No, I didn't take it out on the boat. I did uncheck the Road Map and checked the Winni. I just felt that sitting a couple of hundred yards from the black and red buoys out from the Back Bay bridge, I would see the markers.
As far as the Markers for Bizer are concerned, at the settings I use, I can see the RW or BW for Red or Black OK. My biggest problem is my C550 is terrible in bright light. I would guess the Nuvi 500 is much better.
Like you I know the lake pretty well, at least my end, but occasionally I want that final look, first the chart, next the eyes, and then see it on the GPS. If they all work out, I figure I have a 50/50 change of missing a rock

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I am trying to convince my wife we have a real need for the Nuvi 500, but haven't quite got there yet

. Can you spell Santa?