New VHF Aerial - suggestions

[Gsailor]

Ref the Metz:

Are people saying the WHIP can detach from the body or the body can detach from its bracket?

Yes, the Metz I was given was the first time I had seen a pl plug required.

I used silicone grease, screwed pl259 tight, used liquid plastic to waterproof it and then self amalgamation tape around that.

Is there a way to stop whip becoming loose? Locktight? Or is that an insulator?

 

[Rappey]

Are people saying the WHIP can detach from the body or the body can detach from its bracket

Some stainless whips apparently snap off over a period of time. The shakespear whip is much thicker where it enters the base.

 

[kwb78]

It is worth using a better coax than RG58 for longer runs. The longer the run, the more important it is. RG58 is a specification for cable dimensions and says nothing about the quality of construction or how much copper is used, so beware of comparing on price alone. The cheapest will have less copper in the screen and some may even use copper clad aluminium for the centre conductor, which will perform worse than a more comprehensively screened cable with copper conductor.

My personal recommendation for what it's worth is to use the largest diameter Messi and Paoloni cable that you have space for - They have 10mm, 7mm and 5mm and all of them are more flexible than other cables like RG8 which can be very stiff and hard to work with. Their cables are high quality and perform well - even the 5mm one is considerably better than even a decent RG58. It's also worth getting good quality connectors, ie not the screw on type.

 

[PetiteFleur]

Ref the Metz:

Are people saying the WHIP can detach from the body or the body can detach from its bracket?

Yes, the Metz I was given was the first time I had seen a pl plug required.

I used silicone grease, screwed pl259 tight, used liquid plastic to waterproof it and then self amalgamation tape around that.

Is there a way to stop whip becoming loose? Locktight? Or is that an insulator?

Yes, the whip can come loose which is what happened to mine - it's fixed to the body with a nut and compression olive - which you can buy as a spare. I fitted a replacement whip and found you have to fit the nut & olive VERY tightly. The body had come loosened from the threaded coupling which had a blank central portion of thread root diameter, so the fixing nut was only just on the threaded portion and had obviously worked out of the threaded portion and consequently wobbled. I fitted a plain threaded coupler and this is now a spare. I was disappointed as the Metz was supposed to be the best although expensive. I fitted a Sirio(from radiosuperstore) whip antenna which had the same pl259 fitting.
Metz are now supplied by
'Seas The Day Marine'

 

[Gsailor]

Thank you. Good to know.

Yes, the whip can come loose which is what happened to mine - it's fixed to the body with a nut and compression olive - which you can buy as a spare. I fitted a replacement whip and found you have to fit the nut & olive VERY tightly. The body had come loosened from the threaded coupling which had a blank central portion of thread root diameter, so the fixing nut was only just on the threaded portion and had obviously worked out of the threaded portion and consequently wobbled. I fitted a plain threaded coupler and this is now a spare. I was disappointed as the Metz was supposed to be the best although expensive. I fitted a Sirio(from radiosuperstore) whip antenna which had the same pl259 fitting.
Metz are now supplied by
'Seas The Day Marine'

 

[Refueler]

I would avoid connecting an AIS transponder (transmitter) to the same antenna as the main VHF as although theoretically possible they would be fighting each other for access to the antenna possibly at times VHF where the radio was in use for a conversation.

Actually not always true .... Splitters prioritise the VHF and should you transmit - the AIS does not get through.

The AIS will work perfectly well using its own antenna at another location on the boat.

Yes true to an extent based on Horizon line from Antenna etc,

My Antenna for AIS when tested on my home berth up river etc. - I received max 3 targets as pushpit rail mounted ... but 19 targets when masthead on its own .... and when via splitter - received over 13 targets ....

 

[savageseadog]

Thank you. Good to know.

Actually not always true .... Splitters prioritise the VHF and should you transmit - the AIS does not get through.



Yes true to an extent based on Horizon line from Antenna etc,

My Antenna for AIS when tested on my home berth up river etc. - I received max 3 targets as pushpit rail mounted ... but 19 targets when masthead on its own .... and when via splitter - received over 13 targets ....

Useful if you think it's worth tracking AIS targets 10+ miles away?
It is actually useful for racing to see how the fleet is getting on behind you.

 

[Plum]

My personal recommendation for what it's worth is to use the largest diameter Messi and Paoloni cable that you have space for - They have 10mm, 7mm and 5mm and all of them are more flexible than other cables like RG8 which can be very stiff and hard to work with. Their cables are high quality and perform well - even the 5mm one is considerably better than even a decent RG58. It's also worth getting good quality connectors, ie not the screw on type.

Thanks and have just looked for Messi and Paoloni coax and there are different types, such as Airborne and Hyperflex and ultraflex. Which do you recommend? Thanks

 

[kwb78]

The numbers refer to the cable diameter. The Airbourne series are designed to be light weight. They use aluminium conductors (but are well designed so they still have decent performance) - it's probably not necessary. Ultraflex is their kind of standard cable, and Hyperflex has more strands that are thinner to make the cable more flexible. The RF performance of Ultraflex and Hyperflex is largely the same at marine VHF frequencies, so it's only worth getting hyperflex if you really need the extra flexibility such as for an antenna on a rotating mount or something like that as it costs a bit more.

If you have the space, then I'd go with Ultraflex 10, but Ultraflex 7 is a good compromise - that's what we used when we replaced the antenna with a Metz one and it's been performing well. If you are really tight for space, Hyperflex 5 still outperforms RG58 despite being a similar diameter.

 

[Refueler]

Useful if you think it's worth tracking AIS targets 10+ miles away?
It is actually useful for racing to see how the fleet is getting on behind you.

During my Merch Navy Cadetship ... one of the lecturers at College said :

Collision occurs when two idiots are in same place same time.

Why pass so close to another when you have an ocean to play in ?

OK ... look at this way ..... you detect at a good distance off ... track indicates a close passing situation .... given the distance and time - you can alter course and or speed to a much less degree - with minimal disruption to your schedule etc.
If you only detect at short range - then alteration of course and or speed is more pronounced and can have greater effect on schedule.

So why not ? Act earlier ... less stressful ... more calm.

Also - just because you have greater range ... does not mean you have to display / work at such range ... there's always the user control. But at least you can feel comfortable - your AIS Tx is getting out further ...

 

[st599]

So why not ? Act earlier ... less stressful ... more calm.

In the Solent, it would be going off every 30secs. On the charity boat I worked on, skippers found it so annoying, they'd pull the power lead.

 

[Refueler]

In the Solent, it would be going off every 30secs. On the charity boat I worked on, skippers found it so annoying, they'd pull the power lead.

Agreed ... I may list as Latvia / Baltic ... but I grew up sailing the Solent / South Coast .... my main boat here was Solent based for many years ...

But anyway - Solent is not the only area people sail. I now sail Baltic and having good range is actually good idea .....

 

[Stemar]

In the Solent, in any weather I'm likely to be out in, AIS is more of a nuisance than anything else, and the longer the range, the worse it is, with alerts popping up every few seconds on a busy Sunday afternoon. Mine's set to ignore anything more than a couple of miles away, and probably ought to have its own switch so I can turn it off completely in favour of the Mk1 eyeball.

However, if I cross the Channel, I'm going to be happy to have course and CPA of any of those big buggers that are going by, but I don't think I need more than about 10 miles warning that they're going to be within a mile of me, so a pushpit level antenna would be fine. Line of sight from 2m is 5km, and the antenna on a ship probably around 10, giving 11km. I can live with 16km of range.

 

[samfieldhouse]

So all the work is done!
I went for a Glomex stainless whip for the masthead and a Glomex GRP AIS aerial which is mounted to the bimini arch. Both use FME connectors and RG8X cable.
So here's the interesting thing.. lots of aerials come bundled with 18-20m of RG58, but my Standard Horizon DSC explicitly states that RH58 should not be used for runs of more than 7m and various other sources say it's unsuitable for runs of 8m+.
The difference is very noticable: for the AIS aerial mounted at deck level I can pick up the IOW fast cats leaving Cowes when moored at the top of Southampton Water.
On the VHF yesterday, and the conditions were very good, I was picking up CROSS Jobourg from the Western Solent. Normal ship to ship calls are far better quality - generally I'm impressed. I've used a scanstrut deck gland so the cable goes straight from the aerial into the back of the VHF with no connectors or blasted deck plugs which I hate with a burning passion

On inspection/removal, my previously atrocious VHF reception was probably not aided by...
the VHF being connected to a cable that went above the headlining....
that went to another cable that ran behind the galley...
that went to a standard domestic TV female/female adapter...
that went to a cable above the heads headlining...
that connected to a final cable that went to the deck plug...
which was obviously waterlogged and horrible...
that finally went to the run up the mast...

Lesson is... check your aerial cable: is it suitable for the length of cable run and is it of actually suitable cable
I thought about getting an active AIS/VHF splitter suitable for AIS transponders (the choice is limited). But both AIS and VHF reception is so good I didn't want to introduce a break and/or a point of failure. And this way I do have backup for the VHF in the AIS aerial if needed.

Thanks for the input and the suggestion to use RG8X, a well worthwhile upgrade.