At first glance it looks like a rigid inflatable with its side tubes and its familiar shape. It is certainly rigid because it is built entirely of aluminium, but there is nothing inflatable about the Alustar 52 because there is nothing to inflate. The difficulty in describing this boat lies in the fact that it is a hybrid design which adopts the shape of a rigid inflatable, but is entirely of rigid aluminium construction.

Development of this concept was started in New Zealand by Stabicraft, and Thanetcraft in Britain builds the New Zealand designs under license. The concept is catching on because another builder in New Zealand has developed a similar concept, whilst in Italy, the Blob boats follow similar lines but are moulded in plastic. Here too, in the UK, Victor Boats also supply their range of aluminium RBBs.

The idea behind the development was to try and incorporate the benefits of the rigid and performance whilst removing what many people see as the weak point, the vulnerable inflatable tube.

The Alustar is available in five different sizes from 3.10 metres up to 8.50 metres in length. All are based on a deep vee hull and the model tested, the 52, comes in the middle of the range. With a length of 5.20 metres it is competing on the one hand with the smaller sports boats, and on the other with the popular sizes of inflatables and rigid inflatables. The layout of the Alustar is different, though, from either of these concepts because in the bow there is a rising cover which merges into
the windscreen, creating a forward driving position. This leaves the rest of the boat open and clear for extra seating or for carrying diving, skiing or rescue equipment.

This is the standard layout, but in the Alustar everything is changeable and the internal layout can be largely customized to inflatable design, such as excellent stability I requirements. Having the driving position right in the bow, as on the test boat, seems strange at first, but the deep screen with its moulded top deflector offers good protection. There is considerable logic in having the helmsman in this position which is probably the most uncomfortable area in the boat because at least he will suffer first when the ride becomes uncomfortable. However, with the helmsman forward, he will be less aware of what is going on behind him, which could also be a negative aspect.

The helm position is simple, just the wheel and the throttle lever. There is space to fit instruments if required and a handhold on the dash for the passenger would be very helpful. The top of the screen is not rigid enough as a handhold and the grab bar from the console to the tube is not conveniently located. More handholds are also required aft if additional passengers are carried, but there are two very good handholds on the backs of the forward seats for any passengers standing

The seats are small bucket seats which give useful support. They are mounted on boxes which create a dry stowage and footrests in front of the seats help to brace against the movement of the boat. Foam padding on the tube tops can be used for side seating, but it is not secure and the foam is there mainly to soften the impact of the raw aluminium.

The test boat was fitted with a 60hp Mariner outboard, but options include twin outboards up to 100hp total or the compact MerCruiser Sport Jet. The outboard is mounted on a bracket which extends aft from the transom so that the cargo/passenger space is left clear. Mounted here, the outboard is still within the depth of the side tube taper extensions so that it is well protected. Dedicated stowages for the fuel tank, the battery and ancillary equipment such as the anchor is fitted to the inside of the transom.

The Alustar is ruggedly built with 3mm aluminium used for the well polished side tubes and 4mm used for the bottom and deck structure. The space below the deck, within the vee of the hull is sealed off to create buoyancy whilst the side and bow tubes incorporate six separate chambers, making the boat safe even when damaged. The outside of the hull is protected by a heavy duty rubber fender running around the centre line of the tube which also acts as a spray deflector. The deck is covered in heavy duty non-slip material, and whilst it is below the waterline at rest, draining sleeves built into the transom allow any water to quickly drain from this deck when the throttle is opened.

The Alustar 52 is extremely docile at slow speeds and manoeuvres in a very positive way. The deep vee hull gives positive grip on the water. At rest the tubes are well in the water towards the stern which greatly enhances the stability. Indeed, the boat tips only slightly when you step on board on the side tube. When the throttle is opened, you start to notice the difference between the Alustar and a RIB. On the latter, the air tubes quickly lift clear of the water to reduce the drag allowing the hull to act like a conven­tional deep vee. On the Alustar, the rigid shape of the tubes does not deform under load and so they create an additional planing surface which is enhanced by the inverted vee between the tube and the hull.

This means that the hull of the Alustar behaves more like a trihedral than a conventional deep vee. When turning at speed, the hull remains remarkably level with very little heeling into the turn. This gives a good feeling of positive control so that there is considerable confidence in the control of the boat. In slight seas, the deep vee of the main hull slices cleanly through the waves, and it is only in large waves, when the water reaches the inverted vee between the hull and the tube, that you start to feel the force of wave impact and the ride turns harsh.

This could be a useful safety feature, but this increasing impact is a clear indica­tion that it is time to slow down. There wasn't the opportunity to test the Alustar in rougher seas, but the experience of the test suggested that the ride might become uncomfortable and wet in rougher or steeper waves. The Alustar appears to be a boat for calm to moderate conditions.

The lasting impression of this test is that the Alustar is an immensely practical boat. It may not have the rough sea perform­ance of a rigid inflatable and it may not have the style of a sports boat, but for those who want a practical boat for diving, fishing or even cargo or passenger carrying, the Alustar could be a very practical and long lasting solution.