Old 03-18-2019, 12:53 AM
  #16  
TTaxi
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Join Date: Feb 2003
Location: M.Vineyard, MA
Posts: 14,083
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How are you measuring boat speed? GPS or pitot or paddle wheel -fed gauge? I guess even without a boat speed measurement , you would notice the difference between 28 mph and 50.

It's just hard to picture the hub is spun if it accelerates fine to 3900 rpm/ 28mph . Is it a pressed in-type rubber hub ? If the prop shaft is spinning at 6000 rpm and the prop is not spinning faster than 3900 , you should be able to see and smell damage to the hub after a run. You can also mark or scribe across the prop outer metal hub through the rubber hub and onto the other side of the metal prop hub. Go for run past where boat speed does not increase and check the hub when you return to see if the line is still intact across prop & rubber hub.

If the prop is ventilating I would think STW would go down as rpm increases past the point of ventilation. That's ...usually.... the case with spun hub as well.
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