A few weeks ago, we’ve explained here the SA/D ratio.
Another ratio is also commonly used to compare the efficiency and power of cruising yachts: it’s the DLR or D/L ratio. It is a pretty good indicator of the “sea motion” for a yacht, since it will figure how a hull will behave in/on the sea, should it be a long frequency swell or in choppy conditions.
Once again, please note that these ratios have originally been created to compare monohulls, but they could be used for multihulls, too. In both cases, a lower figure would mean excellence, a higher one a relative mediocrity.
In this ratio, with no surprise, a high displacement will boost the value, where an important length will lower it down. For the record, a ratio of 90 is considered “ultra-light” for a monohull, where a ratio of 360+ will be considered “ultraheavy”.

Why is this ratio interesting when comparing fast cruising catamarans?
Because it will underline the fact that, with a given length, a decent displacement will become a factor of performance. And in the case of a fast cruising cat, we’d better have hulls not going too much into the waves, as it would generate a resistance synonym of suddenly decreasing speed. Speed that can be gained by a light displacement will enable the cat to stay on the waves and not in them, and to stay on top of the crests in choppy seas.
Here is the formula:
If you’re looking to acquire a fast cruising catamaran, we invite you to take other catamarans numbers (length at the waterline and light displacement) and to compare their ratios to the ones of the ORCs.
- For our ORC50, the DLR is 78.
- For our ORC57, the DLR is 59.
So, what’s your conclusion?
Let us know here!
Fair winds,
The ORC Team
