helps keep the water cooling
system, impeller and pump from getting clogged up with salt deposits. These don't build up right away, but over time can build up and clog the cooling
system which in turn can cause damage to the motor. If the motor is run often the chance of this build up is much less then say you run it once a week, let it dry out. Weekend boaters come to mind. We always flushed the motor when we got home, but the boat would sit for a week or more before we went out again.
As long as you see water being pumped through the tell tail then you are fine, if this stops or starts to sputter you could have a blockage.
is much easier to do then clean up salt build up, but as you said you don't have access to fresh water. Your motor is small, I would pull it every 6 months or so and have it flushed.
You can also rig a 5 gallon bucket with a hose attachment and value in the bottom running to a set of muffs on the outboard
, fill the bucket with fresh water, hook the hose up open the value, start the motor out of the water, it doesn't need to run long to flush out the lines.