Except for the wetted surface area, the input data for the slender body method is not displayed in the input table and can thus neither be validated nor modified by the user. To make sure that Hullspeed interprets the surface model correctly, it is recommended to check the slender body mesh.

This can be done by turning on the SB mesh option in the Display menu. The number of sections used can be increased for greater accuracy, though this will increase the computation time. Particular attention should be paid to the mesh of multihulls and vessels with transom sterns. See the following sections for more details.

It is also recommended to read the papers on the slender body method listed in the Bibliography on page 52. The following section can be used as a guideline:

The slender body method assumes the vessel to be slender (i.e. high length:beam or slenderness ratios). Ideally the slenderness ratio should be as high as possible, but in practice, good results can be obtained for slenderness ratios of around 5.0 to 6.0. If the vessel’s Froude number is reduced, the minimum slenderness ratio to which the method is applicable also reduces. The maximum Froude number for which sensible results can be obtained depends on the vessel’s slenderness ratio. It has been found that, for very slender vessels (slenderness ratios greater than 7.0), the slender body method may give sensible results for Froude numbers as high as 1.0. The slender body method may be applied equally well to round bilge and chine hull forms. Hulls with transom sterns are dealt with by automatically adding a “virtual appendage”. This method is described in detail in Couser et al (1996).

Also see:

Appendix B Applicability on page 57