We have a repeater and for the past 6 months we have been having a group coming up on our Travel tone. We have tried to communicate with them, to inform them their radios are improperly set up, or they are using our repeater when it sounds as simplex would be sufficient, but no answer. Most of their interfering comms are incomplete and they could not be communication effectively through our repeater, which leads us to believe they are conducting simplex comms on the repeater input frequency and using the Travel tone. They are moving marine vessels and sound as they are on the same vessel, which means no repeater is necessary. As I said we have tried to communicate with them through the repeater, So should we try simplex communication on the repeater input frequency with an HT connected to our repeater feedline? We will have to catch them and then shutdown repeater and make connections to an HT already programed for this event. Anyone have any other ideas or comments?