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Old 11 August 2013, 08:45   #11
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Thanks for your input, it does come down to what the vhf is used for, I have learned that something like a 8ft is about 6db witch goes a long way. I think you have the right application for your needs. Nice pic!
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Old 11 August 2013, 08:51   #12
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With VHF arial's it's the higher the better
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Old 11 August 2013, 12:20   #13
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Originally Posted by zodiac 4.2 View Post
Thanks for your input, it does come down to what the vhf is used for, I have learned that something like a 8ft is about 6db witch goes a long way. I think you have the right application for your needs. Nice pic!
AFAIK (& I might be talking complete b0110cks) the higher the db gain the more directional the signal, in that a high DB antenna "flattens" the radiation pattern from a doughnut to a disc. If the boat is low & rocking, this has the effect of directing the signal into the sea at one side & up into the air on the opposite side. High DB antenna might not be the answer in a low boat as you will only get line of sight anyway. Like I said this might be a load of rubbish, I'm sure someone will be along to clarify.
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Old 11 August 2013, 12:36   #14
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As I've often mentioned, I binned my useless Rib Raider for a 1.2m GRP and the VHF lit up with radio traffic. Never heard a squeak with the Toys R Us black spring.
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Old 11 August 2013, 12:44   #15
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I may use a tv tower off a house lol nice 50ft of powera
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Old 11 August 2013, 13:03   #16
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When I did my VHF course there was a slide on how efficient aerials were, there are calculations you can do to see how much performance/range you would get from different setups.

But how much just a few feet will make I couldn't tell you but maybe someone else can

I have the rib raider, looks good but I don't rate it. Landlord has the right idea on his all black & grey rib, no nonsense and great performance
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Old 12 August 2013, 00:05   #17
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now that's a sweet looking rig!
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Old 12 August 2013, 11:18   #18
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I have both a 1.2m whip & a raider. (Long story involving a low door....)

Personally not noticed a real difference between them on the Clyde / West coast, and I think (open to correction here - there was a thread on the subject way back in the day) that the MK1 Raider was a pile of poo in the durability dept, whereas the MK2 I have was bounced off the garage door about 5 times in the early days (part 1 of the "why I have 2 antenna" story...... ) - It still transmits & receives fine.

The thing that's more likely to kill your comms is dodgy connections on the cables.....
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Old 12 August 2013, 12:35   #19
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To go back to the OP's question, the best antenna configuration for a RIB is, in my opinion, a 3dbi whip antenna on a pole. This gives the right combination of a broad radiation pattern and height. You want height to get a better look at the horizon and you want a broader radiation pattern so that more of the signal is pointing at the horizon at any one time.
Someone earlier explained how on a boat you need the broader radiation pattern that comes from a lower gain antenna because a more focused pattern needs a steady base so it can point at the horizon. Boats are never still.
An 8' fishing rod type antenna gives the benefit of height (actually 4', the radiation pattern centre is halfway up the antenna), but you lose out to the too focused high gain pattern. A whip on a pole gives the best of both worlds.
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Old 12 August 2013, 16:03   #20
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Thank you for the info, Lots more to it then i could have dreamed of, happy i asked!
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