a raked mast shifts the center of effort of the sail which would influence helm balance. However, Brett's placing of the mast in a vertical position has found to be accurate when replicas of the "Anson" proa were built and sailed by the Marinas-based organization 500 Sails that found that in many points of sail under many conditions the proa sailed well with the mast in a vertical position. 500 Sails also found that the mast could be raked to advantage in many situations and noted that the mast step depicted in the "Anson" drawing could be interpreted as depicting a rotational point rather than a rigid mast step that would not allow raking. 500 Sails canoes employ rotational mast steps that allow mast raking. Munroe, however, was a talented boat designer who was able to work around any problems with the drawings. His adaptations can be seen in successive proas. Rather than the deep, asymmetric hull of a traditional proa, Munroe created flat-bottomed hulls (similar to the fisolera referred to by Pigafetta), with keels or centerboards for lateral resistance. His first iteration had an iron center fin with a half-oval profile. Rather than the traditional crab-claw sail's spars which meet at the front, Munroe's sails used what could be described as a triangular lug sail or spritsail with a boom, similar to the modern lateen sail with a shorter upper spar. Munroe's first proa was only long, yet was capable of speeds which Munroe estimated at . His article in The Rudder describes what can only be planing on the flat hull. As this was before the advent of planing power boats, this proa was one of the first boats capable of planing. This helped produce its amazing speed when most boats were limited to their hull speed—they had too little power to achieve planing speed, and yet were not designed to exceed hull speed without planing. For example, a boat with too little power to plane, and with a hull form and displacement that didn't permit it to exceed hull speed without planing, would have a maximum speed of about ; Munroe's proa could reach nearly 2.5 times that speed. This accomplishment was the nautical equivalent to the X-1 breaking the sound barrier. It is not clear that traditional proas of the Pacific islanders could plane, though the long, slender hull would have a much higher speed/length ratio