Reply
 
Thread Tools Search this Thread
 
Old 06 November 2007, 11:47   #1
Member
 
Country: UK - England
Town: Towcester
Boat name: TBA
Make: Delta
Length: 6m +
Engine: Suzuki 175
Join Date: Nov 2002
Posts: 328
Sea Me Active Transponder

Hi
I am just finalising electonics on a new boat.
One that gets added and then removed from the list is the Sea Me. I then reconsider and add it back it on the list again... and then become uncertain of its benefits...

It sounds ideal having a Sea Me installed (in addition to a suitable fixed radar reflector) in that ships and boats recieve back an amplified signal.

The band width of operation is X band (9.32 to 9.5 GHz)

what radars work on this frequency? is it all leisure radars? big ships I am told may operate on S band, which Sea Me will not pick up.
When do ships operate on S band, and why?- do they have two radars operating together giving the advantages of 'S' and 'X' band reception to the ships master/Nav office?
Any advise welcomed
(well except some of course!!)
__________________

__________________
Paul Beaurain is offline   Reply With Quote
Old 06 November 2007, 13:35   #2
RIBnet admin team
 
Poly's Avatar
 
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: 2 stroke YAM 20 HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 10,114
There have been discussions here in the past (following the ouzo tragedy springs to mind) - although I am sure the proponents will express their views again.

Are you planning a radar too? It strikes me that for not an awful lot more money you could have the benefit of you being in control of the observation and decision making rather than waiting for the skipper of the ship to wake/sober up...
__________________
Poly is offline   Reply With Quote
Old 06 November 2007, 14:32   #3
Member
 
Country: UK - England
Town: Exmouth, Devon
Length: no boat
Join Date: Oct 2004
Posts: 765
As I understand it (and i'm sure someone with commercial experience will correct if necessary) is that S-band offers less resolution but also suffers less from clutter. So in open sea, S-band is likely to be used. Closer in, X-band offers better detail and target discrimination but generates more clutter so needs a bit more attention/tuning. 'Leisure' radars are X-band.

If you're coastal crusing, the larger vessels 'should' be more likely using X-band.

I suspect it's the bridge's decision which one they use in any given situation so it'll be the one using S-band that gets you.

As Polwart says, for the price of the Sea-Me you're half way to a radar scanner (assuming you have a chartplotter display than can handle it).

Which fixed unit did you go for? I think the Exhomax or Tri-Lens appear to be the better ones. Various tests have produced slightly different results and of course a lab test is never the same as the real world.
__________________
www.allgadgets.co.uk
Tel 01395 227727
MikeCC is offline   Reply With Quote
Old 06 November 2007, 15:31   #4
Member
 
Country: UK - England
Town: Towcester
Boat name: TBA
Make: Delta
Length: 6m +
Engine: Suzuki 175
Join Date: Nov 2002
Posts: 328
Radar Already ordered

Yes to Radar

Have aRaymarine 2KW Raydome as the main blind tool, with C120 plotter.
What I have found (on a well equipped charter RIB) is that we found us wanting the Radar on a different scale to the main chart plotter and overlaying was thus less usefull.
We had a week in the West Coast of Scotland and had some very poor vis days. What shocked me is how poor some boats (sailing mainly) showed up.
I am trying to avoid that being us.
Paul
__________________
Paul Beaurain is offline   Reply With Quote
Old 06 November 2007, 19:52   #5
Member
 
The Grocer's Avatar
 
Country: UK - Scotland
Town: Kildonan, Arran
Boat name: Cowal (& Bennan)
Make: Quinquari Humber/RC
Length: 6m +
Engine: Suzuki DF150/DF175x2
MMSI: 235036953
Join Date: Jun 2006
Posts: 296
Quote:
Originally Posted by Paul Beaurain View Post
We had a week in the West Coast of Scotland and had some very poor vis days. What shocked me is how poor some boats (sailing mainly) showed up.
I am trying to avoid that being us.
Paul
Hi Paul,

The yotties have a 30 foot (minimum) stick to hang radar-reflective gadgets from. We RIB types are mostly about 6 feet asl. (I'm less, you'll be more... ) If the WAFIs are invisible, what's our return going to be?

Use your radar, and if anything bigger appears - run away!

If you're not convinced they've seen you, you can always use a searchlight or a white flare.

(Para, through the bridge window if necessary )
__________________
Russell
The Grocer is offline   Reply With Quote
Old 07 November 2007, 06:49   #6
RIBnet admin team
 
Poly's Avatar
 
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: 2 stroke YAM 20 HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 10,114
Quote:
Originally Posted by The Grocer View Post
Hi Paul,

The yotties have a 30 foot (minimum) stick to hang radar-reflective gadgets from. We RIB types are mostly about 6 feet asl. (I'm less, you'll be more... ) If the WAFIs are invisible, what's our return going to be?

Use your radar, and if anything bigger appears - run away!

If you're not convinced they've seen you, you can always use a searchlight or a white flare.

(Para, through the bridge window if necessary )
grocer, quality of reflector makes a big difference also though. so investment in a good reflector is worthwhile if you have the space etc for it.
__________________
Poly is offline   Reply With Quote
Old 07 November 2007, 10:15   #7
Member
 
Country: UK - Scotland
Make: HumberOceanOffshore
Length: 8m +
Engine: Volvo KAD300/DPX
Join Date: Oct 2002
Posts: 4,962
Paul, it's fine having your own radar and looking out for yourself and that's generally what I do but there are times when you want a vessel to know you are there and to allow them to see your likely intentions.

I guess, to some extent, it depends were you are boating and whether the commercial traffic is a risk to you and you to it.

Here, in the Firth of Forth, the access to the firth is from any direction and into two chanels which converge into one. Vessels travel roughly centrally and then split into two channels and then one of these splits again and the estuary is generally narrowing. There are various anchorages so vessels also travel outwith the channels. It's seriously spooky the number of times we would have been in a collision with commercial traffic if we had done our journey without paying attention.

Now, it's fine me knowing the other vessel is there but if I was in the commercial vessel I'm sure I'd like to know if there is traffic that could be a risk to me. Giving the skippers of other vessels peace of mind by being aware you are there and giving an indication to them of your intention by your actions, I feel, is good practice.

Should you become disabled in a shipping lane, you'll want a vessel bearing down on you to be aware you're there and you'll want them to know that in plenty of time. Given the speed commercial vessels travel, seeing you just a mile off their bow is not going to be adequate.

Given the poor performance of passive reflectors, I feel an active transponder is a worthwhile thing to have.

Whether the commecial folk are looking out on X-band you have no control over but they should be, especially in restriced waters where they will know X-band radar is more likely to be in use.

Contacting a vessel which may be bearing down on you is another issue. The crude way is a flare and hope someone is looking out of the window but to give a large vessel sufficient warning to take evasive action means you are going to have to release the flare fairly early. Shouting on the VHF and hoping they are monitoring ch16 is another way. Calling the local traffic service and giving them your position they will be able to alert the vessel for you and give you the vessel's name so you can speak directly. Again, time is important.

AIS may be a solution because you will have the vessel's direction, speed and MMSI. This is the route I've taken and, fortunately, I've not needed to use it in anger. Hopefully, I never will.

However, I'm hoping AIS will prove to be generally useful in another way because on a number of occasions I have misread the direction of travel of a vessel. This has happened when the light is such that the vessel is a silhouette and I'm viewing it at an angle. It has been difficult to tell whether it's moving, particularly if it's moving slowly, or whether I'm viewing the stern or the bow. Stopping and viewing the radar to plot its track is one way but when one's helming, decisions are made by what one sees and unless something alerts one to a problem then the incoming information is processed without thought. If some of that information is faulty one may be in for a surprise!
It's a surprise I'd rather not have.

Alerting other vessels brings me on to the crappy design of VHF radios....another time.
__________________
JW.
jwalker is offline   Reply With Quote
Old 08 November 2007, 07:16   #8
Member
 
Country: UK - Wales
Town: Pwllheli-North Wales
Boat name: Delta 1
Make: Delta
Length: 6m +
Engine: Mariner 90hp Optimax
Join Date: Mar 2001
Posts: 2,367
Quote:
Originally Posted by Paul Beaurain View Post
Yes to Radar
What shocked me is how poor some boats (sailing mainly) showed up.
Paul

Whats even more shocking is how many people who have radar don't know how to use it or use it properly, its not like a Chart Plotter where you turn it on and watch. Allot of people leave everything on auto mode rather than setting it up properly. On an RNLI exercise we did a search using the radar on auto setting and missed the casualty, in the same search pattern with the radar being continuously altered and set up manually we got the casualty pretty much straight away.

Look at the slides below, container ship going along at 20 knots, he sees a yacht with a see mee on the stbd bow and calculates it passes in front of him. Its poor visibility so he cant see the yacht and he assumes it passes in front because he he sees it on the radar astern of him, what he actually sees is the see mee on the wreckage still transmitting.

Hes non the wiser.

Jono (not suggesting you don't know how to use it) Garton
Attached Images
     
__________________
JG Marine Services Ltd Specialist Safety Boat Services

Bodfuan Shoot Ltd Traditional British Game Shooting
Jono Garton is offline   Reply With Quote
Old 08 November 2007, 08:36   #9
Member
 
Country: UK - Scotland
Make: HumberOceanOffshore
Length: 8m +
Engine: Volvo KAD300/DPX
Join Date: Oct 2002
Posts: 4,962
Quote:
Originally Posted by Jono Garton View Post
...Its poor visibility so he cant see the yacht and he assumes it passes in front because he he sees it on the radar astern of him, ..
Jono, my response to that is simple.

1) He's a fool to presume that.
2) He might well see the wreckage anyway.
3) Since I've never seen a radar screen which looks like that, I presume this is one of those silly, hypothetical training questions/solutions.

__________________
JW.
jwalker is offline   Reply With Quote
Old 08 November 2007, 10:59   #10
Member
 
Country: UK - Wales
Town: Pwllheli-North Wales
Boat name: Delta 1
Make: Delta
Length: 6m +
Engine: Mariner 90hp Optimax
Join Date: Mar 2001
Posts: 2,367
Quote:
Originally Posted by jwalker View Post

1) He's a fool to presume that.
2) He might well see the wreckage anyway.
3) Since I've never seen a radar screen which looks like that, I presume this is one of those silly, hypothetical training questions/solutions.


1) I agree, but it happens
2) Depends on visibilty and ho many containers are stacked in front of the bridge
3)I think you get the idea about the radar screen

The point is; use your radar to the full and asume that others cant see you. When searching for casualties on the lifeboat we allways find the VHF DF equipment more usefull than radar.

Jono
__________________

__________________
JG Marine Services Ltd Specialist Safety Boat Services

Bodfuan Shoot Ltd Traditional British Game Shooting
Jono Garton is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 03:41.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.