This is the way it is stated in the Rules:
If your boat breaks down before an event, you will be allowed only one boat substitution per Division. Remember that this is a team and machine contest. The ability to keep your boat in running order is equally important to your success. Exception: In the event your boat cannot be repaired because of circumstances beyond your control, you must get special approval from the SKA management to change boats for the remainder of the season or till the problem is resolved. For example, you blow a power head and parts are unavailable for an extended period of time. You will be required to provide proof of the problem for verification.
When you fill out your $10 form list the Mako as your substitute boat and the Onslow Bay you are going to fish the rest of the Division in as your primary vessel.