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Old 23-10-2020, 14:43   #16
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Re: Dinghy VHF

Actually, the ten mile range is probably about right. At 70’ antenna height the horizon distance is 8+ miles. Add a little bit because you’re maybe standing in the dinghy I doubt that you’d be able to conveniently raise the dinghy antenna enough to make much of a difference
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Old 23-10-2020, 18:21   #17
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Re: Dinghy VHF

With a mothership antenna height of 75’ VHF radio horizon is just short of of 20mi.

For the handheld height of 6’ the radio horizon is 5mi and change.

So 25mi.

https://www.everythingrf.com/rf-calc...ght-calculator

10mi out of a handheld with a rubber duck antenna sounds about right with with no intervening obstructions.

If you put a good telescoping whip on the radio the 15-20mi.
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Old 27-10-2020, 07:51   #18
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Re: Dinghy VHF

Quote:
Originally Posted by Jammer View Post
Which is why I'm asking about the experience of others so I can make an informed decision on what to try.

For what it's worth, I've never found the dampness of the foliage to be a major factor in VHF. At 800 Mhz it can be a very big deal especially in pine forests where the wet needles are close to a half wavelength long.
My experience won't be entirely relevant, since my antenna is at 75' above the water.

But we got surprising range between handhelds and mothership, in Greenland two years ago (where there are no mobile phones). Well beyond line of sight. 10 to 12 miles was quite reliable even with a bit of terrain in between, and sometimes much further.

Mother ship: Icom M604, Shakespeare Little Galaxy internal dipole antenna, RG214 coax

Handhelds: Various, including SH HX870.
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Old 27-10-2020, 08:36   #19
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Re: Dinghy VHF

With VHF, the "line of sight" description isn’t a LAW, it’s a guess. All kinds of odd effects can change it dramatically. I once contacted a boat in Monterey Bay from Redwood City, 80 miles away and over a 4000’ mountain range. I’d never use that incident to figure usable range.
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Old 27-10-2020, 13:37   #20
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Re: Dinghy VHF

If the kids get outside the range, have the strongest one of them, climb a hill or a tree to get more antenna height. Teach them first aid. And to swim. Create a plan that doesn't depend on a handheld VHF, because if you put your trust there, and something happens to the radio, both sets of parties are in trouble. Personal locator beacon for the eldest? AIS for the mother boat? Bear spray? smoky fire on the beach?

Fwiw, we had about 5 mi range from our Icom handheld. Statute miles, not nautical. Also, the antennas are not hard to break off.

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Old 27-10-2020, 13:40   #21
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Re: Dinghy VHF

Quote:
Originally Posted by Dockhead View Post
My experience won't be entirely relevant, since my antenna is at 75' above the water.

But we got surprising range between handhelds and mothership, in Greenland two years ago (where there are no mobile phones). Well beyond line of sight. 10 to 12 miles was quite reliable even with a bit of terrain in between, and sometimes much further.

Mother ship: Icom M604, Shakespeare Little Galaxy internal dipole antenna, RG214 coax

Handhelds: Various, including SH HX870.
Ah you have my secret weapon, the Little Giant Galaxy antenna... cheating
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Old 27-10-2020, 14:14   #22
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Re: Dinghy VHF

Ann +1. Using technology is wonderful. Depending on it, or just trusting it is dangerous.
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Old 27-10-2020, 14:15   #23
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Re: Dinghy VHF

Thanks for all the replies. All informative.



Quote:
Originally Posted by JPA Cate View Post
If the kids get outside the range, have the strongest one of them, climb a hill or a tree to get more antenna height. Teach them first aid. And to swim. Create a plan that doesn't depend on a handheld VHF, because if you put your trust there, and something happens to the radio, both sets of parties are in trouble. Personal locator beacon for the eldest? AIS for the mother boat? Bear spray? smoky fire on the beach?

We do always have nonradio procedures, and my youngest swam competitively for a while. I don't think that being in radio contact serves any true safety function in this situation. It's more that I don't want to spend the evening looking for <whoever> if they're overdue when they could have called on the VHF at 2 in the afternoon to tell me that the mainsail ripped in half or the motor won't start or they're lost or whatever the problem is.


We've had other threads on the demise of the mutual aid culture with the rise of cell phones and paid towing services. The days when you could paddle to the nearest dock you could find and expect to borrow a boat to use to go for help have, for the most part, passed.
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Old 28-10-2020, 06:51   #24
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Re: Dinghy VHF

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Originally Posted by s/v Jedi View Post
Ah you have my secret weapon, the Little Giant Galaxy antenna... cheating
Yeah, and you were the one who recommended it to me, all those years ago. I have been extremely pleased with it.
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