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Chart speed vs. boat speed settings

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Jolly Roger:
Hi all,
I always wondered what chart speed in relation to the boat speed would bring the best screen performance. So I did some testing with my 981 and checked what setting at what speed would give a decent picture. Since I mostly use my unit to search for structure, I tested both the 262 kHz and the 455 kHz.

Scanning with 455 kHz shows better details, but also some white clutter if I raise the speed. I guess this might be an electrical interference problem, but haven't bothered to route the cables in a different way. Something I'll do when the weather is bad or next winter.

The 262 kHz screen is a bit darker and seems not as sensitive to the whitening as the 455 kHz.
To get a comparison I used the wreck I found in May as a target.
Speed is shown in Km/h and depth in metres.
For those who don't want to bother to do the calculations:
Speed was 3.5 , 5.1 and 6.1 mph,
depth of target: 67.2 feet,
length of target is 10 metres respectively 30 foot

Here are the 455 shots with the setting menu inserted:







And here the 262 kHz shots








I think I can live with these settings ;-) and hope this might help you to get your unit set up.


Best wishes from Lake Constance
Harry

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