Double the excitement

Graham Lloyd | VOLUME 29, ISSUE 2
There's something special about twin outboards. Mount them onto a RIB and you've got a recipe for fun.
There's something special about twin outboards. Mount them onto a RIB and you've got a recipe for fun.

Twin outboards always offer a special appeal. Being quite rare, they stand out in any company, while the sound of two engines accelerating and cruising together is just marvellous. Of course, there's the safety factor of having a second engine if one should falter, and well set-up boats will still plane at a good speed with an engine out.

My dad introduced me to the joys of twin outboards with one of his boats and, at various later times, I had several of my own, including a bit of a monster with two V8 Johnson outboards. They sounded unbelievable at speed, but their prodigious power was matched by prodigious thirst. Not so with this Zodiac, where the transom is graced by two very neat Evinrude E-TEC 75s, which delivered all the benefits of twin engines, but with economic performance.

The starting procedure with dual power gives an extra punch to the start of the day - having started one engine, it's great to start the other and hear the two powerheads muttering away together. With E-TECs, the noise level is very low, but there's no mistaking the special, more exciting, rhythm of dual powerplants.

The Zodiac is rather special, rather different, and a good example of needing to keep an open mind when casting around for a new boat.

Inflatables are very popular in smaller sizes as general-purpose craft and especially as tenders for cruisers and yachts. The inflated tubes not only provide exceptional lateral stability, but they contribute to light overall weight and double as fenders when coming alongside the pristine hull of a larger boat. A wide anti-chafing deflector strip on the outer edge of the buoyancy tubes of this 650 also helps in that regard.

Putting a deep-vee fibreglass hull under the tubes of an inflatable creates a Rigid Inflatable Boat, or RIB as they're commonly known, and that results in a potent combination of safety and performance. Zodiac is a world leader in these craft and, in many areas, the name is synonymous with the style. The company has a history dating back to 1896, although the Zodiac brand started in 1909 with inflatable airships.

The boat side of the business got underway in 1937 when Zodiac made inflatable carriers for bombs and torpedoes, which led to the invention of the inflatable boat in 1940. By 1969, Zodiac was the world's largest builder of inflatables.

That's an impressive track record and the Zodiac Pro Open 650 is a worthy part of the story.


The Pro Open's 6.5m open-plan layout is ideal for recreational boating and can cater with ease for mild watersports and fishing. The fibreglass hull is conventional in layout, with a fine entry and two strakes either side of the keel. The outer edge of the hull forms another combination of strake and channel where it meets the inflatable tubes, and that contributes to the excellent running characteristics of the 650.

At the transom, the hull carries quite a deep vee with 24 degrees deadrise. That provides a soft ride, enhanced in rougher waters by all that lateral stability from the tubes. The design still turns very well and, in general, gives excellent handling. We had calm waters for our run, although speeding through our wake was indicative of the surprisingly good ride these RIBs are known for across a swell or chop.

Zodiac uses a tough and resilient Hypalon Neoprene 1670 decitex fabric for the inflatable tubes, which have multiple air chambers for safety. The tubes can be removed from the fibreglass hull for more compact storage, if required.

The quiet, smooth-running E-TECs are controlled by SeaStar hydraulic steering. I've driven plenty of boats with SeaStar and I've personally fitted one system to a boat of my own, so I know it's very good and offers light-effort responsiveness. On this Zodiac, though, the steering was quite heavy - I think that must have been caused by something in the set-up. The throttles and shifts were a bit stiffer than usual, too, so maybe all the linkages or lines were being affected between the helm station and the transom. I'd expect a bit of sorting out would overcome the matter.

The Evinrudes themselves are three-cylinder 1295cc two-stroke engines with the now well-proven and highly regarded loop-charged E-TEC direct fuel-injection system. Integral oil tanks under the engine cowls supply the automatic variable oil injection feature that ranges between about one part (oil) in 60 (petrol) at full throttle to one part in 300 at low-stress idle. These engines run quietly, with no smoke, and are very environmentally advanced, winning approval from the Californian Air Resources Board, which sets probably the most severe standards in the world.

Practical layout

Aboard the Zodiac, the driving position is at a console offset to starboard, leaving a clear passage down the port side of the boat. The entire console hinges forward for access to a huge storage area below that could take bulky items such as life jackets, fenders, waterskis and wakeboards. Alternatively, the console can be left in place and smaller hatches in it used to access the storage.

There's more stowage under the seat of the double leaning-post for the skipper and first mate. You can sit on this to drive, but the design is more suited to standing as the wheel and controls are then within easier reach. The seat still provides a good brace against which to lean back, while the console provides more protection from breezes and spray than I'd expected. An optional bimini top is available and would be a big advantage for shade and protection against the fierce Aussie sun.

The dash area has plenty of room for gauges and electronics. For the Evinrudes, we had a pair of analogue tachos, which had easy-to-read black-on-white dials with inset digital read-outs for extra information. Dominant in the upper area of the dash is a large Lowrance HDS-9 GPS plotter/fishfinder, perfectly sighted for both navigation and keeping an eye on the squadrons of fish below. Beside the tilt-adjustable wheel is a set of switches and across to the right are the twin throttles/shifts. All that makes for an efficient set of controls that make driving the 650 a bundle of fun.

In front of the console is an open area with a raised mini-foredeck containing a large hatch over a big anchor locker that has a lift-out storage bin. The fuel filler is also under there. Just forward of that is a bollard and, above that, a fibreglass extension of the hull rises through the inflatable sections to provide a base for the flip-over bow roller, triple fairleads, and a pair of small navigation lights.

At the back of the Pro Open, a full-beam lounge has comfortable seating with lift-out storage bins below, including a 54lt cooler under the centre cushion. With the bins lifted out, there's good access down into the bilges and the battery master switch. The backrests are removable and one can be relocated for use on the driver's leaning-post seat. For both sets of seating, when the backrests are removed, their sockets can be used as rod holders. There's provision behind the aft lounge to fit an optional ski pole, adding to the versatility of the 650 for family boating. Drink holders and grab handles are also provided.

Exhilirating performance

The two Evinrude 75s swept the Zodiac on plane and delivered copious acceleration, both initially and through the mid-range to our top speed of 70.3km/h. That gave an exhilarating ride, close to the factory-rated top speed of 77km/h, which comes with a single 175 outboard. The 75 E-TECs are close to the allowed maximum of 80hp for dual outboards. The dual lower units of a twin installation do create more drag than a single, larger outboard, which contributes to the speed difference as well as the lower 160hp (combined) versus the single 175hp. But, really, 70km/h is plenty fast and gives all the grunt and velocity you'd want to truly appreciate this RIB's special appeal.

Our 650 planed sweetly at 23km/h with the dual 75s spinning at just 2300rpm. Cruising along was relaxed, anywhere from 3000rpm (34km/h) to 4500rpm (57.9km/h). These E-TECs were fitted with three-blade stainless Viper props, 35cm in diameter by 43cm pitch, both right-hand rotation, and just hummed along, aiding the impression of a well-balanced design.

The inflatable tubes hold the 650 quite level during turns while, at rest, you can load the boat on one side to ridiculous levels without disturbing its equilibrium. The tops of the tubes make for quite comfortable seating and there are grab strips and safety ropes as well as handles that can double as tie-off cleats.

All up, the 650 Pro Open is an appealing boat that can be used for anything from family cruising to fun-driving in rougher waters, with the ability to tow recreational skiers or tow-toys, or to take the crew fishing. It would be an ideal tender, too, for large luxury cruisers and yachts. Its stability and load-carrying capacity would be very useful at times and its forgiving hull design would be great for novice skippers. A smaller 550 version is available as well.

The relatively light weight of these RIBs means they need less power than comparable boats built from other materials and thus they are easier to tow.

There's more to find out about both the Zodiac and the Evinrude E-TECs, so do visit the respective websites noted in the specifications panel to discover their full details.

LOA: 6.5m
Beam: 2.5m
Weight (boat only): 670kg
Capacity: 5 persons
Fuel capacity: 120lt
Power: Single outboard to 175hp (131kW); dual outboards to 80hp (59kW)
Power (as tested): Dual Evinrude E-TEC 75hp (56kW)
Price: $70,000 - $75,000
For more information, contact: Zodiac Marine, web: Evinrude, web: