Mazziena 26SP – Twin DF150A Suzuki
Stingher 34 GT – 2 x 300hp Verado 4.6L V8
Mazziena 26SP – Twin DF150A Suzuki
Stingher 34 GT – 2 x 300hp Verado 4.6L V8
FOST Obsession 860 – Honda BF250
If you asked me to describe the Obsession 860 of Fost Rib Boats shipyard in a few words, I would say without hesitation that it is a rigid inflatable boat (RIB) with a purely offshore character, primarily designed to travel smoothly in rough weather conditions, perfectly adapted to the demanding seas of the Aegean.
Its relatively long and narrow hull, with an entry angle of 62 degrees and a deadrise at the transom reaching 26.5 degrees, allows it to cut through waves like "butter" and enter the water smoothly, fully absorbing shocks so that they never reach the passengers.
Despite its narrow bow, the sundeck can comfortably accommodate two adults, featuring an overall length of 2 meters and a maximum width of 1.20 meters in the feet area. Below, there are two independent storage compartments capable of holding all the necessary safety equipment and plenty of luggage.
Above the intersection of the inflatable tubes sits a large fiberglass hard nose, providing stable stepping areas for easy boarding and disembarking. Telescopic cleats are fitted on its main surface, ensuring safe movement without risk of injury, while a small channel runs through the center, housing the anchor chain, which nests into the forward edge.
Between the bow sundeck and the console, a free deck space measuring 55 cm x 130 cm allows for comfortable movement. The console is positioned slightly to the right, leaving a passageway on the left side of the deck, while inside it, there is a large storage area housing the boat’s batteries.
The instrument panel is designed with the appropriate tilt and space for the installation of a navigation screen, engine gauges, audio system, and VHF radio. The throttle control is centrally positioned, with the steering wheel on the left and a useful small compartment on the right for storing small items.
The two independent helm seats are mounted on an elegant fiberglass structure that also supports the stainless steel pillar of the T-top. These seats offer excellent lateral support, feature a shock-absorbing mechanism with adjustable height, and are distinguished by their high-quality upholstery.
Further aft, there is an open deck space 170 cm wide, providing ample room to move comfortably given the boat’s size. The stern bench seat is 155 cm wide and can accommodate four adults with ease. Its backrest is reclining forward, forming a large sundeck measuring 120 cm x 160 cm
Beneath the stern bench lies the boat’s largest storage compartment. Since the batteries are not located there, it offers extensive free space, allowing for the storage of numerous bags and even a small auxiliary engine.
At Sea
The test boat was equipped with a 250hp Honda engine, whose lower unit, with a reduction ratio of 2.00:1 was turning a 3-blade 15 1/4” x 19” stainless steel Honda propeller. This was the first time the Obsession 860 was paired with this engine, and we were particularly curious to assess the performance of this new combination.
Although Honda has remained a conservative player in the marine sector in recent years, with most of its competitors introducing significantly more powerful outboard engines, the automotive and motorcycle giant carries decades of technological achievements and cutting-edge innovations that no one can dispute.
Weighing 287 kg and featuring a gear ratio of 2.00:1, Honda's BF 250hp engine incorporates a range of technological features designed to deliver high power while maintaining fuel efficiency. Oxygen sensors enable the Lean Burn system, which optimizes the air-fuel mixture through computer-controlled fuel injection, ensuring fuel savings at low loads. Meanwhile, the Boosted Low-Speed Torque (BLAST) technology advances ignition timing when the throttle is rapidly opened, enhancing power output.
BLAST is Honda’s unique air-fuel ratio and ignition timing technology, developed to improve torque during initial acceleration, reducing the time required to reach the planning mode.
Furthermore, high torque remains optimal across both low and high rpm ranges, thanks to the electronic Variable Valve Timing and Lift Electronic Control (VTEC) system.
VTEC is an exclusive Honda technology that utilizes variable valve timing and lift control mechanisms to enhance intake performance by adjusting valve opening and timing as engine speed increases. By delivering high torque across the entire rpm range—ensuring strong acceleration at low speeds and steady acceleration through to high speeds —VTEC contributes to improved fuel efficiency.
We were a crew of three, carrying 200 liters of fuel, 40 liters of water, all onboard equipment, and the auxiliary engine stored in the aft compartment.
Pointing the bow into the short, choppy waves—though not significant enough to disrupt our ride—the hull’s soft impact absorption was immediately noticeable. It effortlessly bridged the waves, highlighting the boat’s robust construction.
Obsession 860 performed exceptionally well, even when running downwind, with the bow smoothly passing over the short peaks and effortlessly cutting through the occasional larger waves along our route.
For an extended period, I held the throttle steady at 4400rpm with the engine trim at 50%, allowing the boat to cruise at 30 knots while consuming 1.4 liters per nautical mile. This speed range is where the boat feels most comfortable, making it ideal for long-distance travel.
The boat planed in 6 seconds after a slight bow rise and maintained on plane at 2500rpm, cruising at 11 knots. It accelerated to 30 knots in 10 seconds and reached 40 knots in 17 seconds.
At 3000rpm, we traveled at 17 knots, consuming 1.3 liters per nautical mile, while at 3500rpm, we cruised at 22 knots with the most efficient fuel consumption of 1.26 liters per mile
At 4000rpm, our speed was 26 knots with a fuel burn of 1.44 liters per mile, whereas at 4500rpm, we reached 31 knots, consuming 1.45 liters per mile.
At full throttle, we achieved a top speed of 43 knots, with the engine reaching 6000rpm, though we couldn’t quite hit the manufacturer’s recommended maximum limit.
You can see our measurements in the table below:
Examining the table closely, we can see that the recorded slip values are quite good. However, if we are willing to experiment, we can further improve them.
It is clear that switching to a larger-diameter and shorter-pitch propeller would allow the engine to gain another 300rpm, enabling it to operate more efficiently when carrying typical onboard loads. This change would also enhance throttle response and improve maneuverability—something we would especially appreciate when navigating through rough sea conditions.
- Overall length: the 8.60 m
- Beam: 2.68 m
- Weight hull-deck: 720kg
- Tubes diameter: 55-45 cm
- Fuel capacity: 170+190 lts
- Water capacity: 120lts
- Max power: 400h
Manufacturer:
FOST RIB BOATS
Tohi 1, 19400 Koropi,
Athens – Greece
Tel.: +30 2106022000
https://www.fost.gr
