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