against is that much slower and with is that much faster. It might be a coincidence at the speeds you're running with your setup if that was actually the current speed, but lift is created from the surface area of your boat in contact with the water at whatever speed, so any speed difference will affect lift and drag. Won't be the same for different current speeds.

By my calculations....I dont know.

It appears you have a integration error.

18 mph in still water.


Sent from my iPhone using Tapatalk

Fresh or salt water? Water and ambient temperature? Stationary or movable load?

On a more serious note, I see lots of people determine their max speeds on hand held devices. Realize, that if you move your arms forward just to read the numbers because you're farsighted, this will add at lease 2 or 3 mph to the max reading. It will be higher because you are moving the device forward adding speed relative to the hull. A similar thing will happen when you slide on turns.

The correlation is thus: The older you get and the worse your eyesight becomes, the faster your hull will be.

After GPS, it was both good and bad. You could more accurately determine of course your location but also your speed, so right away you want to improve the number...I got frustrated with that so I just get up earlier in the morning.