RedactedNarrative: V-1 launched from Crandon boat ramp and started taking on water for unknown reasons. The vessel was at Bear Cut when the occupants noticed the vessel was taking on water. Operator used the horn on his vessel to signal a nearby good samaritan, and was given a ride back to Crandon Marina. The vessel was pumped out and towed back to Crandon boat ramp by Fast Response Marine Towing. Fast Response Marine towing arrived on scene to pump out the vessel and tow it to Crandon boat ramp. Operator loaded it back onto its trailer and I inspected it for hull damage and a drain plug. I discovered no damage to the hull and the drain plug was tight in the proper location. It is unknown why the vessel was taking on water. Nobody was injured in the sinking of the vessel and all safety equipment was on board at the time of the accident.