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marine vhf antennas comparison, in stock
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Height: what really gives you range
VHF travels line of sight. The approximate range in nautical miles between two antennas is 1.22 × (√height 1 + √height 2), with the heights in feet above the water:
| Your antenna height | To another boat (antenna at 10 ft) | To a coast station (at 330 ft) |
|---|---|---|
| 5 ft (handheld) | 6.5 nm | 25 nm |
| 10 ft (powerboat) | 7.5 nm | 26 nm |
| 16 ft (hardtop or flybridge) | 8.7 nm | 27 nm |
| 40 ft (masthead) | 11.5 nm | 30 nm |
These are theoretical radio horizon values; power, gain and cable condition decide whether you reach them. Raising the antenna helps more than raising the power of your radio.
Gain: 3, 6 or 9 dB
Gain shows how much the antenna focuses its energy toward the horizon. More gain gives more horizontal range, but with a narrower beam that is lost when the boat heels. Less gain gives a wider beam that tolerates rolling.
| Gain | Typical length | Best for |
|---|---|---|
| 3 dB | 3 to 4 ft | Sailboat masthead, inflatables and small boats that pitch |
| 6 dB | 5 to 8 ft | Powerboats of 20 to 40 ft |
| 9 dB | 15 to 20 ft | Large, stable boats with room for a long antenna |
Tip: on a sailboat that heels a lot, a 3 dB antenna at the masthead usually communicates better than a 6 dB one, because its beam keeps pointing at the horizon even when the boat is heeled.
Powerboat or sailboat: what to mount
- Powerboat: a 5 to 8 ft fiberglass antenna with 6 dB gain, on a ratchet base as high as you can put it (arch, cabin top).
- Sailboat: a short 3 to 4 ft, 3 dB antenna at the masthead. The mast height already gives the range. Carry an emergency antenna in case you lose the rig.
- Inflatables and small boats: a short antenna with a firm base and a short cable, or a handheld with a spare antenna.
Cable and connectors: where signal is lost
The wrong coax eats the gain you paid for in the antenna. RG58 loses around 1.5 to 2 dB per 30 ft at VHF; on a run of 50 to 65 ft, like up a mast, a low-loss cable such as RG213 or equivalent is a better choice.
- Use a continuous cable with no splices and the shortest run possible.
- PL259 or similar connectors must be well soldered or crimped and sealed against moisture with self-fusing tape.
- Keep bend radii generous and secure the cable with ties so it does not rattle.
- Check the installation with an SWR meter if you can; a high SWR points to a bad connector or cable.
Sharing the antenna with AIS
AIS frequencies (161.975 and 162.025 MHz) sit inside the marine VHF band. You can share one antenna with a dedicated VHF/AIS splitter, which protects the equipment. Without a splitter, do not connect two units to the same antenna: you can damage the receiver. An AIS receiver only shows other boats; a Class B transponder, common on recreational boats, also transmits your position.
Watch out: do not key the radio without an antenna connected. Transmitting into no load can ruin the transmitter within seconds.
Common mistakes
- Buying a 9 dB antenna for a sailboat or a boat that pitches.
- Using thin cable up a tall mast and losing half the signal.
- Leaving the connector unsealed: salt wicks up the braid and corrodes the whole cable.
- Mounting the antenna next to other gear or the radar, which creates interference.
See also the electronics and power section. The models above were chosen from spec sheets and verified customer reviews, not our own tests.
Frequently asked questions
What is the best VHF antenna for a powerboat?
A 5 to 8 ft fiberglass antenna with 6 dB gain on a ratchet base, mounted as high as possible. On small boats that pitch a lot, a 3 dB antenna keeps communication steadier.
And for a sailboat?
A short 3 to 4 ft antenna with about 3 dB at the masthead. The mast height already provides range, and low gain keeps radiating well when the boat heels. It makes sense to carry an emergency antenna.
Can I use the same antenna for VHF and AIS?
Yes, with a dedicated VHF/AIS splitter. Without a splitter, do not connect two units to the same antenna.
How much signal do I lose in the coax cable?
More than most people expect. RG58 loses around 1.5 to 2 dB per 30 ft at VHF. On runs of 50 to 65 ft, a low-loss cable such as RG213 or equivalent is a better choice.
