The S4X2 Twin Boat

Twin S4 Multihull Boat
S42X double microskiff
Front view. The front crossbar is attached with straps to the front decks
S42X double microskiff
The rear crossbar is bolted to the boats’ mounting plates.
S42X double microskiff without the center platform
S42X double microskiff without the center platform (early version)

The Concept and Basic Figures

Wavewalk developed a twin S4 “quadramaran” boat – a double catamaran featuring four hulls in total.
People have been tying together small and bigger boats for many years, from canoes and kayaks to larger vessels, and the S4X2 is simply a new version of this concept.
With its total width of over 80 inches, the S4X2 is extremely stable and seaworthy, and its estimated load capacity is over 1,000 lbs, which means that it can carry a driver and three full size adult passengers, plus plenty of camping, fishing, hunting or diving gear. Everyone on board is expected to be able to stand up at the same time as the other passengers, and fish in this position, at least on flat water.

Structure

This double boat is made from a pair of Wavewalk S4 multihull boats attached together by means of a lightweight wooden structure reinforced with bolts and  metal brackets. The total weight of this boat is 230 lbs without the motor and payload. This includes two times the 100 lbs that each S4 weighs, and 30 lbs for the connecting wooden structure.

Partial view of an S4X2 multiboat
Partial view of an S4X2 twin boat made from two S4 skiffs assembled together

Portability and Mobility

The main advantage that this boat offers over other boats of similar size is that even one user can take it apart quickly and easily, and transport it non-assembled without a trailer, if the transporting vehicle is big enough, such as a minivan, a big SUV, or a big pickup truck.
The boat’s easy transportation and assembly capability greatly enhances its users’ ability to launch it almost anywhere, without necessarily relying on boat ramps.

Power and Speed

Being stabler and more seaworthy than its individual component boats, the S4X2 can be powered by a bigger outboard motor. How powerful remains to be seen, and current estimates are up to 20 HP, which means that it may reach 30 mph.
Alternatively, two S4 owners could join them together, and power their ad hoc S4X2 with two small outboards normally used separately on each of the S4 boats. In such case, a wooden connecting structure would not be necessary, since the main purpose of this structure is to enable driving the S4X2 with one powerful motor attached along its center line.
Note that the combination of two small motors will not be yield much more speed than each of the small outboards can deliver separately, but it will be more powerful than a single small outboard, and useful to move heavy loads.

Twin S4 Multihull Boat
Top view of an S4X2 multi boat

Versatility

The ability to quickly assemble and disassemble this boat makes it perfect for multiple uses. For example, in a capacity of a tender (service boat) for a big boat, a group of passengers can go on shore in an S4X2 , and return to the mother ship in different times, in two smaller groups, each using a single S4.
Similar scenarios can be imagined for hunting, fishing and diving trips, and tours with people who have different interests and/and schedules.
In this context it is important to remember that the S4 works perfectly not just as a motorboat, but as a paddle craft (canoe or kayak) as well. Carrying a spare, small electric outboard on board an S4X2, or even a small gas outboard is easy, and doing so can turn the two S4s components into completely independent vessels.
However, if the owner of an S4X2 is interested mainly in versatility, they should bear in mind that a single S4 is not capable of taking a 4-Cycle outboard motor that’s over 10 HP, due to the motor’s weight at the stern. In other words, there will be a tradeoff between maximum speed and maximum versatility.

Skiff Casting Deck

Outfitting an S4X2 with a large size casting deck is very easy – just cover the front end with a sturdy plywood board cut to the desired shape.

Sailing

Four hulls for one boat is excessive,  but the exceptional tracking ability delivered by this rare structure, combined by its extreme stability will be most useful for sailing.

Paddling

Paddling is very limited in the S4X2, pretty much like paddling is for passengers of a good size skiff or a big Jon boat. This could be a bit of a challenge when beach launching and beaching, especially if there is only one person on board.

Sea Trials

Wavewalk has done sea trials for the S4X2 during the summer. The R&D tested the strength of the connecting wooden structure, the boat’s performance in rough water, possible need for a spray shield, launching and beaching, carrying the components over short distances, assembly and disassembly, and so on.

Bigger motors will be introduced at a later stage, possibly next year.

For more info contact Wavewalk.