Hi all. Posted this over in propellers as well, but it may not be a prop issue so I'm posting here as well.
I just purchased a 2016 Grumman Cayuga 16 16' aluminum fishing boat with a 1994 Nissan NS40C manual tilt motor with a 12" pitch prop.
I am a big guy and weigh in at 450 lbs, so needless to say with 1 to 2 passengers, fishing gear, boat gear, motor, gas tank, and all it comes out to around the 1200 lb capacity.
I bought an induction tach (with the wrap around the ignition cable wire) and it reads 960(ish) at idle after warm up. When at WOT, the average RPMs for two runs in opposite directions was 3150 and 3500.
I just can't seem to get on plain.. with a passenger in the front it goes at a top speed of 13 mph, and with the at the rear it tops out at only 8mph.
The engine seems to run fine so I am thinking it may have to do with the way the person who put the motor on installed it, or the way I have it manually trimmed in the water. Ive been keeping it trimmed down at the 2nd bolt hole from the transom when it's in the water.
Again, I'm new to boating so don't know if this is just too low, or if maybe I should go with a new 8" pitch 4 blade prop to get RPMs up to around 4k. The manual says it should be closer to 5500...
I can take pics or try to perform any tests, but I'd like some with more experience to chime in if possible as to what I should do next. Thank you in advance!
I just purchased a 2016 Grumman Cayuga 16 16' aluminum fishing boat with a 1994 Nissan NS40C manual tilt motor with a 12" pitch prop.
I am a big guy and weigh in at 450 lbs, so needless to say with 1 to 2 passengers, fishing gear, boat gear, motor, gas tank, and all it comes out to around the 1200 lb capacity.
I bought an induction tach (with the wrap around the ignition cable wire) and it reads 960(ish) at idle after warm up. When at WOT, the average RPMs for two runs in opposite directions was 3150 and 3500.
I just can't seem to get on plain.. with a passenger in the front it goes at a top speed of 13 mph, and with the at the rear it tops out at only 8mph.
The engine seems to run fine so I am thinking it may have to do with the way the person who put the motor on installed it, or the way I have it manually trimmed in the water. Ive been keeping it trimmed down at the 2nd bolt hole from the transom when it's in the water.
Again, I'm new to boating so don't know if this is just too low, or if maybe I should go with a new 8" pitch 4 blade prop to get RPMs up to around 4k. The manual says it should be closer to 5500...
I can take pics or try to perform any tests, but I'd like some with more experience to chime in if possible as to what I should do next. Thank you in advance!
