In this study 100 groups of five participants were used to discover problems with an interface. The study did indeed find that the mean percentage of problems discovered across all 100 groups was about 85%. However, this figure has 95% confidence level and a margin of error of Â±18.5%.
Keelboats were generally built in Pittsburgh, Pennsylvania and it was here that Meriwether Lewis commissioned the boat used by the Corps of Discovery. The keelboat used by the Corps was sketched by Clark in his journal. It was 55 feet long and 8 feet wide, with a 3- to 4-foot draft. For propulsion it had a 32-foot sailing mast, 22 oars, a rudder, and a tiller for steering. Protection against hostile encounters were a swivel cannon on the bow and two smaller guns called blunderbusses.
How large a boat to cross an ocean? John Guzzwell sailed around the world in Trekka which was 20 feet 6 inches long. Robert Manery sailed across the Atlantic in Tinkerbell, a 13 foot sailboat. Nordhaven 46 foot motor trawlers cross the Atlantic, Bruce Kessler circumnavigated in a Delta 70 foot trawler. Yet it is routine for 150 foot motoryachts to be carried across the Atlantic on Dockexpress type ships. It all depends on how comfortable you want to be and how seaworthy the boat. Dave.