The honest answer is that no rule tells you how far you may go — a combination of four limits does, and the strictest of them is your limit for that day. Boaters get into trouble when they measure the distance against the one limit they happen to know.
1. What the boat is built for
Recreational boats carry a design category or a rating that describes the conditions they were built for, from sheltered water to offshore. It is not expressed in miles, but it answers the real question: how far is reasonable.
A boat rated for coastal waters does not become an offshore boat because the forecast is good. The rating describes what happens when the forecast is wrong.
2. What you carry
Equipment is what turns distance into an acceptable risk. As you go further out, the list that matters grows:
- VHF radio — mobile phone coverage disappears; VHF is what reaches a coastguard, and its range is roughly line of sight.
- EPIRB or PLB — beyond VHF range, a satellite beacon is the difference between being found and not being found.
- Lifejackets worn, not stowed, plus flares and signalling equipment.
- Redundant navigation — a second GPS source, a compass, and a chart.
- Ground tackle, first aid, and a means of dealing with a flooding hull.
Legal minimum equipment lists depend on your country and, in the United States, on federal rules plus the state you are in. Check the applicable requirements — the safety case for carrying more than the minimum is usually stronger than the legal one.
3. Fuel, with the rule of thirds
One third out, one third back, one third in reserve. It sounds conservative until the wind gets up on the return leg and your consumption doubles because you are punching into a head sea.
Fuel is the limit that people most often calculate wrongly, because they calculate it on flat water at cruising speed — the exact conditions that will not exist on the way home.
4. Crew and situation
A single engine, no crew capable of taking over, no float plan filed with anyone ashore: each of these should pull your limit closer to land. Seasickness alone can turn a competent crew into a passenger, and it usually appears at the worst possible moment.
Two horizons worth knowing
Sight of land. From a small boat with your eyes about 6 feet above the water, the visible horizon is roughly 3 nautical miles. You will see high land much further — a 1000-foot hill is theoretically visible from about 40 miles in clear air — but low coast disappears fast.
VHF range. Also roughly line of sight: from a small boat to a coast station on a hill, typically 20-30 miles; boat to boat, often much less. Beyond that, you need a satellite device.
Before you go
File a float plan with someone ashore: where you are going, your route, and when you will be back. It costs nothing, and it is the single measure that most improves your odds if something goes wrong. Then set your limit as the smallest of the four above — and treat it as a decision already made, not one to renegotiate when you are out there and the fishing looks better a bit further on.
Domande frequenti
How far can you see land from a small boat?
With your eyes about six feet above the water the visible horizon is roughly three nautical miles, although high land is visible much further — a 1000-foot hill from around 40 miles in clear air. Low coast disappears quickly.
What is the range of a VHF radio at sea?
Roughly line of sight: from a small boat to a coast station on a hill typically 20 to 30 miles, and boat to boat often considerably less. Beyond that range you need a satellite device such as an EPIRB or PLB.