Suitable Prop

[shley87]

I know this sort of question is asked a lot and there are hundreds of answers about how to find the correct pitch, however I don't have a tachometer and my current prop is not in a good state. Basically 3 metre SIB and 8hp Yamaha 4 stroke outboard currently with a 8.5" Diameter 6.5" Pitch Prop (quite badly worn) do I replace with the same or go for a larger pitch? Is there a good starting pitch to try or am I best off getting a tachometer and running the tests on my current prop and then doing the maths? Any help is much appreciated

[Poly]

You won't get a brilliant answer even with a tach and a damaged prop. in any case a sib is so sensitive to assembly, pressure, loading etc that a prop an inch or two different is not necessarily going to change much. Does the current prop give ok performance? If so then I'd replace with the same. especially if they were bought together as someone presumably chose them for a reason, if only because they were the default which is what you are asking for.