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30 December 2015, 13:05
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#1
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Member
Country: UK - England
Town: Liverpool
Length: no boat
Join Date: May 2015
Posts: 219
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Metz aerial..what height?
I am attaching the above aerial directly to the A frame which is approx 4 or 5 feet above sea level. I appreciate height is range. What height on an extension pole do you think I could get away with before it starts to look a bit "odd".Is it even worth extending it in the first case? Any smart ways of attaching it to the frame so it can be removed on car journeys? Nik
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30 December 2015, 14:16
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#2
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Member
Country: UK - England
Town: South Yorks
Boat name: Black Pig
Make: Ribcraft
Length: 5m +
Engine: DF140a
MMSI: 235111389
Join Date: Feb 2008
Posts: 12,166
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Quote:
Originally Posted by matata
I am attaching the above aerial directly to the A frame which is approx 4 or 5 feet above sea level. I appreciate height is range. What height on an extension pole do you think I could get away with before it starts to look a bit "odd".Is it even worth extending it in the first case? Any smart ways of attaching it to the frame so it can be removed on car journeys? Nik
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There's a formula kicking about somewhere which basically says that any height gained, exponentially increases the range, so on a RIB, you can't have too much height...in theory. In practical terms "generally" you don't need massive ship-ship comms range, any fellow cruisers will usually be within a mile or 2 of you, so won't be a problem. If you need to call the coast guard, his antenna is sat on top of a cliff on a ruddy great mast, so a couple of feet on your rib, ain't going to make a difference. As for removing for towing, a stainless steel ratchet mount is the way to go.
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30 December 2015, 16:05
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#3
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Member
Join Date: Jun 2010
Posts: 2,934
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I had the same aerial on my last RIB in an attempt ton cure a fault, turned out it was the vhf but alas, I digress.
I mounted it ontop of the A frame and with a new vhf never had any concerns contacting anyone and it was certainly better than the rigid raider aerial it replaced.
I wouldn't go looking for problems, just fit it and I am sure it will be fine.
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30 December 2015, 17:30
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#4
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RIBnet admin team
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: Tohatsu 30HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 11,627
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Quote:
Originally Posted by matata
What height on an extension pole do you think I could get away with before it starts to look a bit "odd".Is it even worth extending it in the first case? Any smart ways of attaching it to the frame so it can be removed on car journeys? Nik
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Surely the aesthetic depends on your boat, the design of a frame etc?
Sadly whilst height really does matter, it's not actually exponential - essentially it's proportional to the square root of the antanae height (Beware this is not the tip of the antenna). Moving from 2-3m in most circumstances doesn't give a great range enhancement. However the key thing to remember is vhf will not travel through waves. If you regularly go out in big waves height might help more than someone going far off shore in benign conditions. Similarly if you spend a lot of time with kayaks or dinghies using a handheld at just 0.5m above the water.
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30 December 2015, 19:09
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#5
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Member
Country: UK - England
Town: Southampton
Boat name: 'Mojo'
Make: Searider
Length: 4m +
Join Date: May 2013
Posts: 398
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My Metz is mounted directly on top of a standard Ribeye a-frame.
Not had any issues and range is a well as can be expected.
Mind you- I don't do any of that Off-shore malarkey or 'big wave' shizzle.
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30 December 2015, 21:48
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#6
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Member
Country: UK - Scotland
Town: Aberdeenshire
Boat name: Sula
Make: Ribcraft 4.8m
Length: 4m +
Engine: Tohatsu 70hp + aux
MMSI: 235087213
Join Date: Jun 2007
Posts: 4,645
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Put my Metz onto a bespoke stainless steel light-pole which comes in three sections. The lightpole measures 54" high from the top of the transom to the light. The aerial is 36" high. From sea level to the tip is probably in the region of 7.5' high. On a good day I can even pick up Channel 4!
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Is that with or without VAT?
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30 December 2015, 23:51
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#7
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Member
Country: UK - England
Town: Down South
Make: Northcraft 5.8m 1999
Length: 5m +
Engine: 2012 Tohatsu MD90C
Join Date: Sep 2013
Posts: 181
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My Metz picks up Qhm and Yarmouth harbour from Southampton in my rib the antenna is hooked upto a Icom M323
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31 December 2015, 09:33
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#8
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Member
Country: UK - England
Length: 7m +
Join Date: Aug 2009
Posts: 1,619
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Fit a folding stainless base, you can then just fold it down on car journeys, I don't know of any removable types.
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31 December 2015, 13:45
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#9
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Member
Country: UK - Scotland
Make: HumberOceanOffshore
Length: 8m +
Engine: Volvo KAD300/DPX
Join Date: Oct 2002
Posts: 5,596
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I reckon the sea will become a ground plane and I've a recollection (somewhere deep in the grey matter) that 5ft above a ground plane is not a good height for an antenna. Some quirky thing. Probably more applicable to a horizontal antenna but just thought I'd drop that spanner into the works.
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JW.
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31 December 2015, 22:01
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#10
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Member
Country: UK - England
Length: 3m +
Join Date: Sep 2008
Posts: 2,767
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Quote:
Originally Posted by Solent Bombard
My Metz picks up Qhm and Yarmouth harbour from Southampton in my rib the antenna is hooked upto a Icom M323
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Where is QHM's antenna? I'll bet its not on their roof.
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01 January 2016, 08:46
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#11
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Member
Country: UK - England
Town: Southampton
Boat name: 'Mojo'
Make: Searider
Length: 4m +
Join Date: May 2013
Posts: 398
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Quote:
Originally Posted by ShinyShoe
Where is QHM's antenna? I'll bet its not on their roof.
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I'll take that bet with you.😁
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10 January 2016, 09:19
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#12
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Member
Country: Other
Town: Stanley, Falkland Is
Boat name: Seawolf
Make: Osprey Vipermax 5.8
Length: 5m +
Engine: Etec 150
Join Date: Mar 2006
Posts: 3,726
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Quote:
Originally Posted by Wibs
My Metz is mounted directly on top of a standard Ribeye a-frame.
Not had any issues and range is a well as can be expected.
Mind you- I don't do any of that Off-shore malarkey or 'big wave' shizzle.
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Big waves add height thus range. You just need to talk quickly while on top of the wave, then pause in the troughs. It's called packet voice transmission
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10 January 2016, 17:17
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#13
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Member
Country: UK - England
Town: South Yorks
Boat name: Black Pig
Make: Ribcraft
Length: 5m +
Engine: DF140a
MMSI: 235111389
Join Date: Feb 2008
Posts: 12,166
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Quote:
Originally Posted by Wibs
Mind you- I don't do any of that Off-shore malarkey or 'big wave' shizzle.
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You don't know what you're missing👍
__________________
Rule#2: Never argue with an idiot. He'll drag you down to his level & then beat you with experience.
Rule#3: Tha' can't educate pork.
Rule#4: Don't feed the troll
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10 January 2016, 20:31
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#14
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Member
Country: UK - England
Town: Southampton
Boat name: 'Mojo'
Make: Searider
Length: 4m +
Join Date: May 2013
Posts: 398
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Quote:
Originally Posted by Pikey Dave
You don't know what you're missing👍
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Yeh I do-but i own a Ribeye.
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