464 w/ and w/o foils — By Capt. Bill Pike —
Cuttin’ Edge Cat
|Part 2: While the cat without foils was more efficient at lower rpm, she was comparatively inefficient on the high end.|
Other findings were also impressive. While the cat without foils was more efficient at lower rpm (quite likely because of lower underwater drag), she was comparatively inefficient on the high end and offered significantly less range. Note that 178 statute miles at 2900 rpm is nearly 67 percent less than the 266 statute miles the hydrofoil boat gets without its aft foil tilted. And it’s darn near 60 percent less once the tilt toggle is deployed!
I struck one minor snag with the foil boat, however. While the cat without foils tended to plane seamlessly, as indicated by the smooth, parabolic ascent of its acceleration curve, the foil boat did some mild struggling between 12 mph and 25 mph, as indicated by the shallow pothole, both in the curve with the stern foil actuated and the one without. Again, this was probably due to the foils’ extra underwater drag.
Then there was another problem. Most likely because my test boats had been topped off with questionable fuel prior to our comparison wring-out, the engines in both failed to turn up to a maximum-rated 3300 rpm. While this detail certainly cut performance, I don’t think it skewed the message of my test results, especially since all four engines turned exactly the same rpm at WOT.
Conclusion? Without a doubt, next time I hit the trail for Tortola to charter a NauticBlue powercat, I’m holding out for super-fast, super-efficient hydrofoils—not just because they can optionally reduce running time, but because they’ll save me a bundle on fuel.
NauticBlue Power Yacht Vacations Phone: (800) 416-0224. www.nauticblue.com.
This article originally appeared in the May 2004 issue of Power & Motoryacht magazine.