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harstonwood
08-11-12, 08:09
I know this subject has beed debated to death previously, but I need to make a decision imminently, on this matter

The boat is a Dufour 405GL

Mast mount:

Already have a bracket in the garage, fitting possible via cherry picker this winter as boat coming out.(some costs involved)

Issues: cabling difficult, and radar will definitely foul Genoa. Could sideways mount but bracket not really suitable due curvature of fixings

Not really into drilling lots of holes in the mast!

Pole mount:

Would have to purchase and install 900 prob all in maybe a bit more if I go for a SS one (not sure I like the aluminium one)

Issues: looks a bit crappy
Easy to install and service radar
No cabling issues
Can easily put other arials/lights etc on the pole

Need a decision soon......am really 50/50 at the moment

Hopeing for some good advice...Thanks!

pvb
08-11-12, 08:21
I agonised for ages before deciding on a stern pole. I went for a ScanStrut pole, and I don't think it looks "crappy". It's certainly easy to get at the radar; the pole is ball-jointed at the base, just release the 2 struts holding it and it folds down on to the deck. No wiring issues if the mast has to be removed. Some minor radar improvements - reduced mast shadow, reduced sea clutter.

sailorman
08-11-12, 08:30
i had an s/s pole made that take radar,wind gen,various antennas.
the mast has been struck 3 times since the pole was fitted & i do not have to un-wire the radar.
the radar can still see a box ship at 10 mls in good conditions

harstonwood
08-11-12, 08:32
Ok so its 2 to 0 in favour of pole so far

Sorry pvb. Crappy a bit harsh.....i certainly want to make it look good though

charles_reed
08-11-12, 08:33
Common mount on mast - gives greater range and, with overlap genoa probably needs a guard. Disadvantages, bad coverage when heeling, increased movement in a seaway, more weight aloft. Definitely not for a bendy-mast 3/4 rig.

Pole mount needs to allow variation for tack angle (scanstrut expensive and fixed) keeps seaway movement down, can foul leech lines if lacking reefing discipline, reduced range but better close quarter coverage.

Final point, where do offshore racing boats mount the radar dome?

I made my own aft-fixing 20 years ago - total cost 100 and it supports radome, aerials, PV panels and windgen.

harstonwood
08-11-12, 08:36
Ok I think thats 3 to 0

Not sure I understand your point about reefing, but perhaps applys to other makes of boat

Reefing lines will be no where near pole, possibly only furling line


Thanks for all the points so far.....very useful

sailorman
08-11-12, 08:39
Ok I think thats 3 to 0

Not sure I understand your point about reefing, but perhaps applys to other makes of boat

Reefing lines will be no where near pole, possibly only furling line


Thanks for all the points so far.....very useful

measure up its position & make sure the fixed length cables are long enough

harstonwood
08-11-12, 08:49
Thanks sailorman.

Need to measure carefull as needs to mount on Transom, and clear rails which are angled
Looking at a custom job probably.

sailorman
08-11-12, 08:53
Thanks sailorman.

Need to measure carefull as needs to mount on Transom, and clear rails which are angled
Looking at a custom job probably.

mine was made by a fabricating Co i used to use for work.
the quality is not quite as good (they had probs bending the tube) but quite acceptable. it was 1/2 the cost of the other quote. the invoice also stated :- to supply R.S.J :)

Sequoiah1
08-11-12, 08:53
Mast mount means no ungainly pole at the back end.
Canting brackets mean either pole or mast mount allow for angle of heel. (Expensive but worth the extra)
Teak decks and older fashioned boat with pinched stern meant pole took up too much room. No problem with disconnecting radar every time mast comes out modern connections mean its easier.
Radar tyransmissions well away from the skippers and crews head.
No problem with tacking 115% overlapping headsail no guard required.
Pole needs stabilising and or big bury in the deck.

harstonwood
08-11-12, 09:29
3 to 1 now

Thanks

Baggy
08-11-12, 09:37
How about one of those

Self leveling Radar Mounts on Backstay

harstonwood
08-11-12, 09:43
Twins backstays not suitable i don't think?

Only ever seen on a single one?

Unless someone knows otherwise?

charles_reed
08-11-12, 09:44
Ok I think thats 3 to 0

Not sure I understand your point about reefing, but perhaps applys to other makes of boat

Reefing lines will be no where near pole, possibly only furling line


Thanks for all the points so far.....very useful
My jiffy reefing lines, in a blow, can come very close to to both windgen and radome.

But then mine is a small boat with a very large main and I'm nearly always single-handed. The 2 last of 4 reefs are conventional horn and leech-line reefing - the 1st 2 are single line all done from the cockpit. I have to go to the mast-base to bring in the reef-lines, past slovenliness resulted in the problem referred to when tacking.
My overlap genoas are either 140 or 150% - a 115% is near enough a working jib.
In a windward blow I either use a 100% solent or a 65% yankee jib - the latter would never foul a forward mast-mounted radome.

harstonwood
08-11-12, 09:54
Yep i think mine is a 140% so concerned about fouling

The backstay mount may have just entered the debate, though I have never seen one in the UK, plenty in septic land

sarabande
08-11-12, 10:43
I'd go for a multi purpose strut at the stern. It makes it possible to add emergency VHF aerial, solar panels, high stern light, etc etc. And with a clever design it would look good on a modern boat.


As SM says, a reasonable range is 10 miles or so. A mast mount will give you more range, but the pitching angle for a fixed mast scanner will be greater than the stern one.

EDIT Ignore everything after the last comma please. :0

pvb
08-11-12, 11:01
A mast mount will give you more range, but the pitching angle for a fixed mast scanner will be greater than the stern one.

:confused:

sarabande
08-11-12, 11:03
yes, I'm thinking about that ! umm. Dunce !

lw395
08-11-12, 11:25
....
Final point, where do offshore racing boats mount the radar dome?
......

Are you referring to the satcomms domes on ocean racing boats?

john_morris_uk
08-11-12, 11:41
I don't know where this 'fouling the genoa' comes from?

We didn't have a choice where our radar was as it was already fitted to the boat, but we've never fouled the genoa on it! The radar reflector is above the radar and we can get lines caught round the reflector and/or the radar, but its very rare, and you have to be pretty stupid (or distracted!) to let it happen.

Ours is a 39' boat with a mast head rig and a big overlapping genoa. The radome is just above the spreaders and is a large old fashioned Raytheon scanner in a radome. I have never noticed any problem with the mast shadowing the radar signal, but the key arcs are forward and clear when the radar is on the mast.

We do get fantastic range from the radar, and I agree that the radiation is well out of harms way, but if the pole on the back of the boat is big enough, it shouldn't be radiating you from there either.

Ex-SolentBoy
08-11-12, 12:00
http://i1063.photobucket.com/albums/t512/44littledove/606a9ca6c3d58d12f4b7f93537fc77b6.jpg

harstonwood
08-11-12, 12:22
John
I think it could get wacked everytime you tack?

Not sure if you are advocating pole or mast......however i would value your advice

4 to 1 so far!

harstonwood
08-11-12, 12:23
http://i1063.photobucket.com/albums/t512/44littledove/606a9ca6c3d58d12f4b7f93537fc77b6.jpg

Thanks for that?...Nice job......but is the scanner not in line with boom? Needs to be higher I would have thought

Also need to be able to attach to chain plate..need to check ours out

Could be a contender!

john_morris_uk
08-11-12, 12:32
http://i1063.photobucket.com/albums/t512/44littledove/606a9ca6c3d58d12f4b7f93537fc77b6.jpgBarefoot on a boat!

(I know opinions differ, but I've seen too many damaged feet and broken toes)

Anyway I don't want to drift the thread.

To OP: I think I was voting for mast - but I'll not die in a ditch over the choice.

harstonwood
08-11-12, 12:35
Barefoot on a boat!

(I know opinions differ, but I've seen too many damaged feet and broken toes)

Anyway I don't want to drift the thread.

To OP: I think I was voting for mast - but I'll not die in a ditch over the choice.

Ok probably 4 to 2 then, though i may be leaning to backstay mount as there is a nice american unit I could get hold of

Boathook
08-11-12, 12:36
Mines a scanstrut mast mount well below crosstrees and protected from genoa by the baby stay. Not wanting to feed the cable through the mast I painted some trunking matt black to match the mast and pop riveted it on for the cable. With all the other bits on the mast it is not noticed and does not seem to get damaged either.

Chris_Robb
08-11-12, 12:37
I think the deciding factor to me would be, not the ultimate range, but the clarity of 6 to 10 miles range, and also in a rough sea. This is where there is a real down side to the amount of sea clutter on a mast mounted one.

Having got a mast mounted radome, If I was fitting again, I would have a pole, but it must be high enough not to irradiate your head!

I have never had problems with it fouling the leach of my 130% Genoa.

harstonwood
08-11-12, 12:38
Mines a scanstrut mast mount well below crosstrees and protected from genoa by the baby stay. Not wanting to feed the cable through the mast I painted some trunking matt black to match the mast and pop riveted it on for the cable. With all the other bits on the mast it is not noticed and does not seem to get damaged either.

Don't suspose you have a picture?

Was worried about drilling lots of holes.....any issues?

harstonwood
08-11-12, 12:39
I think the deciding factor to me would be, not the ultimate range, but the clarity of 6 to 10 miles range, and also in a rough sea. This is where there is a real down side to the amount of sea clutter on a mast mounted one.

Having got a mast mounted radome, If I was fitting again, I would have a pole, but it must be high enough not to irradiate your head!

I have never had problems with it fouling the leach of my 130% Genoa.

Thanks Chris
Am leaning towards a pole or back stay solution now

As you say 5 miles is sufficient

5 to 2

concentrik
08-11-12, 13:05
This is what I decided on:


For much the same reasons as have been mentioned already. There was already a wind gen on the stbd side so a radar pole just balanced it out. There's a cluster of antennae on there now so I'm glad I went for the 'bird table' version. The only prob was getting it made... you'd think it would be easy to have this fabricated but I approached SEVEN firms and none would do it.... some promised to but failed, others never sent quotes from the drawings I supplied.

The two sets of support struts are bolted to existing deck fittings. They really are needed - I started with one set and it just wasn't steady enough.

In the end I sourced the plate (metal merchants) and pole (s/s exhaust) and had it welded at my local garage. Total cost about 65. The s/s pole needs a rub down occasionally but other than that it all works fine - except the SeaMe picks up the radar, but SeaMe said it doesn't matter.....

harstonwood
08-11-12, 13:22
Thanks concentrik , looks a nice job
6 to 2 now I think
What diameter is the stainless tube?

Rogershaw
08-11-12, 13:32
This is how I did mine

Ex-SolentBoy
08-11-12, 13:37
Thanks for that?...Nice job......but is the scanner not in line with boom? Needs to be higher I would have thought

Also need to be able to attach to chain plate..need to check ours out

Could be a contender!

It's well above it.

http://i1063.photobucket.com/albums/t512/44littledove/10a1cea1628f5cfd9d8c82fd483d62cc.jpg

john_morris_uk
08-11-12, 13:39
I think the deciding factor to me would be, not the ultimate range, but the clarity of 6 to 10 miles range, and also in a rough sea. This is where there is a real down side to the amount of sea clutter on a mast mounted one.

Having got a mast mounted radome, If I was fitting again, I would have a pole, but it must be high enough not to irradiate your head!

I have never had problems with it fouling the leach of my 130% Genoa.Chris, can you just run past me your explanation of how the clutter is less from the lower scanner height!

pvb
08-11-12, 13:58
Chris, can you just run past me your explanation of how the clutter is less from the lower scanner height!

Sea clutter is affected by the angle of the wave face relative to the radar beam. The lower the scanner, the less sea clutter you get.

Bobc
08-11-12, 14:02
Barefoot on a boat!

(I know opinions differ, but I've seen too many damaged feet and broken toes)



I always sail barefoot when it's warm enough (which isn't too often in this country :( )

pvb
08-11-12, 14:06
What diameter is the stainless tube?

I reckon that the tube diameter is a crucial factor in achieving a stern pole which "looks right". Most custom poles are too thin, in my opinion, and look weak and spindly, although I'm sure they're strong enough. As I posted earlier, I went for the ScanStrut pole because I think it looks good, and is very easy to fit.

http://i87.photobucket.com/albums/k126/pvbpics/scanstrut.jpg

ghostlymoron
08-11-12, 14:07
This is how I did mine
With respect Roger, that looks like a bus shelter on the back of your boat.

pvb
08-11-12, 14:09
With respect Roger, that looks like a bus shelter on the back of your boat.

A tad harsh, perhaps. ;)

prv
08-11-12, 14:11
Not very keen on backstay mounts. I viewed a boat which had one, and it seemed to be loading the stay quite unfairly.

Don't think I've sailed on a boat with a pole - but I do currently have a mizzen mast which I find very handy to hold onto / lean against / etc and it seems like a pole might provide the same (at least on one tack).

Pete

Rogershaw
08-11-12, 14:17
With respect Roger, that looks like a bus shelter on the back of your boat.

Designed to keep the sun of in the tropics.

Pic taken our winter 2010.

Chris_Robb
08-11-12, 14:41
Chris, can you just run past me your explanation of how the clutter is less from the lower scanner height!

See PVB response - got there first - good job too as I had no idea for the technical reason!

ghostlymoron
08-11-12, 15:05
Designed to keep the sun of in the tropics.

Pic taken our winter 2010.
Looks better from further off - didn't mean to be rude.

john_morris_uk
08-11-12, 15:31
See PVB response - got there first - good job too as I had no idea for the technical reason!
Hmm - I get the idea, except I still think that the limited range of a lower radar is too big a price to pay. We get some clutter - but only when its really rough and even then its only out to a few hundred metres and who cares about those distances? If something gets in close without being spotted first it still shows up when the clutter is turned down.

For my money lowering the radome and putting up with reduced range to 'reduce the clutter' is all wrong.

pvb
08-11-12, 16:04
For my money lowering the radome and putting up with reduced range to 'reduce the clutter' is all wrong.

Do you realise how little difference it makes? Maybe 10 miles range with a pole mount, versus maybe 12 miles with a mast mount.

Chris_Robb
08-11-12, 16:20
Hmm - I get the idea, except I still think that the limited range of a lower radar is too big a price to pay. We get some clutter - but only when its really rough and even then its only out to a few hundred metres and who cares about those distances? If something gets in close without being spotted first it still shows up when the clutter is turned down.

For my money lowering the radome and putting up with reduced range to 'reduce the clutter' is all wrong.

Our set dates from 91. The clutter is quite extensive in a bad sea, even twiddling the knobs. I have used the same set on another boat - pole mounted, and there was far less clutter. So not sure whether new sets are much better. Reducing clutter obliterates small targets.......

harstonwood
08-11-12, 18:58
Not very keen on backstay mounts. I viewed a boat which had one, and it seemed to be loading the stay quite unfairly.

Don't think I've sailed on a boat with a pole - but I do currently have a mizzen mast which I find very handy to hold onto / lean against / etc and it seems like a pole might provide the same (at least on one tack).

Pete

Yep i had same thoughts, but looking at detail most weight is take by the deck or chain plate.

The one I am looking at is stainless steel tube

http://www.questusmarine.com/welcome-13.html

Ex-SolentBoy
08-11-12, 19:26
Yep i had same thoughts, but looking at detail most weight is take by the deck or chain plate.

The one I am looking at is stainless steel tube

http://www.questusmarine.com/welcome-13.html

The Scanstrut one doesnt really load the backstay very much at all.

The forces at the bottom end are big though and need a substantial mounting like this.

http://i1063.photobucket.com/albums/t512/44littledove/file-11.jpg

harstonwood
08-11-12, 19:38
Nice job

Will look at the scanstrut offering

Thanks for all the photsos today....very useful

Boathook
08-11-12, 22:36
Don't suspose you have a picture?

Was worried about drilling lots of holes.....any issues?

Not the best of pictures but not to many holes as the trunking had the sticky strip on the back. The paint has now faded and matches the mast better IMHO.

prv
08-11-12, 22:48
Yep i had same thoughts, but looking at detail most weight is take by the deck or chain plate.

It wasn't so much the static weight as the way the thing was swinging around from side to side and fore and aft. Exacerbated on that particular boat by a rather slack backstay - perhaps it wouldn't be a problem with a properly set up rig.

Pete

Adrian_
08-11-12, 22:56
You need to consider wether you're going to install (or already have) a fixed satphone antenna).

The radiation beam of the radar will interfere with the satphone antenna, so you need to have the satphone antenna higher then the radar dome and at a safe distance to it as well.

Satphone antenna on the mast and radar dome on a pole would be a good setup.

Boo2
08-11-12, 23:23
If you are going to have a mast mounted radar, is it better to mount it on the spreaders to the side or on a bracket at the front ? If there is a baby stay close in front does that affect the radar at all ?

Boo2

john_morris_uk
09-11-12, 00:16
Do you realise how little difference it makes? Maybe 10 miles range with a pole mount, versus maybe 12 miles with a mast mount.
Yes I do know - except I can see ships out to 15 or 20 miles (not that I am interested in ships 20 miles away and its not that reliable at that range.)

I've already got a wind generator on a pole on the back of the boat and as the Radar doesn't snag anything I think I'll leave it where it is.

We don't get much clutter from the sea as I said before.

Malcb
09-11-12, 01:52
As I have a 23 foot boat, I didn't want any extra weight up the mast, so I went for a Scanstrut backsaty maount with the self levelling mount. This gives very little sea clutter. Thae weight is mainly taken through the chain plate as photos show.
http://i27.photobucket.com/albums/c197/mbethwaite/P5030002.jpg

http://i27.photobucket.com/albums/c197/mbethwaite/P5030003.jpg

pvb
09-11-12, 08:10
As I have a 23 foot boat, I didn't want any extra weight up the mast, so I went for a Scanstrut backsaty maount with the self levelling mount. This gives very little sea clutter. Thae weight is mainly taken through the chain plate as photos show.


Presumably your wish to avoid extra weight up the mast was for stability reasons. But you'll most likely have ended up with even worse stability with your current arrangement.

ghostlymoron
09-11-12, 12:35
I've just done a quick review of boats on Boatshed (http://www.boatshed.com/sail_boats_27_to_34_foot-category-2.html) and the majority seem to have the radome on the mast.

johnalison
09-11-12, 13:47
I think there are national differences here. My impression has been that German, Dutch and other Northern sailors have largely opted for aft-mounted radars and a liking for mast mount is beginning to look old-fashioned and peculiarly British.

Scarboroughsloop
09-11-12, 13:56
Mine is currently on the mast, but if I was fitting it I would use a pole aft on a self levelling fitting due to less weight aft, reduced sea clutter with minimal loss of distance, ease of washing the scanner and also maintenance.