270 outdrive slippage?

[am_dew]

Yesterday, while on plane in my 17' v-hull runabout while cruising through some areas that had clumps of floating grass in it, suddenly it sounded like my prop slipped. I immediately backed off the throttle and turned the engine off, the raised the outdrive to check and see if any grass had wrapped in the prop. There was some but not alot and I cleared what was there. I lowered the drive, started the engine and cautiously increased throttle to get on plane. It then was fine for the rest of the 15 mile or so trip back to the launch ramp. The prop had not spun on the hub nor had it spun on the shaft...it's the kind of prop secure where you have the tabbed washer...not centter bolt. Does the 270 have some sort of internal protection that would have caused this "slippage" (for lack of a better term)?

 

[sandkicker]

The weed on your prop caused the prop blades to loose their "grip" on the water momentarily... It does not take much. Also, the very act of slowing to a stop will cause some of the weed to drop off, misleading you as to how much was on your prop. That said, there is "internal protection" on Volvo props as the inner hub is pressed into the prop with a thin rubber sleeve. It is a one time protection in that once it slips, it will continue to slip. Any competent prop rebuild shop can do a "re hub" if continuing prop slippage is a problem for you.

 

[am_dew]

Thanks. The fact that my boat performed normally for the next 15 miles tells me that the hub was not causing any prop slippage, or can the slippage be so minimal that you would not notice it?

 

[sandkicker]

If you are really worried about prop slippage, draw a line on the prop hub extending it onto the spinner. Run boat. If the line "breaks", prop is slipping.

 

[am_dew]

If you are really worried about prop slippage, draw a line on the prop hub extending it onto the spinner. Run boat. If the line "breaks", prop is slipping.

Yea, I know about doing that and will do. Luckily, if it slipping, the prop I was using is a lower pitch than the prop I normally run with because we had 4 people in the boat this time.

 

[RicardoMarine]

Yesterday, while on plane in my 17' v-hull runabout while cruising through some areas that had clumps of floating grass in it, suddenly it sounded like my prop slipped. I immediately backed off the throttle and turned the engine off, the raised the outdrive to check and see if any grass had wrapped in the prop. There was some but not alot and I cleared what was there. I lowered the drive, started the engine and cautiously increased throttle to get on plane. It then was fine for the rest of the 15 mile or so trip back to the launch ramp. The prop had not spun on the hub nor had it spun on the shaft...it's the kind of prop secure where you have the tabbed washer...not centter bolt. Does the 270 have some sort of internal protection that would have caused this "slippage" (for lack of a better term)?

The fact that my boat performed normally for the next 15 miles tells me that the hub was not causing any prop slippage, or can the slippage be so minimal that you would not notice it?

Regardless of how the spinner (aka cone nut) is secured to the prop shaft, the inner prop hub itself is splined to the prop shaft.
This portion will NOT slip.

Depending on the load, Prop hub slippage may vary.
Take heed to Capt Bob's comment in post # 4.

As for the cone-clutch system slipping, it is doubtful.
Once the sliding sleeve achieves gear cup friction, the steep spiral splines (vertical shaft) pull the sleeve further into the gear cup, creating eventual full lock-up.

The only internal "impact" protection (within the drive), would be the lower gear unit's vertical shaft's shear point.
Although I have seen it occur several times, it requires quite a "hit" for this area to shear!

 

[am_dew]

Thank you Ricardo and Capt Bob. I may have previously drawn a line across the hub/face of the prop so I will remove the prop and check to see.