Scuba Diving

Queue for the Dive Lift

The dive lift is a standard accessory to any good dive boat these days. I had one fitted as soon as I purchased the boat. Just because, I felt it was no longer a luxury but something that should be part of any good dive operation. The first dive lift I came across was in Skin Deep in the days of Andy Smith. Designed by Len Hurdiss it was a revolution to the diving at the time.

The problem is that it now seems too popular at times. Here you see a queue already forming to use the lift.

Divers waiting to get on the dive lift

Divers waiting to get on the dive lift

What is a Dive Lift

Technically a dive lift is a man-over-board recovery device. A dive lift is a platform which can be lowered into the water to recover people from the water. As divers seem very keen on doing this the MOB system seems very useful. For divers it is a stress free way to be picked up out of the water and be raised to deck level for them to step off for an easy return to the boat.

Diver stepping onto the dive lift

Diver stepping onto the dive lift

The platform lowers into the water to a depth of a few feet so a small bend of the knees enables the diver to stand upright onto the dive lift. Once the crew see the diver is stable the lift is raised to the deck level.

Diver on-board

Diver on-board

Once at deck level the diver can walk off the lift to the seating to get unkitted without the fear that the exertion of climbing a ladder could raise issues for of DCS. Te diver ussually has a big smirk on his face at this point, particularly if he has not used a dive lift before.

The best dive lift

This picture shows the commercial dive lifts that lower the diver right down to the wreck. This may be some time off for the recreational diver.

Commercial dive cage

Commercial dive cage

 

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Sea Bream Nests

Black Sea Bream Nest

The Black Sea Bream (spondyliosoma cantharus) is a fairly common fish off Sussex coast particularly in the months of April and May when they come into lay their eggs. Sea bream are unusual in that they lay their eggs in a nest. The bream nest is a depression in the sand which the male excavates. The eggs are sticky and remain in the bottom of the bream nest. The male guards the nest until the young hatch.

Several trips to Kingmere Rocks have been made to photograph the bream nest with a fish in it. These have been unsuccessful. Bream are very rarely seen by divers. Kingmere Rocks have recently been designated one of the Marine Conservation Zones as it is a bream nest site. However, controls have not yet been put in place to protect the species during the breeding season. Consequently the fish in the nests are targeted and large numbers are being taken by anglers and commercial fisherman, who, with the technology available today, are able to target the breeding grounds successfully.

As a commercial skipper I cannot dive unless I have another skipper on-board. I have just taken the opportunity to dive a small area near to Brighton where Bream are often caught in significant numbers and was very likely to be a bream nest site.

The site consists of many hollowed out areas which I assume to be made by the bream. The depressions are very localised. Drifting off just 50m and they all disappear. There are no silt in the depressions, so they are recent and probably well tended. Unfortunately I did not see any bream or eggs in the nests.

Bream Nest

Bream Nest

Some of these depressions are up to 2m across and  have been cleaned out completely right down to the rock below. The picture below shows how free the nest is of silt. Even fossils can be seen in the rock below.

Bottom of Bream Nest

Bottom of Bream Nest

The stone and sand from in the bream best area has been banked up around the area to quite a significant depth of almost 300mm.

Side of Bream Nest

Side of Bream Nest

Bream Nest looking out at banked up stone

Bream Nest looking out at banked up stone

Other Marine Life

The area is a low energy site. I saw 1 Ballan wrasse (Labrus bergylta) and a few cuckoo wrass (Labrus Mixtus). Along with a few gobies e.g. Common goby (pomatoschistus microps) and a larger variety I did not recognise. A few swimming crabs (Liocarcinus Puber) were present and a few shells of edible crabs. The Common starfish (Asterias Rubens), but very few molluscs. I saw two Dead men’s fingers (Alcyonium digitatum) and a few orange sponges.

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HSE Recreational Diving – Approved Code of Practice

The HSE have published a guidance book on the Diving at Work Regulations 1997 for recreational diving projects.

HSE Approved Code of Practice

HSE Approved Code of Practice

This Approved Code of Practice is one of five Codes that give advice on meeting the Diving at Work Regulations 1997. The Code applies to divers who are engaged in recreational diving projects.
Among the areas covered are: responsibilities of clients, contractors, supervisors and divers; project plans and risk assessment; diving teams and working practices; diving plant and its maintenance; medical checks.

The Code of Practice applies to projects where at least one person is employed or self-employed and engaged in work and recreational divers and the purpose of the project is recreational diving, that is diving carried out by a person for recreational purposes while not at work.

The Code of Practice  covers  instruction and being a dive guide, underwater journalists, stills photography.
A free downloadable copy is available from the HSE Recreational Diving – Approved Code of Practice.
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Regulator Servicing – 1st stage Assembly

Now that all the parts are cleaned we can start the process of assembly. First we get all the parts and tools together.
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Step 1 – Diaphragm End

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Take the main body and drop the mushroom into the body. The diaphragm can then be pushed into place and the metal disk that the spring sits on goes next. The top part of the body can now be fixed ensuring that the body does not clamp onto the disk. Set the body upright and make sure it is free to move in its housing. Then tighten down with the pin spanner.

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The main spring goes in next and must sit on the metal disk centrally. Then screw down the adjuster so that it is almost flush with the body. This pushes the spring and so the mushroom down

Step 2 – Valve Seat Assembly

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This is the only tricky bit. Grease and press the small O’ring into the top of the body. Also fit the medium sized O’ring around the middle.  The spring goes on and then push the valve seat into the centre of the small O’ring. That’s it. The larger O’ring and bearing washer is in fact easier to fit at the next step.

Step 3 – Turret Assembly

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Grease the large turret washer and fit to the body. Place the turret on top. Then fit in the blue bearing washer and larger Valve O’ring into the top. With the valve upright the valve assembly can be dropped down into the body so that the hole in the seat itself sits on the mushroom from the other side. A small amount of pressure is needed to push down to be able to tighten everything up.

The turret O’rings are the main moving parts and may need a bit more grease. All other O’rings should have just sufficient for assembly.

It is very important to assemble the diaphragm end before the turret as the spring keeps the seat of the knife edge in the body. If that is damaged it is likely to be the end of the valve.

Step 4 – A-Clamp or DIN fitting

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There is a slight difference between the two systems. For the A clamp the white filter is pressed into the shaft from the “cylinder” end. The DIN fitting has a cone shaped filter inserted from the “valve” end.  With the filter in place the shaft goes through the A-clamp or DIN fitting through the plastic spacer and screwsinto the main body with the O’ring in to seal. It is best to put it all together and hold everything upright to screw into the body as the O’ring can easily pop out and be damaged when tightened.

Step 5 – Attach the peripheral parts.

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Step 5 – Testing

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With everything back together the valve is connected to an air supply. This should be around 70 Bar and not a full cylinder.  For the first time at least it is a good idea to press the purge on the second stage when applying the pressure to bring the pressure up slowly. Purge the valve several times to allow for a bit of settling.

Attach a pressure gauge to one of the intermediate ports. Adjust the pressure using the allen key to the required pressure. This is typically between 9 and 10 Bar, but may vary due to the application. It is better to purge the air first before each adjustment.

Step 5 – Refit dry seal

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Lastly the dry seal system can be attached with the new service date sticker fitted to below the clear plastic membrane.

The second stages may also need adjustment to match the new interstage pressure.

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Regulator Servicing – 1st stage Cleaning

Inspection

The reason to service a regulator is to maintain it in first class working order. To keep the regulator working the parts that deteriorate with age such as O’rings and the parts that wear with use need to be replaced. It is also an opportunity to inspect all the parts for damage. The picture below shows where the chrome has disappeared, this is probably due to the regulator being left with water inside.

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Cleaning

Cleaning is also important in this process. It is the opportunity to remove foreign particles that may have entered the valve. Removing all the old grease so that new can be used. Also all the limescale that inevitably builds up can be removed. The photograph below shows limescale build up from just over a years use.

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Cleaning is best done in an ultrasonic bath. Limescale is removed with acid. You can use vinegar but other acids are preferable. e.g. citric acid. Better still are the cleaners specifically designed for this purpose.  The parts should only be left in the bath long enough to remove the limescale. Leave the parts too long and the metal will become damaged. If the brass parts become pink in colour they have definitely been in too long.

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Once out of the bath then the parts need to be rinsed in fresh water. Hot soapy water is also a good cleaning process but again rinse in fresh water afterwards.IMG-20140326-00455

Oxygen cleaning

Oxygen cleaning involves the removal of hydrocarbons from the parts.  Again this is done in an ultrasonic tank with a specialist cleaning solution. I use Metaclean. A good tip with an ultrasonic bath is to use a container within the main bath. It saves on expensive chemicals and the solution can be made deeper than the main bath to totally immerse the part. The ultrasonic waves pass straight through the container and into the liquid inside. Once again rinse in freshwater after cleaning.

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The last stage is to dry the parts. This is best done having done the last rinse in fairly hot water and then using an air gun to remove the excess water. With all this done you have a set of shiny parts ready for reassembly.

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Regulator Servicing – 1st stage Disassembly

A starting point is the need to service some regulators. The ones shown are all Apeks regulators. (Actually there is also a domiflow oxygen valve on the right). These regulators are typical of diaphragm first stages. Other manufacturers will look very different but on the whole the principle of operation is the same and the servicing procedure is very similar.

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A few tools are needed. Most are standard, but a pin spanner and a bar to insert into the regulator ports are fairly essential.

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Step 1 – Remove all the peripheral parts

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By this I mean the contents gauge, inflation hoses and the second stages as well. Also remove the blanking plugs and any dust covers.

Note: that a numbered box is really useful to keep parts together and to identify the regulator if you are servicing more than one.

Step 2 – Remove dry seal and cylinder adapter

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Use the special tool to lock the valve body. Once in place a large spanner can remove an A-clamp adapter or use an Allen key to remove the DIN adapters. The dry seal system can be removed using a pin spanner.  This stage is not required with the non-sealed first stages.

Step 3 – Remove the IP adjuster

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With the dry seal system removed the intermediate pressure adjuster can be removed with the spring below. Once this is done the top body part can be removed with a pin spanner. This reveals the diaphragm with its protective metal plate. This can be removed with the metal mushroom below.

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Step 4 – Remove Valve seat

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Now the turret can be removed with the valve seat assembly.

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And that is it, the first stage disassembly is complete. Here is the exploded view:

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