help sorting out sounder/gps confusion!

[chiroken]

I'm finding this very confusing...not much experience with these combo units. I'm thinking of replacing a portable fish finder that came with my boat. It'll be used mostly for trolling (downriggers) or perhaps jigging, saltwater for salmon. I would like to be able to determine speed along with having the depth maps for my region (west coast Canada).

Locally seems to stock Garmin and Lowrance. Don't know if the Garmin products are in my price range, I'd like to be able to afford to get into a 5" screen if possible rather than the 3.5" screens. A split screen on a 3.5" screen seems awfully small until you're right up close to it.

I don't need every feature under the sun. Basics being an accurate sounder, split screens, prefer colour, accurate trolling speeds, chart plotter/maps, saving of way points (or previous tracks would be nice).

Someone locally is selling a NavMan 6500, haven't heard whether or not this is new or used. Never seen a NavMan before around here.

The lowrance doesn't allow you to show speed if on fish finder full screen it seems whereas the garmin does. What measures the actual speed? Is it the transducer or the gps? I'm not talking about running the boat at 25mph, I mean a speed of 2.2 or 2.8 when trolling. The shop with the lowrance said I needed to add an extra speed wheel ($80) that plugged together with the transducer before it plugged into the unit to give me speed but aren't those for higher speeds? Will certain transducers give you detailed slow speeds or is it the gps that actually gives you your speed?

The fact that there are so many tranducers alone gets confusing. Any advise?

Thanks

 

[Pez Vela]

Re: help sorting out sounder/gps confusion!

You're going to want a tri-ducer which provides depth, speed and temp. The speed comes from the tri-ducer's "paddlewheel" which provides your speed through the water, which is what you want to know if you're fishing/trolling/mooching. It works at high and low speeds and everything in between. Your chart plotter will provide your SOG ("speed-over-ground") which is derived from the GPS, and it useful for knowing your progress to a destination, among other things. With a combo GPS chart plotter and sounder (equipped with a tri-ducer), you'll have it all. So, buy right the first time with one multi-purpose tri-ducer, and the biggest screen you can afford and mount properly. I'm partial to the Raymarine units because that is what I know, but I'd recommend whichever unit you find to be simple and easy to use.