New Caymas CX20 severe rolling/wobble at 63 mph

A friend of mine just purchased new CX20 with 250 ProXS. He just got the motor break-in completed, but is having trouble driving the boat. It runs fine until 63 mph at which point the bow drops severely to the port side and the rear starboard raises and slides. Then it catches and rolls the opposite (bow to starboard and rear to port). Hence a very severe rolling "wobble" almost to the point of a bow-hook. He is familiar with chine walk from other boats but says this feels totally different. Any thoughts or suggestions?

FYI - I went through another thread here on Caymas chine walk being more of a "rolling" action than other boats due to a larger pad. So perhaps this is what is happening. My plan of attack here is 1) make sure the steering is "tight" and all mounting bolts are snug and 2) Raise the jack plate a bit (1/4") and start experimenting from there.

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Originally Posted by LeeBassMan

A friend of mine just purchased new CX20 with 250 ProXS. He just got the motor break-in completed, but is having trouble driving the boat. It runs fine until 63 mph at which point the bow drops severely to the port side and the rear starboard raises and slides. Then it catches and rolls the opposite (bow to starboard and rear to port). Hence a very severe rolling "wobble" almost to the point of a bow-hook. He is familiar with chine walk from other boats but says this feels totally different. Any thoughts or suggestions?

FYI - I went through another thread here on Caymas chine walk being more of a "rolling" action than other boats due to a larger pad. So perhaps this is what is happening. My plan of attack here is 1) make sure the steering is "tight" and all mounting bolts are snug and 2) Raise the jack plate a bit (1/4") and start experimenting from there.

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I bet the motor is setting too low, 2 1/2 to 3 inches below pad is where mine runs the best, it gets a little tricky to drive at 80 but not too terrible.

Sounds like chine walk that is getting out of hand. Raise the jackplate as happykamper said above. Load the boat as it will be used if it is not already. The plan above is good, but I suspect it is also a driver training thing. The first time I went full out after breaking in my boat, it was completely empty and I was going downcurrent 75mph it walked pretty bad if I wasn't driving it hard. Was definitely driveable like that, but it was work to do so. Soon as I put gear in the boat she settled down nicely so its just a casual chine walk. I wouldn't expect severe chine walk at 63mph unless the boat was empty and the driver wasn't correcting it at all.

keep raising the motor

Thanks to all, I will keep the thread going as we go forward with fine tuning!

Had the same problem with cx21 when I first got it.
My Solution:
1. Most important: moved one of the three trolling batts from port side to starboard to balance weight. Simple math: the factory setup is like having 2 batts on port and 0 on starboard…. With dual console and 2 people in boat, this batt setup is the imbalance.

2. once weight is balanced, found the right height for jack plate with 3 blade fury by running up to chine, then raising jack plate until chine calms, but rpm’s don’t spike or speed doesn’t drop. i.e. the “sweet spot”. With battery weight balanced, the wobble is MUCH less pronounced.

3. I now run a Bravo I FS prop (4 blade). I can now run 70 mph trimmed out jack plate at “8” on gauge and I can let go of the wheel.

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Originally Posted by CX21

Had the same problem with cx21 when I first got it.


3. I now run a Bravo I FS prop (4 blade). I can now run 70 mph trimmed out jack plate at “8” on gauge and I can let go of the wheel.

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Out of curiosity, (and just for reference), what is the JP height when looking at the tape on the plate? And do you happen to know what your prop to pad is at that height?

Measure your prop to pad before you start raising the motor. Cx20 is a very easy boat to drive.