cavitation or Tranny slip?

[trailgypsy]

How can I tell if I have a cavitation issue or Tranny slip. I can drive full throttle with 5-6 people and have no problems. When we load the boat up to surf (2k lbs) running around 25k I get a lot of what seems to be slipping. No problems pulling people out or driving all day with no extra weight. Boat is a 99 centurion

 

[jimmbo]

I will assume this is an inboard not an I/O. Anytime you increase the load there will be an increase in slip. 2000 lbs is a load? What is happening to the rpms? Dropping, staying the same, or increasing?
Marine transmissions are usually of the type, you are either in gear or out of gear, no clutch or torque convertor to slip

 

[trailgypsy]

Inboard direct drive. Rpms will jump the tiniest bit maybe 100 rpm for less than a second

 

[jimmbo]

When I asked about the rpms, I meant how the numbers compare weighted down as to normal running

 

[trailgypsy]

Will run at any rpm fine before adding weight. After putting weight in the boat you don't really notice it until about 2300-2400 rpm. More rpm and it gets worse

 

[jimmbo]

Well a heavy boat will be a greater load, and therefore slippage will increase. However, if the prop is dinged up, the chances of it losing its bite are greater. Also a prop that is too small of diameter but high pitch is more likely to lose its bite too. There is become difficult to change, clearance to hull, no gear reduction. If your boat manufacturer designed the boat with heavy ballasts that would reflect driveline configuration? Or are those tanks/bladders aftermarket?

 

[trailgypsy]

Only 500 lbs is stock.

 

[jimmbo]

So you've added an additional 1500 lbs plus the 5 - 6, 7 including you(avg weight 165lb/per is 1155lbs).Does your boat have a capacity plate stating load capacity?
Since the engine is now dealing with a load greater than anticipated, a lower pitch prop with more blades will reduce your slippage, but also top speed along with the risk of over revving when lightly loaded