The stacked tube design has been around since the early 50's. The original 20 person reversible raft was designed so that the floor was placed between two tubes and everything that was on one side was on the other. This eliminated the possibility of inflating upside down.

When the floor is placed on the bottom of the tubes, the advantages over a single tube are:

• Structural stability. Two tubes joined together offer more lateral stability than a single tube. The bending moment is increased. This varies with differences in pressures.



• The hoop forces in the stacked tubes are less than a single tube at the same pressure allowing for higher pressures therefore, more stability resulting in greater rigidity.
• Greater displacement given that the rafts or boats are the same outside dimensions.
• 50% more interior space as depicted below.



• When the upper tube is placed slightly outboard from the lower tube, the upper tube acts like a spray shield creating a drier ride.

In the late 50's the Special Forces adopted our design for rough water transit. We designed the RB-12 & RB-15 with two thicknesses of 2-1/2" dropped stitched inflatable floors. The RB-15 had the option of a roll-up sectioned rigid floor that was an integral part of the boat and did not have to be de-assembled except for two stiffing stringers. To the best of our knowledge, we were the first to incorporate this feature.

Nine-man team from 3rd Platoon Charlie Company, 3rd Recon Bn, in a Patten RB-15

In the 1960s we developed the first stacked-tube racing boat:

The first twin-tube race boat, 1960

The 80's brought the design of the Twin Tube R.I.B.

Twin Tube R.I.B.

The latest design configuration - the multi-tube (6 individual chambers) dive/rescue boat 15' to 19' with patented through-the-floor entry system

Specwar 20-foot troop transport/combat boat