Outboard prop guards

[Randle]

Does anyone on this site have any experience using one of those circular prop guards on a small outboard (15 hrs or so)? I run my 16 ft Jon in the MO quite a bit and dont want to invest in a jet but I also dont want to mess up the prop.

I've banged a few rocks but nothing too serious yet but I'm afraid its just a matter of time. I was wondering if those guards are as effective as it seems they would be or if they cause any problems like slowing your speed.

Thanks

[Hotwired]

I have one on my kicker and use it mainly to keep the wire out while handlining and it works great.
I also use the same motor 6hp up north as the primary on my 14' aluminum and it does take about 1-2mph away and collects weeds. I have bottomed out in shallow water and did not break a shear pin.
I think they do their job.