New Pontoon boat cavitation

[59rocker]

Greetings from Rochester, NY. I have owned a 17' Sea Ray runabout in the past but we just purchased and launched a 2014 (new hold-over) 22 foot Harris Flotebote Cruiser Pontoon Boat with a 2015 Mercury outboard 90 HP 4 stroke engine . The initial trial in early May on a sister lake went well and the boat was transported to my marina on Irondequoit Bay. The first use of the boat went without drama but soon after a 'cavitation' problem occurred at approx. 3000RPM and the only speed we could use was slow. I called the boat dealer, the boat manufacturer and the engine manufacturer and researched the web for possible issues including lower unit shaft length, prop size, pitch, blade count, boat trimming, cavitation plates etc. This past Saturday they sent a boat repair mechanic to our boat (45 minute drive) and the fella brought it up to 3000 RPM and sure enough the boat responded with the characteristic cavitation (some will claim the appropriate term is ventilation). He recommended we pull it up on the trailer to take the prop. off but was happy to have me back the boat into the slip and raise the engine to workable height. He removed the prop. without issue and removed the plastic drive sleeve and lo and behold it was cracked. He replaced it with a new model and after quick trial the problem was solved...sooooo my advice to those with this problem is to examine this $20 part first...this is a brand new motor and one would not think to check this part. I am no mechanic but now know one small bit of engine design I had to pass on...Happy boating!!!

[Coldbrew]

Thanks for sharing and welcome to the forum!

[curtiscapk]

yep getting ready to say spun prop!