Best location for radar scanner (radome, not open) on 32' yacht

[jwrhind]

Best location for radar scanner (radome, not open) on 32\' yacht

Hi

I bet that this has been discussed lots of times, but I didn't find the answer with a search of the forum.

Considering the better location for an 18" radom.

Which is better, and why, in your opinion(!)
(a) on the front of the mast on a bracket just above the first spreaders
(b) on a pole on the aft quarter

Option (a) is my preference - jusy wooried that it will tend to damage the genoa or interfere with tacking. I've seen one yacht with the scanner mounted on the mast, but just slightly behind it and to the right. Any thoughts on this position?

Thanks
JR

 

[Freebee]

Re: Best location for radar scanner (radome, not open) on 32\' yacht

the higher it is the further it can see which is the highest?

 

[ashanta]

Re: Best location for radar scanner (radome, not open) on 32\' yacht

The higher it get's the more effect there is against the balance and effect of the keel. I am sure there will be one or two forumites who will be able able to provide the specific data bit, but in a nutshell the higher you go the worse it gets.
I have my radar radome in the conventional position on a Bermudan rig as you described. My boat was an ex racing yacht and it didn't have a radome when I bought her. It depends on what you want to do with your boat that matters. I know when I have to reef my boat as a cruising yacht the radome therfore does not become a liability.

Regards.

Peter

 

[yachtbits]

Re: Best location for radar scanner (radome, not open) on 32\' yacht

Pro's and Con's

up mast.

advantages,
increased waterline horizon due to extra height.
doesn't get in the way in cockpit.

con's
Hassle of scanner cable in mast and the problems it causes during mast removal.
Increased scanner movement in rough weather resulting in poor performance.
Potential for fouling sails/rigging.

On Stern Pole

pro's
Much easier to install.
You don't loose radar in event of demasting
Can provide mounting for permenantly installed reserve VHF antenna
No Aft blind spot due to mast, fwd mast blind spot less noticable due to distance from mast.


Other considerations.
Although waterline horizon will be reduced to say 5-6 miles on a pole, how often do you look for a small target at that range?
Larger vessels and coast lines will be seen at greater range due to their height above waterlevel.

Personally, I'd stick it on a pole. If you buy a scanstrut pole, you can fit it in about an hour.

kev

 

[MarkJohnson12345]

Re: Best location for radar scanner (radome, not open) on 32\' yacht

I installed my radar last year. I decided the mast was the best bet.

Main reason was that a pole on the stern would be a bit fragile on the narrow stern of a Sadler 32, and in Swansea we have to lock in and out of the river. Anything on the stern might get a clout fom another boat, or the lock pontoons.

Once it is up the mast, its well out of the way. I ducted the cables on the outside of the mast, with out a break at the deck.

If I need to take the mast down the radar will have to be dismounted, but that has only four bolts and a wire strop. It will not be too much bother with the riggers when then mast is taken down.

As others have said, range is better, and you won't fry your brains when scanning!

regards

 

[pvb]

I\'ve just gone for pole mounting...

I've just put an 18" radome on a ScanStrut modular pole on my boat. Mast mounting would have been cheaper, but I have in-mast furling and really didn't want to increase weight aloft. I put the pole inside the pushpit, so it's not vulnerable to damage, and I've mounted the GPS antenna on it as well. The ScanStrut gear is very good quality and is substantially engineered.

Mounting the radome on the side of the mast is likely to greatly reduce the radar's performance to one side of the boat. As far as I'm aware, ultimate range isn't really needed in small boat radar, so the extra height of a mast mount doesn't really matter. Also, many people take the view that sea clutter is likely to be less of an issue with a pole-mounted radome.

 

[Das_Boot]

Re: Best location for radar scanner (radome, not open) on 32\' yacht

Why is it so difficult to make any decision when it comes to sailing boats.
I wanted to put my radar on the mast below the first spreaders now having read the posts I am not so sure. I now have more questions than the original poster.
1. How high is the transom mount as this seems a good option.
2. Will it fry my brains I am under 6ft
3. Taking on board the de-masting issue what if you get pooped.
4. Do radars have a 360 view I just assumed they did not look back therefore the mast would not make a difference.

Bugger me this has opened a whole new line of investigation and it took me about a year to decide which radar.

Excuse my ignorance but it is my first foray into the world of radar.

 

[fireball]

Re: Best location for radar scanner (radome, not open) on 32\' yacht

1. Dunno - I'd like to know too ... I would hazard a guess at 3-4 foot above head hight when standing at the helm.
2. Not if it is high enough - and then it depends on the power of the radar
3. If your de-masted you've usually got enough problems - but a pole mount does give a high point for spare antenna ...
4. yup - 360 view ... you'd be b*ggered if you were pottering merrily along in fog - clear radar screen, only to find a big f*ckoff tanker up your stern ....

I'm leaning towards the pole mount myself .. I can see the advantages of up the mast but I'm just not certain ....

 

[Talbot]

Re: Best location for radar scanner (radome, not open) on 32\' yacht

My prefered position is on the mast but under the baby stay. This provides abt the same height as the tallest separate strut without the staying problems, solves the problem of interaction with the genoa, doesnt put the weight too high up the mast, and more importantly does not cast a shade over my solar panel. Howwever, it does still leave a small blind spot right aft - normally covered when swmbo is on the wheel by the snake like pattern introduced into the wake! /forums/images/graemlins/wink.gif

 

[Das_Boot]

Re: Best location for radar scanner (radome, not open) on 32\' yacht

I am begining to prefer the transom pole mount option. The stern of my boat will be adequate. The thing about under the inner fore stay is that I think I bought the 24'' radome. I will have to check when I get home it is still in the box. I would have to bring it pretty low down on the mast to stop it interfereing with my headsail when tacking. I dunno I will have to go down to the boat and check. Thanks for info it has opened a new option that I had not thought of.
I was putting off the decision as a few issues were niggeling me.
cheers

 

[Strathglass]

Re: Best location for radar scanner (radome, not open) on 32\' yacht

Interesting post.
It is helping me to make the right decision.

Iain

 

[Sans Bateau]

Re: Best location for radar scanner (radome, not open) on 32\' yacht

I am moving our radar from the aft to the mast, mainly to get more height. However there is another good reason to have the aft deck clear. In the unlikely event that the boys from the CG needed to make a high wire visit, I would'nt want to have any obstruction in their way, it could just be me that they have come to rescue.

 

[pvb]

Transom mount info....

The ScanStrut modular poles are available in 2 lengths - 1.9m or 2.5m - and people usually use the shorter one for deck mounting and the longer one for transom mounting. They use a fully-adjustable ball-jointed foot, so can be mounted on any surface easily. There's a choice of support struts or rail mounts, and a very neat shaped platform to suit Raymarine radomes (or a plain square one for other makes). Properly fitted, the pole is very sturdy and there would be no problems with it in the event of being pooped. Full details on the ScanStrut website.

My deck-mounted pole puts the scanner above head height when standing on the deck, and well above head height when standing in the cockpit. It won't fry brains!

 

[FullCircle]

Re: Best location for radar scanner (radome, not open) on 32\' yacht

Hi all,
I am also a Radar novice, but I decided to design my own transom strut on the basis:-

Polished Stainless 50mm tube and bottom bracket made to boat hull shape , with bracing to pushpit top/centre rail. Custom fixed radome mounting and stalk brackets. Cable glands for waterproofing. Could add a forward facing deck/cockpit flood light or high mount stern lamp if required.

MOBO's have radars, and they dont have it mounted on a skyhook, so height is not a problem. I have decided not to fry my alcohol sensory receptor centre, so my pole is 2.8m above deck. Also it is just off to the port side of the stern entry. Tried to keep it relatively central.
I didnt think that the 1,9m or the 2,5m Scanstruts were high enough. I could be wrong, as I don't have access to their design criteria.

I have also mounted a spare VHF, GPS and NAVTEX on a stalk bracket under the radome.

The bracket curves outward at pushpit level by about 300mm so the helm doesn't lean on it

I considered gimballing the radome and damping it hydraulically, but decided against eventually. The angular movement on 20 degrees of heel at 2.8m pole is less than a third of 9m up the mast.

Practically zero blind spot as mast is a long way. I calculated that the mast blind spot was 7-8 degrees of rotation if mast mounted

Radome is much more serviceable on pole.

Wiring is simpler, as RADAR/Chartplotter head is in binnacle on deck.

Queue up when I tell you that I paid less than 1/2 a Scanstrut cost, with more functionality, and custom made to the boat where I wanted to fit it. Hydraulic damping would add about 100 quid.

We will see how it works soon! /forums/images/graemlins/smirk.gif


Jim

 

[Sans Bateau]

Re: Best location for radar scanner (radome, not open) on 32\' yacht

Sounds good, but your GPS is best at the lowest position possible ( less movement), pushpit might be better. Also, I know with my Navtex ariel, they suggest mounting it clear of any obstruction, to avoid shadow effect, should be good so long as it is well clear of radar scanner.

 

[anglo_saxon]

Re: Best location for radar scanner (radome, not open) on 32\' yacht

not wanting to make matters more confusing but i am having mine mounted on a gimbled mounted bracket which is mounted on the back stay with suport pole. (extra height and no shadows). see hallberg-rassey site for pics. i belive its made in the uk.

 

[capt_courageous]

Re: Best location for radar scanner (radome, not open) on 32\' yacht

The distance a radar can 'see' in miles goes up with the square root of the scanner hight in feet times about 1.2.
So if your scanner is at 9 feet the distance to the radar's horizon is
3 * 1.2 = 3.6 miles
At 25 feet the range is 5 * 1.2 = 6.0 miles

That does not sound a lot but remember that is to the horizon - not to the actual target. Ships, land etc. can stick up a long way above the horizon and so you can add a similar 'range' for the height of the target. It is a compromise you have to make - more hight more range but the height of the target is also very important.
It does not matter if it is a radome or open type.

 

[pvb]

Just to put this into perspective...

In case you think that the difference in range between pole-mount and mast-mount is significant, let's look at a real world scenario. Let's assume there's a ship over the radar horizon. Say it's 81 feet high. The ship will theoretically be visible when it's 9 x 1.2 = 10.8 miles the other side of the radar horizon.

So the scanner on the post at 9ft high will detect the ship at 14.4miles (3.6 + 10.8).

And the scanner on the mast at 25ft high will detect the ship at 16.8miles (6.0 + 10.8).

Result? Putting the scanner on a stern pole only reduces the range in this instance by 14%.

 

[FullCircle]

Re: Best location for radar scanner (radome, not open) on 32\' yacht

Yes I agree about the GPS, but I won't swipe it at pushpit level heaving the outboard over the rail, so its all a compromise really. Also looks like bloody Jodrell Bank.....

 

[sailorman]

Re: Just to put this into perspective...

i have a Raytheon 18 inch scanner on a pole ( after much thought ) & am able to see a container ship @ 10 N mls + on radar in good conditions.
scanner approx 3 M above the water line. thats good enough for me.
plus side dont have to disconnect anything when mast is struck