The Legendary Bertram 31 and the Proven Cummins 6BT Pairing

Few sportfishing boats are as iconic as the Bertram 31. First launched in the early 1960s, the 31-foot deep-V hull from Bertram quickly became a favorite among offshore anglers and captains who needed a small but seaworthy boat capable of handling rough water. Its sharp entry, wide beam, and efficient running surface gave it a ride and stability that made the model legendary from Florida to the Northeast canyons and beyond.

Many owners have kept these classics alive by repowering them with modern diesel engines. One of the most popular upgrades is the Cummins 6BT — a rugged, 5.9-liter inline-six diesel known for its simplicity, mechanical fuel system, and long service life. The 6BT delivers reliable power for extended offshore runs, excellent fuel economy compared to older gas engines, and a reputation for lasting thousands of hours with proper care. Twin 6BTs fit the Bertram 31 perfectly, providing modern diesel dependability without upsetting the boat’s balance or performance.

At the time of this video, this particular Bertram 31 — formerly named “Cup of Joe” — had just been purchased by Heath Daughtry. Under its new ownership, the boat will be renamed “Hey Darling.”

Why Remove the Engines From a Bertram 31

While many smaller service jobs can be handled right in the bilge, there are times when it’s far more practical — and often the most efficient and reliable approach — to remove the engines completely. For classic boats like the Bertram 31, pulling the engines can save time, reduce frustration, and result in a better-quality repair.

Major Overhauls or Full Rebuilds

When a Cummins 6BT needs a complete tear-down — for example, to replace pistons, bearings, or cylinder heads — doing the work inside the tight confines of a boat’s engine room can be nearly impossible. Bringing the engines into a proper shop environment allows mechanics to stand upright, use precision measuring tools, and keep everything clean and organized. This level of control is critical when you’re rebuilding a diesel designed to run thousands of hours reliably.

Access to Hard-to-Reach Components

Certain jobs, such as replacing a rear main seal, swapping transmissions, installing new motor mounts, or overhauling major cooling system parts, require access that’s simply not possible with the engines in place. By lifting the 6BTs out, mechanics can reach every fastener and sealing surface, ensuring the job is done right the first time without fighting cramped spaces.

Better Quality and Efficiency of Work

Shops equipped with cranes, hoists, engine stands, and specialized torque tools can rebuild and service an engine to factory specifications. Trying to achieve the same accuracy while leaning over a bilge opening is challenging and sometimes leads to shortcuts that compromise longevity. Removing the engines allows technicians to do a meticulous job — which pays off in reliability and performance once the boat is back on the water.

Structural or Cosmetic Upgrades

Engine removal isn’t always about the engines themselves. Owners may need to repair stringers, update the engine room with new paint or soundproofing, or tackle fiberglass work that’s impossible with the motors installed. A clean, open bilge also allows for more extensive electrical rewiring, plumbing upgrades, or fuel system improvements.

The Bertram 31’s thoughtful design makes this process easier than many other boats its size. The removable cockpit deck and relatively open engine bay mean a crane — like the one used in the video — can safely lift each Cummins 6BT out in one controlled motion. For owners planning major service, this accessibility can be a big advantage and often shortens the total downtime of the project.

Cummins 6BT Parts From Diesel Pro Power

Whether you’re removing your 6BTs for a full overhaul, doing top-end service, or simply replacing wear items, Diesel Pro Power makes it easy to get the exact parts you need. We stock a wide range of Cummins 6BT components, including:

• Complete overhaul kits — pistons, liners, gaskets, bearings, and seals for full engine refreshes

• Individual cylinder kits — for single-cylinder repairs or partial rebuilds

• Cooling system components — fresh water pumps, raw water pumps, thermostats, and heat exchanger parts

• Fuel system parts — injectors, lift pumps, and fuel filter housings

• Air and exhaust system components — turbos, manifolds, elbows, and blowers

• Top-end parts — cylinder heads, valve train components, and gasket sets

All parts are sourced to meet or exceed OEM standards, and our fast worldwide shipping keeps downtime to a minimum. With 40,000+ satisfied customers, Diesel Pro Power has become the trusted supplier for both professional marine service shops and individual boat owners.

Whether you’re simply swapping out one worn cylinder kit or planning a complete repower project, having the right parts on hand — backed by knowledgeable support — ensures your Cummins 6BT engines will run strong for years to come.

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