Yanmar - 8LV-ZT370 Joystick
The Yanmar Joystick
Yanmar has developed its own joystick and ECU software to match the characteristics of both its engines and sterndrive lower unit. Because all software and ECUs are developed by Yanmar it is not reliant on a third party vender for updates. Both updates and modifications can be made by the boat's dealer or the engine distributor.
Yanmar made its own joystick and ECU software in order to make sure everything works seamlessly.
No Bow Thruster. Yanmar's system does not need a bow thruster to work and all of the boat's docking maneuvers can be accomplished by the twin sterndrives.
Docking Mode. When docking or in close quarters the joystick can be activated to direct both the engines and the lower drive units, work that is done by the dedicated ECUs. The ECUs are custom programmed to match the characteristics of the boat and the application it will be put to. Obviously docking is done while operating at low rpms. Typically, the upper limit is set from 1200 to 1500 rpms, but it can be adjusted up or down.
Remotes. In larger boats a remote joystick can be installed in the cockpit or even the stern of the boat to make doing other maneuvers easier. In flybridge boats with lower helms, both stations will need a joystick.
The Yanmar 8LV-ZT370 propulsion system.
The Holy Grail
The quest for fuel-efficiency points in one direction: lightweight diesel power with an efficient propulsion system. Since sterndrives are more efficient than conventional inboard drives, and significantly lighter and far less costly than pod drives, the best solution is obvious. Add to that the ease of boat handling offered by joystick control and it becomes apparent that the Yanmar 8LV-ZT370 propulsion system is a compelling one.
Powerboats under 40' (12.19 m) are logical candidates for this twin engine solution both for new boats and for re-powering. In single engine applications (without the joystick), the 8LV-ZT370 is a good choice in boats, say 32' (9.75 m), and smaller. This includes not only cruising boats but also diesel-powered center consoles. Diesel sterndrive power can give these small boats the range they need to get out to the canyons and back…or even down to the islands where there is no fuel and back.
The 370-hp Yanmar 8LV marine diesel has a lot going for it -- its block was developed by Toyota, the company that makes the oh-so-quiet Lexus.
Advantages of the 8LV-ZT370 System
Engineered and developed by Toyota for its automotive applications, this diesel had to be lightweight to meet global mileage hurdles, have low emissions to meet Tier 3 standards, and be quiet to meet the expectations of Toyota's discerning Lexus customers. Yanmar has benefited from that costly Toyota R&D and marinized the engine to meet the demanding requirements of saltwater applications.
Specs. The 8LV is a 4-stroke, 90-degree V-8 with 4.46 L displacement. It has direct injection and a common rail. It is freshwater cooled with a heat exchanger. Bore X stroke: 3.38" x 3.78" (86 mm x 96 mm).
Weight. The 8LV diesel is from 350 lbs. to 500 lbs. (159 kg. to 227 kg.) lighter than two of its popular competitors. That means for a twin engine installation, the Yanmar engines can save a builder 700 lbs. to 1,000 lbs. (318 kgs. to 454 kgs.) in total.
Fluid checks are made handy on the inside for twin-engine installations.
Performance. The 8LV is one of the few engines in class that has twin turbos. They are smaller than single turbos, so they spool up faster for increased low-end torque. At high rpms they cram air into the intake manifold from two different directions, maximizing flow which results in increased acceleration across a wide power band.
Low-end performance is enhanced because of the engine's low-idle of 550 rpms, 50 to 100 rpms slower than many diesels.
More AMPs. The 8LV's alternator puts out 180 Amps per engine which is plenty to power all of the electronics that boats often carry these days. In some applications this prodigious power creation may even eliminate the need for a generator.
Twin 8LV-ZT370s are appropriate for boats 40' and under.
The Yanmar ZT Lower Unit
Several years ago Yanmar developed its own sterndrive lower unit to mate with its growing line of diesel engines. It was specifically designed and engineered to be able to handle the high-torque that only diesel engines can produce. As a result, its shafts and gears are robust. Not surprisingly it is heavier than competing lower units by 15 lbs. (6.8 kgs.) or so.
No Clunk. Because the Yanmar sterndrive uses a hydraulic clutch there is no "clunk" when putting the unit in gear. Reversing gears is smooth. The gears themselves are precision forged for extra long life.
Programmable Turning. Because the lower units each have their own dedicated ECUs (electronic control units) they can be programmed to behave asymmetrically in certain situations such as when making tight turns. In this example the inside unit would turn tighter than the one on the outside.
The Yanmar sterndrive unit has a tilt angle of 51-degrees.
The lower unit has dual counter-rotating stainless steel props.
Dual Props. The ZT drive has dual, counter rotating props for better acceleration. In single engine applications the unit keeps the boat straight in idle and low wake situations, eliminating the tendency of the boat's stern to walk to one side.
The feel of the wheel and its turns lock to lock can be controlled and modified.
Yanmar Steering System
Part and parcel with this whole system is Yanmar's electronic steering which has programmable capabilities. For example, when at low rpms the number of revolutions of the steering wheel can be reduced to make handling easier. Likewise, when traveling at high rpms the number of revolutions from lock to lock can be increased to aid precision handling.
Feel the Wheel. Often boaters complain about the lack of "feel" that seems to be inherent in some power steering systems. Again Yanmar's dedicated ECUs can be programmed to create just the amount of "friction" that each individual owner would like in the steering. The wheel can become stiffer or less resistant to movement.
It is important to note that Yanmar makes or is responsible for every component of its entire 8LV-ZT370 system from the joystick to the prop. If something goes wrong there is no finger-pointing. The buck stops with Yanmar.
Possibly one of the most important aspects of this system is not part of the hardware or software -- that would be the dedicated support staff both at the factory and at the Yanmar distributorships. Yanmar has built its company's reputation and success on giving personalized help and service even to one-off installations.
It is for that reason that Yanmar leads the industry in diesel re-powering. Each installation must be engineered for the proper performance of the engine and boat. That level of service to individual, time-consuming installations is how the company built its business.