Safe Wave Height for Your Boat
Select your approximate boat size and forecast wave height to see the relative-risk classification in Getfished’s reference table.
How this works
This tool compares your selections with the reference data used by Getfished’s Safe Wave Height guide. Boat lengths are grouped into representative sizes, so you can choose the closest size to your boat. Metric and Imperial choices use the same reference classes.
The result compares your selected boat size with the forecast wave height you enter. It doesn't assess the design or condition of your individual boat.
Reference table
Match a wave-height row to a boat-length column. Both units identify the same reference class.
| Wave height | 3.5 m / 12 ft boat | 4.3 m / 14 ft boat | 5.0 m / 16 ft boat | 6.0 m / 19 ft boat |
|---|---|---|---|---|
| 0.2 m / 1 ft | SAFE | SAFE | SAFE | SAFE |
| 0.5 m / 2 ft | CAUTION | SAFE | SAFE | SAFE |
| 0.8 m / 2.5 ft | DANGEROUS | CAUTION | SAFE | SAFE |
| 1.0 m / 3 ft | DANGEROUS | CAUTION | CAUTION | SAFE |
| 1.2 m / 4 ft | NEVER | DANGEROUS | CAUTION | CAUTION |
| 1.5 m / 5 ft | NEVER | DANGEROUS | DANGEROUS | CAUTION |
| 1.8 m / 6 ft | NEVER | NEVER | NEVER | CAUTION |
| 2.0 m / 6.5 ft | NEVER | NEVER | NEVER | DANGEROUS |
Understanding the result
- SAFE
- These conditions fall within the safe range in the reference table for a boat of this size.
- CAUTION
- These conditions fall within the caution range for a boat of this size.
- DANGEROUS
- These conditions fall within the dangerous range for a boat of this size.
- NEVER
- The reference table indicates that a boat of this size should not be used in waves of this height.
The reference table and this tool are based on the same data. The result is a relative-risk classification for a boat of the selected size in waves of the selected height. It does not assess the design or condition of your individual boat. Use the result as a guide only and make your own assessment of the conditions and your boat. Use the result as a guide only and make your own assessment of the conditions and your boat. It is not a guarantee of safety.
- "Safe on paper" doesn’t factor in hull type: The calculator treats all boats of the same length equally. A light, flat-bottomed tinny handles a 0.5m wave completely differently than a heavy, deep-V fiberglass hull with high sides (freeboard).
- The "BOM Double-Up" Rule: Always remember that BOM forecasts significant wave height (the average of the highest third of waves). This means maximum waves can be double the forecast size. If the calculator says a 0.5m wave is safe for your boat, you need to be prepared for the 1.0m rogue peak that will roll through.
- Wave Period Matters: A 1-metre swell out in the ocean with 12 seconds between waves is a gentle roll. A 1-metre chop in the Bay with only 3 seconds between waves is steep, wall-like, and will easily swamp a small boat.
Read the Safe Wave Height guide for wave behaviour, wind, wave spacing, forecast limitations and the reasoning behind the reference data.