Page 15: of Maritime Reporter Magazine (August 2022)

ways be unpredictable at the design stage, and can also occur in their own form in airplane designs, which is actually why airplanes require so much testing.

The ABYC tests are unlikely to identify all instability modes, since some instabilities could be the interplay of a number of subtle variations that do not occur during the

ABYC test sequence (changing throttle settings during turns or unusual loading con? gurations), but if the boat becomes squirrelly at any one point in its performance envelope, the designer/builder can either modify the design, reduce the ability of the user to get into that part of the performance envelope, or provide a clear wheel stand warning not to enter that part of the performance envelope.

That warning is similar to the reduced speed warning pro- vided on road signs in turns on country roads, or the Do-

Not-Enter portion of a performance envelope of an airplane.

Those of us who have operated outboard or outdrive power- boats may or may not know that in the engine manual there is generally a warning like this:

This behavior can be described as bow hooking at higher speeds. Meanwhile in the industry at large, capsizes due to chine tripping are often described as having been caused by making a hard turn while the engines are trimmed out (bow up) and engines should be tucked in (bow down) when mak- ing a hard turn. Yes, those are contradictory instructions, and certainly would not allow a user to ? gure out how to operate the vessel. Regardless, I have never seen any of those warn- ings on the wheel stand of high speed powerboats. Therefore, it is impossible to argue that a vessel is operated outside its “normal” performance envelope since no performance enve- lope has been provided. Until the industry takes responsibil- ity, performs proper tests, and provides reasonable warnings, blaming the customer makes little sense.

For each column I write, MREN has agreed to make a small donation to an organization of my choice. For this column I select the American Boat and Yacht Council Foundation. They try to make things safer. https://www.abycfoundation.org/

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