Hi Andrei, Assuming that there's nothing wrong with your motor, my guess is that the propeller isn't deep enough in the water. From your description of the symptoms the propeller seems to be sucking air, rather than pushing water, which is what it is supposed to do. As a quick test, get all the way aft in the boat - sink the transom as far into the water as you can get it to go (add a case of beer bottles - they weigh more than cans do - all the way in the back of the cockpit, and see if that changes the way the motor functions (a 200 pound friend sitting back there with you would be another way of running the test) If deeper submersion of the propeller in the water improves the boat's performance, you have an answer to your question. The next question is then how to get a lower position of your motor on the transom of the M17, .....a lift motor mount may be the answer. Also, make certain that the cooling water intake of the engine is under water. If the engine doesn't get enough cooling water - you should see a steady stream coming out of the ports under the cylinders - you will ruin your engine. Connie Andrei Caldararu wrote:

Hello all,

I have a question on my 4hp Evinrude outboard. Yesterday, in a no-wind situation, the boat (M-17) was barely moving with the power at maximum. Maybe I was getting 2 knots, at best. What did seem strange was that when I moved from one side of the boat to another, the prop seemed to rev up, as if just by shifting the weight and lifting slightly the motor, the prop was about to cavitate. As it is mounted right now, on the original (1982) motor mount, the motor is in the water up to the bottom cavitation plate, just above the water pump intake.

Is the problem the motor itself, or the fact that the motor is not deep enough in the water? It seemed to run fine except for the lack of power/speed. It is the original motor that came with the boat, 1981 Yachtwin, the boat is 1982 M-17.

To give you an idea, with my Compac 16 (lighter, 1100 lbs versus 1600, but still), a Johnson 3hp was pushing it at hull speed with only 60% power.

Thanks for all input,

Andrei.

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Andrei, I had a Yachtwin 4 hp on my old Balboa 20 and had similar problems. The solution was to change the prop to what Evinrude called a ""power prop". The stock prop on that motor was probably intended for a light john boat or small dinghy. The flatter the pitch, the lighter the load on the motor and the higher it will rev. Two cycle motors don't deliver much horsepower at low RPMs and your motor should run at maximum RPM at Wide Open throttle with a light load in the boat. Iboats website has a prop selector guide that may have your motor listed and the recommended prop for heavy load applications. My 21 foot pontoon boat was not performing well with the origonal 16 pitch prop that came with the 40 HP Mercury and I used the iboats prop guide to determine that I need a 9 or 10 pitch prop. The boat performs best with the 10 pitch when lightly loaded and best with the 9 when loaded with a half dozen or more people. I have a longshaft full gearshift Evinrude 4hp on my M17 which works very well but it has the "power Prop". Ron M17 #14 Griselda

From: andreic@math.wisc.edu> To: montgomery_boats@mailman.xmission.com> Date: Sat, 19 Jul 2008 09:35:02 -0500> Subject: M_Boats: Is my outboard in trouble?> > Hello all,> > I have a question on my 4hp Evinrude outboard. Yesterday, in a no-wind > situation, the boat (M-17) was barely moving with the power at > maximum. Maybe I was getting 2 knots, at best. What did seem strange > was that when I moved from one side of the boat to another, the prop > seemed to rev up, as if just by shifting the weight and lifting > slightly the motor, the prop was about to cavitate. As it is mounted > right now, on the original (1982) motor mount, the motor is in the > water up to the bottom cavitation plate, just above the water pump > intake.> > Is the problem the motor itself, or the fact that the motor is not > deep enough in the water? It seemed to run fine except for the lack of > power/speed. It is the original motor that came with the boat, 1981 > Yachtwin, the boat is 1982 M-17.> > To give you an idea, with my Compac 16 (lighter, 1100 lbs versus 1600, > but still), a Johnson 3hp was pushing it at hull speed with only 60% > power.> > Thanks for all input,> > Andrei.> > > _______________________________________________> http://mailman.xmission.com/cgi-bin/mailman/listinfo/montgomery_boats

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