Mission of the Yanmar Pod Drive/Joystick System
By mating its 8LV diesels to pod drives and then plugging in its own joystick and ECU steering software, Yanmar has created one of the most compelling propulsion packages on the market. Each of the system’s four major components has demonstrable advantages over competing brands’ systems, because Yanmar makes three of the four major components.
Not only does the Yanmar package give boat builders and naval architects a much-needed choice, but it also offers substantial savings for consumers and improved boat handling and fuel economy.
All pod drive systems are not the same as this report will demonstrate.
Advantages of the Yanmar Pod Drive System
The Yanmar 8LV engine is rated from 320 to 370-hp at 4000 rpm.
Yanmar 8LV Diesel Engine—
Lightweight. At 992 lbs., bobtail, the 8LV is lighter than any other major alternative on the market in its horsepower range – from 400 to 500 lbs. lighter per engine. That means that the 8LV weighs from 40% to 50% less which is a huge difference in engine weight. Lighter weight means higher top-end speed and greater fuel efficiency, all things being equal.
The 8LV engine is offered as a 320-hp or 370-hp model.
Twin Turbochargers. The Yanmar 8LV is the only diesel engine in class with twin turbochargers. Both turbos pump air into a single intake manifold. We are told that factory tests show that the twin turbochargers cause the engine to reach maximum torque at just above 2000 rpm. A flat torque curve like this is very desirable for strong throttle response in the mid range. Fuel consumption charts show the best fuel economy is reached at about 3000 rpm, with plenty of power to spare if needed.
Simply put: two turbochargers can cram more oxygen into cylinders than only one.
Boaters who have owned automobiles with twin turbos can well understand the mid-range boost that is available as well as the fuel economy in the mid range.
Because it has a V-8 with cylinders at a 90-degree angle, the 8LV is able to have a relatively low profile.
A Compact Package. The size of the Yanmar 8LV diesel is 44.6" (1,133 mm) long, 34.8" wide (884 mm) and 30.85" (783.5 mm) high. It fits in the same space as big block gas engines which it might replace, as well as being competitive with other diesels. In fact, this 8 cylinder engine can likely fit into any engine compartment that a 6 cylinder diesel can.
180 AMPs. The 8LV’s 12V alternator generates 180 amps, which means that the boat can be loaded up with electronics – plus redundant electronics -- and be powered without concern.See BoatTEST.com's video of a test of the Yanmar 8LV 370-hp diesel engine--
The ZF POD 2800 has the beef necessary to harness the torque and horsepower of a 370-hp diesel engine. The upper and lower sections of the pod drive are separated with a double rubber gasket and are fixed together with nearly two dozen bolts.
ZF POD 2800 Drives--
More Efficient Propulsion. Over the last eight years BoatTEST.com has proven to its satisfaction that pod drives are far more efficient than conventional inboard systems at “best cruise.” We have been able to do that by comparing our tests on a number of boats with conventional drives with newer models powered with pod drives.
Typically, pod drives give a boat 25% to 30% better fuel efficiency at mid-range cruising speeds, but we have seen cases where it is nearly 50% better. Mid range speed is also usually increased. Pod drives can also give a boat a higher WOT speed, which we usually find, but the percentage increase seems not to be predictable. These observations hold for all pods, not just Zeus.
Software takes the movement of the joystick and translates it to pre-determined commands to the engines, transmissions and pods.
Proven Pods. By mating its engines to a transmission and pod drive system engineered by the leading marine transmission maker in the world – ZF – Yanmar can offer its customers the reliability and durability that comes from a product built by experts in power transmission.
The aft-facing props of the ZF POD 2800 system and the sacrificial skeg are strong selling points for this drive.
Aft-Facing Props. The counter-rotating props on the ZF PODs face aft just as most marine props have since the beginning of recreational boating. If an underwater obstruction is hit, chances are that it will be by the skeg on the bottom of the pod. This skeg is designed to absorb the impact energy, break away from the pod torpedo and thereby protect the pinion gears and shafts in the pod from catastrophic damage.
See BoatTEST.com's video explaining the important details of the Yanmar pod drive system--
The tip of the torpedo and the skeg are designed to break away on impact to protect the gears and shafts.
Yanmar made its own joystick and ECU software in order to make sure everything works seamlessly.
A Proprietary Joystick. Yanmar has developed its own joystick device and software to match the characteristics of both its engines and the ZF POD 2800s. Because all software has been developed by Yanmar it is not reliant on a third-party vendor for updates. Both updates and modifications can be made by the boat's dealer or the engine distributor. In case of problems, there can be no finger pointing at or by a third party because there isn’t one – the buck stops with Yanmar.
Docking Mode. The system is custom programmed to match the characteristics of the boat model 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.
Station Keeping. The joystick software interfaces with the vessel’s gps to execute a “station-keeping” mode which holds the boat in position automatically. This is handy when waiting for a bridge to open or space at the fuel dock to become available.
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.
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 joystick software translates movement of the joystick into commands for the propulsion system.
Instant, Accurate Response. There are several joystick systems on the market and all work on the same principals. What BoatTEST.com has discovered during its testing is that all joystick systems do not behave the same way. We have found the Yanmar system to respond to joystick commands with alacrity and accuracy.
The feel of the wheel and its turns lock to lock can be controlled and modified.
Boiling down the advantages of the Yanmar pod propulsion system still further there is a unique set of advantages that can be found with no other engine-pod drive-joystick-steering package: