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.
Hull thickness may vary from boat to. boat. Older boats were often laid up with a solid glass laminate thickness of 1Â½ (3.8 cm) to as. much as 5 (12.7 cm) in the keel areas of the more heavily-built boats. Today, however, the. trend is toward thinner, lighter laminates, making the structural integrity of each of the. laminate components all the more critical.