Just want to point out that gps gives speed over ground while an in-water "wheel", which I assume the Luhr Jensen is, will give speed relative to the water. If you are going into a 5 knot current and your gps says 3 knots your lure is travelling against 8 knots of current like a pinwheel. Same problem with the current when GPS says 5 knots and current is 5 knots your bait is static.
Interesting...I never even thought of this. Okay a few ignoramous questions coming up here...
I get if you are, say, going into a 5 knot current and you are moving at 5 knots then 5+5= 10 knots that your gear is moving. Same idea if you are going witth the current eg moving with a 5 knot current at 3 knots = 5-3 = gear moving at 2 knots.
Now does this only apply to fishing where there is current, as in the river or ocean? As far as I know there is no current in lakes, just wind. In other words, a handheld GPS which shows speed over land should be the same as speed over water???
Do boat GPS units measure the current and give you a speed over water reading...in other words...how is one to know the speed of the current?
If I'm going to buy a handheld GPS I want to make sure it'll give me a proper reading when trolling, otherwise I might as well not bother and just guesstimate with rod bent, etc