How shallow can planned wreck 'artificial reefs' be?

[CT-Rich]

not an expert on any of this (actually talking out of my hat), but it is probably different depending on the conditions. open ocean will create big swells that may have large wavelengths (the distance from peak to peak the wave action can be felt on those waves down to 1/2 the wavelength. In a big storm that can throw a wreck around quite a bit, and contributing to the break-up of the wreck over time. If the wreck has a profile that is perpendicular to the current, a big storm could probable move a good sized wreck into a less favorable position, I would think, and contribute to her breaking up. Wave height would could add or subtract 20'+ to the depth and make hitting her an issue.

One of the rationales for creating artificial reefs is to prevent beach erosion, so some of those wrecks might be much shallower.

Just found this, people in Florida might find it interesting. It has the locations, type of reef, depths and relief (height off the bottom) for artificial reefs in Florida. It looks as though depths start around 60-70' for ships.

http://myfwc.com/media/131585/reefs.pdf

 

[OkByMe]

Hi:

I'm mainly a coral reef diver, but I like wrecks and have gotten to dive a few here and there out of Key Largo and various Caribbean destinations. Most of them have something disturbing in common; they're really deep. Granted, 'real' wrecks (e.g.: ship goes down in war time from a torpedo) sink wherever they got hit, some wrecks are planned for artificial wrecks, and even they tend to be deep. Which limits NDL on air, MOD with nitrox EAN 32 may keep you shallower than you'd rather go, we go through gas fast due to pressure at those depths, and a number of divers would need AOW or Deep Diver cert.s before a given op. would take them to some wrecks.

What really got me thinking about this months ago was diving the wreck(age) of the Benwood out of Key Largo. I was either told or read somewhere that the military used it in the past for some sort of bombing practice; it had been deemed a 'navigation hazard.'

What does that mean? That ships whose hull goes deep might hit it, I suppose?

Or let's take the Oriskany, which I've never dove (but hope to someday as a novelty, since I was born in Pensacola, Fl). That was a planned sinking to make an artificial reef, but that sucker is deep, and from what I understand a long boat ride to reach. I'm a rec. diver; even if I rent a steel 120 or two & someone get EAN 28 to max. me out at NDL within recreational dive limits, I won't touch the main (flight deck?), and it won't be a long dive.

But my main question is, what's the minimum depth that a planned wreck can be sunk at (I mean, how shallow can the upper part of the wreck be, more so than what depth is the sea bed it rests on)? And at what depth would it be deemed some sort of hazard & bombed or what-have-you?

Richard.

P.S.: For comparison, I dove the Butler Bay wrecks not far off shore of St. Croix back in January; not so deep.

I belive the requirement for a planned sinking is that the top of the structure has to be 60' - 80' below the surface. That why the carrier is so deep. There are some wrecks off Key Largo in very shallow water. Big, deep draft ships don't go there. The Speigle Grove is deep since it is near a shipping channel.

 

[Diver0001]

What really got me thinking about this months ago was diving the wreck(age) of the Benwood out of Key Largo. I was either told or read somewhere that the military used it in the past for some sort of bombing practice; it had been deemed a 'navigation hazard.'

What does that mean? That ships whose hull goes deep might hit it, I suppose?

That's pretty much it, yeah.

I suppose shallow shipwrecks degenerate faster. Most of the ones I know about are in the 25-40m range but some are shallower. The Abu Ghusun, although it's a natural wreck starts at 6 metres and goes to the hard bottom at 25. It also fell apart fairly quickly. It sunk in 1993 and it's already too unstable to penetrate.

R..

 

[Ste Wart]

HMAS Perth, Albany West Australia. Sticks out of the water and it's an artificial reef. (MAX depth 35m though)

 

[nolatom]

A typical loaded large cargo ship say 750' in length would draw about 45 feet.

Some mega-ships (tankers) that call only at offshore lightering areas or offshore terminals such as the LOOP, these "orphans of the deep" may draw 55-60 feet.

I don't know of any much deeper than that.

You'd want to have a safe 20 feet under keel of the deepest ship that might transit such an area, at the lowest expected tide. That's how the math typically works out.

 

[Diver0001]

A typical loaded large cargo ship say 750' in length would draw about 45 feet.

Some mega-ships (tankers) that call only at offshore lightering areas or offshore terminals such as the LOOP, these "orphans of the deep" may draw 55-60 feet.

I don't know of any much deeper than that.

You'd want to have a safe 20 feet under keel of the deepest ship that might transit such an area, at the lowest expected tide. That's how the math typically works out.

Rotterdam harbour is 25 metres (82ft) and I hear that there are a few ships around that can hardly make it in/out.

R..

 

[LeadTurn_SD]

This document from NOAA does not specifically answer the depth question, but does give an idea about what goes into selecting a site for an artificial reef:

http://www.google.com/url?sa=t&rct=...6RaRv3yr0BKZOpCLstD7iyA&bvm=bv.65397613,d.aWc

Best wishes.

 

[Stoo]

Any legislation that exists would presumably be to make certain that the wreck doesn't constitute a hazard to navigation... (although it would be cool to sink a wreck designed to b*gger other ships so you end up with a pile of wrecks, but I digress...)

Apart from that, I suspect that there are several other factors... Weather can have a huge effect on wrecks and damage them or even move them. (I think that this happened to one of the ones sunk off the Keys didn't it?) I can speak from experience about the Carolyn Rose in Tobermory. It was sunk accidentally in about 60' - 70'. I dove her the next day to clean up some entanglement risks and she was a nice, intact little schooner. The following week, a storm blew through and pushed her at least 100' closer to shore and beat her to matchsticks in the process. Had she been in 100+ feet to start with, she might have survived that storm.

Another reason (and this is my guess), is that if the ship being sunk is BIG (and nobody sinks bass boats as dive sites) you need some depth just to fit the boat in the water column, unless you like the idea of the Navy doing that bombing thing again. Beyond that, there's LOTS of us that like to do deeper gives. I rarely dive shallower than 100' up here, and I'm not alone. My favorite wrecks are 110' to 160' +...

 

[drrich2]

Thanks everybody. Now that you mention it, the Spiegel Grove used to be on its side, and even deep, a hurricane came through and stood it up. Huge, 510 feet long, and even at that depth, the hurricane stood it up. Now that is some power.

Richard.

 

[dmoore19]

Not that I know why but the Kittiwake was sunk and it sits in +/-65FSW. As I recall it too was moved closer to shore by a hurricane.