1968 – Dr. Tom Lang of the Naval Underseas Center (NUC) in San Diego begins intensive development of his concept for a “high speed ship with semi- submerged hulls”, for which he was awarded a U.S. patent in 1971. A key element of the concept is the provision of movable horizontal fins located aft of the vessel’s center of gravity to stabilize vessel trim and pitch motions at higher speeds.

1970 – Mitsui Engineering & Shipbuilding Co., in Tokyo, begins basic research on the “semi-submerged catamaran”, or SSC.

1972 – Construction begins on the 190-ton SWATH workboat SSP KAIMALINO for NUC after 18 months of research by engineers at NUC and nearly 2.5 yea

rs of design and confirmatory model testing⁴. Launching occurs in March, 1973.

1973 – The acronym “SWATH” is coined by U. S. Navy technocrats who promote its use, rather than “semi-submerged” ship or catamaran, to distinguish this concept from conventional catamarans.

SWATH actually stands for Small Waterplane Area Twin Hull… In simple terms, it means take two submarine hulls, tie them together horizontally and vertically, and you have a VERY stable platform in some pretty high sea states (15 ft plus waves for example)…

RV Kiamalino in the mid 70’s- note, it’s NOT pretty, all the money went to the underwater portions; the rest, well it was kinda like, oh just put a box on top to hold the engines and test people…

Ironically it was originally powered by two helicopter jet engines, with chain drives running down to the props… Bonus points if you can name the type and squadron of the helo on the deck. 🙂

Kiamalino today- It sits forlornly in a back dock in Hawaii, but there is apparently a move afoot to actually put her back in service as a test asset. Note the Plimsoll marks on the vertical connectors, she is actually capable of ballasting from eight feet to twenty feet down on the hulls for test purposes…

Kiamalino hull connectivity-The light patch is the aft horizontal plane connecting the two underwater hulls, there is also one forward…

And this is her ‘daughter’, the RV Kilo Moana, pulling into the pier at Sand Island, HI. Kilo Moana draws 24 feet and is stable in pretty high sea states.

A rather interesting ‘problem’ with doing research from KM (or any SWATH hull), is that even though the ship is extremely stable, as soon as you put any research package in the water and it is still attached to the ship, there is a SIGNIFICANT disconnect between the package (which is now reacting to the water column it is in) and the stable ship which doesn’t react… It’s lead to some ‘interesting’ strain readings on sensors…

Anyhoo, this is your two minute history lesson for the day… Now back to the regular BS…