Radar detectors

[codprawn]

Anyone remember the Lokata Watchman? They were hand held radar location units ideal for small boats like RIBs that don't carry their own RADAR. You could pick up bigger ships and tell what direction they were coming from. They tried to ban them as they used technology similar to RADAR homing missiles.

There don't appear to be many products out there these days that do the same job - a big gap in the market.

The only one I could find was this

http://www.survivalsafety.com/

£250 makes it a lot cheaper than any RADAR!!!

Don't know if it would stand up to use on a RIB though - would be ideal for many uses - especially if you have a Crompton........

I also wonder if a car type RADAR detector would work - DF would be difficult but at least you would know when you are being pinged - NautiBoy could have done with one!!!

[Poly]

Originally Posted by codprawn

I also wonder if a car type RADAR detector would work

How wide a frequency range do they pick up? I'm pretty sure speed traps normally use a different frequency to boats - otherwise presumably when driving near the coast within range of ships you would get constant false alarms on your radar detector if it was sensitive enough (and if it wasn't it would be of little use on a boat).

[jwalker]

Originally Posted by codprawn

..but at least you would know when you are being pinged ..

In busy areas you'll be pinged most of the time and I guess the local navigation service radar will be pinging you too. If you have your own radar you'll ping youself.

[havener]

These days, an AIS detector is probably a better bet...

[Poly]

Originally Posted by havener

These days, an AIS detector is probably a better bet...

An AIS detector? I presume you mean receiver - in which case it tells you a ship is there but doesn't tell the ship about you. It also will only (in general) show you boats large enough to be required to carry the transmitter. It also assumes they are operating the equipment correctly and paying attention to it...

[havener]

Originally Posted by Polwart

An AIS detector? I presume you mean receiver -

Yes, I meant receiver.

in which case it tells you a ship is there but doesn't tell the ship about you.

Yes, it doesn't tell the ship about you, but neither does the CARD device mentioned earlier.

It also will only (in general) show you boats large enough to be required to carry the transmitter.

It will show all ships >300GRT, which IMHO probably present the largest collision risk group, much more than, say, motor cruisers or yachts.

It also assumes they are operating the equipment correctly and paying attention to it...

No, it doesn't. AIS is a passive system for the bridge - i.e. you don't need to be watching it, making it work, etc. The vessel MMSI information is a constant real time broadcast, and the course / cargo / port of call / destination info is again an automated data burst, usually every 10 minutes. AIS systems are inspected as part of any Port State Inspection, and there are heavy penalties for disabling it.

The inbound AIS data (i.e. from other vessels) is automatically fed into the radar system on the bridge, and will trigger all the usual bridge alarms, etc depending on CPA setup (closest point of approach). Yes I accept all the points about poor bridge watchkeeping, which is why I'd never rely on someone else seeing you. AIS will give you that "heads up" to something large being around.

Simon

[Poly]

Fair points Simon.

I am interested that you are only concerned about hitting a ship though? are other small craft not just as likely to present a problem - albeit they may be more manouverable. There is less chance they will have seen you (no tools to help). There is a reasonable prospect that they will do something unpredicatable in response to a potential collision situation (whereas the ship has a qualified watch officer and is more likely to follow the ColRegs). At night I suspect spotting a yachts masthead light from a rib will be harder than spotting those of a large ship.

[havener]

I'm probably biased towards the risk posed by big ships because I spend most of my life on the things

Seriously though, if you're talking about close quarters incidents, the risk with a big ship is, simply, size.

At night, or in poor vis, a large container vessel /VLCC can block out the horizon from a small boat to the point it is almost invisible. If you're doing 20 knots towards a yacht, and suddenly realise it's there, almost any change of course will get you out of danger, either a U turn, or around the bow / stern. If you're faced with something 400m long, and suddenly realise it's there, then the around the bow/stern options suddenly disappear, and the bow wave will probably make the U turn option pretty difficult.

And it does happen - I had a rib stuff itself into the middle of our vessel a while back, claiming he had seen the superstructure and thought it was at the stern (we are a large salvage tug and the accommodation is all forward). He therefore attempted to skirt around the stern - only to find he was midships

The only funny side was that he hit us almost in the middle of the large yellow painted letters saying "Rescue Zone"