One Wire to Rule the Waves?

Why Saltwater Makes Verticals Shine (and what “one radial” really means)

If you’ve ever operated from a beach, a dock, or a boat, you’ve probably noticed something that feels almost unfair: a modest vertical near salt water can sound like a much bigger station inland. That “saltwater advantage” is real… but it’s worth describing it in a way that’s technically accurate and repeatable.

Below is the physics, the practical takeaways, and a reality-check on the claim that “a single radial in the ocean beats dozens on land”.

What radials are actually doing

A quarter-wave vertical is only half an antenna. The other half is the return path: currents must flow back to the feedpoint somehow.

On land, that return path is usually created with a radial field (wires on or just under the surface) or an elevated counterpoise. Radials help in two main ways:

• They provide a low-loss return path for the near-field currents around the base.
• They reduce soil losses by keeping RF current out of resistive earth (which otherwise turns power into heat instead of radiation).

So when hams say “radials are critical,” they’re really saying: the return path is critical, and forcing that return through typical soil is expensive (in dB).

Not all “ground” is equal, and seawater is in a different league

Soil conductivity varies wildly, but “poor ground” can be extremely lossy compared to seawater. Typical rule-of-thumb numbers often quoted are on the order of:

For a vertical, the biggest “ground penalty” is usually near the base, where currents are concentrated. Improve the medium right where the current is highest, and you improve efficiency fast.

The key saltwater insight: the surface matters more than depth

At HF, seawater behaves like a good conductor, but RF return currents live mostly in a thin layer near the surface (skin effect). That changes what “a radial in the ocean” really means in practice.

So… can a single “saltwater radial” replace a whole land radial field?

The part that’s true

Over seawater, a vertical’s efficiency can get very close to the ideal case. When the environment is already highly conductive, adding more and more radials often becomes far less important than it is inland.

In other words: saltwater can make a minimal ground/return system behave like an excellent one.

The part that needs tightening

“One wire in the ocean beats everything” is catchy, but it’s not universally true as stated… mainly because a single radial is an unbalanced, asymmetric return path.

With only one radial/counterpoise wire, you should expect:

• Pattern skew / directionality (sometimes useful, sometimes not).
• More common-mode current risk (your feedline, body, or boat structure becomes “the other radial” unless controlled).

A more accurate, repeatable claim is: Saltwater can let a very small counterpoise system (one or two wires, or a well-coupled metal structure) rival a much larger land radial field, because the environment dramatically reduces ground-loss resistance.

What “one radial” really means in the field

When someone says “I used one radial into the sea,” there are usually hidden contributors:

• The feedline shield (common-mode current makes it part of the return system).
• The operator and gear (your body, table, tripod, or battery wiring can become part of the return).
• Nearby metalwork (dock hardware, railing, a boat’s bonding, an outboard motor bracket, etc.).

None of those are “bad” by default — but they make performance less predictable unless you control them.

Practical, field-tested guidance

Shore portable: “drag a wire”… but do it smart

If you can only deploy one conductor, a single counterpoise wire that reaches wet salt sand (or runs along the waterline / over shallow water) can produce a noticeable improvement. The big win is getting the return current out of dry, resistive ground and into the conductive saltwater surface layer.

• Best practice: use two quarter-wave radials in opposite directions for a more predictable pattern and less feedline misbehavior.
• If you must use one: add a serious feedline choke and expect some directional behavior.

Dock / pier installs

Saltwater sites can be incredible, but be mindful of how and where you route conductors. Avoid “mystery losses” from odd materials, tight stapling, or routes that put RF where you don’t want it.

If you’re experimenting at higher power, keep an eye (and hand) on anything that could heat up due to RF losses.

Boat operation

On a metal hull, the hull can act as a large coupling structure to seawater, often reducing the need for elaborate radials (but you still want to manage RF on the feedline). On fiberglass boats, a dedicated counterpoise (wire/foil/plate) plus good feedline choking usually matters more, because the system can otherwise “float” electrically and force return currents onto the coax shield.

Reality-check summary

• Saltwater doesn’t add magical “gain.” It removes loss — so more of your power becomes radiation.
• Over seawater, fewer radials can work extremely well. The environment is already close to an ideal RF return medium.
• “One radial” can be great… but it’s rarely only one conductor doing the work. Without control, part of your station becomes the counterpoise.
• Two opposing radials is the “portable sweet spot.” Predictable pattern, good efficiency, less common-mode drama.

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