This calculator says that you need 7.8 h.p. to push the boat at hull speed.
http://www.geocities.com/jvandrey/fl...alculator.html
But, hell, a Honda 4 stroke is a nice engine. Give it a whirl. It will get you in and out.
But, you won't make much progress against a chop or strong current.
I get currents of about 2.5 knots. Can be slow going, even with an 8 h.p.
If you get a new engine, be sure to get a long shaft.