Displacement Length Ratio Calculator
Fill in the values and the answer updates as you type.
How the Displacement Length Ratio Calculator works
Ratio = (displacement in long tons) ÷ (0.01 × waterline length in feet)^3, where one long ton is 2,240 pounds. A low ratio means a light, easily driven hull, and a high ratio means a heavy, seakindly hull that carries more gear. Compare boats only at the same loading, and use the waterline length, not the overall length. Use the sail area ratio next to this one to see the full picture of a sailboat. Example: with Displacement 14000 lb, and Waterline length 30 ft, the result is Displacement length ratio = 231.5; Displacement (long tons) = 6.3; Weight per foot of waterline (lb) = 467.
Inputs and results
The Displacement Length Ratio Calculator takes 2 inputs and gives 4 results.
What you enter
- Displacement (lb) — starts at 14000.
- Waterline length (ft) — starts at 30.
What you get
- Displacement length ratio
- Displacement (long tons)
- Weight per foot of waterline (lb)
- What this means
Example: Displacement Length Ratio Calculator with the starting values
With displacement 14000 lb and waterline length 30 ft, the calculator returns:
| Displacement length ratio | 231.5 |
|---|---|
| Displacement (long tons) | 6.3 |
| Weight per foot of waterline (lb) | 467 |
| What this means | Moderate: a balanced cruising hull |
Change any value above and the results update straight away.
Displacement Length Ratio Calculator FAQ
How do I use the Displacement Length Ratio Calculator?
Enter displacement and waterline length in the fields, then read displacement length ratio, displacement (long tons), weight per foot of waterline (lb) and what this means in the result panel. The answer updates as you type, and you can press Calculate or Enter to refresh it. Use “Copy link” to share your exact numbers with someone else.
What does the Displacement Length Ratio Calculator calculate?
Rate a boat as light, moderate, or heavy for its waterline length. It returns displacement length ratio, displacement (long tons), weight per foot of waterline (lb) and what this means from the 2 values you provide.
What values does the Displacement Length Ratio Calculator start with?
It opens with displacement 14000 lb and waterline length 30 ft so you can see a working result straight away. Replace them with your own numbers, or press Reset to return to these starting values.
Is the Displacement Length Ratio Calculator free and private?
Yes. It is free, needs no account, and runs in your browser, so nothing you type is sent to or stored on our servers. See the Privacy Policy for details.
Can I rely on the Displacement Length Ratio Calculator for important decisions?
Treat the result as a well-rounded estimate. Real situations often have details a general calculator cannot know, so confirm important decisions with a qualified professional. See the Disclaimer for more.