[Here is an excerpt, discussing alaias, from LEGENDARY SURFERS: A Definitive History of Surfing's Culture and Heroes, a great site about the history of surfing.]
The ancient Hawaiian surfboard, or papa he’e nalu (pa-pa HAY-ay NA-lu), came in four types. Listed in order of length, these were (from longest to shortest): the super-long olo (O-lo), kiko`o (key-CO-oo), alaia (ah-LAI-ah) and paipo (pie-poe) bodyboard. The olo and alaia were both used under different surfing conditions and by different classes of people. According to Abraham Fornander (1812-1887) in Hawaiian Folk Lore, the alaia averaged 9 feet long. It was best suited for kakaha, “a curling wave, terrible, death dealing.” That is, a wave that broke quickly and had a hollow curl section to it. The olo, on the other hand, averaged 18 feet long, and was ideal for opuu, “a non-breaking wave, something like calmness.” Waves like this are typical at Waikiki on days when the surf is not big.
In Surfing, the Sport of Hawaiian Kings, academian Ben Finney and writer James Houston, noted that in both the olo and alaia, “the top and bottom were convex and tapered to thin rounded edges, so that either side seems to have been suitable as a riding surface.”
Historian Ben Finney acknowledged that, “between the biggest surf and the low easy swells of Waikiki, there were not many waves suited to the big olo boards. Consequently, limited maneuverability usually restricted their use to those few suitable areas with ample space for their characteristically long rides. Waikiki is such an area. But Waikiki’s combination of long, low swells and sandy shore is not common in Hawai`i. Along the Kona coast, for example, one finds more often... rocky terrain... with steep walls of water breaking closer to shore. These latter conditions seem to have allowed only the use of the smaller alaia.”
Compared to the olo and kiko`o, the alaia was shorter, broader, less convex and more plank-like in its thinness. Hot Curl surfer John Kelly pointed out that, “Today’s guns and light short boards have basic features including shapes, contours and breakaway edges handed down from or similar to the ancient alaia boards.” The largest alaia boards in the Bishop Museum collection – including the Ka`iulani alaia -- range from 7-to-12 feet long, average 18-inches in width, and are from a half-inch to an inch-and-a-half thick. Alaia boards were used by the common people, but the ali’i were also known to ride these shapes. One particularly representative alaia board was collected by J. S. Emerson, in Kailua, Hawai`i, in 1885, and later donated to the Bishop Museum. It is made of koa, is six-and-a-half feet long, and is a little over a half inch thick at its center. The bow end is curved in a convex shape and the stern end is cut off square. Its widest point toward the bow is 14 3/4 inches and the narrower stern end is 10 3/4 inches.
The alaia board was the preferred shape for steeper, faster-breaking surf. “The board’s thinness and shorter length,” wrote Finney and Houston, “gave it much greater mobility on the sheer faces of fast surf. The technique of sliding at an angle to the moving swell, which alaia surfers had obviously mastered, was called lala.” The alaia ranged from a child’s board of approximately six feet to about twelve feet long for adults. The adult board was about one-and-a-half inches thick through the center, leveling off on both top and bottom to about one-quarter inch at the edges. The comparatively small size of the alaia board made it easy to handle in waves that wall-up quickly and form tubes or hollow sections in the process.
“The alaia board,” wrote Nineteenth Century historian John Papa Ii, “which is 9 feet long, is thin and wide in front, tapering toward the back. On a rough wave, this board vibrates against the rider’s abdomen, chest, or hands when they rest flat on it, or when the fingers are gripped into a fist at the time of landing. Because it tends to go downward and cut through a wave it does not rise up with the wave as it begins to curl over. Going into a wave is one way to stop its gliding, and going onto the curl is another. Skilled surfers use it frequently, but the unskilled are afraid of this board, choosing rather to sit on a canoe or to surf on even smaller boards.”
The alaia shape made it possible for ancient riders to avoid getting worked on close-out sets and kept them from pearling. “It was the board most suitable along the frequent rugged coasts,” wrote Finney and Houston, “and it is no wonder that most of the ancient boards remaining (ten of thirteen in the Bishop Museum collection [in 1965]) are of the alaia type.” As to who rode these boards, Finney and Houston believed that, “whereas the olo was reserved exclusively for the ali’i, it seems obvious that the commoners had no such exclusive rights to the alaia. The greatest number of early reports tell of surfing alaia style, and many legends mention chiefs surfing along rocky shores where an olo board would be difficult to handle. These two board types, then, allowed the separation of chief and commoner if desired, but never to the point of depriving the ali`i of the faster and more hazardous surf.”