Help me understand the basics of choosing an impeller with a twist (pun intended)
I picked up a project that will probably neither fly, nor make me scream, but it should be fun. I'm looking to take a very small glass boat and cut the hull to graft in a jet something.
the boat is 4' wide and just under 8' long, tri-hull, fiberglass. Designed for an electric trolling motor probably, but I have a 3.5hp 4 stroke for it. The primary use of this thing will be fishing on the Susquehanna river which (in Harrisburg) is pretty shallow. It also might get an electric tiller for the smaller lakes around here. Normal (zero stage) depth off the river at city island is about 2-3' with lots of jagged rocks. In my experience a caged prop works OK until you whack the lower unit that one time just right and crack it.
The plan is to jet it. Obvious answer is to find a wasted jetski and hack the boat and glue in the whole jet drive. My problem with that is 1) the price of donor jet skis these days, 2) most jets are 600cc and up and weigh more than I want, and 3) I have no need to buzz up the river at 40 mph with the potential for jagged rocks ripping a hole in the hull or ejecting me from the boat. The goal is to plane where I know it's safe, and have enough oomph to get back UP river without needing a novel and two meals along the way.
I was thinking GY6 or other smaller engine. I'm probably looking to make 10 ish hp at the crank so I put the equivalent of 7 ish to the water? Sound right?
The idea of grafting a jet ski hull is still attractive, but if I downsize the power, will I be able to find an impeller to match? How much does the housing play a role? Say for instance I find a 600cc jet ski and throw a 150cc in front of it... possible to tune the jet housing, or do I need a whole new idea?
Looking for the basics of how to choose a jet unit to go with the engine I choose.
