I just put a tiny tach on my new to me 27 kohler mud buddy longtail. I was surprised to see that at full throttle I was only getting RPM's in the 3350 range. I have it on a welded regular square bottom 14/48 with large pods and with that shape and the ribs on the bottom I know I am not going to get the absolute best performance but I expected higher RPM'. I even went with a 9 x 6 prop rather than the 9 x 7 (recommended by the guys at mud buddy) for higher RPM's and top end speed. I did check and there is no more play in the thottle arm or linkage on the back of the motor and no extra play in my throttle cable. When the prop comes out of the water it does rev up to 4100. with the RPMs in the 3350 range I was getting between 16 and 18 mph depending on if I was going with or against the wind. I was hoping others out there with similar hp longtail motors might reply with what top end RPM's they are getting to see if I am close or if I have a problem of some kind. Thanks.

25 gdlt on 1644 godevil boat. turning about 3400 with NEW 9X6 prop. I get the best speed with a somewhat worn prop turning just under 3600 and running about 18 mph with a light load (i.e. me at 220 lbs and an 85 lb dog).

Well for what's worth, that's about what I get with mine with a heavy hunting load. I have a 1750 beavertail with 27 LT

1448 riveted pos alumacraft with a 27 beavertail, new Ron hill 9x7 prop, turning 3750-3800 in water. Gps reads 22 with me (220) and 12 gallons of gas and 1 battery. Turns 3650ish in water with a bow fishing or hunting load. Lucky to turn 3400 once its loaded down with fish though lol

Thanks for the good info- it is really helpful. To me, I had a relatively light load but that did include the dog, 10 gallons of gas, 2 mower batteries, 2 boxes of tools and assorted spare parts in case the recent work I did on the motor blew apart, and a full length blind so I was probably loaded more than I thought. Not to mention the dog jumped out in a mud bank and coated me and everything else with at least several pounds of the slimiest mud I have ever seen. With a similar load my 13hp beavertail longtail only pushed it 8-9 mph so this is still a huge improvement. I may try a 9x7 prop as according to the prop calculators online even if I lose an additional 200 rpm, I might pick up about 2-3 mph.