I use a Delorme pn - 60 and its dead on accurate for speed when long lining and trolling, and with a map of the lake its more accurate on bottom features if you download USGS topo maps of the lake and install on it. But,,I also use it for hunting and backbacking western mts. and southern mts as well. There are other units that are just as good as delorme, like the garmens. Delorme has a pretty steep learning curve and have used it since delorme started making them...before that,,I used delormes mapping software with a hand held lorance model. One thing you have to get really used to is the small screen..but fishing out of a jon boat,,this works for me with my lorance fish finders front and rear. You can use most hand helds with a 12v cable attached to them, or with delorme, I get about 8 hrs of battery time before switching out the lith. ion batteries that are rechargeable. Waypoints are dead on accurate as well with hand helds today. If it were me,,I would read up on each at their websites. I never have like Magellan but my 2 picks for best handhelds are Garmen and Delorme. both are waterproof and shockproof to some extent. Both have fantastic service and warrantee depts. as well. Good luck on your picks.