Join Date: Mar 2007
Location: New England
Thanked 7 Times in 7 Posts
Rep Power: 11
Most likely dirty prop
Sounds like you have a dirty prop or bottom. When the motor is under load, it works to move the boat. When prop/bottom is dirty, the motor must work harder to move the boat, which puts a strain on the motor more so than a clean prop/bottom. Hence, you see more smoke.
Your smoke is probably a mix of steam and unburnt fuel. When was the last time when to prop/bottom was cleaned?
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