I have a 17 1/2 ft aluminum Crestliner with a 115 Yamaha. I have read about using Keel guard to protect the bow/hull when pulling up on beaches etc. Does anyone have any experience using it...and if so....how far back do you have to go with the keel guard to protect it? Or is this another gimmick?<br /><br />Thanks for the help,<br />Glen