Emaginashun

We may both be correct. Found this.

Currents, tides and wind - Kayak Example.

The GPS does not know if the tide, currents or wind is a factor. You might be paddling at 3 1/2 knots and maybe there is a current of 1 knot directly in the direction you are paddling or directly against you.

In the first situation, your paddling speed would be 2 1/2 knots and the second example your paddling speed would be 4 1/2 knots. The GPS would give you the correct kayak speed, but not your correct paddling stroke speed. If you had 4 miles to paddle and you figured your speed at 4 1/2 knots but the tide is now against you, the calculated arrival time based on the GPS would be inaccurate.

You would have calculated about 50 minutes and now it might be 1 hour and 15 minutes due to the current. You must be aware of all factors.

CigDaze

I like what you said the first time better, before you edited it.

Don't put too much faith in your professors. When you graduate, you'll really begin learning a thing or two.

The point of interest to boaters is how fast a boat is capable of moving through water - UNAIDED. Follow me?

No one is arguing the results that a GPS provides.

It does one thing and one thing only, regardless if you're walking with one or have one mounted in an aircraft or boat. We are all clear on what it does. It provides your position, and calculates speed based on a delta position over a given period of time. We're all clear on that, no need to further explain it professor.

The point is, that the speed shown by a GPS is that with which you traverse distances, and that is of less importance to boaters, than knowing how fast you move through water. Thus, it is of no wonder that any official record is conducted using the average of two passes in opposing directions. Why?.....Because, in order to measure speed through water, you have to eliminate the fact that the water may be moving, and the wind may also be affecting your results.

I don't know about you, but when I'm in an area where the water is really moving, locally for instance I know of a shallow cut that can flow water at about 5 mph...When I look at the GPS and it tells me, I'm going 5mph faster than I've ever gone before, I don't start jumping for joy, or have the right to say my 80mph boat does 85, because my GPS said so.

CigDaze

There yo go. When we speak of paddling speed, or a performance boat's speed capability, you're interested in your ability to move through water -- Not how fast you'll reach your destination with or without the aid of a current or wind.

customryder

one is a chart plotter with gps... 1 driver 1 passenger 1 rear passengers.