Ribcraft 6.8m

There is no compromise with a Ribcraft, which is obvious the moment you cast your eyes around one.
…it is still sufficiently family-friendly in design and appearance to appeal to those outside the drysuit brigade.

Ribcraft 6.8m
Greg Copp gets behind the wheel of a craft primarily built for commercial purposes but that will also appeal to those looking to use their RIB for pure, unadulterated pleasure…
Having been key players in the RIB revolution, Ribcraft have set a benchmark in the art of building rigid inflatable boats for many years. RIBs are a British passion, and over the last 20 years we have seen many come and go. The most successful designs have by and large survived, and some, like the Ribcraft 6.8m, are of a long-standing design whose timeless qualities, with a bit of tweaking here and there, have kept them in production for nearly two decades.
Based in Yeovil, Ribcraft have always focused on building boats for the commercial and military markets, as well as supplying the needs of serious civilian users. The 6.8 is a perfect example of this yard’s versatility as this boat has proved its worth in a variety of different guises. The boat’s core design focuses on a ‘warped deep-vee hull’ with a transom deadrise angle of 24 degrees. However, unlike many deep-vee designs, the deadrise sharpens amidships, in this case to 26 degrees – hence the term ‘warped’. This is often what yacht builders refer to as ‘variable deep-vee’, which the likes of Fairline and Princess have used to good effect. The concept is simple and effective – the best of both worlds, if you like – as you get that extra bit of stability and lift from 24 degrees at the stern (still sharp by any standards), while 26 degrees amidships is pretty rakish, and just what you need for landing on a short, sharp chop.
As I found out, the hull on the 6.8 works a treat, providing a deceptively soft ride when running into sharp head seas. The boat keeps her nose down pretty much all the way up to 35 knots, and even then only needs a bit of extra leg trim to squeeze out the last few knots. Most of the time I drove the boat with just 25% of trim on the gauge, which is what the boat’s owner, Jamie, advised. Encouraged by him to try and lose the stern by throwing the boat into ever tighter circles, it was pretty obvious that I was wasting my time, as she just digs in and tracks round. Running flat out with 75% trim at a shade over 39 knots, she just eats up the distance without the slightest complaint from her bulletproof hull. However, one aspect I would like to change is the throttles, as I found that they were too long if you needed to work them quickly in heavy weather.
Compared to a Ribtec 6.5m that I recently owned, the Ribcraft is noticeably more stable when coming down off waves, and turning hard with the sea on the beam. The Ribtec was pretty good, to be fair, but nowhere near as forgiving and easy to drive as the Ribcraft. The heavier build and the low-mounted tubes help in providing a reassuringly planted feeling that you do not often get with middleweight RIBs. Having a 2.7m beam helps, as does having a lattice construction of full-height laminated marine ply cross members and stringers, beneath a laminated ply deck. Halmatic used this same construction with their Arctic, Atlantic and Pacific RIBs, all of which had to be able to withstand being parachuted into the sea. Not surprisingly, this standard of build complies with both Lloyd’s and DNV GL regulations.
I did wonder about having two 155kg 90hp engines on the back, compared to the biggest engine option – a 264kg 225hp Suzuki DF225. It is an easy one-handed steer, though it does not turn as quickly as one larger engine, however the difference is negligible. This boat can be ordered with twin 115hp Suzuki DF115s, but the extra 60kg of these engines over twin DF90s is quite a big chunk when they are hanging off the transom. My preference for this boat in a non-commercial environment would be a single 235kg 200hp Suzuki DF200A, as this engine offers great power to weight. Jamie chose twin DF90As for the offshore security of two engines, and the bottom-end grunt that a twin rig gives you. In real terms, twin 90s give you the same low-down pickup as one single 200hp engine. Further up the spectrum, the power delivery will drop off due to the extra drag of having a second outboard leg in the water. Given the fact that this boat displaces 1300kg all up, she accelerates briskly with twin 90s.
Having done quite a few long offshore passages, Jamie has found that his boat averages 4.5mpg from both engines at around 25 knots, which equates to around 4500rpm. This is pretty good going considering he is often out on heavily laden diving trips, and this figure fits with our independent calculations. With just three of us on board, the 6.8 has a distinct sweet spot around 30–33 knots at 5000rpm. Though the hull is still getting into its stride, above this speed, with twin DF90s, the exhaust tone tells you that the motors are starting to work harder – with a subsequent jump in fuel burn.
The design of the boat is classic old-school RIB, which rightly has been unchanged for years – two rows of jockeys with adequate space to access all areas of the deck. The difference is that the rear double jockey seats unbolt to accommodate dive bottle racks – a simple idea that I have not seen on a RIB before, and you can’t detect this feature with the seats fitted. The console is wide enough to keep you dry, but does not force you to clamber over the sponsons to get to the foredeck as some designs do. You either love or hate jockey seats, but if you want to stand with any degree of security, outside of costly shock-absorbing seats, nothing keeps you as planted as a simple GRP box with a padded lid.
Jamie’s boat is built around the concept of two totally independent systems, to the point of each wiring harness having its own bilge pump in a separate splash well. Ribcraft build all boats with sealed secure rigging tunnels beneath the deck to keep all control cables and wiring harnesses free from salt water, and long-term moisture penetration. To be doubly sure, both rigging harnesses emerging from their tunnels at the transom are sealed in prophylactic-like rubber sleeves, to a height of 12″ above the deck.
A heavy-duty waterproof hatch opens on the front of the console to reveal the battery master switches and fuse panels – all easily accessed. Unlike many RIB manufacturers, Ribcraft make their Hypalon tubes in-house, and these are fixed and bonded onto oversized collars for maximum strength. There are no fewer than nine different tube colours available, should you not want commercial grey or military black. Jamie’s boat sported non-slip, texturised, heavy-duty wear patches, and tube armour around the bow to provide extra reinforcement in head seas. The under-deck stainless steel fuel tanks are mounted amidships to enhance hull balance, and are crafted to fit their confines exactly to maximise capacity. All decking is covered in an exceedingly thick and texturised non-slip coating, which is about as ‘grippy’ as non-slip gets. There are various different hull colours available, but the standard hull is white.

Verdict
The Ribcraft 6.8m is primarily built as a commercial boat that also appeals to those serious about clocking up the sea miles for pleasure. There is no compromise with a Ribcraft, which is obvious the moment you cast your eyes around one. However, it is still sufficiently family-friendly in design and appearance to appeal to those outside the drysuit brigade. This goes some of the way to explaining why Ribcraft have become such an iconic British brand over the years.

Fuel Consumption (both engines – PBR calculations)
Engine speed         GPH         Knots          MPG
3000rpm                      3.2          15.0             4.7
3500rpm                    3.8          18.0             4.7
4000rpm                    4.8          22.0             4.6
4500rpm                    6.2          26.0             4.2
5000rpm                    8.5          32.0             3.8
5500rpm                  11.3          34.0             3.0
6200rpm (wot)         14.5          39.0             2.7

Specifications

LOA: 6.8m
Internal length: 5.4m
Beam: 2.7m
Internal beam: 1.7m
Transom deadrise angle: 24 degrees
Tube diameter: 530mm
Displacement: 1300kg (dry with twin Suzuki DF90As)
Power options: Single 150–225 hp outboards; twin 70–115 hp outboards (all Suzuki)
Fuel capacities: Single 150hp engine – 40gal (180L), going up to 31gal (140L) for twin engines
RCD category: B for 14
Test engines: Twin 90hp Suzuki DF90A outboards