The log on my 26 footer seems to over read by 1 knot when compared to speed registered on my GPS ( please ignore tide in this discussion). having enjoyed the false feel good factor that we are sailing wonderfully for long enough, I am now wondering if i can recalibrate the log to read more accurately. Can anyone advise if this is possible and if so how do i go about it? (Switch it off and stick to the GPS???) Thanks