Just put a 35hp Backwater on a 16/48 boat with 16in transom and hunt deck. With 3 men (about 550lbs. total) we could only get 16mph. The boat jumped on plane really quick. I'm thinking we may need a different prop?? Any ideas why we're not getting more speed or does that sound right?

Have you ran it solo, also was the cav plate on top of water with three man

How fast did it run empty? Did you try shifting the weight in the boat around? Did you happen to notice if you were plowing water at the time?

What size prop, condition of prop. , is your backwater new?. What type hull is your boat ? A lot of factors to sort thru to determine if that is accurate. Let us know we will try to help you .

H Finn

Did not run it solo but ran it with 2 men and was still running 16 stready, we did bump 17
We put both shims in to get the cav plate to run at the surface


We did try shifting the weight around but didn't get much change, maybe 1 mph difference
we were not plowing water, the boat was up on plane, from the way it felt I could run 16mph with 2 men or I could run 16mph with 4 men and a hunting load

everything is brand new, I don't have the motor here in front of me but whatever comes stock on the 35 is what it has
hull is a true flat mud hull, tapered chine


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how many rpms was it turning?

That seems to be the normal speeds (maybe a little low) with that type of heavy hull. I myself have a heavy 1748 and can hit 20 solo or 18 two man or 14 with 4 man huge load. From what I see on here and hear from Backwater the speeds of 20-25 come from boats that are thinner ga metal, light boats with no front deck and bare. Like everyone else has stated, what are your rpms?


Other than the speeds, these motors handle like a dream. I may be a little slow but can maneuver my motor with hardly a hand on the handle and they are built the best.

I appreciate the responses. The prop is just the stock prop that comes on the 35. Wasn't fighting tiller. Cav plate was riding near surface however it did have a tendency to pull to the right just a tad. I supposed this is just due to the direction that the prop spins and them not bending the tail like on surface drives. It didn't come with a tac so let me install one and see where I'm at as far as rpm's. What is safe to run 4100 in water??

ok, should the cav plate ride just above the water or just below

from my understanding the shims are used to get the cav plate where it needs to be due to differing transom angles on different boats and the "trim" screw on the back is used to fine tune it with different loads in the boat??

The plate should ride just UNDER the surface of the water. As far as the bump stop knob, I adjust mine all the way up and leave it there. That way I'm able to better use the skeg to dig around our spoon the boat around if necessary.

ok thanks for all the help, it'll be a few days before I am able to get a tac on it and run it again. I think we have the cav plate set right with 2 shims but I'm thinking our rpm's may be a little low.

Is the plug in,anchor up, and choke closed tight? - don't ask why I would think to ask these questions . It could be a combination of a heavy hull without a lot of surface area and getting the motor/cavitation plate dialed in to your boat.

I had to use both shims and move to the forward most hole on the transom mount to get mine to run right on my big boat. Running on a 19" transom at 17*. I have a very small cutback to help with backing up as well. My bottom is 44". Backwater said that could be the problem but I said no way. And I was right. I think it's mostly the high transom. Turning 3990-4010 rpms with a stock prop. My boat isn't light either. I have almost a 12 gallon gas tank in the front along with a deep cycle battery and a winch along with other crap in the hatch. Hull is all 1/8 front deck including extended deck is 55" and the main hatch is .100 ga and the extended deck and double bottom is .090. I run 21-22 with a light load.

This is all good advice. Raise the bump stop and experiment with the weight distribution on your boat. I ran that motor on a 17/52 boat last year and got 17mph almost regardless of the load. The speed your getting with that kind of load doesn't sound to far off.


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I'll remove shims and raise back stop and see if she'll ride just under the surface. I definitely didn't have it all the way up so the tail could drop real deep. I'm used to a surface drive so seeing the cav plate under the water didn't seem right

What hole is ur engine mount in? U have 3 or 4 holes u can put it in


If its up high, it's coming to the ground

i know you stated that you dont have a tach on it but you may check the gov. adjustment on the back of the motor to make sure you are able to get wide open out of the water to the point the engine cuts out due the coils limiting the rpms

when i got my 35 hp it needed some adjustment to be able to get to wot, i was considering one of these on another boat of mine due to what i was hearing about them but with that much hp and only 16 mph i may rethink that