|It is widely held among boatbuilders that diving clubs judge everything by the invoice. One company of well-built but expensive boats, Ribtec, has withdrawn from the diving market as a result. And Delta, a traditional builder of divers' RIBs, elected not to submit details of craft for our survey because it sees its boats as too well-built and pricey for sport diving customers, though it is planning a "recreational range" for 1999.
There are signs, however, that the supposedly bottom-line attitude among clubs may be changing, helped in no small part by the money coming into the sport from grants bodies (see Diver November 1998, p82).
One company that claims to have done particularly well out of the grants situation is Tornado. Laurence Lock, of Tornado dealer Barnet Marine, told Diver: "I reckon we've had about 1.4 million of that money - and our boats aren't cheap."
So, with healthy funds available, clubs have been buying some very nice rigs. And the world of RIB manufacture is looking healthy, with a strong group of companies offering a large choice of boats suitable for diving.
Our survey concentrates on the 5-9m RIBs relevant to club diving. Leisure RIBs padded out for family fun are not included.
Heaven and hull
A club operating in the open sea needs a vessel with a deep-V hull, capable of slicing rather than pounding. There must be enough lift and stability from its chines for it to plane readily when fully loaded, and the boat must be responsive to steer.
Variation in build quality comes in such areas as the strength of a glass-reinforced plastics (grp) hull's lay-up; the bonding-in of a grp-encapsulated marine-ply deck and its supports; and the strength of the hull-to-tube join, dependent on a well-designed hull mounting flange and strong bonding.
The join will be strained least by tubes that have been cut correctly to the sheer of the boat. When inflated, well-made tubes should take up their correct shape and lose signs of creasing when still at moderate pressure.
Tubes are available in two main materials: Hypalon and polyurethane.
Hypalon, engineered specifically for inflatables some 30 years ago, is well-proven. It is used by most RIB constructors, many of whom fit tubes ready-made by a single company, Henshaw. According to British builder Northcraft, which constructs in both materials, Hypalon remains the best-bonding of the two and the least prone to slow leakage.
Polyurethane is employed by only a handful of constructors, including Northcraft, Tornado and Valiant. It has been used in RIBs for about 10 years, says Keith Somers of Valiant-importer Inflatable Boat Supplies, so long-term effects are less familiar. On the other hand, it's an extremely tough fabric with superior abrasion resistance, and it's also thought to be more resistant to colour fading by ultra-violet light.
Major company news is that the French Zodiac has taken over Avon, as traditionally English as straw-berries and cream. As producer also of Bombard boats, Zodiac is now one of the world's largest manufacturers of inflatables and RIBs.
The Zodiac entry on the table overleaf is not that strong, however, because the company's main production is of smaller and semi-rigid inflatables. And some of its larger RIBs are based on general leisure.
Meanwhile, Avon (the name and production line-ups of which remain unaltered) has just launched a new 6.5m RIB that could be a good option for divers. Avon products manager Ken Watson described the craft as a "real sea-going boat", though priced at the "top end of the market".
By contrast, Ballistic, at less than two years old, is a relative newcomer to RIB manufacture. It employs Kevlar reinforcement for hulls that feature concave sectional surfaces between very closely spaced chines, claimed to provide strong lift. "The 7.8, well laden, is on the plane at 10 knots," says MD Nick Parish. "We've sold six to diving individuals who plan to run them for hire."
Bombard is one of the few manufacturers to produce in both polyurethane and pvc, while BWM, a concern that has come and gone over the years, is back in business.
Of some 130 Cobra RIBs produced over the past year by Picton Boats, 15 per cent have gone to divers. The 8m and 8.5m boats are the most recent.
Crompton Marine, a commercial RIB manufacturer that had sold just five boats to sport divers in five years, has made a pitch for the leisure market with its new range of Mini Sprints and Sea Sprints. "They are deep-V, multi-chine boats that cost about half our commercial rates but are still rugged," explains MD Neil Davis.
Flatacraft, too, sells mainly to commercial customers but has supplied eight boats to sport divers over the past year.
By contrast, Humber - probably the largest supplier of RIBs to British sport divers - marches on with its extensive range of craft, majoring on the recently developed Destroyers. Boss Frank Roffe keeps figures to himself but confirms that he sells "some 50 per cent" of his boats to divers.
A RIB with a difference is the Hysucat Stealth, featuring a grp catamaran hull with inflatable collars. Good seakeeping and efficient running are claimed. Originally produced overseas, it is now to be built in Britain.
Also out of the usual run is the new aluminium-hulled Mach 6.5m, which joins a stable of grp boats from the Pepe yard. Mainly an aluminium hardboat builder, Pepe describes its product as "stronger than grp but pricier, as it's more labour-intensive". And because aluminium is a custom-build medium, any size of boat can be ordered.
Northcraft has succeeded in supplying both the commercial and sports worlds. Its expertise is such that it carries out repair work for a number of other RIB manufacturers, including a retubing service. It works with both Hypalon and polyurethane, and builds boats for divers on a custom basis.
Constructor Andy Davison is clear on how a diving RIB should be: "The tubes should be in the water at rest, for a stable platform, lifting out of the water on the move."
And a word of warning about dimensions: "Some builders use the same hull and just lengthen the tubes, turning a 5.8 into, say, a 6.2. And make sure the internal beam figure is for tube to tube, not floor beam, which can be misleading."
Ocean, which produces offshore RIBs of up to 10.4m, has launched a new hull at 8m. Traditionally a grp boatbuilder, the company makes everything itself, from hulls and tubes (in Hypalon) down to stainless-steel fittings such as A-frames and bottle racks.
For Osprey, like Humber, sport divers dominate the market for its extensive range of craft. MD Mike Armitage says: "We're selling a lot of our largest Falcon, the 9.5m" - it must be those grants again.
Plancraft, experienced in grp sports-boat manufacture, has moved into RIB production with a new design, the Seaflite Dive RIB 5.8. Heavily built at 800kg, the deep-V-hulled boat features a moulded grp deck offering lockers at both bow and stern.
With a strong track record in powerboat racing, Revenger uses high-performance hull designs for its range of RIBs, with tubes that taper into characteristically pointy noses.
The easy-planing, highly controllable hulls are also appropriate for load-carrying duties, says MD Mike Sloggett. "We do wider, squared-off bow versions of the 23 and 25, which might interest divers."
Ribcraft is a company that, like Northcraft, has supplied commercial RIBs for years, sells to sport divers as well and builds its boats entirely in-house. Its latest boat is the 6.8 Offshore, designed last year as a heavy-weather "working platform". Hull lay-up, underdeck structure and hull-tube joins are to commercial MSA Type approval.
Ring Powercraft started building RIBs in 1990. Hypalon tubes from Henshaw are bought in and fitted to designs based on powerboat hulls. Boss Mike Ring will, however, fit an extra equipment bar, bilge pump and navigation lights.
Reflecting a view expressed by certain other builders, he says: "Fitting electronics is nothing but aggro. I don't make a great deal of money from it, and, if anything goes wrong, I end up carrying the can for some other manufacturer's faulty product."
Until recently, South Coast RIBs had busied itself for five years building "upmarket RIBs for general leisure". Now, it is producing its first boat suitable for divers. The Scorpion Dive 6.5 features tubes fitted lower than the norm at South Coast RIBs to create a more stable platform for diving.
Tornado, along with Humber, Osprey and Ribcraft, is one of the more mainstream suppliers of diving RIBs. It has also enjoyed commercial sales successes, and is one of just a handful of builders to employ poly-urethane for its tubes.
Tornado's recently tweaked 6.5 is, says Laurence Lock of outlet Barnet Marine, a "very efficient boat with excellent lift". The 5.8 - a popular choice among divers - is next in line for "hull-lift" treatment.
Portuguese builder Valiant uses polyurethane, Hypalon and pvc for the tubes of its boat ranges. It is a large-scale manufacturer, churning out 700 to 1000 boats a year.
Optional extra bow-fendering on Ribcraft 585
A 5m Northcraft ready for the water
Divers prepare aboard the Reveger 27
A Humber Destroyer 6.5 travels upriver to Humber's yard in Hull
At sea aboard the Valiant 750
Pepe drop tests Mach to gain an ISO rating