Your question, as I understand it is actually two questions. The first question is whether there is a ground plate on the Ariel. If that is the question, then yes, the company issue ground is the water intake on the starboard side and it appears to be bronze. You will find a wire screwed to it.

If you are asking is there is a sacrificial zink anode for corrosion/electrolosis control, the answer is no. The sacrificial zinc plate on my boat is on the motor. The motor is connected to the boat ground because the motor has a generator. But for the generator and its connection to the battery, there would be no direct electrical connection between the hull ground and the sacrificial zinc plate.

As for the concept of a sacrificial plate, what happened is the bronze filter plate over the water inlet was eaten away over time and had to be replaced. Now, I have installed a 6"X18" copper plate to the bottom of the boat which is the hull ground to protect against lightning strikes but should not be sacrificial (I hope).