VHF antenna on side of A-frame

Ovey · 11 August 2014, 13:55

Have any of you ever mounted their VHF antenna on the side of your A-frame? And have you had any issue when doing so?

My A-frame has a SS cross member half way up each side to hold the two SS tubes together, and the previous owner had the old 1m GRP whip antenna mounted on the port side with a swivel mount. (As in the pic).

Unfortunately the antenna had shattered near the top and the cable from it had been left coiled up inside the console but was corroded, so I ripped the whole lot out.

Due to the lack of room at the top of the A-frame when the cover is on, I may well be mounting the antenna on the side of the A-frame as previous, but would welcome thoughts. I know the ideal position is on top of the A-frame for height, but I literally wouldn't be able to mount a swivel/ratchet mount on top of the A-frame due to the cover being tight and I don't want to cut a hole in the (rather expensive, good quality, bespoke cover). I'd also need to lower the antenna on a ratchet mount (as previous) if I fit it to the side of the A-frame so it will fit inside the cover.

Recommendations for antenna and/or mount would be appreciated, although I have read the various threads on this so it's not essential. It's more thoughts on mounting on the side of the A-frame (or alternatives) that I'd like to discuss here.

Thanks!

ashbypower · 11 August 2014, 14:21

The Antenna close to a steel object will be affected by it, as you will interfere with the polar pattern and the Steel will act to a degree as a reflector. If you look at TV antenna they have a reflector, active element and a number of Directors.
So in essence your VSWR will be affected and so will your ability/range to transmit/receive in the area of the metal work.

Ovey · 11 August 2014, 14:30

Yeah, I didn't really think about that. So I somehow need to get it on top of the A-frame - but with very limited room due to the tightness of the cover (in pic).

If I drill through one of the flat SS ties on top of the A-frame to the P or S of the anchor light, maybe I could mount an antenna there leaving only the screw connector sticking up. My only concern is how susceptible to damage would an antenna be with constant screwing/unscrewing every time I put the cover back on?

jyasaki · 11 August 2014, 15:42

If you have a longish antenna (mine is a Shakespeare 6', I think) the actual radiating part is tucked away in the top 1/2 to 1/3 of the whip.

I've got mine mounted pretty similar to your pic, though my arch is aluminum, not steel. The only issue I've had is that, when folded down, I have a tendency to run into it when trying to access that side of the boat while on the trailer.

jky

ashbypower · 11 August 2014, 15:50

That is only true if it's a base loaded antenna !!! at 6' your almost a full wavelength antenna !! doubt very much that it's a loaded one.

Pikey Dave · 11 August 2014, 15:57

How about using a short extension pole on a ratchet mount, to get the antenna above the A frame. Glomex do a range of extensions & good S/Steel ratchet mounts.

wavelength · 11 August 2014, 16:20

Quote:

My only concern is how susceptible to damage would an antenna be with constant screwing/unscrewing every time I put the cover back on?

we have a Metz mounted on top of the A frame as you describe. The coil and antenna is unscrewed every time we put the boat back in its garage in order to clear the door frame and that amounts to a lot of times during a year. We have had no issues doing this. We did lose a few rib raider antennas in the past but so has almost everyone

and doubt it had anything to do with taking it off every time it was garaged.

Ovey · 11 August 2014, 19:49

Which Metz do you have? Is there any chance you could take a photo of how you've rigged it? No worries if you can't. Thanks for all the replies so far.

Sent from my iPhone using RIB Net

wavelength · 11 August 2014, 20:28

search Salty John on t'interweb. He also turns up on here now n then.
The normal Metz on there with the red bit at the base (technical description eh!)
Rigged with hole in flat horizontal plate at top of A frame with the screw connector thru this hole (get extra nut off Salty to fix screw threaded bit in A frame). Wire is inside A frame n pops out near the mouting point. Simples.

Ovey · 11 August 2014, 21:33

Ah right, yeah I've seen the antennas on Salty Johns but wasn't sure which of the two you meant - I know now.

Sounds simple enough, do you ever get issues with water/condensation getting in the open connector while towing or do you put the antenna on before setting off?

Sent from my iPhone using RIB Net

Salty John · 12 August 2014, 08:53

I've tried to answer this twice but it won't post even though I'm logged in.

Ovey · 12 August 2014, 09:14

Strange! You made it through that time! ;-) Feel free to PM if you'd prefer, or if there's more chance of that working?

Nick Hearne · 12 August 2014, 11:06

My old Viper had one on top of the Aframe which I just unscrewd to put the cover on had no problems and I now have on on the side of the Aframe (not fitted by me but it works!) not the best place but it dose work!

Ovey · 12 August 2014, 11:17

Nick, that would be almost the same set-up I'd have, although I'd put a 1 - 1.5m whip on there if I chose to go with the side of the A-frame option. I'm leaning towards the Metz type antenna on top of the A-frame, but thinking of the faff with unscrewing/screwing the aerial lead and then the aerial every time is putting doubts in my mind.

Nick Hearne · 12 August 2014, 12:01

I have this one which just unscrews from the base, the lead stays atached to the base when the cover was on!
V-Tronix YRR Raider Antenna For R.I.B.S | eBay

Ovey · 12 August 2014, 12:17

I have looked at those, do you get on with it ok? I've heard (from other threads on here) that there seems to be two extremes - those who love them and those who hate them. It seems some have been fine, but others have had numerous failures?

Nick Hearne · 12 August 2014, 12:35

Yes I know some don't like them but I have had them on a couple of boats now and the only thing that has gone wrong was the bracket braking on the present one which is easily replaced

but if you go for top mount then you don't use one anyway

Ovey · 12 August 2014, 12:55

I reckon I might be looking at one of those then - it seems to fit the bill with only one thing to screw/unscrew! Thanks Nick.

wavelength · 12 August 2014, 16:34

Antenna is always in whilst towing (saves it rolling about in bottom of boat anyway) and I have a blanking plug (somewhere.. cos I can never find it when I need it!) to put in if I need to leave boat anywhere on away trips where antenna might get nicked.

Quote:

of the faff with unscrewing/screwing the aerial lead

why would you wanna do that..antenna just screws off the base which is fixed to the A frame

Ovey · 12 August 2014, 17:48

Oh right, I wasn't sure - the photos I could find of the Metz look as though the antenna is one piece & screws through the metal with the nut holding it before connecting the cable. Didn't realise the base of it stays in place while the antenna comes off.

Sent from my iPhone using RIB Net