Re: 50 hp evinrude- material coming from the prop
Can you tell us what 50 HP Evinrude we are looking at here? Model, year.
That looks either like unburnt premix mixing with water at the exhaust, or the results of a decarb.
First thing I would do is assure myself that you have good compression and spark. If you are not firing on a cylinder, you would get the unburnt fuel and oil passing through the exhaust. When it mixes with water it would look like that.
Also, if its an older motor that hasn't been run in a while, it could be some carbon buildup that has been loosened by running the motor, and that, mixed with any unburnt fuel coming out of the cylinder and water at the exhaust would make that sludge.
Take a look at the compression and spark first, determine if you are running on both cylinders.
Next, check your lower unit oil to make sure you're not leaking gear oil into the exhaust somehow.
Rgds
Eric