The drawings and chart included on this page where taken from Voyaging.2001.

Picking the right hull form for a cruising yacht is not as easy as it might seem. Sure, planing hulls are better for fast cruisers, while displacement hulls are more efficient at leisurely cruising speeds.  But several factors cloud the issue.  Many hulls fall into an intermediate category, known as semi-displacement forms.  And there are hulls with hard chines, rounded chines, or no chines at all.  Then there are hybrids that combine elements of two or more configurations.

There is no single shape that's best for every circumstance.  Variations in hull form reflect the designer's attempt to achieve optimal performance under the conditions in which each yacht is expected to operate.  The right hull shape for you depends on how you plan to cruise.  And though there is no single, simple answer, there are general principles that may guide your quest.

To avoid violating every copyright law I'll refer you to the magazine to read the remaining portions of the article.

Side note:  Beebe mentions a quick formulae for determining approximate hull speed.  Take 1.34 times the square root of the wetted waterline.  For M/V Tortuga, 1.34 x sq.rt.(49) = 9.38 kts.

Another excellent link for the math inclined is http://www.dynagen.co.za/eugene/hulls/index.html