h a l f b a k e r yBaker Street Irregulars
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Smart shrimp/crab pots show images of underwater trap. When deployed, operator may remotely check traps without having to physically haul them out of the water, to see what is in them.
Rugged, underwater camera and light source are integrated into standard crab and/or shrimp traps. Data cable integrated
with buoy line to RF (radio) transmitter integrated with buoy (float which is attached to the trap). Special buoy uses solar cells and Baylis -type generator. Generator obtains energy from an internal weight, moved by wave action. Solar cells likewise trickle charge buoy battery from available sunlight.
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But the marine environment is notoriously harsh. The equipment's going to need some serious hardening, which is going to make it expensive. |
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[+] Sounds like a brilliant idea to me. I presume
crab/shrimp/lobster fishermen waste a lot of time
hauling up pots that ought to stay down longer? |
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I don't see why it needs to be expensive. Cheap
webcam guts $10, add LED lighting $5, encapsulate
the whole thing in PDMS, $2. Cable and
transmitter would be the main costs, I would
guess. |
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Instead of a solar cell and RF transmitter, why not
terminate the cable in a connector? Boat pulls
up, plugs in (both power and data) and there's the
image. |
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Normal lobster creels seem to cost anywhere from
$5 to $30. |
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// I don't see why it needs to be expensive. Cheap webcam guts
$10 webcam guts $10, add LED lighting $5, encapsulate the
whole thing in PDMS, $2. Cable and transmitter would be the
main costs, I would guess. // |
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Oh, the naiivety … guess again. |
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It's going to have to be pressure tight, with a suitable lens and
protective cover. All external fittings (anchor points) need to be
stainless steel. The casing needs to be thick enough to take rough
handling; a rubberised jacket would help. Don't forget, something
may try to eat it. |
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Works inside box- yes, $30 piece part cost. But the enclosure?
$200 and up … |
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Just cast the whole thing into a gob of PDMS. You
will never be able to open it again, but you don't
need to. Total cost will be on the order of $2
(probably less if you buy your PDMS by the gallon).
PDMS (which is glorified, optically transparent
silicone sealant) is tough, waterproof and will
work absolutely fine. |
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In terms of pressure - most lobster and crab
fishing is done at depths that will not bother an
encapsulated camera. |
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Lobster fishing, yes. Some crab fishing is done in very deep
water, maybe not deep enough to harm the camera, but
possibly deep enough to interfere with transmission. The
other factor these things will have to contend with is
bitter, bitter cold. |
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//deep enough to interfere with transmission//
That's why I would suggest a simple wire; I don't
know what the maximum cable length for a
webcam is, but I'd guess it's quite long. |
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//bitter, bitter cold.// Webcams are fine at 0°C,
and even -20°C (I have used one in the -20 room at
work). |
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Incidentally, PDMS can be index-matched to water
quite well. This means that the lens-side of the
PDMS gob only needs to be case approximately
flat, and the image will be fine. Even scratches or
gouges on the PDMS will not really impair the
image. |
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It is not the cost of this idea compared to a normal lobster
pot's which
is relevant. The idea's cost must be weighed against the
benefits gained by the fisherman in knowing whether or not
to retrieve the pot. |
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I tend to agree with [8th] that hardening something to a
degree suitable for seawater immersion and commercial
use will be expensive, but this needs to be offset against
the cost/value of the boat and crew per hour currently
which is wasted pulling pots at the inappropriate times.
[+] |
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I can't wait for this product. I really want to find out how "smart" shrimp taste, as opposed to the less-gifted type...but perhaps the answer is in the idea's subtitle. |
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//I tend to agree with [8th] that hardening
something to a degree suitable for seawater
immersion and commercial use will be
expensive// |
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I truly don't see how or why. Conventional camera
enclusures are expensive because they have to be
openable, and typically protect an expensive
camera. In contrast, placing a webcam-style
camera in a mould, pouring in PDMS and leaving it
to set is cheap and simple. |
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How do you imagine that a camera, encapsulated
in this way, will fail? |
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I used to build underwater electrical connectors and such gear for the offshore oil, oceanographic and military markets. |
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[8th] is correct, much care is taken in the fabrication and still the failure rate is high. One air bubble in the wrong place and it gets forced out during use, making your gear look like somebody shot it. Pressure changes from deployment and retrieval, tidal and wave forces, all continually pull at your best laid plans. |
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// making your gear look like somebody shot it // |
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Errr, no. That was us, actually. We thought it was french, so we shot it. Sorry. it seemed like a good idea at the time. |
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[Max], if you can make it work with PDMS then great. Yes, it's a superb material; we use it ourselves. But expecting it to stand up not just to the pressure but the battering and abrasion and corrosion of the sea is quite optimistic. We wish you every success. |
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Oh, and what [norm] said. |
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Though I have little expertise in marine equipment, several
years of
working in freight rail taught me that nothing is
indestructible and that simple, rugged, well-designed
devices often break in fascinatingly complicated fashion.
Somebody saying things like "how could something like that
go wrong?" often compel me to start compiling a list. Add
use in the open ocean as a factor and that list suddenly
becomes much longer. |
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How strange ... we react to the statement "It's safe. there's no way it's going to go off" in exactly the same way .... |
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// battering and abrasion and corrosion of the
sea// |
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Lobster isn't usually battered. More particularly,
the camera will be inside a lobster creel
(preferably in that part of it which is inaccessible
to the lobster). As to corrosion, silicone is not
noticeably vulnerable to corrosion. |
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Pressure changes and trapped air - well, maybe.
The solution to that is to ensure that the webcam
itself is not airtight then, after immersing it in the
liquid PDMS, stick the whole lot under vacuum
(which is how you debubble and degas PDMS
anyway), wait til it stops bubbling, then let it set
under normal atmospheric pressure. The PDMS
will then have filled every interstice of the
camera and, being non-conductive and optically
clear, it'll all be fine. |
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Another statement that automatically puts me in mind of
twisted metal and bad-order tags. |
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In a TV documentary not so long ago, the Commander of the Britannia Royal Naval College, Dartmouth, was questioned as to why one of the significant parts of the training of a modern RN officer, given the preponderance of high-tech in the Navy, involved learning to sail a dinghy by hand and eye. |
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His answer was, "Because the sea doesn't change." |
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No matter how good your idea, the sea will always find the weak spot. t would be some sort of reassurance of it could be put down to malice; what makes it worse is because it's totally indifferent, and utterly relentless. |
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If you love something, don't put it into the sea. |
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Unless it's a dolphin, presumably. |
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So, if I take one of those super-bouncy balls, tie a
piece of string to it, and then lower it to the
seabed, it'll just spontaneously implode or
something in the first month? Wow - tough gig. I
wonder how they get $10 lobster pots to survive. Or
indeed $10 lobsters. |
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The $10 lobsters survive in the sea because that's what
lobsters do. Even then, it's a hard life. |
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$10 lobster pots don't survive in the sea. That's why we sell
them to tourists. A well-made modern lobster pot like
those used by Maine lobstermen runs around $200. |
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And, no, the bouncy-ball on a string will not explode when
you put it in the ocean; it will just disappear, like most of
the other stuff mankind has put into the ocean throughout
history. |
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In that case, if I'm investing in a $200 lobster pot, I
might not balk at spending and extra $50 for an
encapsulated webcam. Methinks that $50 would do
the trick. |
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//I'm investing in a $200 lobster pot// |
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As I said earlier, the cost of the lobster pot is irrelevant. The point to be considered is the cost of boat time and labour saved with a $50 webcam or even a $200 webcam. I actually voted for this idea but am very leery of casually submersing something in the sea under working conditions and expecting it to keep functioning long-term with minimal maintenance. |
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I think [Alterother] expresses my sentiments very well. Having personally experienced enough of those "how could something like that go wrong?" moments has made even a natural optimist/ 'yes it can be done' guy like me wary. |
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As a diver, I can attest that those lobster pots are scattered all over the bottom in various states of damage and disrepair... |
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The beaches up this way are strewn with horribly expensive-looking stainless steel commercial fishing beacon buoys. These things look to be easily over $1k worth of solar, batteries, electronics and other paraphenalia. There's something like 10 units on the beach every kilometer. |
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I can't imagine they plan to lose this kind of gear, but they do anyway... |
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Look I think it's a good idea, it'll just be down to cost per unit vs acceptable losses. There are ways to harden underwater electronics, and there is also a random failure rate to accept. "Use sillicone" isn't really the answer, but could form part of it. Ultimately it might be cheaper to put a load cell on the winch or davitt arm on the boat to detemrine if the pot is heavier, therefore full, rather than having expensive, inherently fragile electronics attached to each pot. Remember you'll need lighting on the camera, function will be subject to visibility issues (not to be underestimated), as well as have marine growth to worry about. |
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I'm not exactly sure why there has to be an expensive camera system in these crab/shrimp pots. The fisherman is mostly interested in whether his trap is full and worth bringing to the surface. |
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To facilitate that, why not arrange a simple AA battery and LED connected to a fiber-optic strand attached to the trap's buoy line. If the trap is occupied with sufficient occupants, their weight will depress a simple contact switch plate which connects the inexpensive battery and LED and displays a small light on the other end of the fiber-optic strand atop the surface buoy. |
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Now we're talking about a dollar's worth of batteries which get replaced every time the trap is hauled on board. Simple. |
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Would it not be simpler still to make a one-way neck sleeve connecting the trap to the surface buoy? Crabs or lobsters could crawl up but not get back down because of flexible, curved, blunt spines pointing vertically up the neck sleeve. |
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They could then be collected from a much larger container much closer to the surface and the trap can remain submerged. |
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// In that case, if I'm investing in a $200 lobster pot, I
might not balk at spending and extra $50 for an
encapsulated webcam. // |
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You might wish to consider that, as a professional
lobsterman or crab fisherman, you are not investing in a
$200 lobster pot; you are investing in _dozens_ of $200
pots (I neglected to mention previously that this rough
estimate includes necessary gear such as the tackle,
moorline, and bouy). |
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On the coast of Maine, the smallest one-boat
enterprises typically set 30-40 pots. Adding a lobstercam
to each pot, assuming the $50 price tag, tacks on $2K.
Since you already operate on a shoestring, that's probably
two grand you only wish you had. |
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If you are a more successful lobsterman, you may be
running four or five boats, each tending as many as fifty
pots. The cost for lobstercams has now run into the tens of
thousands of dollars. Are you balking yet? |
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