Lonestr

I am new to the forum and I hear alot about this "D plate" what is this and what does it do? I have some bad luck with my gp1200r It ran really good for the first tank of fuel and then something went wrong with the oil delivery to the engine and crapped out the #2 cyl. I'm currently having a recon engine installed and a bypass kit where I will have to premix the fuel myself. Does anybody have any suggestions on any other precautions to keep the ski on the water and not in the shop? Thanks