A 40HP often is bolted to the transom, this takes some more time
to install than a smaller engine. Installing a 9.9 or 15HP can be
done in 5-10min by one person. A heavier engine might need two
persons or a hoist.

How much longer time to install a 40HP than a small engine? Would you
please give me a ball-park figure? Do we need any special expensive
tool that a person is not likely to have?

Sound like this is a two-persons job...

But using an electric motor on a boat designed for a 40HP will
give you very little speed.

Actually, I am just guessing when I mentioned a 40HP gas engine. I
don't really know how much horse power that I will put in a 18-ft boat
that I am looking for. I use that number just because Tracker web site
states that 40HP is the maximum horsepower that we can put in his 16-ft
boat alumimum deep-V boat. 40HP probably represents the upper limit of
what I may put in the 18-ft boat. Actually, I don't intend to put in a
large gas engine in that 18-ft boat; on the other hand, I plan to put
in as large an electric trolling motor as I can find in that boat.

Thanks.

Jay Chan