Home BOAT TESTS Cobra 8m with Twin Yamaha F200s
Cobra 8m with Twin Yamaha F200s

Cobra 8m with Twin Yamaha F200s

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  • … the twin F200 set-up turns a sedate family RIB into a lively Grand Tourer that can cover a sizable distance between fill-ups and has the backbone to take on open-sea crossings.
  • … the 8m Cobra has established herself as a spacious, family sports RIB …
  • The beauty of the 8m over the 760 is the extra cockpit space between the seating; it is worth the extra, if you are debating the point.

Simon Everett revisits the Cobra 8m with what is possibly the ideal set-up.

The 8m is a useful-sized RIB with more deck space than a 7.60 without resorting to the mammoth 10m. The combination of manageability, performance and space on board makes it an ideal choice for the family ribster, and this twin-rig version should provide a happy medium between performance, handling, fuel economy and safety.

When we first tested the Cobra 8m she was sporting a single high-horsepower engine, having been built specifically to take the then new F350. The reason for taking another look at this popular boat is the twin-rig installation with equivalent horsepower that is now available, with Yamaha having launched their F200, which was missing from the line-up back when we did the original test.

The Yamaha F200 is an inline four-cylinder engine, so it could be thought of as the equivalent of a single bank of the V8 F350. Mounting two of the new F200 motors is only 100kg heavier than the single F350, which comes from the second leg, starter motor and alternator attributed to the second engine. The overall benefits, though, are worth the bit of extra transom weight, and the price differential isn’t as great as you would think – certainly not enough to be a deal breaker.

If you are in the market for a Cobra 8m RIB, you really have three choices: 1) the single V8 F350; 2) the single V6 F300; or 3) a pair of inline F200s.

If outright top speed is your underlying requirement, then the single F350 has the edge, but if you want a driver’s boat with all-round performance and drivability in all conditions, then the twin rig with F200s has a lot going for it. The cheapest of the three options is the single F300, but then you lose out on any of the benefits that the other options offer. It still makes for a very useful package that unless you could compare it directly to one of the other rigging options you probably wouldn’t notice – the family certainly wouldn’t.

So, how does the two-engine set-up measure up? Well, for a starter, it is more economic on fuel at cruising speeds than either the single F300 or F350. We returned 8.5 gallons per hour, combined, at 3300rpm, which gave us 22.4 knots against the tide flow of the Solent between Lymington and Cowes. Unfortunately, I couldn’t work out how to change the units to litres per hour, which is down to my inability to work anything more complicated than a wheelbarrow! The fancy new Yamaha digital gauge displays both engine parameters in the one unit, and it replaces the older twin square gauge set-up. The clarity of display and arrangement on the dash are both improvements.

In order to counteract the additional weight on the transom, the boat is ballasted with the fuel tanks set fore and aft, giving higher tank capacity as an added bonus. The result is that the boat sits the same as with a single F350. Each of the tanks feeds one engine and one engine only. The engines are rigged as if they were a single installation, linked for steering, but otherwise kept completely independent, which is another reason why people might like the peace of mind provided by two engines. Unless filled with dodgy fuel, it would be really bad luck to get two breakdowns simultaneously.

Apart from the breakdown mitigation reasons, other benefits of choosing the twin installation over a larger single include much faster acceleration – lifting the boat onto the plane almost instantaneously, and taking just 3.9 seconds from standstill to 20 knots! Impressive indeed, and when battling adverse conditions, the ability to put power on when you need it, and the boat responding, makes driving so much easier.

Now, acceleration may not be high on your list of priorities, but everyone has to put their boat alongside at sometime or other, and with the longer RIB the twin-engine layout has a huge benefit in terms of the ease of manoeuvrability compared to a single-engine configuration. The ability to spin the boat on the spot without touching the wheel or constantly clunking the gearbox makes life so much easier and is worthy of consideration for that aspect alone. Putting the boat into an awkward, tight berth with wind and tide conspiring against you suddenly becomes a piece of cake, provided you don’t get too enthusiastic with the throttles, otherwise that lightning-quick acceleration will bite you. It is wonderful to have, but it needs tempering with a considered hand in close quarters.

On the handling front, there is a physical reaction to mounting two engines compared to a single – this isn’t just true of the Cobra, but any boat. The motors are mounted wider of the keel line than a single would be, thereby raising the props, and so in tight turns it is possible to lose grip sooner than with a single outboard purely by dint of the fact that the props will ventilate as they break surface on the heel over. What happens is the outside motor spins up as the prop is suddenly unloaded in the thin, aerated water on, or close to, the surface. It caught me out, but the Yamaha rev limiter kicked in and protected the engine. The boat didn’t hook or anything, it just lost most of the drive in the corner, slowed, and as the motor revved away I hauled the throttles back and straightened up instinctively. It isn’t a fault per se, just something to be aware of if you are feeling a bit frisky and want to emulate ‘The Stig’ afloat. Provided you drive the boat within sensible limits, she’ll be fine. That doesn’t mean you have to pussyfoot about either – just don’t try and be too clever by turning so tightly that the prop breaks free; a slightly wider arc at a similar throttle setting will return a crisp, curved wake and keep your speed up too.

That is the motorisation side of things taken care of – so what about the boat to mount them on? Well, the 8m Cobra has established herself as a spacious, family sports RIB. The modern console provides extra legroom and better protection than the earlier one did. The hallmark Cobra seating unit comprises moulded bucket seats that can convert to stand-up bolsters, housed in a style matching moulding to the console. The beauty of the 8m over the 760 is the extra cockpit space between the seating; it is worth the extra, if you are debating the point.

Let’s be honest about it – if you can afford a £100,000 RIB the financial considerations between the engine options are hardly likely to be a major factor: the difference between the single F350 (the fastest option) and the twin rig of F200s is only around £6,000. The single F300 doesn’t come top in any of the criteria sectors, except price, and we have already ‘discounted’ that aspect as a reason for choosing any of them. That leaves the twin F200 as the best of the available options, giving, as it does, nearly the same top speed, but overall a much better driving experience. Having the capability to do over 50 knots can hardly be described as slow. I think the twin F200 set-up turns a sedate family RIB into a lively Grand Tourer that can cover a sizable distance between fill-ups and has the backbone to take on open-sea crossings.


Specifications

  • LOA: 8.1m
  • Beam: 2.55m
  • Max. persons: 12
  • Max. HP: Single F300, F350 or 2 x F200
  • Fuel capacity: 380 litres
  • CE cat: B

Performance Figures

  • Acceleration: 0–20 knots in 3.8 seconds

     RPM Speed (knots) Fuel consumption (gals/hr)

  • 700 2.9 0.8
  • 1000 5.1 1.7
  • 2000 7.6 4.8
  • 3000 21.6 8.0
  • 3500 27.9 10.2
  • 4000 33.6 15.1
  • 5000 42.8 26.4
  • 6000 51.2 50.4

Thumbs Ups

  • Great manoeuvrability
  • Neck-wrenching acceleration
  • Good fuel economy
  • Nicely balanced

Thumbs Downs

  • Liability to lose grip on outer prop in tight turns
  • Higher cost and maintenance

Price

TBA


Contact

Cobra RIBs

12 Priory Industrial Park

Airspeed Road

Chichester BH23 4HD

Telephone: 01202 612712

Website: www.cobraribs.com