Unfortunately, you cannot force a partner in a houseboat to pay his share of needed repairs. At best you can simply request that he pay his share of the repairs. If he refuses, your option is to make the repairs yourself and sue the partner for the amount you paid for that was his obligation, or make the repairs yourself and seek no reimbursement.The former obviously will create some strain on the partnership. I suggest that you sit down with the partner to discuss the need for him to contribute to the boat's upkeep. The way the problem could have been prevented is if there was a written partnership agreement signed by you two as to issues concerning the boat and its upkeep. One can be drafted. If that is a possibility, you should consult with a business attorney to do this task.