VHF Exterior Speakers Test: Can You Hear Me Now?

Exterior speakers can increase sound level, enhance audio quality and boost your boats ability to transmit and receive away from a mounted VHF system. Practical Sailor compares 12 different units.


Sailboat Extension Speakers

Past tests of nearly 30 fixed-mount VHF radios (July 15, 2005; Sept. 1, 2005; Dec. 1, 2005; March 2006) give ample indication that adding an extension speaker can greatly enhance the audio performance of many radios. Extension speakers, when used in conjunction with a remote microphone (November 2007), effectively add a second station to your VHF radio. The increased sound level available, enhanced audio quality, and ability to transmit and receive some distance away from the mounted radio all provide good reason to investigate adding an extension speaker to your boat.

What We Tested

We rounded up a dozen external speakers compatible as an add-on to most any fixed-mount VHF radio. We tested both the standard and horn style of speaker.

Icom SP-24

Our biggest product contributors were marine audio system experts Poly-Planar and antenna giant Shakespeare. Together, they made up half the field, each with three models included in the test. We also tested two from VHF radio maker Standard Horizon and two from technology specialist Speco. One speaker from SeaBowld and one from top-rated radio maker Icom (July 15, 2005 and March 2006 issues) rounded out the field.

We selected a top pick in both the conventional and horn-style extension speakers because space and styling constraints might restrict the use of one or the other on certain boats. Horn speakers are generally more efficient speakers than conventional speakers, and our tests proved this.


The black plastic box-shaped SP-24, the same speaker shipped with one of Icoms single sideband radios, provided performance at the low end of our test groups performance range even though it was in the middle of the pack size wise. It did however pass our spray test even though it is not rated as waterproof.

Poly-Planar MB-41

Bottom Line: Average performance coupled with a steep price would steer us clear.


All three Poly-Planar speakers in our test are rated as waterproof and all proved their mettle by passing our spray test with ease. This trio is available in either black or white plastic. The MB-series speakers use a square enclosure with minimal depth to maximize the sound reproduction capability of the internal speaker. For their size the pair performed about average in sound pressure levels with the MB-21 getting a Good sound quality rating and the MB-41 the only Excellent. The smaller MB-21 speaker uses a thin metal bracket and small knobs to lock the speaker in place. We had some trouble tightening the knobs because they are so small and inaccessible. The larger MB-41 uses a plastic bracket with easier to reach knobs. The MA-1000R speaker, designed to be flush mounted in a panel or bulkhead, achieved Good sound quality ratings while trailing the field in measured sound pressure.

Poly-Planar MB-21

Bottom Line: The compact design, excellent sound quality, and two-year warranty earn the Poly Planar MB-41 the Practical Sailor Best Choice rating for conventional-style speakers. Its maximum output was measured at 89 decibels (dBA), comparable to a two-stroke chainsaw (85 dBA).

Sea Bowld

The inexpensive Sea Bowld VHF-100 appears to be identical to the Shakespeare ES-2. It performed about the same too, by passing the spray test, managing to be within 2 decibels of sound pressure, and by getting a Good sound quality rating. The bracket does not have knobs but rather uses tension created by the plastic bracket to hold the speaker in place.

Poly-Planar MA-1000R

Bottom Line: A compact speaker with decent performance, available at an inexpensive price.


Our three test units from Shakespeare are rated as weatherproof and passed the spray test with no glitches. The ES-series speakers use a box shaped enclosure with minimal depth to house the speaker. Compared to others of similar size both perform very well, hitting the highest numbers for sound pressure. The pair also received Good sound quality ratings. One thing we didn't like about the ES-2 was the lack of any locking knobs to firmly hold the speaker on the bracket. Only the tension of the plastic bracket keeps the speaker box in place. The larger ES-4 uses a lightweight thin metal bracket that did not appear as secure as some others.

Shakespeare ES-4

The horn-style speaker from Shakespeare, designated the HS-5, blasted out an astounding 104 decibels of sound and received a Good sound quality rating. It earned a top pick with its construction quality, weather resistance, loudness, sound quality rating, and price.

Bottom Line: The Shakespeare HS-5 earns Best Choice for horn-style speakers with its high volume and good sound quality, all at a reasonable price.

Standard Horizon

The pair from Standard Horizon, the MLS-300 and MLS-310, are similar in style and appearance and both are available in either black or white plastic. Each has a round face with a grille front, and compared to others in the field are a little bit on the large and bulky side. They can be mounted flush with supplied hardware or using a brawny plastic bracket with large diameter knobs that lock the speaker enclosure securely in position. The MLS-310 housing is several inches deeper than the MLS-300 to accommodate the internal 10-watt amplifier. The addition of this amp mandates an extra electrical connection to a DC power source for this unit. Both units are rated as submersible by the manufacturer and passed our spray test with ease. We rated the pair Good for sound quality. The amplifier in the MLS-310 boosted its sound pressure output to 4 decibels over the speaker-only equipped MLS-300.

Shakespeare HS-5

Bottom Line: A versatile mounting system, good performance, and a reasonable price get the Standard Horizon MLS-300 the nod as a recommended product. 

Standard Horizon MLS-300


Both units from Speco were efficient horn-style speakers. The smaller round unit, the SPC-5P, was one of the least expensive units in the field. Even though it was rated as weatherproof, its performance suffered following the spray test. After it got wet, the SPC-5P was difficult to hear. It had a scratchy sound and irregular volume control. We rated it Fair for sound quality.

The much larger SPC-40RP/4 horn has been on our arsenal of test gear for several years. We decided to add it to this review because it fell within the price range of several smaller speakers. It is rated as weatherproof and passed the spray test with no problems. This is a powerful horn and blasted out 104 decibels of sound even with the low-powered amplifier we used for testing. Keep in mind this speaker is able to couple to amplifiers with up to 40 watts or output power. Even though we think this unit is better suited for use as a hailer horn rather than a VHF extension speaker, it could be used for one on a large vessel with lots of room.

Speco SPC-5P

Bottom Line: Neither Speco unit shined enough to earn a buy rating, but Speco was one of only two speaker makers that offer a two-year warranty period.


We picked the Shakespeare HS-5 as our top horn-style speaker because of its good sound quality, the overwhelming sound pressure levels it was able to attain, and its extremely reasonable price tag.

The Poly Planar MB-41 was our top pick in a conventional speaker. This unit provided excellent sound quality, decent overall sound pressure levels, a two-year warranty, and pricing inline with its closest competitors. We also recommended the Standard Horizon MLS-300 and the Shakespeare ES-4, both of which had good sound quality and sound pressure levels along with realistic prices.

Darrell Nicholson, editor of Practical Sailor, grew up boating on Miami’s Biscayne Bay on everything from prams to Morgan ketches. Two years out of Emory University, after a brief stint as a sportswriter, he set out from Miami aboard a 60-year-old wooden William Atkin ketch named Tosca. For 10 years, he and writer-photographer Theresa Gibbons explored the Caribbean, crossed the Pacific, and cruised Southeast Asia aboard Tosca, working along the way as journalists and documenting their adventures for various travel and sailing publications, including Cruising World, Sail, Sailing, Cruising Helmsman, and Sailing World. Upon his return to land life, Darrell became the associate editor, then senior editor at Cruising World magazine, where he worked for five years. Before taking on the editor’s position at Practical Sailor, Darrell was the editor of Offshore magazine, a boating-lifestyle magazine serving the New England area. Darrell has won multiple awards from Boating Writer’s International, including the Monk Farnham award for editorial excellence. He holds a U.S. Coast Guard 100-ton Master license and has worked as a harbor pilot and skippered a variety of commercial charter boats.


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