Maximum effort VHF on cruising boat, dinghy, and handhelds

[Jammer]

This spring I am installing a "maximum effort" VHF system on my 26' Hunter, and am upgrading the VHF on my dinghy and handhelds. I am cruising remote inland lakes and rivers and want the best VHF performance I can get. I have several operational goals:

1. Emergency communications in areas where there is no cellular coverage and where USCG Rescue 21 coverage is marginal.
2. Communications with a 14' aluminum boat we are using as a dinghy over the longest feasible distances in the presence of vegetation and terrain from islands and peninsulas. Stretch goal of clear, solid comms to 20 miles.
3. Solid shorter-range communications out to at least 5 miles with the handhelds.

[Jammer]

Sailboat

I have the mast off the boat for other maintenance and am installing Belden 9913 inside, held in place with aluminum/neoprene cushion clamps every 48", with right-angle N connectors professionally installed at each end by theantennafarm.com, who offer custom cable construction services. The N connectors will connect to bulkhead N barrels permanently installed in the side of the mast, about 12-18" from the top and bottom. There isn't room for a drip loop so I will snake the cable in an S shape a little between the cushion clamps to allow for thermal contraction in the winter.

The antenna is a Laird FG1563. It's a 9' long fiberglass antenna used primarily in land-mobile applications. There isn't much difference from similar offerings from Shakespeare and their competitors except that it has an N connector rather than a PL259 and uses a slightly different style mount. It is also somewhat cheaper than antennas from Shakespeare of comparable quality. It is a phased dipole design with an honest 3 dBd gain, and comes pretuned for 156-162 MHz.

I swept the cable and N barrels with a VNC and measured 0.58 dB loss at 150 MHz. I swept the antenna and the SWR is very low, under 1.1.

I have an RG393 mil-spec whip with N connectors on each end, on order. This will connect the antenna to the mast. RG393 is UV resistant, flexible, durable, and low loss, and I can form it into a drip loop below the mast connection. Ordinarily it costs over $15 a foot but surplus pieces do come up for sale.

I plan to run RG58 from the mast to the radio unless I can find a good deal on RG400. This has to be fished between the deck and the headliner and I'm not going to try to run large-diameter cable for this short distance.


The N barrels were surplus from another project, and the cable cost around $80 including the connectors. The antenna was $182 from Digikey including mounting brackets and shipping. The RG393 jumper was $32 including shipping. The radio is a Standard Horizon GX1400GPS, $163 from Defender. With some hardware and the RG58 the project cost comes to about $500.

Here are photos of the cable being swept, and the antenna along with a detail of just the portion with the mounts and connector.

[Jammer]

Dinghy

I decided on a ground-plane type antenna that takes advantage of the conductive aluminum deck without adding excessive height. This is a 5/8 wave base-loaded antenna, with a spring and a tapered stainless steel whip, and uses an NMO mount. I cut a stainless steel disc and riveted it to the aluminum to provide some extra stiffness and a good electrical connection to the brass NMO assembly. It is about 48" high. I trimmed this using the VNA to find minimum SWR. There is RG58 going the 10' distance from the mount to the radio. The antenna is a MaxRad/PCTEL one as is the NMO mount, cost about $90 including the stainless steel stock I cut into a disc. I soldered the PL259 on myself. As with the sailboat, the radio is a Standard Horizon GX1400 GPS. Total project cost around $300.


Here's a photo showing the antenna. The radio is tucked under the side bench at the very stern where it's out of the way.

[Jammer]

Handhelds


Finally I have upgraded the antennas on my handhelds. These are Standard Horizon HX380 handhelds, which I like because:

1. They allow a battery change in a wet environment without compromising the weather seal.
2. They work well with rechargeable AA batteries using a battery pack that swaps out with the standard lithium one. That means you can prepare a spare AA battery pack for emergency or standby use and have it stay charged effectively indefinitely.
3. The charging cradle runs on 12v and works well on a boat, and can be attached to something so that the radio has a place to live without contributing to cable clutter.
4. There are some excellent, weatherproof headsets available for situations that require them.
5. They can be programmed with amateur radio and MURS frequencies.
6. They have loud, clear audio.

Anyway I got a longer antenna from The Antenna Farm that should have better performance than stock. It does make the handheld more awkward but I don't think this is a bad tradeoff if the range improvement is noticeable.


The antennas were $17 each. I think I paid $120 each for the radios which includes the drop-in charger. Programming cable and software was another $30. The battery trays are about $25 and the headsets are $30 each or so depending on style (in-ear vs over-head).

[Spot]

I find myself suffering from acute dinghy and antenna envy...looks nice Jammer, probably hear/see you out on Pepin sometime this year.

[S/V Illusion]

Originally Posted by Jammer

1. Emergency communications in areas where there is no cellular coverage and where USCG Rescue 21 coverage is marginal.
2. Communications with a 14' aluminum boat we are using as a dinghy over the longest feasible distances in the presence of vegetation and terrain from islands and peninsulas. Stretch goal of clear, solid comms to 20 miles.
3. Solid shorter-range communications out to at least 5 miles with the handhelds.

With the exception of #2, these don’t require any extraordinary equipment or antennas.
VHF Signal attenuation can be severe when the path transits terrain and vegetation unless your antenna exceeds their height which seem impractical on a dinghy. Also, your effective range is unlikely to be 5 miles with a handheld unless it’s in the clear and is equipped with something better than the typical ‘rubber duck’ antenna.

[Jammer]

Originally Posted by Spot

I find myself suffering from acute dinghy and antenna envy...looks nice Jammer, probably hear/see you out on Pepin sometime this year.

Thank you, Spot, big boat is Exuberance, dinghy is the Sixty Gig.


It is a 14' Crestliner from the early 1960s that I bought last summer in fantastic condition but badly in need of paint. I had it sandblasted, and painted it myself with more coats of Interlux primers, Trilux, and Perfection than I care to remember. I bought a new outboard this spring after giving up on finding a good used one. I have a battery tucked under the bow decking and fastened to the keel bolts. I've added 8.5' spruce oars from Canada with Gaco oarlocks from New Zealand and a leather kit from Shaw & Tenney. There's an original oak dashboard to which I've added a compass. After the photo upthread was taken I added a canoe-style seat with backrest on the stern thwart and an inflatable-style bench cushion on the forward thwart. The oversized nav light is original and has been upgraded to LED. I found a machinist on ebay selling reproduction drain plugs, a real boon since the original was missing. I'll be towing her for my river and lakes shenanigans as she's far too big to fit aboard the trailer sailor.


Any relationship between the dinghy's name and millimeter wave technology is purely coincidental.

[murofsresiurc]

Let me add that VHF propagation through dense vegetation is much improved if you can implement horizontal polarization. Easy for the handheld and maybe you can adapt from the main vessel.

[guyrj33]

I'm concerned the stainless disc under the dinghy antenna will cause galvanic corrosion, damaging the aluminum dinghy. Fiberglass sheet stock or an insulating layer between the stainless and aluminum would help prevent the corrosion. Being in fresh water will be in your favor corrosion wise.

[Gypsyjon]

VHF is strictly line of site. That means the higher the antenna the further you can transmit and receive.

[Shrew]

Originally Posted by Jammer

This spring I am installing a "maximum effort" VHF system on my 26' Hunter, and am upgrading the VHF on my dinghy and handhelds. I am cruising remote inland lakes and rivers and want the best VHF performance I can get. I have several operational goals:

1. Emergency communications in areas where there is no cellular coverage and where USCG Rescue 21 coverage is marginal.
2. Communications with a 14' aluminum boat we are using as a dinghy over the longest feasible distances in the presence of vegetation and terrain from islands and peninsulas. Stretch goal of clear, solid comms to 20 miles.
3. Solid shorter-range communications out to at least 5 miles with the handhelds.

The mast on Hunter 26 is 40 feet.

Est. antennae height on Hunter: 38 feet
Est. Antennae height on runabout: 5 feet.

Radio Horizon (Hunter): 9 miles
Radio Horizon (Runabout): 3 miles

Total Line of Site (Hunter <-> Runabout): 12 miles.

Two handhelds (Roughly 5 feet)

Radio Horizon (handheld): 3 miles
Total Line of sit( handheld <-> handheld): 6 miles.

[Jammer]

Originally Posted by guyrj33

I'm concerned the stainless disc under the dinghy antenna will cause galvanic corrosion, damaging the aluminum dinghy. Fiberglass sheet stock or an insulating layer between the stainless and aluminum would help prevent the corrosion. Being in fresh water will be in your favor corrosion wise.

Thanks. I'll watch for that and check it from time to time. It is in a dry area and the electrical bond is necessary to get good performance from this type of antenna.

Originally Posted by Gypsyjon

VHF is strictly line of site. That means the higher the antenna the further you can transmit and receive.

Originally Posted by Shrew

The mast on Hunter 26 is 40 feet.

Est. antennae height on Hunter: 38 feet
Est. Antennae height on runabout: 5 feet.

Radio Horizon (Hunter): 9 miles
Radio Horizon (Runabout): 3 miles

Total Line of Site (Hunter <-> Runabout): 12 miles.

Two handhelds (Roughly 5 feet)

Radio Horizon (handheld): 3 miles
Total Line of sit( handheld <-> handheld): 6 miles.

This is an oversimplification, see extensive discussion in this thread: The VHF radio horizon calculation is wrong


I expect to be able to exceed the purported "horizon" distances with this setup.

[Spot]

Originally Posted by Jammer

Thank you, Spot, big boat is Exuberance, dinghy is the Sixty Gig...Any relationship between the dinghy's name and millimeter wave technology is purely coincidental.

I have to admit I looked for runabouts on 'the craigslist' after seeing pictures of Sixty Gig. I like your attention to detail with the oars and locks and stuff.

Felicity is the 21' (in my profile pic) and Feta is the PDR with the bright blue tarp sail. Both normally fly an orange masthead streamer. It'd be fun to put faces to names on the water.

[KP44]

Hi Jammer,
The three things you want are antenna height, lowloss feed lines, and low standing wave ratio.
Avoid any R58 cable. Use as few connections as possible. This cuts down on loss.

Antenna height is usually mast height for a sailboat. That is why sailboats can usually communicate much farther than powerboats.

Check your impedance match when the system is complete. Matching your 50 ohm VHF to a 50 ohm antenna system will give you the low standing wave you need. If a standing wave is high, your radio will lower its power to keep the standing wave from damaging the radio. (That is why higher power does not help a mismatched antenna.)

Decible "gain" for an antenna is more a measurement of the shape of the signal rather than any actual gain in power. A 3 db antenna sends more horizonal signal but still works for below and above.

[KP44]

Originally Posted by Jammer

Handhelds


Finally I have upgraded the antennas on my handhelds. These are Standard Horizon HX380 handhelds, which I like because:


Anyway I got a longer antenna from The Antenna Farm that should have better performance than stock. It does make the handheld more awkward but I don't think this is a bad tradeoff if the range improvement is noticeable.


.

Improved receive and transmit will be how well the new antennas suit the radio and the bandwidth. A longer antenna that is made for a different bandwidth (frequency) will work but will not be an improvement.
I use an extendable antenna like the one below: