What are the factors that one should consider in choosing the travel length in the hoist? I assume it depends on the placement of the unit. Can there be a problem with the frequency of sonars currently on the boat and some type of interference depending on which dual frequency unit we purchase? We had a electronics guy look at the boat and he said based on the centerline of the hatteras being full of fuel tanks and water tanks that the best place was inside the owners stateroom inside a closet that had a false floor as to access the hull/keel of the boat. The boat has naiad stabilizers but they are a good ways aft of the location of the proposed install. What frequency would be best, we are using the boat for recreational fishing for anything from bluewater trolling to swordfishing and deep dropping. Thanks in advance for your responses.