Its probably been asked before..Avon SR5.4 90hp 2 stroke, how fast & which prop?
I have recently purchased an Avon Searider 5.4 & I have fitted a new Mercury 90hp 2 stroke outboard. Its an extra long shaft (25") which fits the boat well as the transom is level at a height of 25" as it was formerly outfitted with twin engines.
The engine came supplied with a four blade 13 3/4 x 19" aluminium propellor which provides great lift & acceleration but a top end speed of just 32kn with two adults on board. Adjusting the engine tilt has a negligible increase in speed. I was hoping to get a higher top end speed than 32kn.
The engine max RPM is according to the engine plate is 5500, after the engine was fitted at full ahead the tacho read 8000 RPM, clearly something wrong! I brought the boat back to the "technician" to have the tacho calibrated correctly, it now shows 6000 RPm at full ahead.
1:Could anybody with the same boat & a similar engine set up please let me know what size & type of propellor you are using?
2:Is it possible that an outboard can run at an RPM above its rated maximum or should I suspect that the tacho is still not calibrated correctly by the "technician" or is there a general error parameter with a tacho, in this case 10%?