You don't need to convert anything.
Change your unit's GPS format to DD.DDDDD and enter the numbers as they show on the Lake Waco list. If you run out of number spaces, that's OK, use what you can.
I just did that first one with one of my Humminbird units and it is on a line of fish attractors that are on the Lakemaster map north of a boat ramp about 8' depth under a bridge.
Looking at Google Earth, it is on the East side of the fourth bridge piling from the East shore or 597 feet North of the ramp.
Edited by Wayne P. (01/16/18 06:34 PM)
Humminbird Helix 12 CHIRP SI, 1198c SI, 1198c SI, ONIX 10 SI NT, Helix 7 CHIRP SI GPS G2, SOLIX 12 SI, 360, RC-1