English to Spanish Tech/Engineering Ships, Sailing, Maritime Yachts class rules

Hi, I have just finished translating a significant project and there are a few terms I would appreciate you help me with. It's from a technical document describing class rules of yachts and different parts of yachts and I would like to know the exact term. I very much appreciate your input and help.

Context is :
" For purposes of C.2.3, owners shall be defined as members of the X-35 One Design Association and shall hold legal ownership interest in the boat being steered (of at least 30% of fair market value of the new or brokerage boat price for Group 2 competitors and 50% of fair market value of the new or brokerage boat price for Group 3) evidenced by appropriate documentation.

Thanks a lot :)