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97' Bayfisher 16 Yama 90 2 stroke


croakersmoker

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I haven't seen any prop discussion relative to my exact setup. I am currently running a severely banged up 3 blade 13.25" P17 prop that I bought the boat with. I can reach 40mph at 5700 rpms at WOT. I cruise at 33mph at 4600 rpms. The boat has great hole shot with the current setup. I am thrilled with these performance numbers. My only problems are that I blow out on almost every turn unless I slow down to less than 20mph. The motor is mounted on the second hole from the top and sends spray up from the lower unit when trimmed down(seems like a common problem for this boat). I don't want to raise the motor due to blowing out turns, and I don't want to lower the motor and make the spray worse. I am worried that my current, damaged prop could eventually wear out the parts in my lower unit, so I want to buy a new prop. My question is this: If I buy a new 13.25" 17P 3 blade prop, will I blow out less on turns? And can I expect different performance from different props with the same measurements? Also, I have zero experience buying propellers. I would like to buy something that wont break the bank. Please list any specific recommendations or list the prop you have on this same setup. 

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Welcome to the MBG Forum.  Just speculation on my part here, but your banged up and worn down prop is probably the cause of the ventilation in turns.  Your top end RPMs are 200 higher than the maximum factory recommendation as well.  I think a fresh new prop would probably fix it all for you.  However, if a new prop still breaks loose in turns, a good prop shop could add extra cup to the blades, to completely fix the issue.  Michigan Wheel makes a good prop that matches your prop's specs, and it has good grip in turns, out of the box.  It's the 13.25" x 17 pitch Apollo XHS, part# 993144.  You would need the Michigan Wheel XHS II® (Drop-In Hub) Kit #208 as well to fit your motor.  This is not an expensive prop compared to Mercury and Yamaha branded props, but the finish quality is just as good or better and the price is about half what they are.  Hope this helps.

A few pics of the Apollo 17 pitch:

 

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Geeviam, Thanks! This helps confirm my hopes. I also have holes drilled on my lower unit for a stiffy/fibertex cavitation plate. It looks like it was the full length style plate more used on a tunnel hull(I cant imagine why they chose that style). This was removed before I bought the boat. I am positive that my motor has spent its entire life on my boat. Makes me wonder if anyone runs a cavitation plate on these boats. If so, does it reduce blow out in turns, and does it reduce the GD spray that comes off the motor? Id really like to get rid of the spray!

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20 hours ago, croakersmoker said:

Geeviam, I am researching your recommended setup and their website says "Michigan Wheel high performance trim tab Part # 990341 is required when using stainless steel propellers on Yamaha 50 - 130 HP engines". Did you have to buy this part too?

The trim tab (a.k.a. torque tab) that they "require" is optional.  As long as your prop clears your current torque tab, and the torque tab is aligned properly (trailing edge of the tab pointing at 1:00 with motor tilted up looking at the underside from aft of the motor), you're good to go.  I bought one of those from Michigan Wheel, and ended up putting the stock Yamaha torque tab back on.

Regarding your motor making spray - if you will post a couple photos of your motor setup showing motor height on the transom, it would help.  You can also take a measurement, with the boat level on the trailer and the motor tilted down so motor cavitation plate is level with the ground.  Measure the distance from the bottom of the hull near the drain plug to the ground, and measure the distance from the underside of the motor cavitation plate to the ground.

Unless there is a tunnel-like pocket or step at the transom, the underside of the motor cavitation plate should be even with the bottom of the hull, or slightly above the hull bottom by up to 3/4".  If there is a transom pocket or step, the motor can be mounted higher by approx. 1" for every 10" of setback or length of the pocket (bow to stern).

Edited by geeviam
Added motor height guidelines
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