Carbon does short out Microwaves by converting it to heat.

You would need a unusually dense fibre weave several layers thick to cause problems.

You may have such a hull. If your boat simply stops at a repeatable and same distance with no motor or rudder, Could be a Carbon Fibre shorting out the signal.

Your DX system is up there in frequency. I would remove ONLY the DX system, CAREFULLY.
Do not shift other things around. Put in a standard 72 mhz transmitter & receiver.

No change. It is NOT the DX system. You have other problems.

$ 250 service fee.

Rich