327.34 Incapacity of operator.—It is unlawful for the owner of any vessel or any person having such in charge or in control to authorize or knowingly permit the same to be operated by any person who by reason of physical or mental disability is incapable of operating such vessel under the prevailing circumstances. Nothing in this section shall be construed to prohibit operation of boats by paraplegics who are licensed to operate motor vehicles on the highways.