What wind speed is too much for a small boat?

It depends on the boat, but as a rough guide many small craft such as PWCs, RIBs and bowriders become uncomfortable above about 15 knots of steady wind and genuinely difficult above 20 knots, especially with gusts. Bigger, heavier boats tolerate more. Gusts and sea state matter as much as the steady figure.

What is wave period and why does it matter?

Wave period is the time in seconds between wave crests. A long period (8 seconds or more) means a gentle, rolling sea; a short period (around 3 to 4 seconds) means a sharp, steep chop that is far more uncomfortable and dangerous at the same wave height. Always read wave height and period together.

Which single factor decides if it is safe to go boating?

The worst one. Good conditions overall do not cancel out one bad factor — a calm sea with vicious gusts, or a light wind over a short steep swell, can still be unsafe. Judge wind, gusts, waves, period and visibility together and let the worst factor set your verdict.

⚓ Boating weather basics

How to read a boating weather forecast

Last updated: 20 October 2026

A boating weather forecast gives you five numbers that matter: wind speed, gusts, wave height, wave period and visibility. On their own they're just data. The skill — the thing experienced skippers do without thinking — is reading them together, against the boat you're actually in, and turning them into a single decision: go, or don't. Here's how.

1. Wind speed — the headline number

Wind is usually given in knots (1 knot ≈ 1.85 km/h). It drives almost everything else: the bigger the wind, the bigger and steeper the sea. What counts as "too much" depends entirely on your boat — a light PWC or RIB feels 18 knots very differently from a 10-metre cabin cruiser — but as a rough feel, under 10 knots is comfortable for most small craft, 10–15 is lively, and beyond 20 knots things get serious for smaller boats.

2. Gusts — what actually catches people out

The gust figure is the strongest brief burst, and it's often the real hazard. A steady 12 knots gusting 26 is a very different proposition from a steady 12 gusting 15 — the first will knock a small boat around, snatch at a bimini and make handling unpredictable. A good rule: if gusts are more than roughly double the steady wind, treat the day as rougher than the average suggests.

3. Wave height — necessary, but not sufficient

Wave height is the average height of the bigger waves, in metres or feet. It's the number everyone quotes, but it never tells the whole story on its own — because a 0.8 m sea can be flat and rolling or sharp and vicious depending on the next number.

4. Wave period — the number most people ignore

Wave period is the seconds between crests, and it decides how a given wave height actually feels:

Long period (8+ seconds): a gentle, spaced-out swell you ride over.
Short period (3–4 seconds): a tight, steep chop that slams the hull, throws spray and tires the crew — the same height, far more punishing.

This is the single biggest "hidden" factor. If you only learn one new thing from this guide, make it this: always read wave height and wave period together.

5. Visibility — the quiet one

Fog, haze or heavy rain can turn a manageable sea into a dangerous one by taking away your ability to see other traffic, marks and the shore. Good conditions in every other respect don't matter much if you can't see where you're going.

Putting it together: the worst factor wins

Here's the principle that turns five numbers into one decision: the worst single factor sets the verdict. Great conditions in four categories don't cancel out one bad one. A glassy sea with vicious gusts is still a THINK TWICE or NO-GO. A light wind over a short, steep leftover swell is still rough. The sea doesn't average out your optimism.

So your mental checklist before you launch is:

Is the wind — and especially the gusts — within what my boat and crew handle comfortably?
Is the sea manageable, judging height and period together?
Can I see?
Will all of the above still be true for the hour I plan to come back?

If any one answer is "no", that's your verdict — regardless of how good the others look.

Or let the app do the reading

GO / NO-GO does exactly this maths for you — wind, gusts, wave height, period and visibility, weighed against your boat type, crew and plan — and gives you one clear verdict for every hour. Free on Google Play.

Get it on Google Play →