TOPIC: transom height vs outboard shaft length

in the member project section i am working on a whirlwhind with a transom height of 16 inches, originally it had an extra piece of wood that added 2 more inches total 18. I found a mercury 40 ph that was priced right and was running, but it looks like the distance measures to be 21 inches, of shaft length, from videos i watched on how to measure it.

Will an extra 3 inch depth of the propeller in the water be much of a problem?????? i guess I can add an extra piece of wood to make it what the videos say the measurements should be for proper engine height or depth in the water.
I am not a boater im a want a be boater so I don't know if is a big deal or not ??

I do have metal plates to put on both sides of the transom for extra support, they were on their originally

thank for your input

You can use it it will just be suboptimal if you want any real speed out of her. If you're just looking to cruise and fish you should be fine. Other can jump in here who are smarter than me.

Bob

Like Bob said it won't be idea. Plus you may get some crazy spray off the motor.

i'm going add an extra piece of wood