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?

To do that will require a computer system. the Garmin series (72 and above) will recognize a NEMA data stream and have a depth feature that will read from a device that will communicate with it. I think, however, that only some computer based sensor can stream the correct data to the Garmin and I don't think the Garmin will record the data - only display it.

You can purchase small, in dash, waterproof depth units. I once considered making a device that would fit into a port cover with a batterpack underneat. They make depth sensors that will look through the hull (without drilling holes) too. Perhaps just having a depth display might help you?

What you want is available, but I hope you have deep pockets ... to handle the where you were vs. where you're going, FLS (forward looking sonar) is available from several mfg also (for even more $$) ... as for mapping/marking ... Lowrance has sonar/chartplotter combos with WAAS ... if your reservoir isn't on an electronic chart, you could always hand plot it (hit mark for every thin water rock and plot it later by hand) ...of course you still need a real bathy chart of the lake/reservoir ... Check out Humminbird and Garmin as well ... and keep this in mind: plotters using Navionics electronics charts have access to a 8,000-and growing lake database don;t know if your is on it, but ... not sure what freshwater coverage Garmin Blue Charts have ...

hey ... maybe - if the reservoir HASN'T been bathy'd you could get a grant to do so ...

Good luck or keep the boards up!

gary

Sorry I accidentally sent off a reply that was still being cooked up, so I deleted it. Here is the finished one.

Thanks Jake.

Do you know if they can look forward? If so at what angle? Is it possible that they look in the direction that you point the sensor?

If you could put it inside the hull that would be deluxe as I always heard that they were something that you put on the outside which would be bad news. Damage would be a constant nuisance. Our weather radar sits behind a fiberglass cone on the nose of the aircraft.

Just a depth display would be a good start. but having a means to record the depth and position so you perhaps download it to a computer when home to plot where potential danger zones are. I could then make them waypoints and maybe have some sort of alarm go off when in their vicinity.

Years ago when I was into hang gliding I used to go on trips with a few friends who set a few records (Washington state just east of Chelan across the Columbia River). They had devices which recorded altitudes and positions every so many seconds. When we went back to base after a day's gliding they would download the device to a computer and plot the day's ups and downs on a altitude versus position program of some sort. This was around 1990 to '93.

Thanks Gary,

Our Smallwood Reservoir is huge. It is 67,340 square km. Located just north of our airport @ 53.33 North and 64.05 West. There are topos somewhere that would define the water depths and I have looked around for them but no luck yet. Regarding the depths of my pockets, am sort of guessing that they are not deep enough... : ) to sustain the hit from a FLS : )

So Hummingbird and Garmin are the source of the Blue Water charts? hmmmmm sounds (NPI) like thay would be a place to start. I have always heard good things about Garmin.

Another possibility which would be labor intensive would be to put a buoy at danger spots... maybe not <img src="http://www.catsailor.com/forums/images/graemlins/tongue.gif" alt="" />

Jake what ones would you suggest?

My next consideration would be to have a depth unit as you suggest and whenever it showed shallow water I would be able to slow down and take a waypoint manually with a GPS unit. I was thinking that I would just set up waypoints for submerged shoals and thereby avoid them.

any thoughts?

something like THIS . I can't speak for it as I never did buy one to try.

polarized sunglasses help pick out dark spots (rocks) on a sunny day.

By the way, we just became a dealer for Magellan and Garmin. Just go to our web store at www.OnLineMarineStore.com and in the search box type in Either Garmin or Magellan and it will show you the whole list of products we are now handling.

Or, in the left index click on Electronics and follow the trail.

Good luck,
Rick