TOPIC: short shaftvs long shaft

On a '62 Pipestone, with a 21" transom, we are still struggling with frozen steering on our 70 HP Johnson.(long shaft)
I have a 65HP Merc (short shaft) that runs well.
We are thinking of swapping motors, while tearing the Johnson apart to fix the steering.

I have seen the charts, showing transom heights and the recommended motor lengths. I know that the boat wants a long shaft motor.
My question is specifically "why"?

Is it a cavitation/power issue? It looks like the waterline would still be considerably higher than the water pump inlets.

Any chance that this would work for a few trips to see if we even like the general layout of the boat?

Thanks in advance

Mike

You could idle around, but any attempts to speed up would result is severe cavitation and engine over-heat.
In other words,...It simply won't work.
Doc

Your cavitation plate should be below the the bottom of the boat. I felt an inch or less was nice but you may find other opinions on that and I'm not saying I'm 100% correct. You must get water into the beast or it will soon die.

You could mount a Jack Plate to the transom which would allow you to mount the Short shaft motor and Lower it to the proper height and run the boat with it while servicing the 70hp motor and then when it was ready to go, remove the short shaft motor raise the Jack plate and mount the long shaft.