max rpms, loss of power

[fishingfriend]

hi there , ihave a 1978 1150 115 hp merc ,on a 16 foot sunray bowrider my mnual for the motor says it should max out at 5500 rpms , however i am only getting up to 4100 at full throttle and topspeed is 30 mph , i dont think this is running at its full potential . could someone please tell me what to check for.

 

[Sandjob]

Re: max rpms, loss of power

You will need to check prop size. Diameter and pitch. Run at WOT and trim as far as you can befor cavitating. Note speed and rpm. May have to much pitch or too large Diameter.