Tim Lehman's Jon Jr.
JON JR, POWER SKIFF,
12' X 4', 100 POUNDS EMPTY
Jon Jr. is a small
jonboat, sort of a personal sized boat that will take two normal
sized adults. It would be a perfect "back of the pickup
truck" boat. It could be cartopped. (To me the idea of
cartopping a powerboat is a bit strained since you would need
to carry the motor, with its smells and drips, and the gasoline
inside the car). If you are sure from the start that you will
be trailering the boat, you might consider the larger Jonsboat
design which has more capacity, but is not so large that it
will be expensive to build, use and haul.
As for power, I'd
suggest 5hp max. Sometimes you can find low power motors at
yard sales since they don't fit the image of modern boating.
The usual rule I've seen for power on planing boats is a horse
for each 50 pounds and motor salesmen like to quote a horse
for each 25 pounds. I've found that in good conditions a simple
flat shape will plane with less, so this boat with a normal
sized man might plane with 5 hp. Actually, the Coast Guard suggestions
for powering boats comes down quite hard on small hard chined
boats like this and they might advise even less than 5 hp. A
boat like this is unsuited for big waters anyway. So the little
motors will cover the little lake quite well.
Construction is of
the simplest "instant boat" type from three sheets
of 1/4" plywood. All nail and glue construction with a
smattering of epoxy and fiberglass to fortify the chine corners
and help seal the water out of the bottom joints.
The prototype Jon
Jr. (below) was completed by Joe Leinweber and Dan Ellis and tested
to a certain degree.