savageseadog
Well-Known Member
Pro's and con's
Radar Radome Mast or Pushpit (strut) Fitting?
- Thread starter savageseadog
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pvb
Well-Known Member
Re: Radar Radome Mast or Pushpit Fitting?
I went for a stern pole. Pros: easier to install and run cable; easier to access if needed; keeps weight a bit lower down; less sea clutter effect; easy to add other antennae (GPS, Navtex, etc); actually looks quite good (subjectively). Cons: more expensive than mast bracket; slightly reduced ultimate range (but more than enough range for normal use).
I went for a stern pole. Pros: easier to install and run cable; easier to access if needed; keeps weight a bit lower down; less sea clutter effect; easy to add other antennae (GPS, Navtex, etc); actually looks quite good (subjectively). Cons: more expensive than mast bracket; slightly reduced ultimate range (but more than enough range for normal use).
vyv_cox
Well-Known Member
Re: Radar Radome Mast or Pushpit Fitting?
Same choice for pretty much the same reasons. Also makes taking the mast down much easier. I'm still not sure if there is an inline plug/socket for a Raytheon radar but I have never seen one. Also, on my boat the route for the cable inside the boat would be unsightly but unavoidable.
Now about to gain another advantage - the pole will partly support my new solar panel arch.
Same choice for pretty much the same reasons. Also makes taking the mast down much easier. I'm still not sure if there is an inline plug/socket for a Raytheon radar but I have never seen one. Also, on my boat the route for the cable inside the boat would be unsightly but unavoidable.
Now about to gain another advantage - the pole will partly support my new solar panel arch.
savageseadog
Well-Known Member
Re: Radar Radome Mast or Pushpit Fitting?
Which is more appropriate for a smaller boat and why is sea clutter less. What sort of range are you getting compared to the spec for your unit.
I have to confess I always thought the strut a better idea.
Which is more appropriate for a smaller boat and why is sea clutter less. What sort of range are you getting compared to the spec for your unit.
I have to confess I always thought the strut a better idea.
KenMcCulloch
Well-Known Member
Re: Radar Radome Mast or Pushpit Fitting?
On a smaller boat you will need a disproportionately tall pushpit strut to raise the radome above head height. I worry a bit when I see boats with radar scanners mounted in such a way that a crew member can easily expose their body to direct irradiation. you will also be able to 'see' much farther with it up the mast a bit.
On a smaller boat you will need a disproportionately tall pushpit strut to raise the radome above head height. I worry a bit when I see boats with radar scanners mounted in such a way that a crew member can easily expose their body to direct irradiation. you will also be able to 'see' much farther with it up the mast a bit.
pvb
Well-Known Member
Re: Radar Radome Mast or Pushpit Fitting?
Not sure which is more appropriate for a smaller boat - it really depends on the size of the boat and the size of the radome.
As for sea clutter, this is caused by reflections from the sloping faces of waves. The higher the radar scanner, the more likely it is to pick up reflections from waves, especially close to the boat. You'll often find people saying that higher scanners result in less sea clutter, but the opposite is true. Commercial/naval ships have scanners mounted high to get range and to avoid reflections from structures on deck. For a leisure boat, a scanner on a stern pole is plenty high enough for adequate range and will result in less sea clutter effect.
Range does depend on height, but it's not that different. Mounted on a pole, say 12ft above sea level, the scanner would see the horizon at about 4 miles. On the mast, say at 35ft up, it would see the horizon at about 7 miles. Not a big difference. Naturally, the ability of the radar to see vessels beyond the horizon depends on their height. My radar has a theoretical range of 24 miles, but it's always used on much shorter settings.
Not sure which is more appropriate for a smaller boat - it really depends on the size of the boat and the size of the radome.
As for sea clutter, this is caused by reflections from the sloping faces of waves. The higher the radar scanner, the more likely it is to pick up reflections from waves, especially close to the boat. You'll often find people saying that higher scanners result in less sea clutter, but the opposite is true. Commercial/naval ships have scanners mounted high to get range and to avoid reflections from structures on deck. For a leisure boat, a scanner on a stern pole is plenty high enough for adequate range and will result in less sea clutter effect.
Range does depend on height, but it's not that different. Mounted on a pole, say 12ft above sea level, the scanner would see the horizon at about 4 miles. On the mast, say at 35ft up, it would see the horizon at about 7 miles. Not a big difference. Naturally, the ability of the radar to see vessels beyond the horizon depends on their height. My radar has a theoretical range of 24 miles, but it's always used on much shorter settings.
sailorman
Well-Known Member
Re: Radar Radome Mast or Pushpit Fitting?
i done the same after much deliberation
had a bespoke pole made by a local fabricator to my design
i done the same after much deliberation
had a bespoke pole made by a local fabricator to my design
pvb
Well-Known Member
Re: Radar Radome Mast or Pushpit Fitting?
[ QUOTE ]
On a smaller boat you will need a disproportionately tall pushpit strut to raise the radome above head height. I worry a bit when I see boats with radar scanners mounted in such a way that a crew member can easily expose their body to direct irradiation. you will also be able to 'see' much farther with it up the mast a bit.
[/ QUOTE ]An ordinary 6ft pole, deck-mounted, gives plenty of clearance in normal use. The radiation risk from a yacht radome is negligible - a typical 18" radome uses only 28W. Mast-mounting does increase range, but very little in practical terms.
[ QUOTE ]
On a smaller boat you will need a disproportionately tall pushpit strut to raise the radome above head height. I worry a bit when I see boats with radar scanners mounted in such a way that a crew member can easily expose their body to direct irradiation. you will also be able to 'see' much farther with it up the mast a bit.
[/ QUOTE ]An ordinary 6ft pole, deck-mounted, gives plenty of clearance in normal use. The radiation risk from a yacht radome is negligible - a typical 18" radome uses only 28W. Mast-mounting does increase range, but very little in practical terms.
damo
Well-Known Member
I built a stern pole from reclaimed s/s and alu. I already had the mast strut, so I riveted that to my pole.
The pros for me are:
Much easier to run the cabling, and doesn't affect unstepping the mast
Weight lower down and less windage
A place for a spare vhf antenna
Handy place to fix eg throw line, deck brush etc
Easy access
Cons are slightly less range, and it's a bit ugly, but it will do until I build a stern arch one day
The pros for me are:
Much easier to run the cabling, and doesn't affect unstepping the mast
Weight lower down and less windage
A place for a spare vhf antenna
Handy place to fix eg throw line, deck brush etc
Easy access
Cons are slightly less range, and it's a bit ugly, but it will do until I build a stern arch one day
homa
Well-Known Member
blind sector?
I am also debating where to put my scanner.
I would have thought there would be a blind sector where the mast is with a pole mounted scanner at the stern.
Can anyone confirm or dismiss this?
I am also debating where to put my scanner.
I would have thought there would be a blind sector where the mast is with a pole mounted scanner at the stern.
Can anyone confirm or dismiss this?
michael_w
Well-Known Member
Re: blind sector?
I understand that in theory, there is a blind spot caused by the mast. In reality, because your boat wobbles about, this blinds spot is negated.
I understand that in theory, there is a blind spot caused by the mast. In reality, because your boat wobbles about, this blinds spot is negated.
damo
Well-Known Member
Re: blind sector?
The blind spot astern with a mast-mounted radome is surely much bigger?
The blind spot astern with a mast-mounted radome is surely much bigger?
pvb
Well-Known Member
Re: blind sector?
[ QUOTE ]
I would have thought there would be a blind sector where the mast is with a pole mounted scanner at the stern.
[/ QUOTE ]There is, but unless you put the scanner on top of the mast, there's a blind spot somewhere! With a normal mast mount, there's a blind spot astern. With a pole mount at the stern, there's a smaller (in angular terms) blind spot. The one which really amazes me is the radome mounted on the side of the mast (very popular on Hanse yachts for some reason) - in view of the mast profile, this must have a major blind spot.
[ QUOTE ]
I would have thought there would be a blind sector where the mast is with a pole mounted scanner at the stern.
[/ QUOTE ]There is, but unless you put the scanner on top of the mast, there's a blind spot somewhere! With a normal mast mount, there's a blind spot astern. With a pole mount at the stern, there's a smaller (in angular terms) blind spot. The one which really amazes me is the radome mounted on the side of the mast (very popular on Hanse yachts for some reason) - in view of the mast profile, this must have a major blind spot.
FullCircle
Well-Known Member
Stern Pros: Somewhere for the Seagull to sit watching my binnacle instruments
It was cheap, as I had it made in stainless, which I was going to do anyway for the aerial arrays.
It contains my spare VHF antenna, my Navtex aerial and my GPS Aerial
It could be used to hoist my outboard up over the rail. (I use that block for a second flag staff)
It has a smaller blind spot going forward than the stern facing blind spot if it was on the mast.
It doesnt snag the Genoa on tacks
I could dismount and repair it in 10 minutes. Wiring easy to get at.
A smaller weight aloft
I does not swing through as much of an arc as one mounted 10m above the deck, so the total movement is smaller.
The wave clutter is lessened with a flatter horizon view plane
Stern Cons: Perhaps cheaper mast mount (but I dont think so)
Fried brains. Well no as mine is 2.7m above deck level
Less range, well mine is best at 12 miles anyway, so thats enough for a boat at walking pace. 24 miles its all a bit guessworky on a JRC1800.
It was cheap, as I had it made in stainless, which I was going to do anyway for the aerial arrays.
It contains my spare VHF antenna, my Navtex aerial and my GPS Aerial
It could be used to hoist my outboard up over the rail. (I use that block for a second flag staff)
It has a smaller blind spot going forward than the stern facing blind spot if it was on the mast.
It doesnt snag the Genoa on tacks
I could dismount and repair it in 10 minutes. Wiring easy to get at.
A smaller weight aloft
I does not swing through as much of an arc as one mounted 10m above the deck, so the total movement is smaller.
The wave clutter is lessened with a flatter horizon view plane
Stern Cons: Perhaps cheaper mast mount (but I dont think so)
Fried brains. Well no as mine is 2.7m above deck level
Less range, well mine is best at 12 miles anyway, so thats enough for a boat at walking pace. 24 miles its all a bit guessworky on a JRC1800.
Boathook
Well-Known Member
I thinking of buying a furuno and mounting on the mast at low level 'underneath' the inner forestay. Will look a bit odd but well protected and well above head height. Will have to run the cable in duct outside the mast as it has polystyrene blocks inside.
MarkJohnson12345
Well-Known Member
This argument will always go on.
I put my Furuno up the mast, to get it out of the way, better range, and to keep the few brain cells left cool.
It meant taking the mast down to mount the thing, and ducting the cable down the outside of the mast. All a lot of work.
In the four years its been up, I have had to take the blessed thing down twice for servicing (replacing the rubber band)
So if you are buying a Furuno, put it on the stern, any other make up the mast will do!
There is a design fault with my Furuno, and I am now having it upgraded, so hopefully the mast ladder I bought will shortly redundant!!
Make up your own mind!!!!
I put my Furuno up the mast, to get it out of the way, better range, and to keep the few brain cells left cool.
It meant taking the mast down to mount the thing, and ducting the cable down the outside of the mast. All a lot of work.
In the four years its been up, I have had to take the blessed thing down twice for servicing (replacing the rubber band)
So if you are buying a Furuno, put it on the stern, any other make up the mast will do!
There is a design fault with my Furuno, and I am now having it upgraded, so hopefully the mast ladder I bought will shortly redundant!!
Make up your own mind!!!!
jb2006
Well-Known Member
We have a radome on a scanstrut about 2m above the cockpit seats. The radiation from yacht radars is very little hazard - dont stare straight at it from within a metre or so as your eyes are the most susceptible. Some good naval radar safety sites out there if you're worried.
For me, not fouling the headsail and avoiding the windage were significant considerations. We hoist the radar reflector up a shroud with a spare halyard when required for the same reason.
For me, not fouling the headsail and avoiding the windage were significant considerations. We hoist the radar reflector up a shroud with a spare halyard when required for the same reason.
gavin_lacey
Well-Known Member
A vertical mast / pole will not cause a significant blind spot but the horizontal boom will make a big difference if the radar is not well above it.
homa
Well-Known Member
Re: blind sector?
So there IS a blind sector
Personally I'd rather have the blind sector astern than forward.
FWIW some ships have at least 1 radar on top and usually the second in front of the mast, they will also have a large blind sector right astern on the lower scanner.
Cheers,
Homa
So there IS a blind sector
Personally I'd rather have the blind sector astern than forward.
FWIW some ships have at least 1 radar on top and usually the second in front of the mast, they will also have a large blind sector right astern on the lower scanner.
Cheers,
Homa
pvb
Well-Known Member
Re: blind sector?
[ QUOTE ]
So there IS a blind sector
Personally I'd rather have the blind sector astern than forward.
[/ QUOTE ]Yes, as I said, unless you put the scanner on top of the mast, there's a blind spot somewhere! But to put things into perspective, the "blind spot" on my boat represents an arc of only 1.3degrees. The only time this blind spot would be of real significance would be if I could maintain a steady course to within perhaps 1 degree. Usually, I can't! The blind spot astern from a mast mount would be somewhat wider.
[ QUOTE ]
So there IS a blind sector
Personally I'd rather have the blind sector astern than forward.
[/ QUOTE ]Yes, as I said, unless you put the scanner on top of the mast, there's a blind spot somewhere! But to put things into perspective, the "blind spot" on my boat represents an arc of only 1.3degrees. The only time this blind spot would be of real significance would be if I could maintain a steady course to within perhaps 1 degree. Usually, I can't! The blind spot astern from a mast mount would be somewhat wider.
