Good afternoon, we purchased a 2015 22 ft pontoon with 2015 suzuki outboard 115 hp motor at the end of last year. Prior to launching the boat, we had an oil change performed. We also found a cracked weld and took the boat to have the toons pressure tested, and a few welds were fixed.
After launching the boat, the rpm was noted to be about 3,000 and the motor appeared to be vibrating. The marina looked at the motor and replaced the spark plugs and we changed the fuel filter. After this, the rpm went up to about 4,500 max with average mph speed of 16 mph. We contacted the original marina where the boat was sold (out of state) and were told either the prop was too big or overpitched with recommendation for 14 in, 17 pitch prop. We replaced the prop without any change in rpm or speed. We called a local marina who services suzuki outboard motors and were recommended to lower the pitch. We replaced the prop with 14 in, 13 pitch prop as they recommended and rpm went up to 4,800 with still 16 mph speed. We pulled the boat back out and had it looked at by the marina who services suzuki outboard motors and they reported that the spark plugs had carbon build-up and were replaced again (a month after the first time they were replaced) and the changed out the prop for a 14 in, 11 pitch prop. Now, the rpm is within range of 5,000-6,000 however speed is only 17-18 mph max. We spoke with the original marina where the boat was sold and they reported the particular pontoon with motor should be reaching low-mid 20 mph and we cannot even break 20 mph.
Any thoughts on what we can look at or what may be limiting improving the speed?
After launching the boat, the rpm was noted to be about 3,000 and the motor appeared to be vibrating. The marina looked at the motor and replaced the spark plugs and we changed the fuel filter. After this, the rpm went up to about 4,500 max with average mph speed of 16 mph. We contacted the original marina where the boat was sold (out of state) and were told either the prop was too big or overpitched with recommendation for 14 in, 17 pitch prop. We replaced the prop without any change in rpm or speed. We called a local marina who services suzuki outboard motors and were recommended to lower the pitch. We replaced the prop with 14 in, 13 pitch prop as they recommended and rpm went up to 4,800 with still 16 mph speed. We pulled the boat back out and had it looked at by the marina who services suzuki outboard motors and they reported that the spark plugs had carbon build-up and were replaced again (a month after the first time they were replaced) and the changed out the prop for a 14 in, 11 pitch prop. Now, the rpm is within range of 5,000-6,000 however speed is only 17-18 mph max. We spoke with the original marina where the boat was sold and they reported the particular pontoon with motor should be reaching low-mid 20 mph and we cannot even break 20 mph.
Any thoughts on what we can look at or what may be limiting improving the speed?