How shallow can planned wreck 'artificial reefs' be?

[drrich2]

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.

 

[kelemvor]

I wonder the same thing. I asked the captain about it when we were on our way to the Mohawk wreck. I believe he said something about a requirement for it to be deep enough that it could not impede ship traffic or some such.

That's from my bad memory, and the captain might not have really known the right answer - hopefully you'll get a more definitive response.

 

[TMHeimer]

I've had a bit of experience with wrecks on the North Gulf Coast, other than the "Big O". I probably could think of 7 or 8 or more off either Destin, P'cola, Panama City or Gulf Shores, AL that I've dived that ranged from 50 to 120', most in the 70-90' range. Several were sunken barges--one place was old U.S.98 Destin Bridge rubble. So I assume a few of these were planned sinkings, including the Russian Freighter off Pensacola. Nitrox dives, even air at times of course was fine on these. Don't know of situations elsewhere such as S. Florida. The General Sherman off Myrtle Beach, S.C. is in the 50' range. I would doubt any of these metal, somewhat busted up wrecks pose any navigation risk, probably not even after a hurricane would hit. Maybe it's a depth thing with the Oriskany--I read the very top of it is at 70', but the bottom is 180-200'--so perhaps it's height is why it was sent so deep. I'll never dive it--need the bottom to collect most shells.

 

[hroark2112]

You can do Oriskany on EAN32, just stay on the superstructure. It's at 85' IIRC.

 

[wedivebc]

I believe in Canada the magic number is 30' below mean low water level and highest part of structure. Likely US is similar

 

[Steve_C]

There are some off NC in the 60-90 range (Stone, Dredge, Pocohontas, Indra, Gill, Hyde, Markham, Topsail Barge, School House Barge) and some more but those were ones I have dove.

The Sherman comes up only about 10 ft or so from the bottom.

 

[driftwood]

Waves and troughs during severe storms can make sunken wrecks a navigation hazard. It would be very bad timing to get holed by a shallow wreck when everything else is going to hell in a hand basket.

 

[Redshift]

I think becoming a navigation hazard is not the only problem with shallower wrecks, we also need to have in mind that they'll get broken-up faster.

 

[clownfishsydney]

Depends where it is sunk. If in an area where large ships transit, then obviously the shallowest part must be a fair bit deeper than the depth of the largest ship. If not in a transit area, then deep enough for smaller boats to not hit it. That been said, in places like the East Coast of Australia, they need to be deep enough to minimise damage from the huge seas that we get here. Also, obviously a huge wreck like the Oriskany needs to be sunk in very deep water so that its shallowest part is as deep as it needs to be. Most purpose sunk wrecks in Australia in the past 15 years have been warships and the bottom is generally about 30 to 35 metres (100 to 115 feet).

 

[asha]

Don't quote me on this, but I seem to remember that in SoCal the top of the artificial reef structure has to be 40+ feet below the surface.