A catamaran in quartering seas generates relatively large moments between the two hulls as one bow digs in and the stern on the other hull is pressed below its waterline.

Catamaran hull beam. Designers strive to compromise hull fineness ratios place heavy weights towards the CG Center of Gravity and engineer hull and overall beam to achieve a seaworthy balance which is safe yet provides ample liveaboard accommodations. Not to be confused with Kattumaram. LBRC LH BCB.

The suspension arms are pivotally connected with offset spaced connections to the bridgedeck and to each of the hulls for moving said hulls from a substantially horizontally locked position to a vertical position beneath the bridgedeck while. If we set LBRC 22 the longitudinal and transversal stability will come very near to the same value. You need to know that the waterline length of one hull divided by the beam of one hull is 12.

This is because boats with waterline length to beam ratios greater than 81 are not limited by hydrodynamic drag factors whereas smaller boats need to plane to do so planing requires enormous amounts of power for displacement hulls. But since most multihulls have similar DepthWL beam ratios you can pretty much say the SLR equates to the LWLBWL ratio. Usually the waterline dimensions LWL and BWL are used for monohulls or for a single hull of a multihull.

What its used for Performance Larger LB indicates a slimmer hull. Mono-hulled boats have a more predictable roll in the water while catamarans offer a sudden snap roll as it rights itself during a beam or right-angle wave. Fortunately its very easy to check the strength of catamaran beams once youve built them.

Lengthbeam ratio of the catamaran LBRC is defined as follows. The beam between hull centers is named B CB Figure 2. B H1 must be bigger than B WL of the hull.

It is a geometry-stabilized craft deriving its stability from its wide beam rather than from a ballasted keel as with a monohull boat. The opposite bow and stern are unloaded in this condition. Typically this will be 8-101 for a slow cruising catamaran or the main hull of most trimarans 12-141 for a performance cruiser and 201 for an extreme racer.