On my little 3.4 M rib I have a 15 hp Mariner 4 Stroke and she goes quite well I can get about 20 Knots but I don't know the RPM as I have no guage. I have just fitted one of those little electronic gauges for the coming season.
I have took off my prop which I think is a 9 inch pitch by 9 inch dia but the numbers are very hard to read.
In the hub I can see 9 x but then it is blank in the side I hav A12 P9 Mercury.
Now Can anyone advise what they think is the best prop for this set up and would Stainless steel over ali give me any increase in speed.
Really you have to see what revs you are making at WOT to decide on any changes. 20kts from a 15hp is decent performance. It's exactly the speed we achieved 2-up with our 15hp 2-stroke Mariner fitted with the same prop pitch and on a 3.6m light air floor Zodiac.
Good info from fenlander OMO I would stay Ali prop spend on the tinytac revcounter see what WOT is go from there sometimes fine tuning doesn't work for all conditions and if you get it wrong with the s/s it's big bucks
this might interest you dennis there are others if you go to the suzuki UK site click on outboards pick the 15,20,25 hp two SIBS and a 380 rib with the 25 on download the test data not mariner i know but it gives some real info on hp. weigt, prop size & performance achieved.
That's the standard prop on all these little engines and as above to be sure of RPM you need a tinytach and to run that while playing around with engine height and trim.
But 20 knots from a 15 is pretty much all you can ask for and excellent.
Our Aerotec has a 2 stroke 15 and struggles to hit 17.
spy-sea-one
