I accelerated my 25 HP Mercury tiller steer boat today and heard the transom creak. Didn't really scare me, but was a reminder to inspect it.

I have observed the evolution of outboard motors from the 1950's, and wonder if engineers didn't rely on too much, and should have moved away from hand tightened mounting clamps sooner.

Mercurys had black plastic T handles, OMC and others swinging levers. I remember when the clamps first had hex heads and no handles. I wouldn't doubt the first 80 HP 6 cylinder "Tower of Power!" Mercurys still had the T handles, but assuredly had transom bolt holes also.
I remember first OMCs I saw without clamps and how insecure they looked. Sometimes they'd mount the motor high so the little lips weren't even over the edge.

Anybody have an idea of the highest HP outboard ever made that had hand clamps? I'd bet it is a Mercury, and guess it's about 100HP.

Imagine a Seven outboard with a Cadillac V8 with hand clamps.

My Mercury 1500 has the T-handles and two bolts through the transom. I have a block of wood about 1 1/2 inches under the mounting bracket so the cavitation plate is even with the bottom.

We use to build 8-foot hydroplanes out of plywood and cover it with fiberglass. I think a Mercury 16 HP was the largest engine used.

Our first engine was a 16 HP Johnson on a 12 foot boat. We later upgraded to 35 HP Mercury which would push it to about 36 MPH with one person.

The Mercury in line 150 horse 99 cubic inch motors were the largest motors that they built that had T handles and two bolts. The larger V6 150 horse 120 cubic inch motors bolted on with four 1/2" bolts. The is no comparison between the performace of the two motors.

Living lands and waters use 70's on their collection boats
https://www.youtube.com/watch?v=pt1S9ny2TdY