Can a repossesion company get a boat after bankruptcy has been filed on it?

The creditor can repossess the boat, after it files a motion for relief from stay that is allowed or you have agreed to surrender the boat to the creditor. The repo company is only acting as an agent for the creditor.

You do not file bankruptcy "on" anything. You file bankruptcy to have your debts discharged if they are dischargeable. If you have intentionally omitted other creditors, your petition or discharge could be denied.