Where to mount a radar?

[Cheeky Girl]

Hi
As per a previous post, I planning to upgrade my navigation instruments etc.

One of the new purchases was to be a radar.
The original intent was for it to be mast mounted but now I am wondering about a radar pole on the transom.
This would solve the problems associated with disconnecting each time the mast is lowered and also reduce the weight higher up as I also have in-mast reefing.

What are the thoughts?

 

[Zing]

I don’t think poles are great. The mast and boom will block an important area of signal. Especially bad I think is where people put it on the stern at or near the level of the boom. A huge chunk of metal right in-front of it. I’d put it on the mast near the first spreader or maybe actually on it. Pick the stbd one if you do that as that is the side you want best vision from.

 

[Old Harry]

Hi
As per a previous post, I planning to upgrade my navigation instruments etc.

One of the new purchases was to be a radar.
The original intent was for it to be mast mounted but now I am wondering about a radar pole on the transom.
This would solve the problems associated with disconnecting each time the mast is lowered and also reduce the weight higher up as I also have in-mast reefing.

What are the thoughts?

My thought train a few years ago, & in good conditions see a Box Boat over my horizon 10+ mls

 

[[70521]]

My radar is mounted on pole attached to the transom. I've NEVER had any issue with blind spots due to the mast or boom. OK, I think Noah's dad this model, it's a Raytheon R10 X, if all this new 4G stuff can't see past a mast or boom it is all pretty flaky.

 

[Zing]

My radar is mounted on pole attached to the transom. I've NEVER had any issue with blind spots due to the mast or boom. OK, I think Noah's dad this model, it's a Raytheon R10 X, if all this new 4G stuff can't see past a mast or boom it is all pretty flaky.

It’s quite clever the way radar hides obstructions. My radar is on the mast and the obstruction rearwards is rather big, yet if you just look at the radar and pretended you didn’t know the mast was there you would think it wasn’t there. The radar ignores it and does not reveal it, yet it is there and it does hide the signal and targets disappear. Maybe you just haven’t noticed this.

 

[Zing]

And another thing. Poles are visual clutter. If you like clean lines on your ship then a pole is no good. Not that radar on the mast is great of course.

 

[Old Harry]

My radar is mounted on pole attached to the transom. I've NEVER had any issue with blind spots due to the mast or boom. OK, I think Noah's dad this model, it's a Raytheon R10 X, if all this new 4G stuff can't see past a mast or boom it is all pretty flaky.

Zing steers a very accurate course without any yawing at all

 

[pvb]

The original intent was for it to be mast mounted but now I am wondering about a radar pole on the transom.
This would solve the problems associated with disconnecting each time the mast is lowered and also reduce the weight higher up as I also have in-mast reefing.

I had a pole mount on my last boat (which also had in-mast reefing). It's easy to mount it at a height such that the boom doesn't interfere with the signal. The mast will still cause a shadow, but because the distance between pole and mast is some metres, the size of the shadow in angular terms is much less than the backwards shadow experienced by a mast-mounted radome.

As you say, it avoids problems with the wiring when unstepping the mast. And it makes the radome more easily accessible if you need to get at it - I used a ScanStrut pole with a ball-jointed base, so I could just loosen the struts and lower the pole to the deck if needed. A pole mount can also be used as a base for an antenna, light, etc.

Radar range is still more than adequate with a pole mount, and an added advantage is a reduction in sea clutter.

If you decide on a pole mount, I'd recommend the ScanStrut system, it's well-engineered and easy to DIY fit. It's not cheap, but a custom pole won't be especially cheap, and the ScanStrut pole looks right too - nicely finished and fairly chunky. I think one mistake many people make with custom stainless steel poles is to have the pole diameter too small, so they look spindly.

 

[pvb]

I’d put it on the mast near the first spreader or maybe actually on it.

I'd caution against mounting a radome on a spreader; they're not designed for that!

 

[Zing]

I'd caution against mounting a radome on a spreader; they're not designed for that!

Obviously not on your dinghy’s spreader.

 

[pvb]

Obviously not on your dinghy’s spreader.

Not on the majority of cruising yacht spreaders either.

 

[doug748]

You probably have room for one of these:

Self-Levelling Radar Mounts SCANSTRUT

The Rolls Royce solution with a price to match.

I would avoid putting a scanner on the mast of a modestly ballasted boat alongside existing roller main.

.

 

[PaulRainbow]

I don’t think poles are great. The mast and boom will block an important area of signal. Especially bad I think is where people put it on the stern at or near the level of the boom. A huge chunk of metal right in-front of it. I’d put it on the mast near the first spreader or maybe actually on it. Pick the stbd one if you do that as that is the side you want best vision from.

It’s quite clever the way radar hides obstructions. My radar is on the mast and the obstruction rearwards is rather big, yet if you just look at the radar and pretended you didn’t know the mast was there you would think it wasn’t there. The radar ignores it and does not reveal it, yet it is there and it does hide the signal and targets disappear. Maybe you just haven’t noticed this.

Think you might want a r-think here

Putting a radome, which is likely to weigh in excess of 7kg, on a spreader doesn't seem like a great idea to me.

You then talk about the "rather big rearwards obstruction" because yours is mounted on the front of the mast. What sort of port obstruction do you think there would be with the radome being mounted on the stb spreader ? Bare in mind, the masts side profile is probably 5 times that of the front profile.

 

[Zing]

Think you might want a r-think here

Putting a radome, which is likely to weigh in excess of 7kg, on a spreader doesn't seem like a great idea to me.

You then talk about the "rather big rearwards obstruction" because yours is mounted on the front of the mast. What sort of port obstruction do you think there would be with the radome being mounted on the stb spreader ? Bare in mind, the masts side profile is probably 5 times that of the front profile.

That depends on your spreader obviously. I can stand on mine, so they are fine. If you can't then put it somewhere else.

Radar needs to look forwards for 99% of what you need it for. So rearward obstructions don't matter much. Side obstructions are not ideal of course (but not terrible), hence why in front of the mast is best.

Not mentioned, but a tight fitting solent self tacker would be an important constraint on this also.

 

[johnalison]

I had a radar put on a pole back in 2000 and never regretted it. The radar antenna is not a point source and only has to cope with with lateral section of the mast, albeit slightly offset, so any shadow would only be partial.

Advantages of a pole-mounted radar include much less weight aloft. 7Kg or so halfway up the mast is a not insignificant factor in a small boat.
Wiring and servicing the radar is easier, and there are no problems is the mast needs to be taken down.

A radar mounted low is hardly affected by sea clutter.

A potential problem is loss of range. For my basic set, ships are seen at 10-20 miles, so I consider this acceptable.

A pole mount should be on the starboard side. This allows a rescue helicopter to make its normal approach from the port quarter.

 

[[70521]]

It’s quite clever the way radar hides obstructions. My radar is on the mast and the obstruction rearwards is rather big, yet if you just look at the radar and pretended you didn’t know the mast was there you would think it wasn’t there. The radar ignores it and does not reveal it, yet it is there and it does hide the signal and targets disappear. Maybe you just haven’t noticed this.

Oh well, if what you say is true and I have some missing returns from the front and you have some missing returns from the rear they cancel each other out. I'm not worried about incoming Exocet missiles - just as long as I can work out where the hard stuff is so I can avoid it in fog.

 

[LadyInBed]

My radar is half way up my mizzen. I've never had a problem with the main mast or with wet sails.

 

[Star-Lord]

My Radar is on the mast. With a small boat I see there are advantages of having it on a pole astern. This pole imho would be custom made and suitable for a bunch of other stuff as well! Like a spare VHF antenna, Navtex antenna, Wifi booster, Iridium, and any other arial or antenna you can think of.. I would also double the poles duty and use it as an outboard davit like this ┤I often see antennas and such on stern guardrails and they are asking to be knocked off... I have knocked mine off till I mounted everything on a solar arch.

 

[jiris]

I'd caution against mounting a radome on a spreader; they're not designed for that!

Can you list the design features preventing this type of mounting?
I am interested, because I have this solution on my 40 ft sloop for some 10 years and never seen any problems with it. Always happy to learn.
The advantages of the spreader mount:
1) Mechanically easy
2) Easy to access for maintenance
3) If on the right spreader, the only sector obscured by mast is a few degrees on the left hand side - the side you don't have to give way from. The all important bow and stern sections are unobstructed.

I dare to say, from the functionality point of view it is the best position there is.

 

[pvb]

Can you list the design features preventing this type of mounting?

Spreaders are designed to take loads axially, not the bending loads associated with mounting a heavy radome on top.