Right thought I would come back here. I had decided to not bother changing props and stick with the stock 11.1 x 13 one, but after double checking my WOT rpm’s I was a little shocked at my findings!
First of all that high pitch noise which I could often hear at WOT with just me in the boat IS the rev limiter! With the wind and engine noise it was hard to make out but when I put my head close to the throttle/control box I realised it was making a constant beep noise when I am at 6000 rpm at WOT. I looked in my manual and it says the rev limiter kicks in at approx 6000 rpm and emits a constant beep noise!
I have also checked the WOT rpm with my dad and I in the boat and its 5800 rpm, and also with my mum, dad and myself the WOT is 5500 rpm.
So after double checking my WOT rpm's with different loads, I think I definitely need to change my prop for a bigger pitch just for the sake of my engine as its over revving with just me in the boat!
The manual says WOT should be 5150 – 5850 rpm. I can go to a 11.1 x 14 or 11 x 15 according to Tohatsu. I think I would prefer the 11 x 15 as it will give me a better top speed which I prefer to acceleration.
How much rpm do you loose by going up 1” in pitch though? I think someone said before it's 100 rpm, in which case with an 11 x 15 prop and 3 up in my boat WOT should be about 5300 rpm which is within the recommended WOT range.
I can get the OEM Tohatsu 11 x 15 prop for £165 delivered, a Solas 11 x 15 for £120 delivered or a Vortex 10
x 15 for £95 delivered.
Unfortunately price is a factor in my decision and therefore I would go for the Solas over the OEM as it’s the correct size and after a bit of research I have only found good things about Solas. What about this Vortex one though? I am put off by the fact it is 10” diameter instead of 11”. What difference would this make? Would it help the engine rev ever so slightly easier due to the slightly smaller diameter? If so maybe this would be a good thing, though that said Tohatsu recommend 11 x 15, not 10 x 15!
Thanks for your help!