From the combination of a concept that is revolutionary in its own way and a turbodiesel renowned for its fuel efficiency comes an eight-and-a-half-meter walkaround capable of cruising at 20 knots while burning only one liter of diesel per nautical mile
This boat is an eight-and-a-half-meter model from Bimax, a boatbuilder from Lazio known for the quality of its hulls, marketed under the name “Alchimia” and available in the “28” and “32” versions—designations that naturally refer to the overall length expressed in feet. The first is a 32-quintal walkaround characterized by sharp waterlines designed to ensure maximum cruising efficiency without sacrificing the minimum habitability typical of these boats, which are essentially intended for day use or short cruises.
The bow is almost vertical, the deep V-hull opens as it rises toward the deck, and the deck itself tapers toward the stern, where the hull sides curve inward and the transom angles forward. In essence, it is a well-designed hull, though nothing about its appearance suggests anything revolutionary—at least not until the engine compartment is opened, revealing the position of the powerplant: a 230-horsepower FPT Industrial turbodiesel of the “F 30” series. Renowned for its reliability—so much so that many boaters consider it “eternal”—and equally well-known for its low fuel consumption, this engine is not installed in the traditional manner, meaning with the flywheel facing aft, but rather the opposite way, with the flywheel facing forward.
Tilted seven degrees relative to the horizontal, it connects via a short propeller shaft to a forward-facing propeller, thus operating as a pulling rather than a pushing system. This solution is conceptually similar to Volvo Penta’s IPS systems, with the key difference that this is not a pod setup but a fixed installation. Configured in this way, the system ensures that when the boat is underway and trims stern-down, the propeller works in an almost horizontal position, converting most of the available engine torque into forward thrust.
It is worth recalling that there is a reason why outboard and sterndrive engines allow the trimming of the propeller relative to the horizontal: the more the thrust is parallel to the water’s surface, the greater the propulsion efficiency. In shaft-drive boats this optimization is not normally possible, and the propeller typically operates at an angle ranging from a minimum of seven degrees—the installation angle—to as much as twenty degrees when the hull is stern-heavy. Under such conditions, propeller thrust splits into two components, one of which is directed vertically and therefore contributes nothing to propulsion.
In the case of the “Alchimia 28,” this does not occur, because although the shaft is installed at a seven-degree angle, it tends to align itself horizontally when underway. Bimax has named this solution “EDS,” or “eco drive system,” promising those who adopt it fuel consumption of just one liter of diesel per mile at 20 knots.
230 Eternal Horses
The four-cylinder FPT Industrial engine powering the “Alchimia 28” is an “S30” three-liter turbodiesel with electronically controlled direct injection and a four-valve-per-cylinder valvetrain. Boost is provided by a fixed-geometry turbocharger controlled by a wastegate valve and supported by a water-to-water aftercooler. In essence, it is an engine that incorporates all the latest sector technologies while combining them with proprietary thermodynamics that allow for a minimum specific fuel consumption of 185 grams of diesel per horsepower. Weighing 330 kilograms and compact in form—78 centimeters long, 77 wide, and 75 high—it is one of the best choices available today for those wishing to equip their boat with a diesel engine that, in addition to being considered ultra-reliable (a quality that at sea should be prioritized above all others), is also economical to operate and maintain, with service intervals extendable to every 600 hours of operation.
Title: Bimax Alchimia, boat “made in Lazio”
Translation with ChatGPT
