Displacement–length ratio explained

The displacement–length ratio (DLR or D/L ratio) is a calculation used to express how heavy a boat is relative to its waterline length.^[1]

DLR was first published in Book: David W. . Taylor. The Speed and Power of Ships: A Manual of Marine Propulsion . 1910 . en . 99. John Wiley & Sons. ^[2]

It is calculated by dividing a boat's displacement in long tons (2,240 pounds) by the cube of one one-hundredth of the waterline length (in feet):^[3]

DLR = (displacement ( lb ) ~/~ 2240)/(( 0 . 01 x LWL ( ft )) ^{3})

DLR can be used to compare the relative mass of various boats no matter what their length. A DLR less than 200 is indicative of a racing boat, while a DLR greater than 300 or so is indicative of a heavy cruising boat.

Displacement	DLR
ultralight	under 90
light	90 to 180
moderate	180 to 270
heavy	270 to 360
ultraheavy	360 and up

See also

• Sail Area-Displacement ratio

Notes and References

1. Book: Rousmaniere . John . The Annapolis book of seamanship . October 1999 . Simon and Schuster . 0-684-85420-1.
2. Web site: Eric W. . Sponberg . The Design Ratios . Sponberg Yacht Design Inc..
3. Web site: Paris . Jay E. . Comparing Design Ratios . Sail Magazine . 31 May 2018 . 9 July 2020 . en-us.