Hugo Montgomery-Swan tests the very first jet rib ever produced by Scorpion Ribs and reveals how, with this form of propulsion, the new model compares in terms of handling and performance with its fellow stable-mates.

There are times when the launch of a new model is significant enough for it to be a ‘must have’ inclusion within the pages of this magazine. But, some of you may say “I’m never going to be able to afford a RIB of that type so this review is of little relevance to me.” However, a detailed look at an example of cutting edge RIB technology must surely make essential reading for anyone with an interest in RIBs. Where industry leaders take the RIB concept, others will most certainly follow and standards will be raised.

If this seems far-fetched, just look how the RIB industry has matured over the course of the last 12 years and how the RIB as a stand alone vessel has advanced in terms of aesthetics, quality of finish and design. This advancement has been fuelled both by public demand and by the work of leading manufacturers continually raising their game with new model development and progressive refinement. Progress in terms of quality and design always filters down from the top but never works its way up from the bottom! This fact has been even more reinforced in my mind over recent months as new RIB designers and builders have discussed their ideas and plans with me. In every case they’re seeking to emulate the product quality and design skills of the established builders whom they perceive to be the market leaders.  In this feature, we have chosen to review the very latest and best from a builder who is widely regarded by both the industry and the buying public as being amongst the world’s finest.

The Scorpion 8.5m Jet RIB from Graham Jelly’s Lymington yard is an interesting craft, not least for the fact that, surprising as it may seem, it is the first jet driven boat Scorpion have ever made. Yes, that’s right, the very first, so I was keen to establish how successful they had been in transforming their paper plans into reality. For instance, would this model still handle and perform as effectively as her fellow ‘stablemates’ or would she be seen purely as a hybrid - perhaps even being destined to the ‘bottom drawer’ collection of once tried, never to be repeated build projects?  

Getting a RIB to work effectively as a jet-powered craft is not as simple as it may first appear. The differences in weight distribution and how it may affect the vessel’s central point of gravity, the overall length, and the design of the hull, will all have a strong bearing on whether the vessel’s dynamics are going to be enhanced or negatively influenced. I have driven some jet powered RIBs whose hulls, when fitted with a conventional drive have been very surefooted indeed, but when coupled to a jet, have been nothing short of disastrous. It’s quite clear that exchanging one for the other in many instances is not a straightforward matter.

To avoid the dreaded start/stop motion a jet powered craft often suffers from when ‘traction’ with the water is lost, it must have adequate length with correspondingly adequate weight. If it is to maintain good steerage, particularly in a following sea, then amongst other things its hull must also possess a sufficiently deep-vee, and be of a design which encourages it to hold to the water both when being driven in a straight line and through a turn.

The Scorpion 850’s sea trials, up to and including the day of our test, were sufficiently extensive to discover whether the RIB was truly suited to the waterjet alternative - we’ll reveal our findings in just a moment.

But first I’d like to say a few words about her fitout. She is unquestionably a very handsome craft indeed, resulting directly from the thousands and thousands of pounds which have been invested by this private company in the development of both tooling and moulds. The result is a rigid inflatable that would rank alongside any craft, of any description, anywhere in the world. Attention to detail is superb and the vessel demonstrates a pleasing combination of functionality, ergonomics and aesthetics; three attributes which, when achieved harmoniously, become the ‘holy grail’ sought by all designers. Thanks to Jelly’s constant program of ‘field’ research and development, vital aspects of the boat’s anatomy don’t just look good, but more importantly, they also work well! The windscreen is a good example of this; stylish and unobtrusive, yet at 40knots the helmsman can still have a perfectly normal conversation without any wind in his face. The engine housing is another example; it’s one of the most attractive I’ve seen but still boasts a lounge deck, a large passenger seat at the front, decent storage and helps support a bathing platform at its rear.

Just switch on the electric hydraulics which lift the lid, and you’ll see how well engineered this whole section of the boat really is. Great thought has been given to the installation of the Yanmar 440hp diesel inboard and the accompanying electrics, fire extinguishing equipment, internal lighting and  battery are all carefully housed. The lid itself is double sealed, and this, when added to the unique design of the air intake system and the effective routing of deck water, ensures that the engine compartment is wholly waterproof and will remain totally dry at all times and in all sea states. For a serious offshore powerboat such as this, secure housing for the inboard diesel is absolutely essential.

Of course, by the time you’ve installed an inboard diesel and waterjet, even to an 8.50m RIB, deck space is greatly reduced. The upright design of the helm console, the stowage in it and the  cox/navigator bolster support behind it helps to take up as little room as possible, but if you want plenty of free deck space, an outboard installation is your only real option. The deck itself is finished to a very high quality in Flexi-teak with the foreword section stepping up to provide more stowage below.

This RIB has been built specifically to the order of a client who required a waterjet from which one could step onto a beach, (as opposed to climb out,) when landing his guests ashore. In order to comply with the client’s request, Jelly has designed a very neat set of boarding steps that are actually integral to the hard-bow itself. A simple lift’n’lock arrangement allows this design to work well and though highly functional, once again, Jelly has achieved the objective without detracting in any way from the good looks of the craft. The design brief was very exacting in a number of areas, including the vessel’s proportions as it had to fit into the holding bay of a mother ship - a bay that had been based upon his existing Scorpion design. Jelly knew he was working to a 10cm tolerance - a fraction over this and it simply would not fit!

Seamless hypalon tubes, first-class stainless steel work, sumptuous upholstery, gleaming white GRP, all the elements of this RIB’s manufacture spell quality. Yet what gives a Scorpion its true pedigree is of course the line honours. Long distance record titles, championship race wins, and the many hours that this breed of RIB has undertaken offshore cruising in the hands of private owners, all go to substantiate what a fine seagoing craft the Scorpion truly is. In other words, this 8.50, like the other models in the range, has been built to be really used at sea.

So, when all is said and done, does it actually work? Well, the Hamilton waterjet is more than tried and tested, having been in service with a whole host of operators all over the world now for years. Being fairly compact, the Hamilton HJ274 is suited well to the 8.50m and the best proof of this can be seen in just how well balanced the RIB is. At speed, she runs in an exceptionally level fashion with no sign of her powerpack and drive unit causing her to be tail heavy.

When the turbo kicks in, acceleration is impressive, delivering a real jolt in the back when the throttle is rammed to the stops. On the day of test the Yanmar achieved a sound 46 knots and bearing in mind the engine had yet to be run in, no doubt it will do more than this when it has loosened up. Her first trial was in a force 7, the second occasion was the RIB International test. This foray out into the blue was amidst a brisk force 5 in the short steep seas of the Solent, so there were plenty of opportunities for handling misbehaviour to manifest itself. However, no such problems occurred and Jelly told me that even in the force 7 seastate, at 36 knots and below, she never once left the water.

So yes, Scorpion have got it right - and first time at that! This RIB handles in a very reassuring way indeed; in fact, the whole experience was very impressive. Thanks to their new client, and with talk of another Jet RIB on the way, it seems Scorpion have acquired yet another new model to add to their already highly successful range of offshore RIBs.

HMS