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Reverse cavitation

BakedZiti

Jet Boat Junkie
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Location
Milledgeville, Ga
Boat Make
Yamaha
Year
2019
Boat Model
SX
Boat Length
24
Fins It appears visually that the fins block the new buckets sideways thrust. On the old buckets the result would be to focus the flow. Here I wonder if it causes turbulence at the worst or blocking the intended function at the best. My reverse was sluggish today unlike before I had fins. I have raised them and will test later in week.

The boat is new to me so I do need more testing before I say something conclusive.
I would be interested to know the answer to this although I would be shocked if @Cobra Jet Steering LLC would design something that would cause this problem, this is a picture of my setup, doesn't look like the fins are in the way, btw i have since added the fangssuper_magnum_ak-19_system_on_a_customers_2019_24_foot_yamaha_jet_boat_v2.jpg
 
Last edited:

bronze_10

Jetboaters Admiral
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Location
Raleigh / Wake Forest Area..
Boat Make
Yamaha
Year
2008
Boat Model
SX
Boat Length
23
I have always wondered if at higher rpms in reverse if the twin engine boat loft the back up a little and cause the pumps to suck in the disturbed water causing cavitation...
 

Cobra Jet Steering LLC

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Florida
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Yamaha
Year
2021
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Other
The steering for the 2019 boats have 2 different settings so experiment , put it on the other setting and see how you like that but remember the reverse on your 2019 is not reverse it is about a 45 degree angle this will never produce the reverse thrust that a real straight reverse nozzle will produce, actually the more you get away from real reverse the more you loose in that respect and the other thing is that half of the water from the angled nozzles is being sent into the pump opening where it can not do you any good.
 

mwalker4

Jetboaters Lieutenant
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Location
Delaware County, Ohio
Boat Make
Yamaha
Year
2019
Boat Model
SX
Boat Length
19
The steering for the 2019 boats have 2 different settings so experiment , put it on the other setting and see how you like that but remember the reverse on your 2019 is not reverse it is about a 45 degree angle this will never produce the reverse thrust that a real straight reverse nozzle will produce, actually the more you get away from real reverse the more you loose in that respect and the other thing is that half of the water from the angled nozzles is being sent into the pump opening where it can not do you any good.
Agree completely, the reverse has never been strong directly in the reverse but did steer well. I didn't feel it steered as with the ultimates. I think raising the fins will restore it. Sorry I hijacked the thread, but I do agree the new reverse bucket has downside of lower backing or stopping power.
 

Cobra Jet Steering LLC

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Location
Florida
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Yamaha
Year
2021
Boat Model
Other
Boat Length
Other
I made the new super fins with the extra top surface area to help in forward and reverse when driving in off plane mode. But any cavitation must be from water and air being pushed into the intake grate, I know on my skies you start to cavitate if you try to go too fast in reverse.
I do the reverse move numerous times a day but can never really get the hull moving very fast throttle up or not it seems to work better giving it moderate throttle.
 
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