Another item gleaned from The Hawaiian Canoe, by Tommy Holmes:
Pre-European contact Hawaiians living on headlands without access to gently sloping beaches used canoe "ladders" as a means of launching and landing their boats. This was made necessary because Hawaiians relied on the sea for the bulk of their protein -- in other words, if you couldn't launch your fishing canoe, you did without protein almost entirely. Holmes writes that "No other culture has ever been known to overcome the problem of providing boat launching and landing capabilities from a wave-lashed cliff-bound shore."
The canoe ladder was a kind of slipway built along a sloping rock or series of rocks -- always on a headland, and never in a cove or inlet. Looking much like a regular climbing ladder (or a series of them joined end-to-end), the canoe ladder consisted of a pair of parallel poles up to about 30 feet long, with "rungs" up to 12 feet wide spaced anywhere from a few inches to a few feet apart. The upper sections of ladder were tied into holes bored right into the rock. The lowest section was tied only at its upper end, essentially hinged at the top so that the lower end floated with the level of tide and waves. This lower section was installed when needed, and removed at the end of the day when the last canoe had been retrieved. From photos in the book, it appears that ladders were sometimes quite steep -- maybe as much as 20 degrees from horizontal.
In exchange for a share of the catch, helpers on land would assist the canoe's crew in launching and retrieving from the ladder. The canoe's captain would call the shots, judging the waves and deciding when to go. In both launching and retrieving, the canoeist would attempt to go when the wave was at its highest -- when landing, to bring the boat as high up the ladder as possible and prevent subsequent waves from disturbing the landing; when launching, so that the boat would be drawn as far as possible from the rocks when the wave retreated.
In some landing circumstances, the crew would jump out of the boat just before it made contact with the ladder, leaving the steersman in the stern and the helpers on the ladder to grab the boat. Although Holmes doesn't explain why, it would appear that the crew's extra weight in the boat might have presented a problem in these instances. The notion of jumping into surf below rocks just as a wave is coming in is a bit frightening, but so is the whole notion of landing a dugout canoe in this manner, for the boat, the crew, and especially for the helpers on land who had to stand by as this wooden missile, weighing several hundred pounds, rushed toward them on the face of a wave.