20 hp merc diagnoses

We have an old 20hp merc outboard from the 70's which was always running fine. We were cruising thru a narrows when it felt like we hit a rock / log so I stopped and took a look at the prop but did not see any impact damage. When I started up again it would only get up to trolling speed. When I gave it more throttle it just would not give any more power. Does that sound like a shear pin problem or did something else let go? The motor sounded like it was reving higher but the power was not getting to the prop. Thanks for any suggestions and if you think its worth fixing.

could be the impact spun your prop bearing an easy fix for a prop shop unless you do have a shear pin then it could be that doesn't sound to serious pics help a ton

just a question as a layman,what would happen if the bottom end or shaft was cracked?

Cracked case?, rusty gears and bearings. Cracked shaft, never heard of it but, bent shaft, the bearings will grenade, depending how bad the shaft is bent, pretty bad vibrations which will cause more damage.

My old Johnson did that when i hit a rock once. It kept running slowly until it finally gave up and a nice guy towed me in. It was a sheared pin and a quick fix. Hope that's the same for you.

Hope it's none of that..

Thanks all for the input on my situation

I hit something once way back in time. Did same thing, everything sounded good, but as soon as you gave it gas it would start to go then back to a troll. Spun the hub, which I know, but no spare prop. Cops came a long and didn't believe me, figured I was just going slow to spend time with the girls we picked up, I was very young. I was few hours late in reporting in so the cops were called. They never even offered a tow, just cruised along side watching us. Had 5 miles to go so took over an hour to get to the ramp with them in tow.