alluminum vs fiberglass question

I have a bass tracker (alluminum of coarse) and i was curous about the hardness of fiberglass. I have several dents in the bottom of my boat where i have hit stumps, etc., I was just above idle!, and was wondering if fiberglass will break or crack under the same circumstance. I know when i've fished with guys in a ranger they will come across stumps and to my knowledge it doesn't hurt the fiberglass?? Any info on this be appreciated. I dropped a chair on the rail around my boat and it put a 4inch dent in it???

fiberglass will chip, crack or perforate, due to impact from right sized object and force of blow. You could drop a concrete block on the gunnel of a ranger from 3 feet and it might crack, but it might just scratch the hell out of it too. Stumps are usually somewhat softened by water and a fairly large area impacts the boat.
Aluminum is thin and flexes and that is why it dents. If it didn't flex, you' have holes, not dents.
Ranger is tough as they come when it comes to fiberglass fabrication. Some fiberglass boats are very thin and wouln't take too much stump teetering. Hardness is professionally tested by a method using a very sharp point and the depth the point makes defines harness level. Aluminum is a soft metal, the thinness of hull to save weight is what allows it to yield, bend. Fiberglass is pretty hard (it doesn't flex much) but it really cannot be tested in the same manner as metal.

They both have their places in the marine world.