Engineering:Displacement–length ratio

From HandWiki
Revision as of 19:15, 4 February 2024 by Scavis2 (talk | contribs) (simplify)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)

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 Taylor, David W. (1910) (in en). The Speed and Power of Ships: A Manual of Marine Propulsion. John Wiley & Sons. p. 99. https://books.google.com/books?id=Xy86AQAAMAAJ. [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]

[math]\displaystyle{ \mathit{DLR} = \frac{\mathit{displacement}(\mathrm{lb}) ~/~ 2240} {(0.01 \times \mathit{LWL}(\mathrm{ft}))^3} }[/math]

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

References

  1. Rousmaniere, John (October 1999). The Annapolis book of seamanship. ISBN 0-684-85420-1. 
  2. Eric W., Sponberg. "The Design Ratios". https://www.ericwsponberg.com/wp-content/uploads/2021/09/THE-DESIGN-RATIOS.pdf. 
  3. Paris, Jay E. (31 May 2018). "Comparing Design Ratios" (in en-us). https://www.sailmagazine.com/boats/comparing-design-ratios. Retrieved 9 July 2020.