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FAD - How long will it last?

Old 07-27-2015, 02:58 PM
  #21  
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Originally Posted by REDWEISER View Post
Do a search for the specific gravity of your concrete and saltwater, the deeper it goes, the lighter it gets from the pressure.
This guy knows what's up...
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Old 07-27-2015, 03:08 PM
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If your dropping it on rocky bottom wouldn't a grappling anchor be much better and much cheaper not to mention easier to deploy... If you use like 1" rebar I kind of doubt it will come loose no matter what kind of current you're going against. (well a hurricane might mess it up) I'd probably mark and hook the anchor with my boat, dive in and tie on the "fad" at the depth I want it.
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Old 07-27-2015, 03:24 PM
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Originally Posted by REDWEISER View Post
Do a search for the specific gravity of your concrete and saltwater, the deeper it goes, the lighter it gets from the pressure.
You sure? Water doesn't compress.
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Old 07-27-2015, 03:47 PM
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Best anchor to do it with would be a mushroom anchor as the rotate in the current they just drive themselves deeper into the bottom. It's what they using for the moorings if lets say anyone was planning on doing something like that.
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Old 07-27-2015, 04:08 PM
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Originally Posted by Milehog View Post
You sure? Water doesn't compress.
Weight a gal of saltwater and a gal of the concrete for a comparison.

Steel bolts will float in melted liquid lead .... (specific gravity).
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Old 07-27-2015, 04:51 PM
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Originally Posted by REDWEISER View Post
Weight a gal of saltwater and a gal of the concrete for a comparison.

Steel bolts will float in melted liquid lead .... (specific gravity).
Based on some quick research:

The density of salt water at the surface: 1020-1030 kg/m3

The density of seawater at the bottom of the ocean: ~1050 kg/m3

The density of concrete: 2400-2700 kg/m3

Concrete will always provide SIGNIFICANT negative bouyancy, anywhere in the water column.
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Old 07-27-2015, 04:56 PM
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I can tell u hypothetically 500 lbs of concrete hypothetically works in 600' and hypothetically used orange safety fence as the FAD about 60' below surface
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Old 07-27-2015, 05:47 PM
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Two anchors with about 50' of chain each. Read up on FAD design in other parts of the world online. They construct them using 80% of the depth length in floating rope then a longer stretch of sinking rope to floats on the surface. Doing it this way eliminates some of the stretch on the anchor system and gives a cushion for wave action.
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Old 07-27-2015, 06:20 PM
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Originally Posted by Ron@.38 Special View Post
Anchors with a design holding power are much better than concrete weights. Holding power can be a hundred times more with an anchor of the same weight as a concrete block.

Used anchors are cheap. When we built ours,(theoretically ) we used (would have used) an anchor and pvc pipes to make a large cross section floating in the water. It lasted for a year, (theoretically) and we caught dolphin and wahoo when no one else was catching them (theoretically of course).
It was designed to "fly" about 75 ft down in 450 feet of water.
What were the dimensions of the cross and the diameter of the pipe? Theoretically of course.
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Old 07-27-2015, 10:06 PM
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Theoretically, how heavy and what type of used anchors would work? If one were to do this SEVERAL swivels (one at top one at bottom one in the middle) would be a must... What would be the most cost effective line to use hypothetically? Hypothetically, would a 10'x10'x3' ish 1/2" PVCrectangle with fabric/ rope/ CDs tied at each corner work well? Hypothetically, would a man hole cover work as a weight? How many lbs concrete? What kind of anchor?
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Old 07-28-2015, 06:41 AM
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Find some old anchors and chain on craigslist, the biggest you feel comfortable dealing with on your boat. Don't skimp on the swivels either.

Here is a guide for use by fisherman in the Pacific and Indian oceans that has pretty much everything you would ever want to know about FAD construction. Perhaps it's a little overkill for a couple hundred feet of water off South Florida but you can scale your (hypothetical) FAD down as you see fit. You'll note there are two designs here, the one proposed for the Indian ocean looks a lot easier to construct as it's surface float is just a chain of buoys.

http://www.spc.int/DigitalLibrary/Do...6_FAD_Vol2.pdf
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Old 07-28-2015, 06:53 AM
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I think the mgfb has been experimenting with fads. Mark, the guy that does these videos, does all of the monitoring dives on the wrecks out of ms. Here are a few fad's he has deployed over some of the current structure. His anchoring problem is solved easily as he hooks to current structure, however, you can see the design of some of his fads and how they have matured over the last year.

https://www.youtube.com/watch?v=Vgv-RulIwwo

https://www.youtube.com/watch?v=IUHqhtpPKuE

https://www.youtube.com/watch?v=wE0SWrBDNVA

https://www.youtube.com/watch?v=sjX7haL0_wQ
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Old 07-28-2015, 08:48 AM
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Not to be the junior law enforcement guy here but you are discharging plastic. I would be careful how you document your endeavors.
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Old 07-28-2015, 09:14 AM
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Originally Posted by hamma job View Post
Not to be the junior law enforcement guy here but you are discharging plastic. I would be careful how you document your endeavors.
No worries junior..

This is all hypothetical!!!
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Old 07-28-2015, 09:42 AM
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This is a very interesting topic. I have theoretically been making mental notes. It would make a slow day on the water potentially have a plan-b. Instead of hunting for flotsam and hoping to get lucky, you would have a "area" that could be productive for a length of time....very interesting indeed.......
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Old 07-28-2015, 10:08 AM
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What about floating FADS:

What if I theoretically created a 20X20 PVC frame and cross section brace and zip tied a 20 by 20 tarp to it. Then attached crab floats to the corners and middle.

What If I then didn't connect the cross brace together and folded it into one long roll of pipes and tarp.

What I then trailer the boat to Islemoarada, drove out the the stream and theoretically deployed the FAD with my Theoretical Spot GPS Device in a waterproof bag attached to the center float.

What if the next Day I went fishing out of Ft Lauderdale and theoretically traveled to my Spot Device and Fished and retrieved my device?

Theoretically of course.


What if it worked and on Weekends I started deploying a Dozen of the devices on Thursday and Friday night and sold the GPS coords through the weekend to other Scientific Anglers. All in the name of studying ocean currents of course.
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Old 07-28-2015, 10:20 AM
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I may have an older spot tracker that could be theoretically donated for the purposes of research...
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Old 07-28-2015, 10:22 AM
  #38  
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2 problems with a floating fad.

1. Navigational hazard
2. Giving up the location

Many days I've been 20 miles offshore and someone finds a log or something, one boat turns to 2, 2 turns into 4 and so on.. Within 45 minutes there's 6 or 7 boats fishing the same log in the middle of the ocean.

It would have to be a subsurface device to work in my opinion.
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Old 07-28-2015, 11:09 AM
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Originally Posted by SRQMynatt View Post
What about floating FADS:

What if I theoretically created a 20X20 PVC frame and cross section brace and zip tied a 20 by 20 tarp to it. Then attached crab floats to the corners and middle.

What If I then didn't connect the cross brace together and folded it into one long roll of pipes and tarp.

What I then trailer the boat to Islemoarada, drove out the the stream and theoretically deployed the FAD with my Theoretical Spot GPS Device in a waterproof bag attached to the center float.

What if the next Day I went fishing out of Ft Lauderdale and theoretically traveled to my Spot Device and Fished and retrieved my device?

Theoretically of course.


What if it worked and on Weekends I started deploying a Dozen of the devices on Thursday and Friday night and sold the GPS coords through the weekend to other Scientific Anglers. All in the name of studying ocean currents of course.
This is actually how many commercial fishing operations use FADs, particularly purse seiners. They make the floating FAD out of bamboo (cheap and bio-degradable) and attach a vertical piece with a flag or something to make it easy to spot, a GPS tracker would work even better. They'll hang rope or old pieces of net off it to create structure. Your method wouldn't have the FAD in the water long enough to really attract the life that attaches itself to the FAD although baitfish would probably use it for cover and you might pick up bigger fish around it.

Make a website that takes donations and launch the floating FADs in the keys with a sign on them linking to your website and saying if they caught fish off it donate to placing more.
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Old 07-28-2015, 11:19 AM
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Originally Posted by HurricaneBK View Post
This is actually how many commercial fishing operations use FADs, particularly purse seiners. They make the floating FAD out of bamboo (cheap and bio-degradable) and attach a vertical piece with a flag or something to make it easy to spot, a GPS tracker would work even better. They'll hang rope or old pieces of net off it to create structure. Your method wouldn't have the FAD in the water long enough to really attract the life that attaches itself to the FAD although baitfish would probably use it for cover and you might pick up bigger fish around it.

Make a website that takes donations and launch the floating FADs in the keys with a sign on them linking to your website and saying if they caught fish off it donate to placing more.
I would make them reusable, once you fish the day you pick it up. I think they could hold fish immediately. Mahi, Wahoo, flying fish would find 20 x 20 shard/cover in hours IMO.
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