Outboard Cavitation / Ventilation Issues

[Wirehair]

Son recently purchased a 2014 Tracker Pro-Guide V-175 with a 115 HP Merc four stroke. The prop is an aluminum 17 pitch Mercury Black Max (recommended by Merc). With the engine trimmed down, prop seems to cavitate or ventilate when powered up and boat attempts to plane out. Prop looks next to new with no apparent damage. When boat is out of water, engine cavitation plate seems to be positioned properly. Previous owner had installed a sidescan transducer about 8 inches to the right of the engine, but can't imagine that would be a problem. First thought was to suggest a different / SS prop but hate to have him throw $$ at this if not the primary issue. Have never encountered anything like this. Any suggestions will be appreciated!

 

[Davey Crockett]

Are you sure it isn't the hub slipping ?

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I've never had one slip but I would imagine you should be able to center punch a small dimple on both outer and inner parts and see if that's the problem. Or maybe someone will loan you a spare prop for a day.

 

[eyexer]

Does this prop have a flow-torque hub in it?

 

[Wirehair]

Does this prop have a flow-torque hub in it?

It does. Didn't feel any vibration when opening throttle, thinking we would feel vibration if hub is slipping. Didn't have time to remove prop yesterday to check hub. Have never had a hub slip on any outboard. Assuming one would see evidence of deterioration on inside of hub if that is the problem? Thanks!

 

[eyexer]

If you spun a flow-torque it would cease to spin the prop at all. So when you taking off from a dead stop the motor is trimmed all the way down?

 

[Wirehair]

If you spun a flow-torque it would cease to spin the prop at all. So when you taking off from a dead stop the motor is trimmed all the way down?

Trimmed down all the way. My thought as well regarding spun hub. Hope to have time tomorrow to pull the prop and check hub.

 

[NDwalleyes]

When you changed your prop did you put the plastic exhaust sleeve back in? I forgot to put mine back on and it cavitated terribly at mid-speeds.

This guy.

 

[eyexer]

This��

 

[Wirehair]

When you changed your prop did you put the plastic exhaust sleeve back in? I forgot to put mine back on and it cavitated terribly at mid-speeds.

This guy.

Sleeve is in, but I noticed it was loose on prop hub... you've got me wondering if loose is normal (tabs may not be holding). Just checked out u-tube regarding this and sounds exactly what may be occurring. Will pick-up a new one and try that. Thanks ND! Appreciate all the Great feedback!

 

[NDwalleyes]

Sleeve is in, but I noticed it was loose on prop hub... you've got me wondering if loose is normal (tabs may not be holding). Just checked out u-tube regarding this and sounds exactly what may be occurring. Will pick-up a new one and try that. Thanks ND! Appreciate all the Great feedback!

It may have cracked as they get brittle over time. Amazing how a $0.50 plastic POS can impact performance.

 

[hookemup]

I can help , I have same boat same motor, here is what i found out.
black max 17p ok for straight runs burns out on corners and sometimes while coming onto plane.

changed to a 17 pitch aluminum spitfire prop 4 blade again burnout on takeoff.

from there changed to a 19 pitch SS spitfirex7 great prop ran bout 41 slipped a bit when using in the river currents, but too much pitch can only get 5100 rpm out of it .

From there changed to trophy plus 4 blade 17 pitch great prop for the boat excellent bow lift, no burn out great cornering, 40.5 max speed at about 5600 rpm. never tried a 17 pitch spitfire it gets a bit expensive buying all these props. trophy plus was the winner it works great for this boat and motor combo.

 

[Wirehair]

I can help , I have same boat same motor, here is what i found out.
black max 17p ok for straight runs burns out on corners and sometimes while coming onto plane.

changed to a 17 pitch aluminum spitfire prop 4 blade again burnout on takeoff.

from there changed to a 19 pitch SS spitfirex7 great prop ran bout 41 slipped a bit when using in the river currents, but too much pitch can only get 5100 rpm out of it .

From there changed to trophy plus 4 blade 17 pitch great prop for the boat excellent bow lift, no burn out great cornering, 40.5 max speed at about 5600 rpm. never tried a 17 pitch spitfire it gets a bit expensive buying all these props. trophy plus was the winner it works great for this boat and motor combo.

hook,
Appreciate your insight on props!! First boat for my son, willing to do about anything for him to have a positive experience. Will check the flo Torque tube tomorrow as well as exhaust sleeve and then try the Trophy Plus four blade for sure. Have never run a four blade on my boats. Again, I sincerely appreciate all the suggestions. Have been around boats / outboards all my life and never had an issue like this.

 

[eyexer]

There’s always nice used props in bismanonline

 

[hookemup]

hook,
Appreciate your insight on props!! First boat for my son, willing to do about anything for him to have a positive experience. Will check the flo Torque tube tomorrow as well as exhaust sleeve and then try the Trophy Plus four blade for sure. Have never run a four blade on my boats. Again, I sincerely appreciate all the suggestions. Have been around boats / outboards all my life and never had an issue like this.

https://www.boatpropellerwarehouse.com
best place to get it, comes with a flo torque II hub kit. everything ya need.

click on image for larger view​

TROPHY PLUS (13 3/4 X 17") MERCURY RH PROPELLER, 48-825930A46

Mercury

Trophy Plus (13 3/4 x 17") MERCURY RH Propeller, 48-825930A46

​

 

[JayKay]

In my humble opinion, doesn't that transducer sound kinda close to the centerline of the boat? It's amazing what a little flow-disruption will do. I was cruising downstream on the river once, in a pal's boat. We were on plane, hit a suntan lotion squeeze bottle, and it somehow ended up wrapped across the leading edge of the lower unit. You'd have thought the engine was destroyed. It sprayed like a fountain, RPM's raced, and we fell off plane immediately.

Any disruption to smooth flow to the prop, is huge!

 

[eyexer]

Transducer is much higher than the area supplying the prop. And it’s barely in the water. You’d have to have the transducer hanging a foot below the boat and a few inches away.

 

[JayKay]

Transducer is much higher than the area supplying the prop. And it’s barely in the water. You’d have to have the transducer hanging a foot below the boat and a few inches away.

Agreed.. It was just a thought. Seems like usually the 'ducers are further out to the side. Mechanical "noise" from the lower unit could mess with the transducer too, I suppose. Again, just a thought..

 

[eyexer]

Yes interference is the big issue with being too close to motor.