A power alternative

Most modern sail boats are equipped with some form of mechanical propulsion for those times when the wind is uncooperative. Unfortunately, the benefits of this auxiliary power are accompanied by a number of penalties like noise, vibration, heat, the use of prime belowdecks space, and difficult access for inspection and maintenance.

There is an alternative to plunking a diesel auxiliary in the middle of the boat and directly linking it to the prop shaft. Instead, why not place the engine anywhere on the boat that is convenient and use it to power a hydraulic pump? Then, hydraulic fluid would be piped to wherever it is needed. This method could be used, for example, to drive the prop via a small, hydraulic motor. Other pieces of equipment could also be powered by hydraulic lines. This approach has the potential to eliminate or mitigate most of the negative aspects of auxiliary power systems.

Back in 1940, for example, automatic transmissions in automobiles were very rare. Automatic transmissions in trucks were virtually unknown. Mechanical power was normally transmitted from the engine to the driving wheels via mechanical gearboxes, with clutches providing off-on control. Today, vehicles, including automobiles, trucks, and even large earth movers, use automatic transmissions. The transfer of power is largely accomplished with hydraulics.

With a few exceptions, though, power transfer (from the engine to the propeller) on a sailboat is still accomplished via a simple mechanical gearbox. Undeniably, this simple system works well. However, by applying some of the technical progress made in the past 50 years, we can devise a system with many advantages.

The use of a conventional mechanical transmission and prop shaft to drive the propeller places a number of constraints on the placement and capability of the components of the system. Generally, the engine must be placed low in the boat and in-line with the prop shaft. The engine must be inclined so that the crankshaft of the engine is at the same angle as the prop shaft (plus or minus any offset angle built into the marine gear).This necessary angling of the prop shaft reduces its effectiveness. The inclination angle also creates P-factor, the offset thrust effect that creates much of the grief encountered when trying to back down with a single screw vessel. The P factor also creates the need for a rudder offset when moving ahead. The rudder offset creates drag and consumes energy.

Access to the engine is restricted, frequently to the point where even simple maintenance tasks are difficult. Removal of the engine for major maintenance or replacement may be extremely difficult. Engine noise is so poorly controlled that noise levels in most sailboats operating under power are higher than in even the least expensive automobile. Engine heat pervades the boat’s interior, which, in warm weather, makes temperatures very uncomfortable below and reduces the effectiveness of on-board refrigeration. The powertrain of the modern sailboat has more in common with a Model A Ford than with any modern automobile.

The automatic transmission used in most of today’s automobiles is a hydro-mechanical marvel. It transmits power in a smooth, virtually seamless manner, constantly varying its overall input/output speed ratio to match the momentary demand of the vehicle. Its performance is based on the use of hydraulics in the torque converter and in gear set selection.

The transmission of power in various earth-moving equipment and industrial machines is often accomplished with hydrostatic transmissions. A hydraulic pump is driven by the engine and the pressurized fluid carries the power to hydraulic motors, actuators and cylinders, at the point where the power is needed. Hydraulics are also used to provide the force required in modern aircraft, both for intermittent loads, such as landing gear and flaps, and for continuous needs, such as control surface movement. Modern hydraulic systems can also be used to improve the value, utility and performance of boats.A fresh approach

When providing mechanical and electrical power for a sailboat, the power source and the various places where the power is required can be considered separately. Each is placed in its optimum location, without initial regard for how the power will get from the source to the load.

A first step is to place the primary power source, the diesel engine, at an optimum location. Anyone who has ever worked on a marine diesel has probably wished that it was mounted at a reasonable height, accessible from all sides, not sunk in a well with a generous half inch of clearance on all sides. Easy and complete access is necessary for inspection and maintenance. A related consideration is that routine checks should be automated to the maximum extent practical. Where possible, built-in test equipment (BITE) should be incorporated, replacing the common low oil pressure, and high coolant temperature alarms, which announce the existence of faults only after the fault has occurred. A BITE system with trend monitoring can warn of an unsafe condition before it causes a power failure. The BITE system can also identify what has malfunctioned, thus speeding failure analysis and repair.

Noise is an undesirable and largely avoidable by-product of most power sources. Noise contributes to fatigue, can make communication difficult, and is generally irritating. The engine must be housed in a carefully engineered sound shield. The sound shield should limit the full engine power operation noise level, measured in the saloon, cabin or cockpit to not more than 70 decibels (measured on the slow response A scale, 70 dbA). If the engine is used to provide AC electrical power, a sound level of 64 dbA is desirable.

Transmission of vibration into the vessel’s structure must be prevented. Flexible engine mounts can be used. To be most effective, they must be tuned to the vibration characteristics of the engine. Application engineering is required to select the optimum isolation characteristics. It is also important to account for the motion of the vessel and the engine. When the boat rolls, pitches or falls off a wave, the engine, on its flexible mounts, must not impact on its enclosure or damage its interconnections. The setup we are describing will eliminate the need for a drive shaft from the engine to the propeller, thus increasing the effectiveness of vibration isolation.Thermal control

All internal combustion engines are more efficient at converting the energy in fuel to heat than they are at converting fuel to mechanical energy. Although there are some uses for the waste heat from the engine (heating water, possibly heating the interior of the boat), allowing the heat to leak into the belowdeck space is undesirable. Much of the heat from the engine is absorbed by lubricating oil and by the engine’s cooling water system. Any residual heat must be removed from the air in the engine compartment. Keeping the engine space cool has several benefits: Alternators will provide more satisfactory output and enjoy longer lives if they can operate in a lower temperature environment. And, perhaps more important, the engine will operate most efficiently when it is provided with cool combustion air.

As the temperature of the charge air increases above the normal reference level (25 deg C) the power decreases; it drops by 1% for each 5.5 deg C increase. Since a typical engine compartment temperature can reach 50 deg C, a power loss of 9% may occur. When providing for cool combustion air, it may be worthwhile to draw air from the bilge area. This keeps air flowing through the bilge and helps in reducing nasty odors.

The air exhausted from the enclosure must be discharged overboard. To prevent leakage of noise or heat into the vessel’s interior, the discharge air duct must be properly designed. For most installations, an exhaust blower with a capacity of approximately 250 cubic feet of air per minute will suffice. An additional advantage of such a blower is the ability to remove the heat remaining in the engine and its surroundings after engine shutdown. On a hot day, the exhaust blower can make a remarkable temperature difference below. Thirty minutes of blower operation will usually suffice to remove the majority of the heat.

An interesting possibility is the incorporation of an air to water heat exchanger and air circulation blower within the engine enclosure. With such a system, the engine enclosure could be almost entirely sealed. The air in the engine enclosure could be maintained at a suitable temperature and adequate alternator cooling assured. The need to extract hot air via an air duct is eliminated. The engine would act as a pump, constantly moving air through the enclosure. Combustion air is routed directly to the engine air intake, insuring optimum engine performance. The chance of diesel odors in the interior of the boat are also diminished.

All engines require access for inspection, routine maintenance and repair. The easier and more complete the access, the more likely it is that the engine will receive proper attention. The need for noise and heat control runs counter to the need for quick and complete access. The engine housing should be constructed with as many access ports as required to permit routine checks. These access ports must be very well gasketed and secured with adjustable clamp-type latches to compensate for compression of sealing gaskets. Noise is like water, it will leak from even the smallest of holes and gaps. Access requirements, however, shouldn’t degrade noise and thermal sealing needs. It is necessary that the enclosure be able to be disassembled, without a saw, when full access to the engine is necessary. When reassembled, the enclosure must provide the same degree of acoustic and thermal isolation as before.

The basic law of mechanical devices is that they will eventually fail and require major repair or replacement. It is probably not necessary to point out that all failures will occur at the worst possible time. (Remember O’Brien’s Law: Murphy was an optimist!) The engine installation should be designed so that the entire unit can be removed from the vessel, without disassembling other elements and without damage to the surroundings. Ideally, the engine should be located directly below a suitably sized hatch. Regardless of where the engine is installed, building in some provision for moving it to a place under a hatch should be taken into account. Placement vs. load requirements

Although one might think that the engine is a major element in a cruising sailboat’s weight budget, the total weight of the engine and its accessories is approximately two to three percent of the weight of the vessel. For example, the weight of a typical Yanmar diesel engine, complete with marine gear, varies from 498 pounds for the 50-horsepower 4JH2E to 542 pounds for the 88-horsepower 4JH2andndash;DTE. The small relative weight of the engine provides some interesting opportunities for placing it on the vessel. Freed from the necessity of placing the engine ahead of and in-line with the propeller, it’s possible to consider transverse mounting. Perhaps the engine can be placed far aft in the vessel, in the lazarette area. Placing engines in such a location is common in motor yachts. The advantages include relative isolation from the occupied spaces below and easy disposal of exhaust and compartment ventilation air. With the power package located in the lazarette, water and fuel tankage can be placed amidships, below the cabin sole. Placing these tanks near the center of the vessel prevents trim changes as fluid is removed from them. (A 170-gallon fuel load weighs 1,147 pounds, 300 gallons of water, 2,500 pounds.)

Such a location would also make engine removal quite simple, especially on a ketch, where the mizzen could be used as a derrick. Another possible location might be in the forward end of the boat, ahead of the mast, possibly in a forepeak sail locker. When evaluating this idea, consider the weight of anchor chain often carried in the forepeak: 300 feet of 3/8 inch hi-test weighs 480 pounds. The chain locker could be placed just ahead of the mast, in the form of a vertical pipe. This configuration offers excellent chain storage.

Since the engine enclosure must be airtight and well sound-proofed, it is also possible to make double use of the engine and its enclosure: it can support the saloon table. This location offers the advantage of centering the weight over the ballast. Access for maintenance should also be excellent. (If such a location is used, be sure to have oil proof covers for everything in the saloon.) There is no place on the vessel that should be ruled out for an engine location. A naval architect can evaluate the possible choices to insure that the stability and dynamic response of the vessel will be satisfactory.

Most of the consumers of power on a boat requires rotary motion. The speed of rotation and power required varies greatly. Fortunately, even the most power-hungry consumer, the propeller, can be driven from a fairly small hydraulic motor: a motor capable of delivering 50 horsepower at 1,800 rpm is 16 inches long, has a maximum diameter of 12 inches and weighs 106 pounds. Some types of hydraulic motors are best suited for moderate- to high-speed applications. There are also units that can operate with high torque and very low speeds, allowing direct connection to slow turning loads. High torque

Hydraulic motors also offer the advantage of offering very high torque at stall. In most hydraulic systems, one will not harm a hydraulic motor by placing an impossible load on it, it will do its best and then simply stop turning, protected by a pressure-actuated safety valve automatically bypassing the hydraulic pressure. Try that with an electric motor and the usual result is a tripped circuit breaker, blown fuse, or perhaps a burned-out motor. The opportunity to drive a watermaker’s high pressure pump with a very small hydraulic motor may make it possible to place the watermaker in space that would otherwise be unsuitable. Driving refrigeration and air compressors with hydraulic motors can be a very attractive approach.

Not all power consumers can be driven by hydraulic motors. There is an increasing need for electrical power on boats. In warm climates, air conditioning can become a virtual necessity when the boat is in a harbor and the breeze dies. Air conditioning on a 40- to 50-foot boat can require 6,000 watts. A number of alternative alternator-drive systems are possible. These include automatic variable ratio v-belt drives, hydraulic motors that will precisely maintain the alternator speed regardless of pump speed, and a cog belt driven from the engine, with the engine speed precisely controlled by its governor.

As long as the total horsepower demand on the engine (for propulsion, other hydraulic supported loads, and electrical power requirements) is less than or equal to the engine’s power capability at the chosen speed, all consumers can be served simultaneously. In the event there is a need for full engine power for propulsion, the alternator can be automatically disconnected from its loads. This power delivery approach offers considerable flexibility. Power can be applied where it is needed, via the hydraulic or the electrical system. Engine operation at constant rpm can make sound suppression and vibration isolation more effective than if a widely varying rpm range is used.

The diesel engine is often totally dependent on its electrical starting motor. With most modern diesels of more than 20 horsepower, hand starting is often impossible. With a hydraulic starting motor in place of the normal electric motor, energy stored in a hydraulic accumulator is used to power the starter. Should the pressure in the accumulator be depleted, it is possible to recharge it with a small hand pump. Commercial hydraulic starters are available for some engines. The ability to manually store energy for engine starting can be very attractive, especially when compared with the typical depleted battery situation.

The autopilot is a natural for hydraulic power, in fact many of those used on sailboats are already hydraulic units. With a hydraulic power distribution system, it would be logical to use a combination of a hydraulic power accumulator and a small electrically-driven auxiliary pump. With an accumulator in the system, considerable energy could be stored while the main engine was operating. Then, when the main engine was shut down, the auxiliary electric pump could be used to recharge the accumulator.

One major advantage of hydraulic power distribution on board a boat is the compatibility of hydraulics and water, even salt water. Today’s hydraulic motors have excellent shaft seals, and experience very little leakage. Since the internal chambers of the motor are pressurized, any leakage is from interior to exterior, and salt water can’t find its way in. Compare that situation to the typical electric motor in the same environment.

The other components used with hydraulic systems are equally suited to the salt water environment. The hoses and fittings used in modern hydraulic systems are very reliable when properly chosen and installed. Of course, no system is failure-proof; however, the ability of hydraulic systems to stand up to the environment on earth-moving machinery speaks well for reliability. Propulsion power

Propellers must be capable of operating throughout a wide range of speeds and must also be capable of reversing their direction of rotation. These needs are elegantly met by using a variable displacement, reversible-piston-type pump to provide hydraulic power from the engine. This type of pump is fitted with a mechanical camplate control arm that can be moved by a familiar cockpit-mounted control lever via a flexible cable. With the pump’s cam in the neutral position no pumping occurs – no hydraulic fluid flows to the propeller drive motor. As the camplate is moved away from the neutral position, an increasing volume of hydraulic fluid is delivered to the prop motor. The result is single-lever control of the prop’s speed and direction of rotation. This setup allows a rapid change from full speed ahead to full astern.

It is also possible to achieve very slow rates of rotation, slower than possible with conventional transmissions. The very flat torque output of the hydraulic system will eliminate much of the problem of matching the prop to the boat and engine. The gear ratio needed to match the speed requirements of the propeller can be obtained by choosing a hydraulic motor whose displacement per revolution is larger than the displacement per revolution of the pump. For example, with a 1.24 cubic inch displacement pump and a 2.48 cubic inch displacement motor, a drive speed reduction of 2:1 results.

One advantage of driving the propeller with hydraulics is that whenever the prop is not being turned, it is held stationary by the hydraulic fluid in the system. It is possible to add a relief valve, or to obtain a built-in relief valve in the system pump. This will allow the prop to free wheel when desired. It also may be possible to add valving to permit the prop motor to act as a pump whenever the prop is spinning. This will provide limited power to operate energy consumers such as small alternators. (Owing to the limited power available from the freewheeling propeller and the efficiency of the hydraulic system, taking power from the propeller may not be practical in most installations.)

One of the major advantages of a hydraulically-driven prop is the ability to make the prop shaft parallel to the longitudinal axis of the boat. When a prop shaft is connected to a conventional marine gear, it must exit the boat at an angle, sometimes up to 15 deg from the horizontal. Since the thrust developed by the propeller is generally in line with the propeller shaft, a part of the thrust is directed downward, less thrust is available for forward propulsion. With a 15 deg down angle, approximately 3.5% of the horizontal thrust is lost. In addition, the downward angle of the typical prop shaft creates P factor, or asymmetric thrust. This thrust requires rudder offset when moving ahead, which, in turn, causes additional drag and loss of propulsion efficiency.

In most cases, a small-diameter hydraulic motor (roughly 12 inches) can be used to drive a sailboat propeller. And since there are no service checks required on the motor, it can be placed very low in the aft end of the keel. Although the mechanical efficiency of the hydrostatic transmission is likely to be almost 20% less than that of a simple clutch and single gear reduction unit, some of the efficiency deficit can be recovered from the elimination of the downward shaft angle.Reducing P factor

When a vessel with an angled shaft must move astern, P factor typically causes considerable grief. Without a propeller-boosted flow of water past the rudder, P factor causes the stern to move sharply to port or starboard. Anyone who has reversed into a slip is familiar with this characteristic. With zero angle on the prop shaft, there is no P factor. Although a vessel will still be challenging to control when moving astern, the entire maneuver will be much more predictable and, therefore, less thrilling.

An interesting possibility is to use a pump made of material which can handle the sea water environment and mount the pump outside the hull. If the pump were faired into the aft end of the keel, no shaft log would be required. Only three hydraulic lines to the motorandmdash;supply, return and case drain – would have to penetrate the hull. The trade-off between ready access to the motor and elimination of the stuffing box would be an interesting one.

A bow thruster can be operated in the same manner as the main propeller. The obvious way to provide power and control for the thruster is to duplicate the main propulsion drive, using a much smaller variable displacement pump mated to the main pump on the engine. A joy-stick-type control handle can be fitted at the helm to control thruster operation.

Using hydraulics to power a windlass or any other on-deck machine makes great sense. Hydraulics are probably the power source best suited to the harsh marine environment. Depending on the power demand of the windlass, it may be possible to use the small-gear-type pump, which is required as a charge pump for the main propulsion pump, to power the windlass. If a large load must be moved, a fixed-displacement pump can be added to the main engine system.

Among the other uses for the hydraulic power are the operation of sheet winches and sail furling devices, powered davits for the dinghy, a powered deck crane, and an emergency bilge pump with a large pumping capacity.

It is possible to store energy, in hydraulic form, in a hydraulic accumulator. An accumulator is typically a steel or aluminum pressure vessel, with a rubber bladder inside. The bladder is usually filled with nitrogen gas. The pressure of the gas is made somewhat higher than the minimum desired working pressure of the hydraulic system. When high-pressure hydraulic fluid enters the accumulator vessel, the gas-filled bladder is compressed. Eventually, the fluid pressure is no longer sufficient to further compress the bladder. With the hydraulic pump off, the bladder exerts pressure on the hydraulic fluid, providing a continued source of hydraulic energy. Thus, hydraulic accumulators function somewhat like storage batteries. The accumulator can be charged from a number of different sources, including a hand pump. This allows the accumulator to be charged up and used for starting the engine should electric power not be available. Hydraulic disadvantages

Every system has its disadvantages. The hydraulic system proposed here is no exception. Although there are few reliability, size, weight or operational disadvantages in a hydraulic power distribution system, it is reasonable to examine the other possible negatives of such a system

A quality hydraulic system is not cheap. A variable displacement pump assembly, capable of absorbing 50 horsepower, will cost approximately $1,400. A fixed displacement motor of suitable size costs about $2,500. (The motor costs more than the pump since its displacement is twice that of the pump in order to provide the desired prop speed. It is possible to use the same displacement motor as pump and use a gearbox to reduce the prop speed to a desirable level.)

In addition to these elements, a hydraulic reservoir, a water-cooled heat exchanger, hydraulic lines and hoses, control valves, and miscellaneous parts are required. The total cost of a hydraulic system, including a motor capable of operating an anchor windlass and another which can be used to drive a refrigeration compressor, will be approximately $5,500 to $6,000.

Offsetting the added cost of the hydraulics is the opportunity to eliminate the engine normally used in a genset. Although there are some main engine installations that can accommodate an AC alternator, they are relatively rare. However, with the hydraulic power system, it’s possible to have both propulsion and electrical power, with dedicated genset performance, from the same diesel engine. Elimination of the genset engine and its accessories can save $5,000 to $6,000. In addition, when using the hydraulic power system, the cost of a marine gear can be saved. This can provide an offset of approximately $700. So, it’s possible that the hydraulic system can be used with little or no net increase in the cost of the vessel.

Hydraulic pumps and motors can be noisy. The good news is that the types of units used in the system described create noise which is somewhat less intense than that produced by the diesel engine. Fortunately, with the type of careful engine noise isolation design required for system success, the added noise of the hydraulics will not be a problem. The small motors which are used to drive sail handling winches and davit systems create little noise.

Plumbing a hydraulic system is not very difficult when using modern hose and tubing assemblies and connectors. The techniques may be foreign to many boatyards, but are easily learned. Boatyards have learned to cope with the hydraulic sail control systems now common on race boats. Although the proposed hydraulic power system is very different in both pressures and flow rate, the basic skills required for installation are similar. For example, a fitting capable of working at a given pressure will work at that pressure even if the fluid flow is many times greater.

Hydraulic systems are similar to electrical systems in offering advantages from operation at higher pressures. Higher voltages deliver the same energy with lower amperage, therefore smaller conductors. The same holds true for hydraulics. With high pressuresandmdash;for example, 3,000 psi – the size of lines and fittings can be reduced over those of lower pressure systems. The bottom line of the plumbing question is that there are no dark secrets that must be learned to work with hydraulics. The 3,000-psi operating pressure envisaged for this system is not a challenge with today’s equipment and materials. Controlling leaks

Wherever there is fluid, there will eventually be a leak. As soon as that fact is accepted the reality of a hydraulic system can be viewed objectively. In some ways, hydraulic leaks are preferred to equivalent leaks in electrical or pneumatic systems. Hydraulic leaks can generally be seen and can often be detected by smell. When the hydraulic line routing is planned, it should be done with the realization that a joint may one day leak and then require access for maintenance. Putting a multi-line junction block in the overhead is probably not a good idea. Route the lines so that couplings and joints are placed where a small leak will not do significant damage and where it can be easily reached for repair. The fact that so many hydraulic systems are in daily use, in difficult environments, including automobile power steering, earth movers, fishing boats, and aircraft should ease one’s mind.

The engineering of a hydraulic power system requires the attention of someone who has successfully done it before. Fortunately, there are numerous hydraulic power equipment distributors, many of whom will be delighted to assist with the design of a suitable system. The basic rule is the same as for any other similar system: if one doesn’t know, ask; if one is uncertain, stop.

The most oft-heard reason for not using a hydraulic power system on a boat is that the system is not as efficient as a simple marine gear. The losses in a marine gear are often less than 5%. A typical hydraulic power system may operate with a loss of up to 25%. Why lose that extra 20% of power? As pointed out, the use of a horizontal propeller shaft not only eliminates the undesirable downward thrust vector, it also eliminates the need for counter rudder when moving ahead or astern. With this power delivery system it is likely that a significant part of the efficiency deficit will be recovered. The fact that the torque of the hydraulic motor that drives the prop is essentially constant, regardless of speed, makes matching of the prop to the vessel much easier. The efficiency of the propeller should be improved, especially if a variable pitch prop is fitted. It should be possible to tune the prop to an optimum operating condition.

Add the elimination of the engine formerly required for the genset, the superior performance of drives, such as the hydraulic anchor windlass, and the argument in favor of hydraulic innovation can become compelling. There is an additional small increment of efficiency improvement available in the choice of engine operating speed. The typical diesel engine provides more horsepower-hours per gram of fuel at speeds in the 3,200 rpm range than at lower speeds. A properly designed power package will operate the engine at or near this optimum fuel efficiency speed.

The hydraulic power delivery system will be more space efficient than the mechanical system it replaces. This space efficiency derives from both the small size of hydraulic components and from the flexibility in location of the main engine afforded by the hydraulic approach. It is true that a hydraulic reservoir and a cooler must be placed somewhere. However, the value of space below decks on the typical sailboat varies greatly. There is A+ space and there is Candndash; space. Nooks and crannies, whatever they are, are obviously less valuable than space within +/- 5 feet of the centerline and within -/+ 15 feet of amidships. A hydraulic installation can economize on use of prime space. Eliminating the separate genset can save between 6 and 14 cubic feet and as much as $5,000. Cooling needs

When hydraulic fluid is moved through lines at high pressures, considerable heat is generated in the fluid. When pumps exert high pressures on the fluid considerable heat results. The hydraulic fluid must be cooled if the system is to operate properly. The necessary cooling can often be done at the reservoir, a low pressure point in the system. This avoids the need to use high pressure materials in the water – hydraulic fluid heat exchanger. Cooling is an important part of the system, but it holds few mysteries or problems.

With the one engine providing all of the motive power, engine wear-out may appear to be a possible problem. The facts are that on most recreational boats, especially sailboats, engines rust out long before they wear out. Even generator sets on sailboats rarely see enough use to make total engine hours a concern. An argument can be made that in most cases the reliability and performance of the engine will be enhanced by additional use, especially more frequent use. Rather than being a detriment, the added use created by using the one engine for both propulsion and electrical power will be a net benefit. (This would not be true for a high-powered sport fisherman. Long hours of engine operation at low load might be detrimental to those powerful engines. For such vessels it would be preferable to fit a separate engine-driven alternator and equip that engine with a hydraulic pump. When operating at the low speeds required for trolling, the genset pump would provide energy for the propellers, saving wear on the main engines.)

The fact that things have been done one way for a long time is no reason to continue to use those techniques when better alternatives are available. An interesting example from marine propulsion history is the story of the adaptation of steam turbine power. In 1894, the Parsons Company in England tried, without success, to interest the British Navy in their turbines. After building a demonstration vessel, Turbinia (100 feet long, 9 foot beam, 3 foot draft, 2,000 horsepower) and powering through the fleet massed for Queen Victoria’s Diamond Jubilee celebration, at 34.5 knots, the Lords of the Admiralty could no longer dismiss the turbine as impractical. Within a few years, vessels were being outfitted with 75,000-horsepower turbine power plants. This is one of the most rapid technology acceptance examples known. Perhaps a new look at sailboat power systems will prove equally productive.

Contributing editor Chuck Husick is sailor and pilot who often writes on technical topics.

By Ocean Navigator