The Right Thru Hull Transducer For Offshore Fishing Boats

See bronze, stainless, and plastic thru hull transducers for Furuno, Garmin, Raymarine, and more.

Shop thru hull transducers

Thru Hull Transducer Advantages For Serious Boats

Mounting through the hull changes what your sonar can show at speed, at depth, and in rough water.

Cleaner Returns At Cruising Speed

A thru hull transducer sits in solid water beneath the hull rather than in the turbulence trailing off the transom. That placement keeps the face submerged and the signal clean as speed climbs, which is why many offshore boats lose fewer bottom readings after switching. Flush housings add very little drag, and owners running offshore at 30 knots or more often notice the difference on the first trip.

Stronger Performance In Deeper Water

Mounting through the hull also allows larger, more powerful elements that suit canyon and deep-drop fishing. Our guide to CHIRP vs. Traditional Sonar explains why a CHIRP sweep separates fish from the bottom so clearly at depth, while traditional dual-frequency elements still deliver dependable depth and fish detection for many owners.

Choosing The Right Thru Hull Model For Your Vessel

The best model matches your display, your hull angle, and the depths you actually fish.

Power Output And Connector Compatibility

Confirm which display or sonar module will drive the transducer before you compare models, because power and connector type have to match it. The Garmin model below delivers 1kW through an 8-pin connector, the Furuno model delivers 600W through a 10-pin connector, and the Raymarine RealVision models use a 25-pin connector. A mismatch means adapters at best and lost features at worst, and higher wattage also needs a display or module rated to deliver it.

• Furuno – 600W, 10-pin (520-5PSD kit)
• Garmin – 1kW, 8-pin (B175H kit)
• Raymarine RealVision – 25-pin (RV-412 kit)

Matching Element Tilt To Deadrise

Measure your deadrise at the mounting point before comparing models, since guessing the angle is a common reason a new transducer reads worse than the one it replaced. A few simple rules help:

• If Your Deadrise Is 16° To 24°: A tilted-element model such as the Garmin B175H keeps the beam vertical without a fairing block.
• If Your Hull Is A Deeper V Up To 26°: A split pair such as the Raymarine RV-412 uses two angled elements joined by a Y-cable to cover the extra angle.
• If Your Deadrise Falls Outside An Element's Range: A fairing block levels the transducer so it points straight down and smooths water flow over the face, which reduces noise at speed.

You can compare tilt ranges and power ratings across brands in our Marine Navigation and Instruments Transducers collection.

Recommended Thru Hull Transducer Kits By Hull And Display

Each kit below works within its own brand's displays and sonar modules, so start with the display you run and choose the tier that fits your hull and depths.

Good: Furuno 520-5PSD Plastic Thru Hull Transducer

Best for fiberglass or aluminum and metal hull boats on Furuno displays that need solid dual-frequency depth and fish detection without CHIRP.

• It delivers 600 watts at dual-frequency 50/200 kHz, which gives dependable depth and fish detection for owners who value simplicity over CHIRP detail.
• Beam angles of 46° and 10° and an 8-meter cable with a 10-pin connector make it ready to connect to compatible Furuno equipment.
• The plastic housing keeps costs low and avoids the galvanic corrosion risk that bronze carries in aluminum hulls, although bronze generally offers more long-term durability.
• For a bronze housing with a built-in temperature sensor, our Furuno Transducers collection also lists the 525T-BSD.

Add this kit to cart

Better: Garmin B175H Bronze Thru Hull Transducer

Best for offshore fiberglass or wood hulls (16°–24° deadrise) on Garmin, running canyon and deep-drop depths at cruise.

• A 1kW high CHIRP element rated to 3,000 feet gives canyon and deep-drop fishing the depth range it calls for, and the 8-pin connector fits compatible Garmin equipment.
• The tilted 20° element covers that deadrise range without a fairing block, which simplifies the install.
• The flush bronze housing protrudes less than a quarter inch and can sit on trailer rollers or bunks without damage, and it includes a temperature sensor and a 39-foot cable that often reaches the helm without splicing.

Add this kit to cart

Do not install bronze housings in aluminum hulls because of galvanic corrosion.

Best: Raymarine RV-412 Stainless Steel Thru Hull Transducer Pair

Best for deep-V powerboats on Raymarine RealVision that want 3D, down, and side imaging plus CHIRP sonar at speed.

• RealVision 3D, CHIRP DownVision, SideVision, and high-frequency CHIRP sonar share one low-profile stainless housing, and our DownVu vs. SideVu sonar guide explains how to read the down and side imaging views.
• The split pair with a Y-cable accommodates deadrise angles up to 26°, and a built-in attitude and heading reference system (AHRS) steadies the picture in waves and when maneuvering.
• Each transducer includes an isolation kit that separates the stainless body from dissimilar metal hulls to prevent galvanic corrosion, and the pair comes with a Y-cable and an 8-meter extension cable.
• For flatter hulls, the single-transducer RV-400 offers the same sonar suite.

Add this kit to cart

Recommended Accessories For Thru Hull Installs

Fairing blocks and tilt adapters

Level the transducer on steep deadrise and smooth water flow over the face.

Shop the Transducer Accessories collection

Isolation kits for metal and cored hulls

Prevent galvanic corrosion and protect cores from water intrusion.

Shop the Transducer Accessories collection

Cable extensions and waterproof glands

Let you reach the helm or sonar module without splices and seal hull and console penetrations.

Shop the Transducer Accessories collection

Thru Hull Transducer Installation Done Right

A thru hull transducer is only as good as the hole, the seal, and the cable run behind it, so here are the DIY install notes and warnings worth knowing before you drill. The mistakes we correct most often are guessing the deadrise, skipping the backing and seal on cored hulls, and splicing a cable to make it reach.

Reasonable DIY:

• Haul-out available and you are replacing an existing thru hull in the same location.
• Solid fiberglass hull and like-for-like housing material.
• You are comfortable drilling, sealing, and routing cables cleanly.

Call a pro when:

• Hull is cored, aluminum, or steel and you are unsure about backing, isolation, or sealants.
• You are changing locations or adding a new thru hull below the waterline.
• Boat cannot be hauled or downtime is tight around yard windows.
• Vessel is 70 ft+ with crew or charter and sonar failure is a trip risk, not a nuisance.
• Space And Location: Choose a spot with solid, bubble-free water flow, away from strakes (the raised ribs along the hull bottom), intakes, other fittings, and propeller wash, and check it from both inside and outside the hull, since moving a thru hull later means a second hole.
• Sealing: Use marine sealant rated for below-waterline use, back cored hulls (those with a foam or balsa core) so the laminate cannot crush or absorb water, and tighten the hull nut to the manufacturer's specification, since overtightening can crack plastic housings.
• Cabling: Plan the route before mounting so the cable reaches the display or module without splicing, secure it away from high-current wiring, and leave a service loop near the transducer for future inspection.
• Tools And Hardware: Expect to need a hole saw sized to the housing, marine sealant, and the right fairing block, isolation plate, and bushings, which our Transducer Accessories collection covers.
• Estimated Time: Plan on a haul-out and a project that typically takes a day or more once sealing and a sea trial are included, since commissioning finishes on the water by confirming bottom tracking at idle, at cruise, and through turns.

Prefer professional installation? South Florida customers receive a 10% installation credit on all shop purchases with Concord Marine Electronics at Safe Harbor Lauderdale Marine Center.