Mast or stern pole for Radome ?

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PembrokeshirePromise

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Trying to decide between the two.

Pole would be about 10 foot above water level, Mast would be about 20 foot - with obvious height advantages.

However, Topping lifts exit the mast a few feet above where the Radome would have to go - how likely are these (or anything else) to tangle. Also mast is keel stepped - but removed every winter - so I would need to join the radar cable behind the headlinings I guess (can't find any plugs ...)

Pole mount would be easier - not need to be removed each winter - but obvioulsy has less range - and more chance of frying what brians I have left.

What would you do .....
All views appreciated

Thanks
 
Bin there.Got the tee shirt

after the very same deliberations designed a pole to take all antennas + radar + wind genny.
radar range in clear calm conditions - large container ship @ 10 mls, well over the horizon.the hand hold provided by the pole is very usefull for the call of nature
 
That's not fair to them ! Perhaps you should czeck out some other support which would serb your purpose as well.
 
You can get some very good supports which attach to the backstay and then swivel to remain horizontal. Sorry can't remember the name!
 
I had a pole made locally to my design. Total cost about 300 quid, but that includes the GPS antenna, Navtex antenna, Emergency VHF antenna and a mini flag halyard.
Mine is 2.5m above deck overall, and is angled out so you dont bang into it while in the cockpit. It also has a bracket waiting for me to fit a deck floodlight too.
The stainless supports I made last year from bits supplied by picea-316.co.uk, in 2005, I had two 6mm braid on braid ropes to brace it with no problems at all, just to get us on the water.
The only downside is the flare it picks up from the radar reflector on the mast, which obscures the view for 25m round the boat on the 0.02m setting of the radar.

P1010045-1.jpg



Gravelines11.jpg
 
Not going to disagree with the pole - we have a Scanstrut - expensive but well made. I think they also make the self levelling backstay platform - probably outrageously expensive.

We were advised against the mast mount for use with laminate sails due to friction on the dome. one day I might be able to afford laminates too
 
Pole...

I like the pole option. You really don't need scanner height - in fact the lower position of a scanner on a pole reduces sea clutter on the radar. There's no real danger of frying your brains, because the power output is so low. It's easier to get to, provides a mount for GPS or other antennae, and keeps weight lower. And you don't need to muck about with radar wiring to unstep the mast.

But it's important to get the pole right. It needs to be fairly rigid, which might mean supporting it with struts or braces (don't rely on the pushpit giving adequate support). And I think it's important that it looks right - many custom poles are too skinny in my opinion. And of course it's got to fit the boat. I considered the various options for a long time before going for a Scanstrut modular pole. It's more expensive than many custom solutions, but it's easy to fit, very rigid, adjustable, and it looks right!
 
Re: Pole...

[ QUOTE ]
I like the pole option. You really don't need scanner height - in fact the lower position of a scanner on a pole reduces sea clutter on the radar. There's no real danger of frying your brains, because the power output is so low.

[/ QUOTE ]

It's 2kw!! your microwave at home is probably 750w and think how quick that will boil water.
They go on about mobile phones and they are probably miliwatts.
Rob
 
Re: Pole...

No need for hysterical response. We are talking radar not microwave cookers. Cookers are average power, radars are peak power. Typical small marine radars transmit a pulse of about 1 microsecond duration at a rate of maybe 1000 pulse per second - you can work out the average power from this duty cycle. Lots of other considerations for radar as well like beamwidth (typ. 3 deg), a scanner rotation rate of 20 rpm, Ae gain, beam pattern etc. - you will be doing more harm using your mobile phone or VHF. Now if you are talking about a 2MW radar transmitter with a much longer pulse width then keep well away!

BTW RF radiation effects are cumulative and permanent so if your eyes are starting to look like part boiled eggs then you have had too much exposure, and other dangly bits are probably not working as intended :>)

Common sense does say minimise your exposure to the transmissions though i.e. switch off when not needed, site appropriately to minimise crew exposure.
 
Re: Pole...

[ QUOTE ]
It's 2kw!! your microwave at home is probably 750w and think how quick that will boil water.

[/ QUOTE ]The typical consumption of an 18" Raymarine radome is 28W - yes, just 28 watts.
 
Pole makes a lot of sense - have a pole with some bits stuck on myself - but not radar.
Reason: at some time in the future I plan to install an SSB radio and to use the backstay as an arial. A radar and an SSB in close proximity and both on TX at the same time could prove "interesting". (RADHAZ)

If you don't plan to ever install an SSB - go for it - if you do, you might want to install your radar on the mast.
 
Re: Pole...

[ QUOTE ]
[ QUOTE ]
It's 2kw!! your microwave at home is probably 750w and think how quick that will boil water.

[/ QUOTE ]The typical consumption of an 18" Raymarine radome is 28W - yes, just 28 watts.

[/ QUOTE ]

Which will be something like 10 times the average output of a mobile phone, albeit a bit further away from the head.

leaves me uneasy /forums/images/graemlins/confused.gif
 
Oooh! What is the recommended distance between the SSB and Radome then?

I have a radar / GPS / Wind Genny on a gantry at the back of the boat and have just bought an SSB which has a big fibreglass whip arial to be mounted on the transom - Arial will end up being about 3.5 ft away from the radome and about 2ft astern of it ... should I expect problems?

Jonny
 
[ QUOTE ]
Pole makes a lot of sense - have a pole with some bits stuck on myself - but not radar.
Reason: at some time in the future I plan to install an SSB radio and to use the backstay as an arial. A radar and an SSB in close proximity and both on TX at the same time could prove "interesting". (RADHAZ)

If you don't plan to ever install an SSB - go for it - if you do, you might want to install your radar on the mast.

[/ QUOTE ]

Wouldnt worry too much - cant see that the radar scanner would be vastly nearer the ssb aerial wherether on a strut or mast. But if it were any sort of problem the appropriate low pass filter on the ssb output should cure it.

Had no probs with this on my last boat
 
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