HF Antenna

I am seeking suggestions and information on installing a HF antenna of a fiberglass boat. I will be operating in fresh water only.



The boat is 38ft fiberglass --- I plan to use a Yaesu Ft890 with built in tuner. I also plan to run a 500 watt solid state amplifier. I would like to be able to operate on 15m, 20m, 40m and 80m bands --- 160m would be nice but I realize that may be stretching it.



Any help on an antenna system would be appreciated.


Terry

Unlike in saltwater where a sintered bronze ground plate is the norm for HF installations, fresh water is not likely to give your HF rig a very good ground. Assuming you plan to do most of your radio work while at anchor or moored to a pier, you might want to look into a temporary rig like a copper rod speared into the shallow bottom and connected to the rf ground of the radio by appropriately sized cable.

Rich, thanks for the reply, but I would rather have the option of using the rig while underway.

I’ve run HF on smaller boats. 27 and 32’. Both down to 3.5MHz.

Have run Hustler whips, 27’ Shakespeare and 32’ whips. Grounding will be the trick in fresh water. Tie in to both prop shafts with shaft brushes. Use the hopefully already extensive bonding system. Include fuel tank, engines, bow rail, transom anode, rudders etc.
I do not value small dyna plates and the like. Problem with in radio tuners is high VSWR on feedline, and feedline radiation. Use an effective CM choke. I like balun designs stuff.

Also, what tuner will the amp feed??

I’ve installed several HF radios with the last one an IC-M802. I tie the tuner to the fuel tanks, steering hydraulics, engine and thru hulls. We’ve talked all over the world with people thinking we’re on a sailboat. It might be the radio but I don’t think so. Keep your antenna wire (GTO-15) to tuner as short as possible and don’t cheap out on the 2” copper foil to tie it all together. Some is about as thick as aluminum foil and the good stuff, you’ll need scissors to cut.

I know little about building a ground plane. Down in the bilge there's copper straps -- each being about 1.5 inch wide spaced every 3-4' apart. They seem to be connected. Not sure how many but I suspect they from from front to rear. Could this be a ground plane or used as a ground plane?


Thanks

Those are likely bonding conductors. You should see a number of offshoots connecting to engines, thruhulls, etc

Yes, they all become part of the antenna counterpoise.

IF you are interested I have a WWII life boat collapsible antenna made of monel.


Goes about 25ft when extended

A whip antenna is the easiest antenna to implement. Alternatively you could run a wire from bow to a high point then down to the stern. That would give your tuner a bit more of a workout though.


As others have said, the ground plane will be the biggest issue. What I would suggest is that you install as much bronze screen as possible against the hull below the waterline. Connect pieces of screen to each other using 1" or wider strapping (not wire). Also keep the amount of screen to a minimum (preferably zero) in areas that will be occupied when you are transmitting. Remember your ground plane radiates too.


Why do you want to run an amplifier? The 100 watts that most HF rigs put out is adequate for the vast majority of communications, at least in my opinion.


Todd (AA1ZS)

TDunn said:

....Alternatively you could run a wire from bow to a high point then down to the stern. That would give your tuner a bit more of a workout...
Todd (AA1ZS)

Click to expand...

If 160m becomes real, u will need more wire to let an internal tuner provide the needed inductance to tune.

External amp is also a complicating factor for tuning. Few remote autotuners take 500 w. I think there is a SCG model for $$

I have done manual tuners aboard, certainly ok for casual use with a real radio operator [emoji41]

FF, I'm not familiar with that type antenna, but I could be interested. I'm assuming it to would require a Ground Plane, so I'm still in the same situation. When you have time, PM me with the details. Thanks, Terry



Todd, I could put screening against the inside wall of the hull in the engine room area. it's not likely anyone would be in that area while the radio equipment is in use.

I understand the ground radiates RF. Would this be a safety hazard since I am running gasoline engines and generator?


You asked about the amplifier. I agree the 100 watts most equipment produces is sufficient for general conversation. However, I do enjoy finding me a nice anchorage, kick back, and work some contests. At times, a little help is needed.



Thanks, -- Terry (ko4cx)

Dave, If I can get the Ground Plane issue resolved, then I would address the amplifier. As mentioned earlier the radio has a built in tuner. My plans would be to have the radio's tuner tune to the amplifier, and have a manual (high capacity) amplifier on the outboard side of the of the radio, between it and the antenna. Doing this, I can manually tune the antenna. As we all know, these tuners are not really tuning, they are just providing a false reading so as not to damage the equipment.



In your opinion, would this work using a manual tuner?


Thanks,


Terry (ko4cx)

High capacity amp? Not sure what that is. Maybe to be a high tuning range manual tuner, I think. Don’t think even a tube amp will have enough tuning range for 80 and 160 with such a short wire.
DD. WB4SPT

Dave, I didn't mean high capacity amp. I was talking about the manual tuner having enough capacity to handle the 500 amps. (I corrected my screw-up)

TRD said:

Dave, I didn't mean high capacity amp. I was talking about the manual tuner having enough capacity to handle the 500 amps. (I corrected my screw-up)

Click to expand...

I had dreamed of using a weather balloon to hoist a 1/4 wave vertical on the low bands. In settled weather, that may be an option. 160 m would be a short hop daytime or a long hop nite band, I think.

Doesn't the hull material affect HF design? Say metal Vs wood Vs FRP.

sunchaser said:

Doesn't the hull material affect HF design? Say metal Vs wood Vs FRP.

Click to expand...

If u are blessed with a metal hull, simply connect the tuner return to the hull. Pretty much done.
There is another plastic boat option that others have used, when a mast is used. A vertical loop. Doesn’t require a counterpoise.
Note that using high power transmitters on small boats does expose the boat to corresponding high rf fields. My last home had its garage doors open and close with my 1500watt signal. Yes, there have been times I wished that power level aboard, but 150 watts worked 80% of the time. As a current EMC engineer, I can almost guarantee that running that field strength will affect some equipment on a small boat. But, that is why CM chokes and ferrite exists[emoji106]

My gal runs a wire bow/mast/stern on my boat, seems to work OK. Also built a mount for a whip off the stern to port that works OK.
We ran 100w amp only once, it cross talked to the boat wiring, ran the stern thruster.
Biggest complaint I hear is about noise from non-compliant cheap Chinese converters on other boats in harbor.

She goes home to use the big beam/amp/automation for contests.

At least in a sparse anchorage, u should be able to control all man made emi. Certainly the case in my experience. That leaves lightning crashes for a thousand mile radius. [emoji30]

On SGC’s website you can download a manual on how to setup your boat for HF radio. Go to sgcworld and look under the technical tab.

Are you hooking up a marine radio, or amateur radio?

I use a Yeasu FT-891 and a ATAS-120 screwdriver antenna hooked up to a laptop running Ham Radio Deluxe. I have worked station all over US, Europe, South America, and even Antarctica. All with 100 watts on the Great Lakes from a Tow/Tugboat.

I have a standard model SGC 2000, a 2000 PowerTalk, PowerCube 500 with remote, and SGC Navtex modem. I haven’t messed with any of it yet... still looking for the 235 tuner.

Vinny I am hooking up Amateur radio. You mentioned you were using a ATAS Screwdriver antenna. I have considered several antennas. 1 that I have is a Tarhill. It seems my problem is building a ground plane since the boat is fiberglass. I am told I need a minimum of 100 sq ft of ground plane.



I am looking at taking fiberglass panels (abt 1/8 inch thick) covering them with copper tape. Installing the panels in the bilge, mainly supported against the outside walls of the boat and connect them together with copper. At that point I will ground all thru hull fitting and connect them to the ground plane.



I don't know if this will work, but we shall find out.


Thanks for the reply


Terry

HF Radio on a Boat

Afternoon all, and Dave.

First there is electrical grounding for HF and then there is the radio ground plane. Two different things.

Think of the sintered metal plates as great DC grounding plates and pretty good for static discharge, though most will not stand a direct hit. They are not a very good RF ground. You do need a good RF ground for the HF work properly OR a good ground plane. The different ways are cabling all the big metal in the boat together and a sintered metal plate. Makes a good radio ground. Or use copper strapping BELOW the waterline to get good capacitive RF coupling to the water without much chance of electrolytic/galvanic corrosion.

Down side to cabling is the issue of galvanic corrosion. The copper strips works well, and you need lots of them and they should be cut to lengths that are near resonant for the frequencies you want to run ...

OR you can hook a KISS counterpoise system to the ground lug of your tuner. Works well in small and medium fiberglass boats without lots of room. I have mine mounted horizontally under the cabin top roof.
KISS-SSB TM

Now about the tuner in your ham rig, forget it. It is not designed to handle the short lengths of whip antennas. Maybe in a sailboat with a long backstay antenna, but forget it on whips. Use a marine tuner that can handle 1.8mHz to 30mHz.

Antenna ... the longest fiberglass whip you can mount ... 30ft plus. Why, so you can easily tune the lower freqs. Since you look like you want to run a HAM rig, you want to be able to run 80, 40, 20 meters for marine radio nets, and maybe 15m.

ICOM and MFJ make good tuners that will handle 1.8 to 30mHz. As for the 500W amp, unless you have lots of power on the boat to spare, forget it. You do not need it. Most of us on boats run 150W or less and work stations all over the world.

You might also want to consider using a marine HF radio like the Icom 802. You can open it to run transmit/receive from 1.8 to 30 mHz. This covers the ham and commercial HF bands. Operator licensing required for both.

If you look at Conepatus on the Trawler Forum, you will see the 32ft HF antenna on her. She is a 30 RHIB with fiberglass hull. I run an ICOM 802, ICOM AT140 tuner and a KISS counterpoise. I have worked HAM 160m, 80m, 40m, 20m from the boat. Tuner loads the radio nicely at medium power, about 100W RF out. I also run Winlink (ham) and Sailmail (marine bands) for email communication from the boat via a Pactor Dragon modem.

Best I can tell you from running HF radios on boats for 50yrs.

Craig

Terry, download that manual from SGC... it’s a lot of good reading on the subject for what you are trying to do. It’s written for knowledge of the subject and not towards SGC’s product line.

I use the Yeasu because it’s as small as a run of the mill mobile VHF Radio and mounts right on top of a Samlex 35 amp power supply nicely, plus the Vertex ATAS-120A interfaces directly with it... a single push of the button and it tunes 40 meter- 54mhz. It’s menu driven which can be troublesome, but I use the computer to operate it away. I work it on voice, SSTV, and other digital modes including Winlink.

Yeasu, Vertex, and Standard Horizon are all the same company BTW. The Vertex ATAS-120A is designed to work 40 meter- 70cm (UHF) with an interfaced tuner.

With RF grounding issues on a fiberglass boat, you may have to dial back your expectations on what you can run... you may be limited to 40 meter on up. I don’t have the RF ground issues that you have, but I have height issues. I can’t use a 23’ or 30’ antenna because I have to duck bridges on the rivers... or waste a lot of time waiting on bridge lifts.

Another thing you have to keep in mind is that, yes an antenna tuner will tune your possible antenna setup, but what you are really doing is “matching” your antenna impedance to the 50 ohms that the radio wants to see. The trade off is power lost through resistance in the pi network for the matched antenna. Antenna tuners are really not tuners, but they are matching networks.

An example... Your new found 500 watt setup may be only radiating 50 watts at the antenna on a poorly designed, over matched antenna system on 160 meter... or a full 500 watts on a properly design and matched antenna system on a different higher band... you never know.

I have an Icom M802on my boat and it was there when I bought her. I play with it once in a while but do not broadcast as I don't have a license. I looked up info on antenna's for it and read about copper grounding plates etc. I have been all over my boat and do not have anything like a grounding plate in the bilge, so the installers grounded it somewhere else. Where and how i cant say. I can say that I am 90% in fresh water and the radio works. I had a friend on board that has a ham license and he put the radio through its paces and said it works fine. I have 2 Shakespeare antennas, both mounted high and about 18 feet long so they are about 30 feet above the water. Both appear to be identical. I assume one is for the SSB and one for the VHF.
John

The SSB whip antenna would have the ATU (tuner) connected close to the base of it somewhere. Just follow the ground lead off the ATU and see what it’s wired to.

Some boats use bilge plates, copper mesh, copper foil, counterpose setup, dynaplates on the outside of hull, and I’ve even seen hydraulic steering piping used.

Several manufactures make their HF and VHF antennas look the same... it adds to the cool factor when mounted on the boat and looks more pleasing... visually balanced.

The Shakespeare 23' HF antenna has great reviews including 40 meter. With your tuner, 80 meters is likely. Which is important now, until the higher bands open up with the new solar cycle. Bonding everything metal on the ship will give a usable ground plane. With a working tuner, I don't imagine you'll need a linear amp. Matching impedance works much better that blunt-force power.