This page is an index to Shonas diving pages. Click on one of the items below to access detailed information on that subject. Any errors or omissions should be sent to the author for inclusion.
A hull porthole from the SS Llama, Westray Sound, Orkney Isles.
Coincidentally, just picked up at the end of a very productive dive
As divers, we come across wrecks in an alarming state of decay, and occasionally some nice fittings which are about to be lost to the 'elements'. How many times have you swum over a porthole in a bit of ships plating and given it a knock to find that it is solidly attached? Chances are that you've swum on confident that nobody is going to take that particular item off in a hurry. Next time you visit that wreck, you may be surprised to find a very neat clean hole which once contained that porthole.
The information below is an attempt to dump all of knowledge in a form that others may benefit from. These techniques have been tried and tested for a few years now and whilst maybe not the 'best' method, have always worked for me.
The still shots are from an infra-red helmet-mounted camera which is carried on every dive. The actual porthole documented here took about 20 minutes to recover from finding it to blowing it. It has since been awarded to me in 'lieu of salvage'. If you want to see the actual video footage of the dive, send me a SAE with a blank CD-ROM and I'll put an mpeg video on it.
Please note that all of the items portrayed on this site have been legally salvaged.
Portholes come in a variety of shapes and sizes and people use different terminology when referring to them. The main components of a porthole are the frame or backplate, which is the bit which is attached to the ship; the door, window or scuttle, which is the opening bit with glass in it; the dogs or turnbuckles which are used to secure the door closed. The door is generally attached to the backplate via a brass pin through a hinge; A deadlight or stormcover can be found on some portholes, which is a solid 'door' which can be fastened over the top of the glass door. Usually these are made of iron, but occasionally very decorative brass ones are found.
Portholes can fixed into ships plating in a variety of methods. They can be attached to the inside or the outside of the plate, and are generally fastened on by nuts and washers screwed onto bolts which go through the ships plate to the other side.
There are at least two different methods of attaching the porthole to the plate:
1) Where the outside of a porthole is easily accessible on the ship such as a cabin porthole looking out onto a deck promenade etc, you'll find that they tend to be attached with the flange on the outside of the plate using brass dome-headed bolts, as this flange can be decorative and is visible to the people outside. These 'superstructure' portholes are generally fitted from the outside of the plate, with the dogs and hinges protruding into the cabin/walkway etc. As such, the holes into which they fit are not round, but have cut-outs in them for the door hinges and dog hinges to poke through. These portholes cannot generally be fitted with their doors attached, as the door hinge pin tends to be too big for the cut-out in the plate. It stands to reason, if you want to tackle one of these underwater, you'll have to dismantle the porthole to get it out of the plate. This will involve removing the door underwater.
2) Where the outside of the porthole is not easily accessible, such as a porthole in the ships hull, steel or iron fittings tend to be used (countersunk steel bolts). These portholes are attached to the inside of the plating, with only a rim protruding through the round hole to the outside of the plate. These portholes can be removed intact.
The porthole flange, which sits against the plate, will have a sealing gasket of a variety of materials to stop water leaks. These gaskets tend to 'glue' to porthole to the plate, so even after removing all of the bolts, the plate will not give up the porthole without a fight.
You may think that access to the nuts would be the only way to remove a porthole, but this is not always the case. Sometimes, it's far easier to remove the porthole from the outside of the plate. If the porthole is lying 'dogs down' and access is restricted, this may be your only option.
If the porthole is fitted with brass nuts on brass bolts, then it's going to be tricky to undo them without the bolts rotating. A pair of mole grips can be used if you can reach both sides of the plate at once. Brass nuts will generally need an adjustable spanner to undo, but it is possible to start them off by chiselling their corners round the undoing them by hand.
If you need to take a superstructure porthole out of a plate, you'll almost certainly have to remove the door first. This will require all of the dogs to be loosened and the door opened and hinge-pin extracted. This will require a crowbar to lever the crudded dogs open. If a deadlight is fitted, then it also will need to be removed, as its hinge pin will almost certainly foul the plate also.
Sometimes you'll find that a hull porthole, fitted from the inside, has a brass ring on the outside of the hull. If this is the case, don't forget to pry this off once the bolts have been punched through (see below).
Some ships, especially early 20th century naval vessels, had 'eyelids' on the outside of the hull. These were semi-circular strips of steel which prevented water running down the hull and in through an open porthole. I've come across these before where they have been fitted by drilling and tapping through the hull into the flange of the underlying porthole. If this is the case, these screws, which are almost always brass, need to have their heads removed before the porthole can be loosened. The remains of the brass screws should pass through their holes in the hull plate easily.
A lot of portholes that you'll come across are made of composite materials. Generally, the frame will be made of iron, and the door, dogs, hinge pin and dog pins will be made of brass. To remove the doors from these, put a crowbar between the door and the frame and lever the door off. Don't forget to recover the dogs also. It's unusual to fit a 'wholly' iron porthole, but they do exist.
Sometimes, portholes have their glass door 'plated' over on the outside, This has been observed in wrecks which sunk during WW1. These iron plates may have been used to 'patch' a porthole which had its glass broken but was not designed to have a deadlight. This can make spotting these quite tricky.
The minimum toolkit I suggest that you carry at all times is:
The hammer should be rigged with a screw-eye into the top of the handle where is comes out of the head. Don't be tempted to drill the wooden handle at the bottom and attach it from there. It will only act as a mini anchor and snag on every piece of wreckage you swim over!
The chisel can be drilled or tied to a piece of cord using an snoopy loop of inner-tube loop to provide grip.
The punch is perhaps the most useful and most overlooked tool of the set. You'll do almost all of the work with the punch. Avoid drilling it - attach it to a loop of cord with a loop of inner-tube instead.
The wedge is a large chisel which has been ground down to provide a flat back with a shallow tapered wedge shape, allowing you to insert it between a porthole flange and the hull where there isn't really enough room to get a chisel or crowbar.
If working on a superstructure porthole, you'll need some additional tools:
The adjustable wrench will be needed to remove brass nuts on brass bolts, as these generally haven't corroded to any great extent. The mole grips will be needed to stop the dome-headed bolts from rotating. The crowbar is best used as a lever. Cut the 'claw' off one end and you'll have something which you can hit with a hammer, driving the 'foot' into small gaps. Ensure that all tools can be securely attached to you.
Alternative tools. Air tools can be made to work off a standard scuba set with little modification as the standard interstage pressure is about right. It my seem like an easy way to avoid a lot of effort, but you're going to have a huge problem getting purchase on any workpiece. You need to lean into the work to make any headway, but you don't have enough gravity underwater to make this work well. There's also the disadvantage of the amount of noise and bubbles which you'll create - generally destroying the vis for not only yourself but anyone else downtide! You'll have to carry the tools on every dive, which also means stripping and cleaning them after every dive!
You're either the type of diver who complains that he never sees anything, or the kind that finds spidge on on every dive, even flat sandy club drifts. There are some useful techniques to actually spotting things in the first place.
1) Slow down and swim with your eyes open. Examine the wreckage in your mind and try to 'see' what it may
have looked like on the ship. You may even start to enjoy it down there
Before working on your chosen porthole, you should examine it and ask yourself these questions:
Sometimes, it's better to swim away and leave it for a day when you have the correct set of tools with you.
If working a hull porthole from the outside, you'll have to clean the hull to identify where the heads of the securing bolts are. The easiest way to do this is to hit the plate obliquely with a corner of your hammer in order to chip large chunks of crud and growth off the hull. Go right around the porthole about 4 inches out. leaving a band of 'clean' metal around the rim of the porthole. Make sure that you don't hit the porthole rim which protrudes through the hole, as any damage to this may prevent extraction from the hole.
If working a hull porthole from the inside, you'll have your work cut out for you. Count the number of nuts and carefully smack each one with your hammer and chisel. Most of the nuts should disintegrate, but if they don't, it's not a big problem.
Make sure that when the porthole drops out of its plate, it's not going to disappear down some narrow slot in the wreckage making it impossible to reach. If in doubt, use a buddy line or similar to tie the porthole to a secure object.
If working from the outside, having cleaned up the outer hull, you should now be able to see the heads of the iron bolts/rivets. Using the punch, it should be fairly easy to punch these clean through the hull and through the flange of the porthole. Usually, they're so rotten, that a couple of hits will knock them through. If the heads of the bolts are still well defined and sit proud of the hull plate, use the small chisel to cut the heads off or slice vertically through the head, cutting the flange of the head off. Remember to count the holes and match this to the number of nuts visible of the other side. If one bolt is left remaining, you won't be able to move the porthole!
Once all of the bolts have been punched through, congratulate yourself on a job half-done. That was the easy bit, and should only have taken you 5 minutes or so.
If working from the inside, you should be able to see the remains of the bolts sticking through each nut or where each nut used to be. It's easy enough to then punch the bolt back through the flange.
Now for the hard bit. It's very tempting to hit the protruding rim of the porthole to knock it out of the plate, but this is not an advisable course of action. Firstly, you'll mar the finished of the porthole, which you've so carefully re-riveted up to now. Secondly, you'll distort the rim which will make it even harder to get the porthole out through its hole. Whatever happens - don't hit the rim!
The solution is to use the punch obliquely though one of the now empty bolt holes to try to connect with the porthole flange. If you examine the holes carefully, you'll see that the holes in the flange and holes in the plate are not perfectly aligned. This allows you to use the punch on the back of the flange pushing the gasket apart. You'll need to give it some welly and then some. Choose a diametrically opposite hole and do the same. This job can take 10 minutes or so, but it is loosening the gasket and the plates grip on the porthole. Don't give up - it will come out!
Something to look for is black 'smoke' coming up through the empty holes. This signifies that the carbon trapped between the hull and the gasket is escaping through a gap. When you get black 'smoke' coming from the rim of the porthole protruding through the plate, then you're almost there. A couple of more hits should do it.
Usually, you're completely knackered and wondering about the effect this is having on your decompression profile, given that your arm is throbbing from all the hammering. The appearance of the black 'smoke' does wonders for your moral and allows that final burst of effort to free the porthole!
With any luck, the porthole should drop cleanly out of the plate.
Loosening the porthole from the inside If working from the inside, how do you now get the gasket seal broken? I would, by preference, now move to the outside of the plate and work on it from there, if access was suitable. If not, then you're going to have to pry the porthole from the plate from the inside! This is where the wedge (modified chisel) comes into its own. You should be able to drive the tip of the wedge between the porthole flange and the hull plate and keep driving it in until the porthole flange is levered out. Be careful - it's quite easy to bend a flange doing this. Once it's in far enough, hammer a chisel into the gap and remove the wedge, placing it further around the flange and repeating the exercise. If you don't manage to loosen the porthole, you're going to struggle to get the wedge and the chisel out of there. A crowbar can be handy in this circumstance.
You'll probably find that the proximity of frames within the hull make it difficult to work around the sides of the porthole, and the proximity of the deck makes it almost impossible to work around the top of it. Having a short crowbar can be very useful in these circumstances.
STOP. Have a rest. Check your gas and time and see if your can find a buddy. Tidy your tools away and regain your composure. Having spent all your energy getting the porthole out, you don't want to rush the next bit and lose it by negligence!
Having remembered to secure the porthole from being lost down a hole in the wreck, all you need do now is to pull it up onto something flat out of the silt, where you can work on it. Attach a lifting bag to the flange, not a door dog, and send it to the surface. If your bag clip won't go through a bolt-hole in the flange directly, put a loop of line from the lifting bag through the hole and put the clip through the protruding loop.
The only thing left to do is to photograph it and send a declaration to the Receiver of Wreck. Provide as much information on the form as possible, remembering that you can request this information to be treated in confidence.