Your thru-hull transducer must be in direct, unobstructed contact with smooth water for optimal performance. For a thru-hull transducer, you should consider the placement with regard to the engine(s) and propeller, the hull, and physical damage.

Thru-hull transducers are the type least affected by damage from turbulence, but turbulence beneath the hull can still affect the signal. Optimal placement is in the bilge near the keel and transom where the water under the hull is smoothest while the boat is moving.

Garmin^® offers thru-hull transducers in two types, external and flush.