2 problems with depth finders-- lms 520c & hub 787c2i

[DTG]

Lms-520c-- loosing digital speed reading but chart will still show correct bottom depth, sometimes?
Hb 787c2i-- speed reading all over the place at .08 or slower.
-- what is my fix for both?

[DTG]

.

[CatFan]

It's virtually impossible for a GPS to display really low speeds. 0.08 is way below the capability, so I assume you mean 0.8mph which is only about an inch a second. The drift on the GPS signal is greater than that, so there is no way for the unit to know if it is moving or if it is seeing position error jumping around.

When does the 520 lose the speed reading? Is it GPS speed or paddle wheel speed?

[DTG]

gps speed, could be the auto sensativity on not sure have tocheck when i get home

[yikess]

I had the same problem with my 787c2i and Humminbird sent me a free external gps puck and that solved my problem down to .4.