I'm not sure if this is the right place to put this (perhaps I should put a feature request in for a 'General' forum topic :) anyway...). What speeds are some of you using to do your mapping? I typically go pretty slow, about 4 to 6 MPH, but I noticed that my map is starting to fill in pretty well for some of the areas I just run.
I'm looking for a good overall speed to pick up decent detail but cover some water too.
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With a modern GPS with 5-10 Hz update rate, you really need a fast boat if you want to "outrun" the sounder and GPS. I usually go 5-6 knots over the really interesting stuff and 20+ knots over areas of less interrest. But making a tight grid-pattern is more important for a quality map then your speed is.
I do two kinds of card, in way to the to fishing spot or during fishing, there is high-speed (30/35nds) which gives me an overall view of the area add up records. The other i do specialy for mapping at low speed (the side is used if it is deep enough) on the point raised on the first maps using the grid to visualize my calculated based on the passage of the cone of the tranducer and the mean depth.
I use a TM258 from airmar at 5°.
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Thanks! That gives me a better idea. My mapping is being done on lakes with a Humminbird 998 out of a 21' Ranger bass boat so it's not like I've got a real elaborate setup. The 998 plots a point every second so I just wanted to get an idea of how much space I could allow between points and still get a good level of accuracy.
The numbers I came up with would suggest that if using a 20 degree cone in 10 to 15 feet of water I can expect to cover 3.5 to 5.25 feet. In order for me to cover these distances and not miss anything, I would need to go about 2.38 to 3.58MPH (between 2 and 3 knots).
I understand that it's all going to be relative, but would it be better to miss every other 3 to 5 foot section using 20 degrees or better to use a 60 degree cone and get lower detail but roughly 3 times the coverage?
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It depend of the structure bottom, if it is flat no matter to do it with less time and large cone, but if you want accurate map, small cone and low speed, Take help of your side and look where you can change speed!
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