GPS Ferries
I paddled up river to explore the whole section from the river mouth to the Big Mandinga Lagoon. I learned something during the 10 mile paddle, that I consider interesting and I can place in two laws. Let me explain. I entered a large lagoon and wanted to reach a fishermen community that I had marked in my GPS beforehand. All the lagoon surroundings look the same, and being the first time, there was no bearing to choose. I started paddling following the GPS arrow to that point. Looking at the arrow aligned with my bow, I chose a bearing in the still countryside.

Getting close to the bearing in the same direction, I realized that the GPS was pointing now to another place very different from the original. If you turn to follow the arrow youŽll eventually reach your objective, but not in the shortest way.

I was making almost 5 mph average going out. Coming back I set my GPS to my starting point and it showed a house in front of me. When getting close to the house the GPS arrow was pointing left, and it was apparent, once close to the house, that the channel I should follow was on my left side.

I started thinking and realized that GPS points the arrow to the front when the paddling motion plus drifting goes in the right direction. And that is not the direction the bow is pointing at. That means that the GPS reads true motion, and true direction is not where the bow is pointing. Therefore I agree with somebody who said last week that he rather relies on his compass and uses the GPS only as a back up. GPS will take you there but the feeling of rounding the path is strange, if you try to fix bearings.

Philosophy is inversely proportional to speed. Then I discovered that the more time I spent figuring out the GPS behavior the more my average speed decreased.

Therefore I must make up my mind. Analyze hard or concentrate on my paddle. Seems like one never stops learning. This is a fun sport.

    Rafael Mier-Maza
    El cayuco chief


Steve Holtzman adds...

Rafael,

You made some very good observations concerning the use of a GPS. The next time you are in a situation where you are using the GPS to navigate, instead of using the navigation screen, use the map screen.

You should make a "go to" or "route" depending on your GPS to your destination from your starting point. Then watch on the map screen which way you are deviating off of the indicated route and correct for that so that your actual track overlays as closely as possible on the planned route.

Depending on your GPS, you can also watch the cross track error and let that be your guide--there is usually a screen that will show how far off from your planned track you are and in which direction. Keep cross track error small, and you will paddle a fairly straight line to your destination.

As you found out, a GPS does not replace a map and compass--it is in addition to.

I love your philosphophy---you are absolutely right. The more time one spends playing with the gadgets, the slower your overall speed is. But then again, if you were looking for speed, you'd be on a jet ski--not in a kayak.

Take care my friend and come back and visit us again,


Submitted on November 11, 2002