36 tournament / Cummins 555 VT

[akitawpo]

Hello,
Anybody know factory prop specs or specs that has work for you?

 

[Scott Danforth]

Is the 555 in good shape? After 52 years, most likely the prop on the boat is correct and either the boat is waterlogged or the motor is tired

 

[Mad Dog 2]

Whats the engines full Rpm at no load (out off gear) and the engines full Rpm in gear wide open? Both engines have same WOT?
What does it cruise at X mph or knots?
How fast is it at full throttle?
Cheap easy test and checks, beginning of a good baseline before hauling the boat.
Take a mechanic with you to check for blow-by and engine performance. (Motor tired? Reported as good.)
When hauled get the travel lift operator to give you weight. (Compare actual weight to mfg advertised weight, waterlogged?)
Waterlogged hull will affect engines performance, may reduce cruise speed and WOT Rpm.
Hull waterlogged and/or needs major engine work, you need to review newer replacement boat cost in the used market.
Old tired boats can be a money pit.
You could have a real good boat good data will tell you.

 

[akitawpo]

Is the 555 in good shape? After 52 years, most likely the prop on the boat is correct and either the boat is waterlogged or the motor is tired

Then engines are in good shape. Currently has 4 blade props 22x22 and recently found some 3 blades but no specs on them

 

[akitawpo]

Whats the engine full Rpm at no load (out off gear) and the engine full Rpm in gear wide open?
What does it cruise at X mph or knots?
How fast is it at full throttle?
Cheap easy test and checks, beginning of a good baseline before hauling the boat.
Take a mechanic with you to check for blow-by and engine performance. (Motor tired?)
When hauled get the travel lift operator to give you weight. (Compare actual weight to mfg advertised weight, waterlogged?

Cruise is around 15.5 / 16 knots at 2550rpms. Have not tried full throttle. Full RPMs are 3000. Seems to me from the limited rsearch I have found it should do around 18knts crusing. Engines do not overheat. Blow by seems normal as per any disel.engine. Currently working on one of the risers and one of the turbos being replaced by a new one that I had halfassed repaired during the pandemic and the limited parts availabe at that time

 

[Mad Dog 2]

Cruise is around 15.5 / 16 knots at 2550rpms. Have not tried full throttle. Full RPMs are 3000. Seems to me from the limited rsearch I have found it should do around 18knts crusing. Engines do not overheat. Blow by seems normal as per any disel.engine. Currently working on one of the risers and one of the turbos being replaced by a new one that I had halfassed repaired during the pandemic and the limited parts availabe at that time

Saw this and copied it from Downeast Boat Forum

"First thing, is the boat loaded the way it normally would be when you took these RPM readings (full fuel, gear, four fat guys, ect)? Or was it lightly loaded? Wide open throttle readings should always be taken under normal/worst case load.

Next thing I would do is verify that the tachometer is reading correctly. You can purchase a hand held photo tachometer on line for not much money. If the tachometer is reading correctly (you can verify this at the dock, no need for checking under load), and the boat is loaded as it normally would (worst case), you have two choices:

Leave it alone. The only downside being a little less speed. Lightly loaded engines have a habit of outlasting their owners, and burning less fuel in the process.

Start playing with the prop. The best way to do this is make up a chart with RPM's from idle vs speed, every 100 RPM's, all the way up to wide open throttle. With this data in hand a GOOD prop shop should be able to "work their magic"."