Buoy Management

[funrecdiver]

How do various dive centers in Thailand cooperate on buoy management?

For example, buoys on wrecks in the Pattaya area have traditionally been paid for and maintained by a limited number of dive centers.

Buoys can be expensive, as the general rule seems to be 3 for 1 in length, so a buoy on top of a 20 meter wreck, requires at least 60 meters. Also, since boats can easily cut rope, ideally a buoy should have a length of chain at the surface to keep the buoy line from being cut, either accidentally or on purpose (and also at the bottom, as I have been told by "buoy experts").

How is this managed in other regions in Thailand? How do dive centers share the costs of (expensive) buoys? How do dive centers work together to insure that one dive center is not paying the lion's share of expenses to place and maintain buoys that are used by all other dive centers?

[funrecdiver]

Having had a few discussions on this topic in the Pattaya area, most agree we need more buoys here, especially on the wrecks (lines on both ends).

The current ad hoc plan is to get estimates for chain and line and the get other dive centers (and individuals if they want to help) to contribute to the material. Then, we will install the line (without cost) on the wreck(s).

If all this scheming actually worked, we would keep the entire process fully transparent so 100% of contributions would go toward line materials, nothing to the boat, dive center, petrol, etc (we are willing to do all that for free since we are already at the wrecks).

So far, the estimated costs are (still working):


Large jugs (plastic bottles) for flotation: Free
60m of high quality line: 100 - 130 baht per meter
15m of chain: TBD
Total: TBD


Will get the cost of good quality chain and post back estimates and suggested contributions from Pattaya dive centers.

Of course, contributing good quality rope and chain is also an option :D

[lord khram]

I think the biggest problem is stopping the fishermen stealing the buoys when they are in place.
Maybe something more substantial such as was in place at the Hard deep last time I dived there would prove to be a better long term solution, and not so easy to steal, and being anchored to the seabed ultimately better for the long term preservation of the wreck.

[funrecdiver]

It is not clear that greatly increasing the expense and complexity of concrete anchors on two relatively recent solid metal shipwrecks is required vis-a-vis the decades old Hardeep wreck,

Mostly, the greatest enemy of "good" is "better" or "perfect" ......

[lord khram]

It is not clear that greatly increasing the expense and complexity of concrete anchors on two relatively recent solid metal shipwrecks is required vis-a-vis the decades old Hardeep wreck,

Mostly, the greatest enemy of "good" is "better" or "perfect" ......

I was simply thinking that maybe it would provide a more permanent solution rather than to continue with a system that has been problematic at times over the years it has been used, with the buoys constantly going missing.
There are always lots of buildings being demolished / re built in the area, I dont think it would be too expensive to obtain some blocks of concrete.

[funrecdiver]

Yes, I agree.

However, from talking to the guys who have been putting the mooring lines on the wrecks, they say the biggest problem is theft of the line and sometimes cutting the line by boat propellers, like long tail boats.

The same folks tell me that the best way to mitigate this is to put steel chain on the surface part of mooring line that is resistant to propeller cuts and knife cuts by thieves. No one I've talked to think the local authorities can solve the theft problem by monitoring the area, since it would take 24 hour a day monitoring.

So, the solution seems to be to use strong steel chain from the surface buoy to some depth, say to the safety stop area at 5 meters or deeper, then rope to the wreck. Chain at where the rope meets the wreck is optional.

Unfortunately, this approach does not stop the determined person who is willing to free dive or scuba dive deep to cut the rope, hence most people are unwilling to invest a lot of money in a solution easily stolen.

A concrete anchor at the bottom is a nice idea, but it does not really solve the problem of rope cuts by both thieves and boat props.

In fact, since the odds are so high of theft, it is unlikely chain will last very long, so it would not be wise to invest in stainless chain, as a regular less expensive steel chain will be "long gone" before it rusts, and if the area is lucky and it lasts a long time, it is easy enough to replace.

[lord khram]

A concrete anchor at the bottom is a nice idea, but it does not really solve the problem of rope cuts by both thieves and boat props.

It does if it is made with a steel cable such as the hard deep.

Also I favour this approach as I said before to protect the wrecks, even the newer ones are not excluded from damage due to idiots.
A couple of years ago I actually witnessed a boat that shall remain nameless, tie to one of the buoys whilst it was wrapped around the mast / tower, hence the said mast is no longer attatched to the boat, and to make things even worse they actually caused the mast to fall onto the main part of the wreck whilst other divers were down there.

Incidents such as this would not happen if there was a solid shot attatched to the seabed a couple of metres away from the wreck its self. Yes initially it may involve a little investment in time and or money but it would provide a more 'permanent' solution. Why do we have to wait untill the wrecks are 60 or so years old and falling apart through age before we decide to protect them from damage?

[funrecdiver]

Point well made.

So, you are proposing a steel cable instead of chain and rope - plus a large concrete block at the bottom for the mooring line.

Guess the next step would be to see if this solution is both economically and logistically feasible.

[lord khram]

I can't remember the exact details of how the shot on the Hard deep was constructed, its some time since I dived there, but can remember a large oil drum at the surface and can remember even in a strong current the line remained almost vertical making the descent to the wreck much easier than having to pull yourself down a loose rope as was the case there in the past. Again no idea who designed / installed the shot but must say who ever did it they made an excellent job.

[funrecdiver]

OK, thanks. Will discuss with Robert of Adventure Divers this week when we dive together.

[funrecdiver]

Hey LK,

Spoke with Robert of AD. Ideally with unlimited funds, a large ship with a crane and underwater communications gear to position a large concrete block, steel cable and an oil drum.

Under more practical and pragmatic economic conditions, 15 concrete poles dropped in the water one at a time, and repositioned by divers walking on the sea bed in the sand. Then, after repositioning the concrete poles, wrapping the steel cable under and around the pile of concrete logs.

He said that would be possible on a dive boat, since we have no dive boats (that we know of) with cranes on board that we know of and we don't have expensive underwater communications gear to position.

This "could" be a more permanent solution for each mooring line but theft by cutting the steel cable remains a possibility.

Assuming that around 100 meters of steel cable is required from the bottom; and then at least 15 concrete poles and a steel oil drum at the surface, we need to calculate the costs.

Since, it seems, that DCs have yet to do a similar community funded project like this with cheaper materials, do you think it can happen with a significantly more expensive community-funded project? With the risk of theft of an expensive steel cable, one could argue that a cheaper, easier dive community-funded project might have a higher probability of success that a more gold plated solution that also has risk of future theft.

[lord khram]

I dont think for one minute that cranes etc as you describe were either needed or used at the hard deep, what is your point?

Why 100 metres of cable? last time I dived at the kood the seabed was around 32m, and the Khram about 29m. Maybe you could visit the hard deep and have a look for yourself before making such elaborate assumptions.

To me it is more economical and practical, to provide a solution that is difficult to steal and unlikely to be a target of theft, rather than one that after a short spell of time will almost certainly be stolen as has happened countless times already. Just my thoughts.

Also I would like to add that I have heard discussions such as this numerous times around Pattaya over the years since the wrecks have been in place and generally nothing comes of it, maybe that is why now people seem to have very little interest in the subject.

Also I would add that in my mind the system has proved its self, the shot line at the Hard deep was installed some time ago and I believe it is still intact and functioning perfectly (certainly was the last time I dived there myself). lets see how long the next plastic buoy lasts on the Kood?

[funrecdiver]

I dont think for one minute that cranes etc as you describe were either needed or used at the hard deep, what is your point?

Cranes are how very heavy concrete blocks are normally loaded on boats and placed in the oceans. Concrete blocks are too heavy to be carried by mere humans onto boats from pier and from boats to dive sites. Your reply seemed defensive, which has me worried.



Why 100 metres of cable? last time I dived at the kood the seabed was around 32m, and the Khram about 29m. Maybe you could visit the hard deep and have a look for yourself before making such elaborate assumptions.

The general rule of thumb according to experts is 3 to 1 on mooring buoys (so I have been told). This means that if the bottom is at 30m, the length of the mooring line should be at least 90 meters. In addition, there should be additional length, for example, to wrap around concrete piles. I am not making any assumptions; however, your defensive tone in reply is not necessary. It seems obvious you don't know about mooring lines and how to calculate a length of one. However, I just spent a hour this evening talking to someone who has placed over 20 on local wrecks.

I am happy to continue the discussion with you, but if you could drop the "edge" in your reply, using terms like "elaborate assumptions" to describe a mooring line standard (as I have been informed) that you are not familiar with, that would be appreciated.

[funrecdiver]

Follow-up:

Just checked on this, and the 3 to 1 scope of a mooring line as we are talking about is actually very conservative. Marine standards for anchoring a boat is 5 to 7 times the depth to insure the boat is not destroyed during rough surface conditions.

If someone had a boat tied to a mooring buoy over the wreck and a very rough storm hit while divers were under water (certainly a high probability), having a dive boat on a mooring line that was 3 times the depth would be on the edge of "unsafe" as the standard Scope is 5 to 7 times depth for safely of the boat moored to the buoy over any site.

My own research confirms what Robert of Adventure Divers, who says he has put at least 20 mooring lines down on wrecks in the Pattaya area over the years (per Robert), is that a 3 to 1 ratio, length to depth, is the very minimum, for boat safety. A minimal amount of research on the net tends to confirm at least a 3 to 1 scope, for example:



http://www.scubaboard.com/gallery/data/5047/SCOPE_34MS.gif

Reference (http://www.boatus.com/boattech/casey/34.htm)


Scope is the ratio of the length of deployed anchor rode to the height of the bow chock above the seabed. The greater the scope the more horizontal the pull on the anchor, and the better it will hold. Pegging 10:1 as the maximum practical scope, the table shows the average relative holding power associated with shorter scope.

[lord khram]

There is no edge in my reply I simply dont agree with what you are saying. As I have said the SHOT line at the hard deep is exactly that, a shot line for divers to locate the wreck and make their descent it is not a mooring line. As my last post suggests maybe it would be worth a trip down there to see what it is like as it is nothing like the diagram you have produced, and you will see your assumptions are incorrect. I had my own boat in the UK before for a time, so am fully aware of the principals behind anchoring a boat to the seabed.

[mgmonk]

oh... it's been so long since I visited this forum. Glad to see everyone is playing in the sandbox so well.

:nailbiter:

[lord khram]

oh... it's been so long since I visited this forum. Glad to see everyone is playing in the sandbox so well.

:nailbiter:

:HHGTTG:

If thats all you have to add to the discussion, pity you didn't leave it a little longer.