Hey guys. Im kinda new to mudmotors but here is my dilema. I know longtails aren't super fast and I'm running the wrong hull, so maybe I already know my problem. I bought a tall transom alumacraft 1650 modv all weld and put a 27 hp back h20 motor on it. I was going to put a outboard on it but low water last year here in MN made me go back to a longtail. (I use to run a alumacraft 1436 with pods and a 20hp GDLT, needed more room) anyway my OOW rpm is 3950 and in water is 3500 with a 9x7 new prop and pre filter removed. Speed is 16mph per gps. I have a set of pods I could add if anyone thinks it would help with the speed. I guess what I'm getting at is how can I pick up some speed? Does anyone know what hole out of the three to put the bolt in under the motor? This is one of thier older models that does not have the adjustable cav plate. - Thanks

^ Also, the prop is about 4" under the water at WOT, but if I load the boat wrong with too much wieght up front the prop wont grab at all. Also if the boat is loaded right and I try to turn hard left or right the prop comes out and wont grab either.


Above pic is of motor swung 180 into boat.

If that's one of the older frames that does not have the adjustable cavitation plate, I am willing to bet that that frame was built for a 16 inch transom. Call the guys at Back Water and see what they have to say. Did you buy the motor new?

Good motor. Definite mismatch if a tall transom. My friend ending up cutting down the transom to 16" and that was that. I see that you have a rear bench- that may negate that move by interfering with the handle. For sure talk to BackH20! Let us know what they say. I have the same Kohler 27 but it is an MB longtail.

On my GD 1648 with GDLT I ran 19mph with 9x6 solo
and 21 mph with 9x7 --- however with a load I actually
ran faster with the 9x6 --- overall performance was
also twice as good with the 9x6 prop too....

So this was a true hull to max out performance and was
only a few mph faster than yours....

The ModV is what is hurting you the most - I'd sure
try going down to a 9x6 to see if that helped get
the most outta your current setup....

Those holes change your balance and where you are
makes it tail heavy - likely the best place for your
transom height....

Moved the bolt to the middle hole and that pretty much solved all my problems. Its not back heavy the cav plate runs where it should even when turning and the boat gets up on plane atleast twice as fast now. I played with the govenor a little more and picked up 1 mph. OOW rpm is still around 3950 but in water with 2 people in the boat today was 3650. I'll maybe try a 9x6 but overrall Im pretty happy with what I have. Thanks guys.

Good deal! Glad you got it worked out. Those motors are super nice. Love my 23.

Its nice to see everyone likes to help out on here, but when it comes to backwaterinc the old model like this one being talked about it was a LS which means it was designed for a tall transom and could be also be run on a short transom if set up right most people woudnt know this and just think its for the wrong transom..right away. no offence guys, The three hole for sure mean something they are not just for looks. the ride ball/ bumper also has a purpose and the same with the cave plate design once they are set correctly everything will fall in to place. some boats need more tweeking then otheirs. glade to see i got you running better after talking you through some stuff last night
any otheir problems let me know

My 23 frame only has 2 of those adjustable positions on the frame instead of 3 like the 27 & 35. It was delivered and set up to be tail heavy. I ran it like that for a while and just to see the difference, I changed it to make it less tail heavy. It didn't run quite as good and the prop wanted to blow out in turns so I changed it back. I've never had to put a shim on the cavitation plate. It runs right at the surface just like its supposed to.

Like I said previously each boat is just a little diffrent and needs just alittle diffrent tuning

The older models u have to make your adjustments with ride stop and when u change the balance of the boat u can have those issues. Try ajusting the ride stop to a position that runs the best at different loads Running to deep ride stop needs moved up wanting to blow out move down just need to find the sweet spot.