How critical is it to use a torque wrench when tightening the prop nut on a 150hp Merc. ?

A whole lot of people that owns boats don't have a mechanical bone in their body and don't have a clue what would be considered snugg or tight, for them one would be highly advised. In the nearly 45 years I've owned boats with Mercs, Johnson's and Evinrudes, I've never once used a torque wrench on a prop, and never had one come loose or be stuck on and wouldn't come off from over tighening.

If you have been twisting nuts on for a good bit of your life and have a good feel for when a bolt and nut assembly is tight enough, by all means go for it. But if you want to error of the side of safty use a torque wrength.

Harbor Freight has them quiet cheep

You don't need a torque wrench for the prop. Tighten the nut far enough so the locking tabs will fully bend into place. Bend the tabs in place and go have fun.

Thanks guys--kinda what I figured. Have a great season.