Collision Avoidance Sonar

[Guest]

I am currently looking for an instrument that detects objects in water which has the potential to damage my craft and steer away from it.
All this will be on autopilot. No human intervention.
Any suggestions?

<P ID="edit"><FONT SIZE=-1>Edited by princepodgy on Thu Nov 22 15:01:04 2001 (server time).</FONT></P>

 

[Guest]

visit www.hydrography.ims.plym.ac.uk or e-mail tcrichton@plymouth.ac.uk Tom Crichton is lecturer in navigation and hydrography at the Institute of Marine Studies, University of Plymouth where they have a survey vessel fitted with the sort of gear you are looking for.

 

[claymore]

One notices that one left price out of that little gem.

I tend to use routes and have the gps linked to the autohelm. If bound for Ireland from Fleetwood my route takes me to Langness then left down to Calf Sound then right and through all the way to Ardglass. It seems to work a treat and I have avoided collisions with the Isle of Man very well up to now. If the object is floating or moving around we have people like myself looking round and this also works well. After dark? Shit sometimes happens.

 

[Twister_Ken]

An extremely long and rigid pole, sticking out from the bow at waterline would hit the threatening object first. Depending on the angle of the blow, it would either stop the boat dead, or ricochet it to P or S. Either way, a collision would have been avoided. The noise of pole striking object would also serve as an alarm for the watchkeeper.

My apologies, though, that this device is somewhat low tech compared with sonar, radar, microwaves, etc.

 

[claymore]

Angled up to the stemhead a bell could be attached which would ring on impact. This improvement ought to satisfy the technocrats and campagnol/campygrnol/damn - bell ringers. Also angled down in this manner it ought to strike the top of the object and push it down and under the keel allowing vessel to proceed safely. Perhaps your new-found tall-building trigonometric abilities could actually suggest the optimum angle?

 

[Guest]

System for sale in Florida

There are some used units whcih do the job for sale in Florida - I used to use one and it was VERY effective.

The one's I'm thinking of are currently fitted to US NAVY Spruance class destroyers which are mostly up for sale for "parts". The sonar dome is about 35' in diameter though, so your local chandler will be quite busy fitting that to your sloop.

 

[Guest]

When you find it please sell it to the Admiralty - they've been looking for a similar device since they invented the torpedo.

))

Ian D

 

[pugwash]

Hey, it\'s not that silly...

If American truckers can buy a box as big as a paperback book to fit on their front grilles for a few hundred bucks and get an audible warning when they get too close to the vehicle in front (it saved the life of the driver I spoke to, who ran into thick grassfire smoke in the dark without realising it), then why can't such a box be fitted to a pulpit and give warning of an object just ahead of the bow? General Motors is designing these things to fit as part of the standard cruise control equipment, so on the open freeway you can set the distance to be maintained behind the vehicle in front, then just hang in there. The only reason they haven't emerged on the market so far, I understand, is the question of legal responsibilities for control of the vehicle, but the technology is there and so is the low cost achieve through mass production. Or so I was told in Detroit a few years ago.

 

[Mirelle]

I have one of those

It extends 4 metres from the bow, with a substantial chain and tackle connecting the outboard end to a strongly reinforced fitting at the bow just below the waterline.

The inboard end of the pole is easily demountable, when entering marinas. It is attached to a fitting which is designed to shear if very high impact loads occur, such as sailing into the side of a ship or a harbour breakwater. Less severe impacts, with buoys, floating logs, etc. usually result in a glancing blow and the object is deflected away without damage.

In fine weather, one can cat nap in the net suspended between the shrouds on either side of it.

Impacts with other yachts are generally avoided because the other boat takes avoiding action, not liking the look of it.

I would like to patent it, but I am told it has been around since the 14th century.

 

[kimhollamby]

Re: Hey, it\'s not that silly...

It would be interesting to get Mike Phillips of Echo Pilot to chip in here...he's been developing forward looking sounders for a few years now (leisure boat prices, not Admiralty nuke submarine standard) and would be able to put a realistic edge on whether or not such a device is possible. I'll see if he is inclined to add a comment.

 

[Guest]

Re: Hey, it\'s not that silly...

Interesting,,How would it deal with a wall of water (called a wave) 10 feet from the bow and then 10 secs later be looking skyward. Down here on the Kent coast we have London Gatwick and Heathrow holding paterns, would it detect low flying aircraft and try to avoid them<s> I would hazard a guess that if such an item was developed it still would not be able to detect a fishermans pot marker,normally a 5 ltr plastic container thats been in the water since Noah was a boy, is covered in weed, and the only obstruction for 20 Nm and you are heading straight for it just so that the nice pot line can foul your prop/keel,,turn you through 180* so that you can see where you have just come from,, make you spill your tea all over the repeater box for this forward looking warning device, knackering the electronics and alarm so that it wouldn't go off if you were 10 feet from a cross channel ferry. Nice idea but I'm gonna rely on the fact that God was good enough to give me 2 eyes and the RYA sold me a book about Colregs pointing out something about "keeping a good look out"<s>

 

[pugwash]

Re: Hey, it\'s not that silly...

You're right on all counts, Captain. You would also have been "right" had you replied in the same terms to a question put 20 years ago on why, with all these satellites in the sky, somebody didn't invent some sort of automatic triangulation system so we could have instant read-outs in the cockpit. But the world moves on leaving old reactionaries bobbing its wake and some day soon an automatic crab-pot detector is bound to be on the market, probably using technology we can't even imagine right now. Meanwhile, the cruise-control electronics I described might well be an interim stage and be useful for detecting, say, semi-submerged containers. I dunno, but it's interesting to speculate.

 

[Guest]

Re: Hey, it\'s not that silly...

aaarrrrrrrr speculation, the mother of invention. When someone invents a pot marker detector (that works) I will KNOW we have arrived. Just think we could fire up the GPS/autohelm and pot marker detector, phone Brighton marina and get which berth were allocated, input this to GPS (including whether we want to be bow or stern first and BINGO sit back with G & T's and let the world go by. Next question + anybody got any idea's on an automatic dock line machine+ <s>

 

[pugwash]

Well why not..?

Think about this. A harvester combining a field has a sensor on each tine that reports the yield every square metre or so and the info is conveyed by gps to a computer in the office. Six months later the seed machine taking info from the computer and gps reaches a spot where, say, the yield is less good than the rest so it automatically dispenses a little more fertiliser. This system is widely used in cereal cropping in developed countries. And a farmer sitting with a computer in his pick-up in the corner of a field can drive four or five combine harvesters at the same time. So why couldn't a little transmitter in the crab pot send a message to your gps? Or a computer program your boat into a marina pontoon? I'm not saying it's desirable, or that we need it, only that the technology is already there, in effect, and whatever the most bizarre thing you can think of, some nutter is going to do it and it will work. Now a haircut by GPS, that might be something else, but don't count on it.

 

[ccscott49]

Re: Well why not..?

Do you know any crab/lobster/welk fishermen who would buy decent marker bouys, never mind electronic thingys' for their pot makers! well do you? The price of wheat hasnt come down either!