Why a Yard Period Is the Right Time

When a sportfishing boat heads into the yard for a refit or extended overhaul, many owners take the opportunity to reevaluate their electronics package. Among the most consequential—and sometimes overlooked—pieces of equipment on board is the sonar.

Whether the boat is equipped with a six-inch searchlight sonar, an eight-inch searchlight, or one of the newer eight-inch Omni sonars, there are many reasons to consider a swap during a haul-out.

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Why Upgrade Your Sonar?

Unlike a chart plotter or VHF radio, sonar is not a plug-and-play upgrade. It requires hull work, specialized installation, and careful calibration. That’s why the boatyard refit window is often the most efficient time to tackle a sonar upgrade.

Owners and captains typically pursue upgrades for several reasons:

• Performance: Newer Omni sonars provide a 360-degree, real-time view of fish schools, dramatically improving target acquisition compared to traditional searchlight models.
• Tournament Edge: Competitive teams are always looking for sharper tools. A sonar upgrade can mean the difference between seeing fish—or not.
• Reliability: Older searchlight sonars can be expensive to maintain, with parts and service increasingly difficult to source.
• Resale Value: A modern sonar installation can help a boat stand out on the brokerage market, especially in competitive sportfish and large center-console segments.

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Searchlight vs. Omni: Understanding the Choices

The six-inch searchlight sonar is the traditional workhorse. A transducer trunk extends below the hull and mechanically sweeps a sector of water. It is effective—but slow compared to real-time Omni systems.

The six-inch Omni sonar offers an option for owners who want to retain an existing six-inch tube. MAQ’s MiniMAQ 90 kHz sonar fits into an existing six-inch searchlight tube and delivers Omni capability at a reduced cost, using a broad vertical beam with a fixed 10-degree tilt.

The eight-inch searchlight sonar is a larger and often more powerful version of the six-inch model, suited for boats that can accommodate a larger tube and offering improved search capability.

The eight-inch Omni sonar represents the biggest leap forward. Instead of rotating a beam, it continuously paints the full circle, delivering faster reaction time and more precise fish tracking—often a game-changer in competitive pelagic fishing.

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Practical Considerations During a Refit

Upgrading sonar during a refit requires planning:

• Hull modifications: Cutting, glassing, or relocating a tube must be done while the boat is on the hard.
• Electrical demands: Omni systems may require dedicated breakers or power upgrades.
• Network integration: Modern sonar ties into MFDs and onboard networks, making helm layout part of the process.
• Crew training: Even the best sonar is ineffective without proper tuning and interpretation. Training is increasingly included with installations.

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Yard Time as Opportunity

Many captains evaluate the “big three” below-deck investments during a yard period: gyro stabilizers, engines/generators, and sonar.

With the boat out of the water, access to cranes, skilled labor, and machinery allows multiple major projects to happen simultaneously—minimizing downtime during the fishing season.

A common upgrade path is moving from a six-inch searchlight to an eight-inch Omni. While the upfront cost is significant, teams often report spotting bait balls hundreds of yards away that would have gone unseen with older technology.

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Common Upgrade Paths

• Searchlight to Omni: Faster, all-around fish detection.
• Manufacturer swaps: Changing brands while reusing an existing eight-inch tube.
• Electronics integration: Sonar upgrades paired with new MFDs and networked systems.

One advantage for owners is industry standardization: most major sonar manufacturers use the ASME ASA 150 flange pattern, making upgrades less invasive than many expect.

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Upgrading from Six- to Eight-Inch Sonar

Moving from a six-inch sonar to an eight-inch Omni requires enlarging the hull opening and completely removing the original tube. This is a structural job best handled during a scheduled yard period.

For new builds or first-time installations, a forward-thinking approach is to install an eight-inch tube from the start, sleeved internally to accept a six-inch sonar initially. When it’s time to upgrade, the sleeve is removed—eliminating future hull work.

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Relocating a Sonar for Better Performance

A growing trend during refits is relocating existing sonars, not just upgrading them. Many original installations prioritize service access over optimal fish-finding position.

In reality, placement matters. The most effective location is typically forward and on the centerline, where the transducer sees clean water and minimal turbulence.

Case in Point

A 75-foot sportfish recently relocated its Omni sonar from the aft engine room to the forward centerline. The improvement was immediate—stronger marks, clearer targets, and more consistent detection on the very first day offshore.

Sometimes, the best upgrade isn’t a new unit—it’s better positioning.

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Why Travel Length Matters: 400 mm vs. 600 mm

Omni sonars are available with different travel lengths, commonly 400 mm, 450 mm, and 600 mm. Longer travel extends the transducer deeper below the hull, away from turbulence, bubbles, and boundary layers.

If space allows, a 600 mm travel unit delivers the cleanest returns and best performance. If vertical clearance is limited, a 400 mm unit can still perform exceptionally well when mounted in clean water.

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Plan Carefully

Sonar swapping isn’t a casual decision. It requires planning, budget, and skilled installers who understand both the boat and the fishing.

But during a refit, the timing is right.

Whether chasing billfish in Los Sueños, tuna off the Outer Banks, or sailfish in the Keys, the right sonar can be as critical as the tackle in your spread. In today’s competitive environment, seeing what’s beneath the surface first may be the ultimate edge.

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By Steve Katz

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Capt. Steve Katz, is the owner of Steve’s Marine Service Inc in Ocean City, Maryland and South Florida. He is the Chairman of the Board of The National Marine Electronics Association (NMEA) and holds ABYC Master Technician certification, NMEA NMET certification along with factory training from many manufacturers. To contact Steve, email [email protected].

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