First post. Sorry if this has already been brought up. I have not been able to locate any similar threads using the search tool but I'm sure someone has brought up a similar query at some point in the past...
Anyway, I'm wondering if I could have some opinions to help me on choosing a new prop for my RIB.
At the moment the propeller I have installed is a Yamaha K series, which I believe is the standard prop supplied with this engine. It is:
This is attached to a very well maintained and low hours Yamaha F100A 4 stroke outboard.
At the moment when I am running at WOT with the boat loaded with about 3-4 people and a full tank of fuel (call it an extra 350kg (the boat has a dry weight of 440kg)) the engine is revving at 5.9 (x1000) RPM. I assume it is higher than 5900 and is just being rounded down due to the resolution of the digital gauge. The boat will just about stay on the plane at about 4000-4500 RPM depending on how it is loaded. It is also worth mentioning that the prop edges have at least a finger sized chip or bend on each blade at the moment.
As I have found in the engine service manual, my full throttle operating range is 5000-6000 RPM. Maximum power (100hp) occurs at 5500 RPM.
I would like to be able to plane at a lower RPM in order to save fuel and perhaps get a higher top speed but I don't want to damage the engine. I have done a fair bit of reading and think it's safe for me to upgrade to a stainless steel prop and increase from 17 inch pitch to 19 inch.
Is this a good idea?
Can anyone recommend any good propellers?
I would rather not spend any more than £400.
The local boatyard have recommended a £395 Michigan Ballistic 13.5 x 17 stainless steel, which apparently has better cupping and edging, equating to around a 1 inch pitch increase. I'm hoping to go to a higher pitch if possible.