In-hull and thru-hull transducers provide cleaner sonar performance than transom-mount alternatives for certain boat types — especially fiberglass hulls where a shoot-through installation eliminates drag and damage risk. Here's what's available and when each type applies.
Thru-hull transducers with epoxy fairing blocks — the highest-performance fixed installation. Compatible with Garmin units via 12-pin or 8-pin connectors. Available in CHIRP-only, CHIRP+DI, and full network-capable versions.
The most trusted shoot-through transducer — polyurethane construction bonds to the hull interior with epoxy, reads through solid fiberglass without hull penetration. Standard 200 kHz.
Humminbird-compatible thru-hull transducer for 2D CHIRP and DI applications — installs through the hull with appropriate fairing block.
Lowrance's thru-hull version of the Active Imaging transducer — CHIRP, Side Imaging, and Down Imaging through a single hull penetration.
In-Hull (Shoot-Through) vs Thru-Hull
In-hull (shoot-through): Transducer bonds to the inside of the hull, reading through the fiberglass. No hull penetration required. Loses 30–50% of sonar signal strength vs in-water mounting. Never works through cored (balsa or foam core) fiberglass, aluminum, or wood hulls — the air gaps in the core prevent signal transmission. Works only through solid fiberglass.
Thru-hull: Transducer installs through a drilled hole in the hull with an epoxy fairing block flush to the hull exterior. Best possible performance — transducer is in the water with no material in between. Requires hull penetration and professional installation on most boats. The standard for sailboats, larger fishing boats, and applications where maximum performance is required.