The base alternator is retained and used to charge the engine cranking battery. An emergency paralleling circuit between the house battery bank and the engine cranking battery allows all batteries to be charged from any alternator in the event of an alternator failure.

Multi-Step Voltage Regulation and Precise Systems Monitoring
Voltage Regulation has been the weak link in DC-based energy systems until recent years. Problems have been resolved with multi-step regulators, which are now on their third or fourth generation and have proven to be both effective and reliable.

Hans Christian Yachts uses the Link 2000R voltage regulator and systems monitoring device from Heart Interface/Cruising Equipment Company, two companies who have been on the leading edge of this technology for a decade; their equipment has a proven record of reliability. This space-age unit not only controls the output of our alternators to produce maximum battery-charging efficiency with the longest possible life expectancy from the batteries, but also keeps track of the state of two battery banks, and of the operation of a 2500 watt DC to AC inverter! Best of all, in spite of its comprehensive software and sophisticated capabilities, it is a snap to use with self-evident messages such as "LO BAT."

DC to AC Inverter
Parallel to the recent advances in DC systems have been tremendous advances in the field of DC to AC inverters. The modern inverter noiselessly and with near 100% efficiency, transforms battery power into 120-volt AC power, completing the picture so far as our basic on board energy systems are concerned. With integrated switching, power-sharing, and dual input capabilities, the Heart Freedom inverter installed on our Offshore Explorer yachts will automatically switch from inverting to charging if an AC source comes on line, will reduce the battery charging load or switch back to inverting if the boat's AC load exceeds the AC supply, and will take input from two separate dockside AC supplies (which is very useful if the batteries are well down, in which case the built-in battery charger will more or less load up one AC inlet.) The Heart inverter's 130 amp battery charger, controlled by a multi-step regulator similar to that in the Link 2000R, is superior to that of just about any stand-alone battery charger on the market!

Refrigeration
For numerous reasons a 1/2 hp or 3/4 hp water-cooled, cold-plate type, DC refrigeration unit provides the optimum combination of efficiency and flexibility. The best units, combining superb design and construction, the highest energy-efficiency on the market, and the use of environmentally friendly HFC 134a, are unquestionably those manufactured by Glacier Bay. Added benefits include an electronic control unit which automatically tops of the cold plates when ever the engine is running, minimizing the refrigeration load on the batteries.

Watermaking
At Hans Christian Yachts we are not advocates of watermakers. The cost per gallon of water produced is far higher than most people realize, particularly with the smaller watermaking units, and the maintenance s more onerous than is often realized. To reduce the need for a watermaker, we have installed substantial water tankage, and also designed the deck so that the entire deck surface can be used as a rain catching area. In a rain storm the initial downpour is used to flush the decks of salt, and then the drains are simply plugged and the rain water diverted into the tanks. Having said that, in terms of energy consumed per gallon produced, the PUR DC watermakers are the most efficient, so we make provisions for one as an option on all our boats. These watermakers, however, are low volume producers. For heavier consumers we recommend a larger, AC driven watermaker which, in its turn, will require the installation of an AC generator.

Alternative Energy
Solar panels and a wind generator can meet a substantial portion of the energy needs of many boats, reducing the amount of engine-running time that is required to charge the batteries. We use only single-crystal solar panels (Kyocera or Solec), since these are the most efficient, and are warranted for at least ten years in a marine environment. Wind generators are a particularly worthwhile option for those cruising in the trade wind belt, notably the Caribbean.

Wiring and Cabling
Cables and terminals are the critical nerves and sinews of an electrical system without which none of the other components can perform satisfactorily. We use only the best, manufactured by Ancor Marine. Cables are tinned, multi-stranded and sized to minimize voltage drop; terminals are tin-plated with a nylon sleeve, and sealed with heat-shrink. All terminals are labeled. There is, of course, far more that goes into the design of the systems on a boat like the Explorer 4750 than we can possibly mention here. In touching on these highlights we hope that we have given you a feel for the years of experience and intensive thought that have gone into producing what we feel is the finest 48 foot cruising boat around.

The Design Objective

• To create a state-of-the-art set of systems using a building block approach that allows a customer to buy a Coastal Cruiser with basic systems and progressively upgrade to a World Cruiser or a Luxury Liveaboard without having to retrofit or discard elements along the way;
• To design systems, and select top-quality components which will minimize maintenance, repairs and discomfort;
• To "keep it simple" and minimize the "learning curve" associated with these systems.

The Mechanism
Until recently, the only way to provide sufficient energy for more than minimal comforts when away from shore power was to run an AC generator, learning to live with the noise, vibration, fumes and maintenance. But in the past decade the development of high capacity DC systems has created a quiet revolution in onboard power systems. Hans Christian Yachts has taken the very best of this new technology to craft a DC-based energy system that provides an unparalleled level of comfort with an absolute minimum of fossil fuel based power generation. To do this we have used the following building blocks:

Gel-Cell Batteries
The limiting factor in any DC-based system is the batteries. From the designer's perspective, the very nature of battery technology results in a number of contradictory factors. Hans Christian Yachts has evaluated these contradictions to arrive at what we feel confident is the optimum battery configuration for our application, which is the use of a series of Prevailer 8D gel-cells wired in parallel.

These batteries require no maintenance; do not require the specialized charging procedures of similar liquid-electrolyte batteries (wet-cells), and as such require no user interaction or "learning curve"; do not produce explosive gases or corrosive fumes when charging; once charged can be left unused for months without damage (an important consideration if laying a boat up for an extended period); can be charged faster than wet-cells (minimizing charging times);maintain a consistently higher terminal voltage than wet-cells under a heavy discharge (important for inverter-based AC systems); can withstand submersion; and will not leak, or produce chlorine gas in a knock-down. Set against these advantages is the fact that in a cycling application the gel-cells do not have the theoretical life of the best wet-cell batteries. However, it is our experience that the wet-cells, for one reason or another, almost never achieve their theoretical life expectancy; that this is, in short, a theoretical rather than a practical advantage. Since all other aspects of gel-cells are superior, we have chosen gel-cells. The Prevailers have consistently proven to be outstanding performers, hence our choice of this brand. By using 8Ds a very modular approach to sizing battery banks is possible, simply adding extra units to increase capacity. The Coastal Cruiser has four 8Ds in parallel, producing a 900 amp-hour battery bank; the World Cruiser has eight 8Ds in parallel, producing a 1800 amp-hour battery bank.

A Single House Battery Bank
Conventional wisdom has always been to alternate two battery banks in house service, so that one is always charged and rested. It is far better, however, to have a single, large house bank with a separate, totally independent, engine cranking battery. The large house bank minimizes the depth of discharge at each cycle (which extends battery life), produces a consistently higher battery terminal voltage under a heavy load (which enhances the entire DC system performance), and simplifies cabling, switching and voltage regulation circuits.

In line with our modular approach, our engine-cranking battery is another 8D gel-cell, providing a generous measure of over-capacity for difficult cranking situations.

High Output Alternators
Alternators rated at up to 200 amps are now widely available. As a battery approaches a full charge, its charge acceptance rate tapers off. As a result, there is little practical advantage in having a charging capability that exceeds 25% of the rated capacity of the battery bank. Given our house banks of from 900 to 1800 amp-hours, this translates into a charging capability of from 225 to 500 amps.

Alternators are typically rated cold, (the SAE rating). When they heat up, there is considerable loss of output. What is more, many cannot withstand being run at continuous, full output in a hot engine room for any length of time. Our alternators are designed to run indefinitely at continuous, full output in a hot engine room. What is more, since much charging may be done at engine idle speeds, the alternators are specially wound to develop full output at lower rpm. In addition to the base 80-amp alternator supplied with the engine, the Coastal Cruiser has another alternator, a Balmar rated at 165 amps SAE, while the World Cruiser has two Balmar alternators, giving a maximum output of 380 amps SAE.

Coastal Cruiser Systems

• 900 amp-hour battery bank comprising (4) Prevailer 8D gel-cell batteries
• Single Prevailer 8D engine cranking battery
• 165 amp Balmar alternator
• Link 2000R systems monitor with built-in voltage regulator
• Heart Freedom 2500 inverter
• 30 amp shore power connection
• Isolation transformer on shore power inlet
• DC panel with master breaker and load breakers
• AC panel
• Glacier Bay 3/4 hp DC refrigerator/freezer with electronic controls DC options
• Glacier Bay air conditioning unit; DC watermaker; solar panels; wind generator AC Options
• (can only be run off shore power except for brief periods of time); stand-alone air conditioning; dishwasher; washer/dryer; trash compactor; icemaker. Luxury Option
• An AC generator which allows all AC options to be run at sea.

World Cruiser Systems

• Expanded 1800 amp-hour battery bank comprising 8 Prevailer 8D gel-cells
• Second Balmar alternator to be controlled by the existing Link 2000R regulator
• Second 30 amp AC shore power connection and isolation transformer DC Options
• Glacier Bay air conditioning unit; DC watermaker; solar panels; wind generator AC Options
• (with judicious use, all but air conditioning can be operated at sea from the inverter); stand-alone air conditioning; dishwasher; washer/dryer; trash compactor; icemaker. A second Heart inverter can be added to boost the short-term inverting capability, and to double the battery charging capability. Luxury Option
• An AC generator which allows all AC options to be run at sea.