I need your advice . . .

I have suspected for some time now that the Mrs. has been cheating. The usual
signs, Phone rings, if I answer the caller hangs up, going out with the girls a lot.
I try to stay awake to look out for her when she comes home but I usually fall
asleep.

Anyway last night, about midnight, I hid in the shed behind the boat. When she came
home she got out of someone's car buttoning her shirt, then she took her panties
out of her purse and slipped them on... It was at that moment, crouched behind the
boat, I noticed a "hairline crack" in the outboard mounting bracket... Is that
something I can weld myself or do I need to replace it?
Just askin', mind you!

the crack can be welded shut

The problem with this sort of thing is it really depends on what kind of metal it is.

If it's aluminum (Al-LUME-eh-NUM) then no it's shot. Aluminum is not molecularly strong enough to repair if it has been cracked. If it is steel it can be welded.

As for the first issue, infrared game camera might give you what you need.

maybe its time to change the boat for one with an in-board motor?

Just keep useing it till its rooted, then tip it overboard and get a younger model.

Yes of course why drive a 65 when there are so many 1980 to 1990 models out there.

alternatively - you may be able to trade the old one in for two half the age but with a little more adventure involved?

Try a Brazilian, that gets rid of the "hairline" part

When my wife turned 40, I had the bright ideal to trade her in on two twenty year olds. I soon found out that I wasn't wired for 220. Are you sure she was putting on her panties? Could it have been a hair net?