Talking with a buddy of mine and his friend bought a 38' Sea Ray from Florida. The broker screwed the guy over BIG time. The boat has Cat diesel's and could not even get on plane up here in Michigan. A place that suggested props suggested that big boats like cruisers have different pitch props for salt water vs a boat in freshwater because of the difference in buoyancy. I call BS on this but it may seem a little plausible.

Sounds like complete baloney to me, but I await a more scientific response.

I dispute the assertion of the unnamed prop selling place and reference page 2 of the linked article as support that their hypothesis is rubbish.
http://hydrocompinc.com/wp-content/u...ts/tex0502.pdf

The unnamed prop shop is Johnny's Prop Shop in Detroit Michigan.

It's not the saltwater that affects the performance it is the tides.

All of us saltwater boaters here know for best performance to run a big wheel for maximin speed and cruise.

In freshwater this can keep the boat from getting up on plane but here in the salt we always attempt to go on plane with the direction of the tide.

Pops us right up.

I had a 41' with Cat diesels and it planed easily. Tabs down a little certainly helped. Even with full fuel and 15 passengers she still had no issues.

A filthy hull in need of fresh anti foul can make a huge difference. You can lose 10 mph, not joking! If the bottom is ok and it doesn't plane he should check his fuel filters first. I got some growth in my tanks one time and it lives on diesel. My filters were getting dirty after half an hour running and the engines were getting starved for fuel and wouldn't reach revs. Had to drain, clean and refill the tanks.

Sea Ray don't provide different props for fresh and salt, I find that hard to believe. (Please tell me that was sarcasm) If in doubt, call Sea Ray, I'm sure they'll help.

The 38 is a nice boat with petrol engines and should be a real blast with Cats. Mountains of torque and a quite quick for a big lump of boat.

RR

Long story short- The guy bought this boat from broker in Florida, had a Cat Mechanic inspect the engines and mechanic said they were ok. Boat gets shipped to Michigan ($11,000 to flat bed it) uncovered and is filthy by the time it gets here. Engine was leaking oil into bilge because cat Mechanic who did the inspection forgot to put in a plug on the engine and the oil leaked out. Boat was shipped with the wrong props and would not get on plane. New props were installed and filters changed, now the boat can get on plane. The guy that owns the boat is new to boating and is a friend of a friend.