I am looking for the following combination.

A GPS (WAAS capable) that has some sort of depth determining capability and a memory so I can map the large reservoir.

The reservoir where I sail has some nasty rocks which lurk below the surface. On my H14 they are not an issue other than inducing a mild heart attack when I grind over one. On my Tiger they get your attention and last summer my girlfriend and I were on a reach when we struck one with the daggerboard about 1/2 extended. She slid into the daggerboard and hurt her ribs. (she had a cold water immersion suit on. She will probably use the life jacket this year. Then of course there was the extensive daggerboard damage. The rock was very dark and almost invisible.

So what I had in mind is if I had a depth measuring device of some sort that recorded the depths while sailing I could set it to alarm at a preset depth. Also I would like the ability for the GPS to obtain a history of the water depths as I sail around so it could map and remember for next time and have some sort of memory that would warn me that I was heading for disaster. Similar to what is used on aircraft nowadays called a EGPWS or Enhanced Ground Positioning Warning System. or TAWS Terrain Awareness Warning System. In the aircraft version they use a database with the maps in the memory combined with GPS etc to show up on a monitor the height of ground that your current trajectory is headed for. The previous GPWS (pre GPS technology) simply used a radar altitude, but that was useless if you were heading for a mountain because the device only saw the ground below so when the Radalt saw the rapidly rising terrain it was too bad so sad. (Controlled Flight Into Terrain CFIT)

I do not know much about the handheld GPS systems or depths sounders or fish finders except they tell you where you were... Which is useless except as a memory for next trip. So if I were to put the depth device on my 14 I could be mapping as I cruise around and then the GPS would have either some sort of waypoint entered over shallow areas or a warning of some sort so when I go "a tigering" I know what to avoid.

Any thoughts?