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Need prop advice

H

Happyprinter

Member
Good afternoon everyone. I have a 2005 Robalo with a Honda bf225 outboard. I am currently running a 3x15 5/8 x 11 prop. It will come out of the hole pretty decent til it hits 4000 rpm and then struggles to get to 4400-4500 where the vtec kicks in and then it goes great. I have tried several different props, 4x14.75x15, 3x15 5/8x13 but they have been worse than what I am currently running. Top speed when it is on plane and trimmed is around 29-30 at 5900-6000 rpm. Gone thru the fuel system thoroughly (pumps, screens, filters etc) 40 lbs pressure. No vapor lock issues. Any suggestions would be appreciated. Do I need to go down on prop size and if so?? The boat weighs about 4000 without the engine. The specs I have given is also generally with 2 people in the boat. If I put 4 or more it really struggles and have to put most everyone in the bow so that it can struggle to get out of the hole and onto plane.
 
WOT at 5900-6000 is good. To understand, the issue is the 4400-4500 struggle? Since when have you encountered this and what was your original propeller?
 
Blacktimes said:
WOT at 5900-6000 is good. To understand, the issue is the 4400-4500 struggle? Since when have you encountered this and what was your original propeller?
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Have always ran the 11 prop that is currently on it. The main issue is between 4000- to approx 4300-4500 when the Vtec kicks in. The boat struggles before the Vtec engages. 6000 rpm I am told is about right so I’m not sure if a
smaller prop would fix the issue?
 
With 6000 WOT you don't have a propeller problem. Have you tried pulling fault codes ? At 3950 the IAB kicks in. Some owners report it corrodes and sticks, first idea would be to gain access to the IAB and check for free movement.
 
Not sure where the IAB is located but I will get in my service manual later today and find out and check it. I will be out at the boat later tomorrow and will definitely check it out. Thank you
 
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