My boat came with a gps thats about 10 years old when I bought it , so I wanna install my humminbird of course and toss the old one. How hard is it to do compared to something like a car stereo? Does the fact that there is already a gps make it easier? Just follow the wires ? Is there a good how-to video online somewhere ? The one I got is a hummibird 798 pre loaded with navionics bundle package. Thanks guys

Is your new GPS unit a GPS unit only or is it a GPS unit AND depth finder?  There's a big difference when hooking the units up.

798 should just be a two wire power hookup plus the transducer cable if you are not linking it with another unit.  Follow your existing power wire and run the new one there.  If your confident that your existing GPS is a two wire as well, you could just tap into that wire and avoid having to fish any wire through your boat. Personally I think its easier than a car stereo to hook up.

I have the 998 which should be essentially the same install...it is pretty strait forward for my boat.  As what was said - there are two wires for the power cord - follow the old units power cord - mine was under the console - I cut the old red and black wires and saudered in the new red and black wires.  The transducer was the harder part for me - you need to make sure and follow the manual's directions pretty close to ensure you do it right - you need it level and in the right position to give good results - the transducer coard was not all that difficult to route through. There was a couple of panels I had to take off or loosen to get the transducer cablet routed appropriately.

Here is a little tip.

If your old transducer is still there and runs through a tight spot hard to get through but is movable - you can tigh your new transducer cable to the old one and use the old one to feed the new one through....that helpd me alot personally.

It was tedious of a job for me - I am a pharmacists though and not very handy - but if this pill counter can do it so can you

I have never installed a stereo, but this should be easier I would think.

Here is a great site for all the SI information you need........personally I mounted my ducer high enough where  I don't have to worry about it, I also have a flasher for when I am on plane.

http://groups.yahoo.com/group/sideimaging/

p.s. a new ducer for an SI system is well over 200.00 dollars.