Exhaust port corrosion

[edzecc11]

Should I assume I'm at the start of exhaust port corrosion? I have a 04/04 225 Yamaha that I use in brackish water only ( the upper Hudson River . Prior to put ting my 25' Parker in the water I filled it w/ 170 gallons of fuel. The engine has 569 hrs. This past week-end I took the boat out and was not able to go faster than 17-19 kt's with the engine revving at 5100 rpm's. Although I'm carrying 1500lbs of fuel i don't think that should affect my speed that much. Is loss of power one of the first signs of exhaust port corrosion and if so what else should I look for?

[Sequoiha]

If you are turning good rpm with no go, I would check the prop hub, could be slipping.

[rodbolt17]

unfourtunatly,or maybe not, loss of power is not a symptom of ex stack failure.

you may have fuel or prop issues.