I am going to fish (in my new boat   ) mostly in the local river there are some shallow spots and the bottom is rocky.

would it be worth the investment to get one of these?

http://www.scottiescanvas.com/products/boating_products/prop_guard/index.php

Jet drive.

I fish in some pretty rocky areas and I've never seen one of those guards on a boat. In theory they seem like they'd work. Not sure how they would affect performance. I tend to worry more about my lower unit housing than my prop but then I don't have a high end prop either. At the river tourney I was in last month a guy had an Xpress bass boat with jet drive. It was the perfect set up for that environment.  

Jet drives might be in trouble in some tournament trails someday, already if I remember correctly. Where did I read that?  :-/

That last prop guard posted above would probably make backing up pretty hazardous. The first link is a better idea for rocks but if anything solid got wedged in it.....

Better yet don't use your best prop. Carry a spare and tools to replace a damaged prop. Raise the prop as high as you can and still get coolant water pumped and move the boat. You don't want to get disabled in a shallow flowing rocky river. Use the trolling motor in the shallowest parts and navigate upstream if possible. If you can't see bottom turn the sonar down to low sensitivity so you can watch bottom, or use a paddle to sound it.

Jim

I to do a lot of river fishin with some shallow rocky places to run through.  As said above best not to run your best prop and always have a spare and tools just to be safe.  Seen this at bass pro and think it might work well.

http://www.basspro.com/servlet/catalog.TextId?hvarTextId=20945&hvarDept=200&hvarEvent=&hvarClassCode=2&hvarSubCode=7&hvarTarget=browse

Dont know how it would effect the top end of the boat though?

Jim what was the reasoning behind banning jet drives?