As posted above by lonkm
If you read the book CAREFULLY it will tell you how to do this properly. The 2009's will have an even more accurate gps. One meter! There is an unofficial web site for Hummingbird on Yahoo.
the Hi accuracy ant. Referred to in above post can only be gotten/bought as an optional accessory for I believe $199.00. Supposed to be good to one meter or less....
The new standard 50 channel ant that comes with ALL the new 2009 models, & can also be bought for $149.00 is supposed to be good to 2 & one half meters or less. The old 16 channel ant. that came with earlier units is supposed to be good to 3 meters or less Needless to say the problem of SLOWGPS cannot be resolved with a new ant/puck or with the instruction book cause the fault is in the working of the main unit processor itself.