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The whole thing began with a puzzle. Our water-in-oil alarm kept reporting "moderate contamination," yet every time I cracked the filter drain, the sample came out perfectly clean. No water, no emulsification, nothing. Either the sensor had developed a personality disorder, or something upstream was tricking it. The uncomfortable possibility: stray electrical currents wandering through the engine block and upsetting every grounded sensor they could find. Rebuilding Vanguard's engine charging system after the Gulf of St. Lawrence flooding only added to the mystery. Once everything came back online, the earth-leakage monitor began shouting about two faults: a positive-to-earth on the port engine and a negative-to-earth on the starboard. That combination strongly suggested the alternators were no longer floating as they should. Finding the Culprit The first clue was on the starboard engine. The alternator leads had been installed backwards. Fixing the polarity mismatch didn't clear the leakage by itself, but it did at least bring both engines back into the same electrical universe. The real culprit was on the port engine: a bent positive cable lug pressed just close enough to the alternator casing to make intermittent contact. On an isolated-return alternator, that tiny contact defeats the entire point of isolation. The alternator suddenly uses the engine block as a return path, and the boat's earth-fault system reacts accordingly. also explains why the Water-in-Oil sensor thought something terrible was happening stray current and grounded sensors make very poor companions. Why Isolation Matters on Aluminum Hulls Marine alternators on aluminum vessels must remain electrically floating. Both B+ and B– are insulated from the housing. The alternator case should never carry current. When it does, you get false leakage alarms, false contamination alarms, and a growing suspicion that the yacht is trying to gaslight you. The fix was simple: reposition the cable eyes, ensure proper clearance from the alternator case, support the conductors, and verify isolation. Once done, every fault cleared immediately Water-in-Oil included. A final thanks to David Millard of Manxme.com an exceptional marine electrician in Charleston and a patient teacher for aging engineers who are still convinced they already know it all. Keeping an Eye on Stray Currents Metal hulls and stray electrical currents coexist about as well as cats and swimming lessons. Any unintended current path accelerates corrosion to the hull or appendages, often quietly and long before anyone sees a paint blister. To stay ahead of that, our Turkish electrical contractor installed a three-channel ground-loop monitor covering the 24-volt DC cabinet and both John Deere engines. It offers three simple functions: a lamp test, and positive- or negative-side ground-fault indication for each engine. So far it has proven easy to use and a remarkably fast early-warning system for problems long before they become expensive. Lessons Learned Verify alternator isolation on aluminum hulls  – Even small contact points can create major fault conditions False sensor readings often point to electrical issues  – Don't assume the sensor is faulty; check for stray currents first Ground-loop monitoring is essential  – Early detection prevents expensive corrosion damage Document cable routing during installation  – Prevents issues during future maintenance or flooding recovery Have you experienced similar electrical gremlins on your explorer yacht?  Share your troubleshooting experiences or questions in the comments below. Related Reading:  Explore more technical deep dives in our Systems & Engineering  section, or learn about Vanguard's complete electrical system design .

Explorer Yacht Electrical System Design – Power System We split Vanguard’s electrical system  into three core components: Power System Hotel System Instrumentation System Because explorer yachts must operate reliably in remote conditions, redundancy drives the entire design strategy. We categorize components into: Fully redundant (duplicated and parallel) High MTBF (such as hull, anchoring gear) Alternative-based redundancy (shore power vs onboard generation) Non-critical systems (luxury items, entertainment) Main Hybrid E-Motors and Power Philosophy Vanguard, like Mobius before her, uses a battery-centric power strategy : Shore power, solar, and the main engines feed the high-capacity banks Propulsion, hotel loads, and navigation draw from these banks Two independent 60kWh banks provide full 50% redundancy Lithium technology was selected for its rapid charge/discharge performance, with design allowances for thermal constraints and safety. High Voltage DC Bus & Propulsion Inverters The power bank floats between 550–770VDC . Instead of multiple complex harness runs, we use a DC bus bar , improving reliability and simplifying fault tracing. Each hybrid motor: Draws power via a VFD inverter Also functions as a charger  when the diesel engines back-drive the hybrid units Each engine can be completely electrically isolated, maintaining safe redundancy pathways. AC Distribution, Transformers & Shore Isolation Two independent transformer systems (20–25kVA each) cleanly supply the 230VAC three-phase hotel load bus. Key features: Active-front-end inverters for pure sine wave AC Delta-configured output windings Harmonic filtering Shore power isolated via dedicated transformer winding Full galvanic and electrical separation from marina earth This prevents hull corrosion and protects crew from floating-neutral faults. Solar, DC Systems & Cold Start Capability An 8kW solar array feeds the hotel system through MPPT controllers. Once the house batteries are full, excess solar is routed back through power inverters to charge the main banks — a cascade charging architecture . House batteries supply: 24VDC 48VDC Emergency cold-start capability Firefly/lead-acid chemistry provides superior performance in low temperatures compared to lithium. Power & Energy Management Systems The yacht includes: Power management : handles shore charging, switching, and source control Energy management : oversees hybrid drives, thruster systems, inverters, and diesel engines in generation mode The system is duplicated and accessible from: Bridge Flybridge Engine room MFD displays Cooling Systems & Future Expandability All major inverters and hybrid drives use: Redundant water/glycol cooling loops Hull skin tanks 50/50 fluid mix <35°C inlet temperature The architecture allows for future hybrid or battery upgrades without redesigning the entire electrical system . A full Factory Acceptance Test (FAT) is scheduled before shipping to catch issues early

I’m writing this partly to organize my own thoughts and partly to document the design safety process behind an explorer yacht . Having ideas is easy; turning them into a final, seaworthy plan is the challenge, especially when your vessel is intended for remote regions where failures matter. A Pragmatic Approach to Explorer Yacht Safety Explorer yachts are designed to operate far from help, which means safety-by-design  and redundancy  are non-negotiable. Instead of pursuing aerospace-grade engineering, we follow a balanced, commercial-grade safety philosophy. We use: Commercial-grade John Deere M1 continuous-rated engines Wills Ridley commercial steering systems TimeZero navigation on independent, isolated marine displays Triple-redundant navigation stations Parallel fuel transfer pumps Redundant steering actuators This approach gives us reliability without unnecessary complexity . Construction Code & Structural Safety To enhance explorer yacht design safety , we follow commercial vessel construction codes as a baseline: Stronger scantlings in the forepeak and skegs (2–3× code minimum) Aluminum hull for high strength-to-weight efficiency Over-spec rudder stocks (double required diameter) Redundant, isolated day-tank fuel system with independent sea suctions These decisions contribute to a yacht that is robust, stable, and damage-tolerant . Identifying Single Points of Failure Small components can cause big problems. We reviewed every system to eliminate hidden vulnerabilities: Replaced HV DC cabling with a DC busbar architecture Added dual 3-phase inverters for 100% electrical redundancy Split battery banks to isolate faults Upgraded from NMEA2000 to redundant Ethernet for high-bandwidth navigation updates Each change strengthens safety without adding unnecessary complexity. Third-Party Classification for Yacht Safety To validate the build, we selected MCA Category 0 (Unrestricted Service) —the highest inspection level for small commercial vessels. This ensures: External verification Documented structural integrity Compliance with global cruising standards Like Caesar’s wife, the vessel must not only be  safe, it must be seen  to be safe. Is All This Overkill? Perhaps, but when your family is aboard, safety is the only acceptable luxury . The goal is balance: enough redundancy for real-world safety without turning an explorer yacht into a floating science project. In the end, the adventures matter, not  the failures avoided.

I’ve spent much of my career surrounded by engineers, often far more knowledgeable about steering systems than myself, so moments like this always carry a fear of self-imposed ridicule. But here we are. This is the story of how we designed the yacht steering wheel system  for Explorer Yacht XPM-002 Vanguard . We were underqualified, yet required to make decisions. That is usually when real learning begins. What Yacht Steering Wheel System Already Works? A useful starting point was examining what already works well. Mobius , our reference point, maneuvers excellently and features substantial redundancy: Duplicate electro-hydraulic steering actuators Independent manual hydraulic emergency system Rudder stock removal cutout without dropping the rudder Jefa water-lubricated, self-aligning rudder bearings We also analyzed FPB78  and Arksen 85  designs to compare rudder areas for similar twin-rudder layouts. A quick review of Lloyd’s Register  and DNV  rules confirmed Mobius’s rudder stock was over twice the recommended minimum diameter, reassuring for our design path. The Vanguard Rudder & Steering Design Initially, the Yard proposed a supported rudder with a lower bearing  mounted on the skeg. But since we requested twin skegs  (to allow drying out on a grid or flat), the lower-support design risked alignment issues on uneven surfaces. So we changed course: Our final rudder approach: Cantilevered blade rudder Large 45° chamfer  on the leading edge to reduce fouling from ropes/debris The stock stops at ⅔  of the blade height The lower third of blade has reduced thickness  to crumple safely under impact 24% area forward of stock axis  (semi-balanced, per Kebelt guidelines) Rudder stock diameter remains at 2× Lloyd’s rule Self-aligning bearings  retained for reduced torque This gave us a rugged, serviceable, and carefully balanced design. Yacht Steering Actuators We evaluated two proven actuator suppliers: Kebelt Wills Ridley Both have deep commercial-vessel lineage, so reliability is not a concern. Each offers: Electro-hydraulic operation Full 100% redundancy Parallel or single-unit running I briefly considered pure electric actuators , but the advantages weren’t compelling compared to a compact hydraulic power pack. For steering, we leaned toward reliable, mature technology. Dynamic Positioning & Split Rudder Control This is where things become more interesting. Short-handed operation of a 78-foot yacht creates challenges. Most vessels rely on bow and stern thrusters unless using podded systems like Volvo IPS or Cummins Zeus, which are elegant but not suitable here. Praxis Automation, our control system supplier, offered an elegant solution: Split Rudder Actuation Instead of linking both rudders: Each rudder can operate independently One engine and rudder provides fore/aft control The other engine and rudder provides lateral control (rudder hard-over) This effectively creates a dynamic-positioning-like capability  without adding the bulk of a stern thruster. We retained the existing Mobius-style bow thruster but upgraded to a proportional model suitable for extended run times. Final Yacht Steering Wheel System Design With all components finalized, Vanguard’s yacht steering wheel system  now includes: ✔ Semi-balanced rudders ✔ Full redundancy from helm to actuator ✔ Ability to hydraulically lock either rudder center ✔ Optional mechanical tie-bar between rudders ✔ Electronic tow-in/out adjustments stored in non-volatile memory ✔ Adjustable response gain ✔ Local emergency steering in the engine room ✔ Redundant Ethernet links to helm, flybridge, and transom stations Call me paranoid, but this is a system built to survive the unexpected. Read Also Explorer Yacht Bow Thruster Seawater Intake System Design Proves Problematic Yacht Stabilizers: Thoughts on Stabilizers

Yacht Generators: How We Picked the Right System (Or Not) What to do about yacht generators ? We debated this topic for longer than expected, because we didn’t simply want a generator; we wanted to understand energy management  onboard the vessel. What uses energy, what produces it, and how do these systems behave at anchor, underway, and in the marina? It turns out the answer was not as straightforward as simply choosing a standalone generator. Solar as Part of Yacht Generator Strategy Hull No. 1, Mobius , uses a pure battery-based system: solar, shore power, and main engines feed into the batteries, and everything else draws from them. Hull No. 2, Vanguard , is different. Our two main engines use standard John Deere alternators, but they can only deliver around 3 kW/hour each, far too little for serious charging. FPB vessels add additional alternator capacity, but even then, diesel engines dislike long periods of low-load operation, which is inevitable during charging. We also have an 8 kW solar array  on the cabin roof. Brilliant in bright sun, zero at night, and reduced at high latitudes. Useful but not continuous. How Battery Type Influences Yacht Generator Choices Battery chemistry plays a major role in whether traditional yacht generators are even necessary: Lead Acid  – Slow to charge, must reach full charge for longevity Carbon Foam (Firefly): Faster charging, better tolerance for partial state of charge Lithium (LiFePO₄)  – Can accept high charge rates, ideal for rapid replenishment Lithium is the game-changer here. With lithium, if you have a large power source, you can dump energy into the batteries rapidly, then rely on battery output for extended periods. But this led us to rethink what a “generator” truly is. Hybrid Yacht Generators: Using the Main Engines for Power We chose a hybrid diesel-electric drive . Initially, we selected 20 kW electric motors  for maneuvering. However, with 2 × 60 kWh battery banks , a full charge would take over 3 hours. So we increased the hybrid motors to 30 kW , which dramatically speeds up charging. Now the crucial discovery: A 30 kW electric motor at 300 RPM becomes ~90 kW of electrical output at 2500 RPM. An AH-HA moment  indeed. This meant: The hybrid motors must be sized not for propulsion , but to match battery charging requirements . This charging strategy requires lithium , and yes, it creates a potential single point of failure (a topic for another post), but the benefits are substantial. Yacht Generator Alternatives: Do We Even Need Them? Our energy system eventually looked like this: Underway  – Engine and hybrid motor provide unlimited  electrical power In a marina , shore power is abundant At anchor —Large house + hybrid battery banks supply energy Daily engine run —~30 minutes to recharge the hybrid and house batteries Solar —tops up batteries whenever conditions allow With this setup, the question naturally emerged: Why install one or even two traditional yacht generators? With: Large lithium battery capacity High-output hybrid charging Solar topping up Redundant power generation via two main engines We concluded: We don’t need conventional yacht generators at all. And the result? A quiet, low-vibration, peaceful experience at anchor with full redundancy. Read Also Preparing for Vanguard Launch Day Explorer Yacht Electrical System Design Building Vanguard

When it comes to superyacht engines , we quickly find ourselves in a quandary. Not all yacht engines are created equal. Put simply, there are big engines, reliable engines, heavy engines, high-performance engines, engines requiring more or less maintenance, engines laden with accessories, emissions-regulated engines, and engines that are not. The list goes on, but at some point, a decision must be made. Redundancy First: Why We Chose Two Super Yacht Engines The easiest part of the decision was this: we wanted two engines for redundancy. Vanguard will have: Two engines Two independent service fuel tanks Separate filtration systems This ensures that if we ever encounter fuel contamination, we can still make progress on one engine, provided we never co-mingle bunkers. Our hull is hydrodynamically efficient, requiring approximately 120 kW for a theoretical 12 knots . That’s extremely modest for a motor yacht of this size, more akin to a fast sailing yacht. Propellers, Shaft Speeds & Eliminating High-Speed Diesel Engines Efficient propellers are slow-turning propellers. Large merchant ships often run at less than 100 RPM. We can’t go that low, but our 700–750 mm propeller diameter limit  requires: A gearbox reduction around 2.5:1 A maximum engine speed of roughly 2300–2500 RPM This immediately eliminates a whole class of high-speed diesel engines. Regulations Matter: US EPA Tier 3 Compliance Because Vanguard will likely operate in US waters, we needed engines meeting EPA Tier 3  emissions standards in this power range. That rules out beautiful classics like the Gardner engines used on Mobius. We also required global parts and service support , leading us to a shortlist: CAT (Perkins) John Deere Yanmar Excellent engines such as Scania or Cummins were eliminated due to minimum power output. The Final Choice: John Deere 4045 AFM85 (M1 Rated) After considerable study, including advice from Steve and Linda Dashew’s FPB series on SetSail.com , we settled on: John Deere 4045 AFM85 M1 rated 120 kW @ 2300 RPM Tier 3 compliant Common-rail, turbocharged, aftercooled Continuous-duty capable Built on a block used in configurations exceeding 700 bhp This gives us a strong, reliable, conservatively loaded engine. The supporting systems (turbo, aftercooler, common-rail injection) add complexity, but the benefits outweigh the drawbacks. And we have two redundancies that continue to be our guiding principle. What About Yacht Generators? That answer will likely surprise you and deserves its own post. 👉 Read next: How We Picked Yacht Generators (or Not) Additional Reading Yacht Propeller Choices: Autoprop vs. CPP? Greening Your Explorer Yacht

Selecting the right hull material for an explorer yacht is one of the most important decisions you’ll make during the design process. Whether you choose aluminum, fiberglass, steel, or wood, each option has advantages, limitations, and long-term implications for maintenance, durability, and performance. This guide breaks down all four hull types to help you choose the most suitable material for your dream explorer yacht. Wooden Hull—Traditional but High Maintenance I’ve owned a wooden boat: a 25-foot, carvel-built beauty with larch planking on steamed green-oak frames, built in 1919. Romantic? Yes. Practical? Not really. Wooden hulls tend to require constant care: Scrape, paint, scrape again Leaks and routine caulking Structural swelling and shrinkage Vulnerability to rot Some patient owners love wooden yachts, and wood is indeed a forgiving material to shape and repair. But for a modern explorer yacht, wood is rarely the best option. Fiberglass Hull—Reliable and Ideal for Series Production Fiberglass (and its derivatives) is extremely popular in mainstream yacht building, especially for production models. When built well, fiberglass is hard to beat: Advantages of Fiberglass Hulls Excellent for mass production Lightweight, yet strong Easy to mold into complex shapes Proven track record with respected builders (Fleming, Nordhavn, Hatteras, Cheoy Lee) Limitations Requires a mold—impractical for one-off custom explorer yachts Potential for osmosis if poorly fabricated Difficult to repair perfectly after major impact Often relies on wood substructures (not ideal) Fiberglass shines for semi-production yachts but is less suited for heavy-duty expedition vessels. Steel Hull—Tough, Cheap, and Familiar to Commercial Mariners Steel is the traditional choice for workboats and merchant ships. I spent years sailing in the UK Merchant Navy on steel vessels. It’s strong, weldable, and readily available worldwide. Advantages of Steel Hulls Extremely tough and impact-resistant Straightforward to repair almost anywhere Cost-effective per ton Excellent for large, heavy displacement yachts Limitations Corrosion  is the biggest enemy Crevice corrosion in stagnant bilge areas Higher ongoing maintenance Heavier than aluminum Not ideal for smaller explorer yachts due to weight/stability trade-offs Many builders mix materials: steel hull + aluminum superstructure to lower weight up high and improve stability. Well-known examples include Knud Hansen’s 24 m explorer designs and several Turkish-built Bering yachts. Aluminum Hull—Lightweight, Strong, and the Explorer Yacht Benchmark Aluminum (yes, spelled correctly!) is more expensive than steel—but the advantages for explorer yachts are substantial. Most modern long-range designs (FPB, Circa Marine, Arksen) rely on aluminum with oversized scantlings. Advantages of Aluminum Hulls ⅓ the weight of steel —allows for more range and payload Strong when properly sized (1.25–1.5x steel thickness) Faster welding and easier shaping Non-magnetic, ideal for navigation equipment Will bend rather than crack on impact Does not  require paint if you like a raw workboat look Better availability of skilled builders worldwide Limitations Requires vigilance against galvanic corrosion Slightly less abrasion resistant than steel More expensive material cost Aluminum remains the top choice for modern ocean-capable explorer yachts. Learning the Engineering Behind the Materials If you enjoy understanding the engineering as much as I do, I strongly recommend: Dave Gerr—"Boat Strength for Builders and Designers" McGraw Hill, ISBN 0-07-023159 It provides an excellent explanation for why so many serious explorer yachts use marine-grade aluminum  with carefully engineered structural scantlings. The peace of mind is worth it, especially on a dark night offshore. Recommended Reading 👉 XPM-78: Designing the First Hull 👉 XPM-85: A 52-Foot Explorer Yacht Machine

Selecting the correct explorer yacht category  is one of the most important decisions in any new yacht build. Different regulatory systems, especially between Europe and the USA, can influence everything from construction standards to resale value. Understanding what each category means ensures your yacht is safe, compliant, and capable of the type of cruising you intend. Understanding the Regulatory Differences There are fundamental differences between how Europe and the United States regulate yachts: Europe tends to prescribe clear, binding engineering and construction standards. The United States —often provides “non-binding” guidelines, leaving interpretation to owners, builders, and sometimes lawyers. Because Vanguard is being built in Turkey and will likely be U.S.-flagged  but used for worldwide cruising , a consistent and internationally recognized standard was essential. She is too small for full Classification Society rules, so two practical and stringent standards were selected. CE Category A—Ocean (European Union) CE Category A allows a yacht to safely operate in: winds above Beaufort Force 8 , and significant wave heights above 4 meters . This is the highest CE class and is appropriate for ocean-going yachts intended for long-range passages. It also allows the vessel to be commercially sold within the European Union , which is an important long-term consideration. Why We Also Chose MCA Category 0 (UK) Alongside the CE standard, Vanguard was designed to comply with: MCA Category 0 — Unrestricted Service Worldwide This is the strictest  classification under UK Maritime & Coastguard Agency rules and permits: global operation , offshore passages , and cruising far from immediate assistance . A useful summary of MCA standards is available from the Royal Yachting Association (RYA) . It is important to note that “unrestricted” does not mean “invincible.” Vanguard is not an icebreaker or a commercial ship, but the Category 0 framework provides an extra layer of safety and reassurance . Given the build is taking place 6,000 miles from home, a clear and authoritative standard was needed. MCA Category 0 provides exactly that. Explorer Yacht Categories Explained (MCA Classification) The MCA system includes six main yacht categories , each defining how and where the vessel may operate. Category 0 —Unrestricted,—Unrestricted worldwide service Category 1 —Up to 150 miles from a safe haven Category 2 —Up to 60 miles Category 3 —Up to 20 miles Category 4 —Up to 20 miles, fair-weather day operations Category 5 —Up to 20 miles from a nominated departure point Category 6 —Up to 3 miles from land, fair-weather daylight only For full details, refer to MGN 280 , the Marine Guidance Note governing small commercial vessels. What MCA Category 0 Requires in Practice Achieving Category 0 is not simply a paperwork exercise. It requires detailed oversight from a Certifying Authority , who will conduct surveys both in and out of the water  at regular intervals. Key elements include: ✔ Stability Requirements Vanguard has no angle of vanishing stability , similar to a Coast Guard cutter. No matter the heel angle, she will always return upright, ideal for offshore conditions. ✔ Machinery & Electrical Systems All systems must be built and maintained to a standard that supports global operation, redundancy, and reliability. ✔ Life-Saving & Safety Equipment Fire systems, escape routes, alarms, and life-saving appliances must match commercial standards. ✔ Ongoing Oversight This classification ensures that experts continuously monitor the vessel’s compliance over the years, offering peace of mind and long-term operational safety. Why These Explorer Yacht Categories Matter We are not naval architects or regulatory experts; much of what we’ve learned comes from reading, discussions, and working with our Certifying Authority in Turkey. But this process has made one thing clear: A robust category selection is essential for a safe, capable, ocean-going explorer yacht. Choosing CE Category A and MCA Category 0 ensures: A globally recognized safety standard Flexibility to cruise anywhere Improved resale value Higher construction discipline at the Yard External verification and long-term oversight For a yacht designed to operate far from help, these standards are not merely paperwork; they are part of the vessel’s DNA. Further Reading 👉 Explorer Yacht Electrical System Design 👉 Explorer Yacht Options Just Became Wider!

Why Explorer Yacht Design Favors Commercial-Grade Equipment My wife, Sebrina, constantly asks why I always lean toward commercial-grade equipment when the yacht market is full of flashier, more glamorous alternatives. My usual answer is simple: “Fishing boats look like fishing boats for a reason.” Eventually, it was time to explain why A Lesson From My First Years at Sea I first went to sea in 1976. A long time ago now, and I fully admit memory can embellish, but this incident made a lasting impression on me. Most of the details came from the first mate’s retelling in the ship’s bar later that night. We were off the southeast coast of Africa, somewhere near Durban. A seven-hatch geared bulk carrier on passage to Indonesia. It was around 5 a.m., the middle of the 4–8 watch. Two crew on the bridge, the second engineer and a motorman below, and me, the cadet, doing routine chores. Moderate seas. A bright moon. A normal, slightly dull night watch. And then the bridge saw it: a shadow across the sea, low and wide, off the port bow. No clouds. No large swell. Nothing that should cast a shadow. But it moved toward us, and we moved toward it. The Hole in the Sea With a 10–15 mile horizon and 9–10 knots of speed, things develop fast. The “shadow” wasn’t a shadow at all. It was a wide, soft-edged depression . A hole in the sea. Behind it rose a wall of water slowly, silently, impossibly tall. Someone must have called the captain, because suddenly everything erupted. The ship’s general alarm sounded. The Engine Room phone rang. The telegraph twitched double ring astern. The second engineer shouted for another generator. As I moved for the switchboard, the main engine’s turbochargers backflowed as load came off, screaming like I had never heard. Bodies came sliding down ladders, leaping the last few steps into the ER. Everyone was rushing but somehow still doing exactly what needed to be done. I did what I was told, even though I had no idea why. The bliss of youthful ignorance. The shaft stopped. Then, against all odds, the engine went astern on start air. Someone must have opened the receiver valves; they’re normally closed at sea. Fuel trickled back in, the pop-off valves lifted, and there was smoke and debris everywhere. Cylinder head seals blew. The whole engine groaned as it tried to drive the prop backwards. The ship began to tilt, not pitch but tilt , bow-down, as we dropped into the trough. And then the entire engine room began shaking. I had felt that before the lightship, going upriver in Rosario to load grain when the prop tips came clear of the water. Slowly it settled. Slowly it calmed. The telegraph rang again. Order returned. What We Hit In the retelling, we had likely encountered a freak wave or, more probably, the combined peaks and troughs of two large waves meeting at just the wrong angle. A trough followed by a peak. An amplitude of perhaps 80 or 90 feet . A monster. When we entered the trough, the bow drove underwater. The wave climbed up and over, reaching halfway across hatch No. 2, an enormous amount of green water. It killed our forward speed entirely, leaving the prop sucking air. Eventually, very slowly, the ship lifted up and over the crest. The sea returned to normal. But none of us forgot. Another Example: The Derbyshire Two of my friends, Paul King and Eddy Williamson, had a similar encounter far worse aboard the Derbyshire , a Bibby Line bulk carrier lost south of Japan in the North Pacific. The inquest concluded that massive wave compression caused sequential bulkhead failures, sinking the ship within minutes. Everyone aboard was lost. I remember seeing Eddy at the Ocean Fleets office in Birkenhead. He had just signed on as 4th Engineer on Derbyshire . Young. Smartly dressed in the style of the 1970s. Full of optimism. Their faces stay young in my memory, even as mine grows older. And This Is Why Fishing boats look like fishing boats for a reason. Their shapes, equipment, and rugged commercial design exist for one purpose: To survive whatever the sea decides to throw at them. That’s why our explorer yacht leans heavily toward commercial-grade decisions. Not because it looks glamorous but because it looks like it will bring us home.

Thoughts on Electric vs Hybrid Drives Open any yachting magazine, and you’ll see mention of electric and hybrid drives. More than a trend, these propulsion systems offer significant advantages. New technology is exciting, but it’s essential to understand what you’re stepping into before investing in a costly system. What is a Hybrid Drive? Hybrid drives in yachts follow the EV principle used in cars: combining a traditional internal combustion engine (ICE) with an electric motor. The torque and power of both systems are matched to create a performance profile that wouldn’t otherwise be possible. Example application:  a harbor tug operating at low power most of the time, then needing full power for short bursts. By integrating an electric trolling option and a battery bank, the diesel engine can run intermittently at moderate load to charge the batteries, then shut off until more power is required. Benefits include: Improved fuel efficiency Reduced engine wear Lower emissions Series vs Parallel Hybrid Systems Series Hybrid:  Diesel engines run generators to charge a battery bank, powering electric motors connected to the propellers. Parallel Hybrid:  Diesel engines and electric motors can both drive the propellers directly. For Vanguard, we selected a parallel hybrid system  to maintain traditional diesel capability while gaining the advantages of hybrid operation, offering greater redundancy and easier resale in a conservative market. Choosing the Right Manufacturer We evaluated five suppliers: Marine Hybrid, Esco, Praxis, Transfluid, and TEMA. Key requirements: Compatibility with slow-running John Deere diesel engines Ability to power two propellers from one engine Large battery bank for silent, low-speed operations (~20 kW for trolling/maneuvering) The hybrid motor sizing was dictated by the need to charge batteries rapidly, not to power the yacht at full speed. Advantages of Our Hybrid Drive Silent operation  in sensitive areas or during dynamic positioning (DP) at night Space savings  by removing main and standby diesel generators Dynamic positioning capability  with instant torque and quick direction changes Reduced engine hours , driving two props from a single engine when possible High redundancy —flexibility to operate in multiple configurations Future-Proofing Our system is designed to expand as battery technology improves, particularly with advances in electric vehicle (EV) power density. This ensures Vanguard can adopt new tech without compromising traditional diesel propulsion. Conclusion Do we need  a hybrid system? Perhaps not. Do we want to experiment and gain the flexibility it offers? Absolutely. For Vanguard, the hybrid drive enhances efficiency, reduces emissions, and adds fun tech play without affecting traditional propulsion reliability. Fun fact: as a Star Trek fan, I now get to tell my son, “No. 1 – engage hybrids and take us out of here!”

Understanding Yacht Batteries Batteries are deceptively simple: blocks of lead-acid (or newer technologies) that sit in the bilge, charged and discharged daily. That was my understanding… until I started specifying one for a hybrid yacht system. Questions quickly arose: How much power do we really need? What is the maximum safe discharge rate? Which system voltage works best? How can I supply high-current DC loads efficiently? Which battery technologies are best suited for marine applications? After research and testing, here’s what I learned. Three Main Types of Yacht Batteries Lead-Acid Batteries Similar to a car battery Can be sealed or vented (sealed preferred) Maximum depth of discharge ~50% of rated capacity Sensitive to deep discharges → sulfation and shorter life Traction batteries (like forklift batteries) tolerate deeper discharge Slow to charge but inexpensive Carbon-Foam / Firefly Batteries Similar chemistry to lead-acid but with a special carbon foam anode Faster charging (~80% charge quickly) Can cycle partial charges without damage Economical and more stable than standard lead-acid Lithium Batteries (LiFePO4) Much higher energy density (~120 Wh/kg, ~3x lead-acid) Charge rapidly Voltage decreases at low temperatures Some lithium chemistries (LiCo, LiNiMnCo) risk thermal runaway or dendritic shorts → fire hazard Expensive upfront ($600–$1000/kWh) but better lifecycle economics Marine insurance may have restrictions Selecting Batteries for a Hybrid Explorer Yacht Our hybrid drive requires: Large power storage capacity Fast charging Reliability and Class-approved components After reviewing suppliers, two stood out: Corvis (Norway) Praxis (Netherlands) Both offered: Modular systems Built-in monitoring and cooling Fire relays Class approval for marine use Our total installed capacity: 60 kWh , roughly 2 hours of operation at 500–700 VDC . Modularity allows upgrades as technology evolves, especially with the rapid adoption of electric vehicles driving marine battery innovation. Emerging Battery Technologies Battery technology is evolving quickly. Promising developments include: Lithium Sulfur (LiS) Solid-state cells 4–5x power density of LiFePO4 Initially for military/aviation, but may enter marine applications We plan to review our battery selection closer to delivery (about 18 months away) to take advantage of any improvements. Conclusion Specifying yacht batteries is far from trivial. It requires understanding: Capacity and discharge limits Charging rates Voltage requirements Technology suitability for marine safety and lifecycle costs Choosing LiFePO₄ offered the best combination of energy density, fast charging, and reliability for our hybrid explorer yacht.

Learning From the XPM78-01 Mobius The first XPM78, Mobius , was built by Wayne and Christine to an Artnautica design. Both are highly experienced sailors and good friends whose choices reflected their own priorities. That is one of the real advantages of building a boat: you get exactly what suits you . Our boat, Vanguard  (XPM78-02), evolves this design. Many features carry forward, but we made several key changes based on our own experience, needs, and preferences. Here are the major lessons and what we chose to adjust. General Interior Layout: Three Cabins With Natural Light We needed three cabins —master, family, and guest—with each serving a specific purpose. Master Cabin Located near the center of buoyancy This is the most comfortable place aboard in a seaway Ideal for sleeping on long passages Family Cabin Close to the main access points Easy movement, easy watchkeeping transitions Guest Cabin Has its own access  for privacy If we carry crew, they are not intruding on family space Because my wife is claustrophobic and prefers daylight, all cabins include skylights and small through-hull ports  for natural light and ventilation. On a 78-foot hull, this layout is easy to achieve, but it required two structural changes: Raising the saloon by 300 mm  to gain headroom Reconfiguring the fuel tanks below  to match the new levels Expanding and Refining the Saloon We also extended the saloon forward by 1000 mm  to create: More space around the helm Room for an additional companionway An improved day-to-day living area Both the FPB and Arksen designs have excellent saloon arrangements, so we drew inspiration from them rather than reinventing what already works. We added double helm chairs, ensuring my wife can sit comfortably (and give me instructions, as she puts it!). With the saloon raised, we worried the superstructure looked top-heavy. To soften this visually, we added a 300 mm bulwark  running from the foredeck to amidships. This: Raises the visual sheer line slightly Helps shed water with built-in freeing ports Keeps the foredeck drier in rough conditions Stability Systems and Boat Handling Mobius  uses a flopper-stopper rig and derricks for tender handling, with plumbing installed for powered stabilizers (but not fitted). We decided to install stabilizers from the outset , avoiding later complexity and top-hamper. We chose DMS Magnus Effect Rotors  because: They promise superior zero-speed performance They fold away when maneuvering near ice or docks They allow stable operations at anchor without fins Critical Systems: Redundancy and Reliability For an explorer yacht, anything mission-critical must: Be duplicated or Have a very high MTBF (Mean Time Between Failures) This is standard commercial-marine thinking—and one of our main lessons. We chose: Twin Main Engines Identical engines Derated for continuous running Together produce twice  the required installed horsepower Supported by: Two gearboxes Two drivelines Two rudders This keeps us operational even if a major component fails offshore. Hybrid Drive: Efficiency and Capability We are fitting a hybrid drive system , which offers several advantages: Rapid battery charging using surplus propulsive power Ability to drive both shafts from one engine Silent maneuvering on electric drive Dynamic positioning made simple Independence of rudders and thrusters works very well with electric propulsion Hybrid drives are not for everyone—they require careful thinking about goals and redundancy—but for us, the benefits were clear. Electrical System: Battery-Centric Architecture Wayne’s major decision on Mobius  also suits our needs: everything is centered around the battery bank. All charging sources feed the batteries: Shore power Mechanical charging Solar PV All utilities then draw from the battery bank. We specified large banks  (2 × 60 kWh). In the age of EV technology, this is no longer unusual, and the extra mass acts as ballast. We selected type-approved marine systems , each with: Dedicated cooling Heating Charging Safety systems Thanks to the hybrid charging capability and the battery size, we do not need additional generators —two fewer systems to maintain. Final Thoughts There are many smaller changes throughout the design, but the points above represent the major revisions informed by our needs and lessons learned. The last step is to recalculate our stability curves with the final specification—though we expect to fall well within safe limits. As always: each to their own.  What matters is designing a vessel that fits your  life, your  voyages, and your  priorities.