Office of Naval Intelligence Memorandum on Camouflage
OFFICE OF NAVAL INTELLIGENCE.
PAINTING OF SHIPS AS A MEANS OF DEFENSE AGAINST SUBMARINE ATTACK (PART II)
(Reprint from Series L, 15 May 1918.)
Need not be returned. This paper should be shown to all officers interested, but every care should be taken to prevent its contents being divulged to the enemy.
PAINTING OF SHIPS AS A MEANS OF DEFENSE AGAINST SUBMARINE ATTACK. (PART II)
Source: British Naval Officer. 12 April 1918.
I came here gentlemen to try and give you a few practical hints, more on the painting of ships than actually on the conditions of them.
The painting is a matter which you will be able to evolve yourselves, to a certain extent, now that you know the principle of the thing, but I think that at the moment, one of the most important things is the actual painting of the ships, and you have to realize that the fact that a plan has been supplied for a particular ship from which she is to be painted, is not by any means the end of it. In theory, of course, a ship being supplied with a plan, you might assume that if the plan is taken, the painters will go ahead with the painting of the ship to the plan, but in point of fact you will know that questions arise with the painting which will give infinite trouble to painters.
These plans that we issue are very simple profile plans, generally made to the ship when she is built and to the naval architect’s idea of her. Now, especially at a time like this—war time— probably fifty percent of these ships will go to sea with all kinds of deck structure put on them after they have been built. They will have mule boxes and aeroplanes, and endless things of all kinds all over the deck, and you have got to see that those plans are carried out intelligently over all this extra structure, and it is not as easy as it looks.
It is no good of standing within a foot or two of the ship, and just telling the painter that he has to get that black up over there. You want to get back and have a good look at her and have a sketch book in your pocket, and see that he definitely does what you tell him. You have got to remember that while you can devise the best plan in the world, the ultimate end of that plan is being properly applied to the ship, and unless she goes to sea as you mean her to be painted, the whole scheme fails on that particular ship.
You will find that the painters have a great tendency to paint all their black lines very thinly. I have never known why, but they will do it, and you will find that you get a fine healthy distorted plan, and by the time that she is painted you wish you could get another stroke at her.
There are endless questions which crop up during the painting. As to the average Captain you have to make him come around to the point to see that it is going to be some good to him.
You want to see that the after sides of your bridges are properly painted because there are a certain number of cases where the enemy have made attacks on the quarter of the ship as the ship is going away and where they miss the bow of the ship they have tried it from the stern.
The anchors are most important. If the design does not show one or the other of the anchors covered with black, it is just as well to alter the design and carry the black up over one of the anchors.
Another thing you have got to look out for is unnecessary painting. You will find that the ship painters will very likely paint endless unnecessary surfaces which simply mean that they are going to make a bigger job of it. What you want to impress on them is, only to paint that part of the ship which can be seen from the sea’s surface. The submarine cannot see behind doors or around corners. One thing you will find, and that is, it is unnecessary to paint inside.
The whole thing really relies on the Camoufleur at the ports. The whole scheme relies on him and he has to carry out these designs intelligently. I stated to my people in England before I left that they are under no account to alter any of the designs, because these designs are made under special conditions with a lot of thought; they are tested with a periscope, and a great deal of trouble has been put into the original designs.
As to a large number of American mercantile ships which were built before the present ship program, you will probably not have a definite plan for many of these. You will have a certain number of plans which will only fit them moderately well. You may have a plan for a three hundred and fifty foot vessel, and you have got to see that the plan is interpreted to the actual ship in an intelligent way and realize that the mainpoints about the scheme is to get distortion in a big way at long ranges. I do not believe that this particular scheme has any great effect on a submarine at close range. I do not think that any paint is going to get a submarine at close range. A ship is too strong an object against a light horizon and when a submarine is low in the water it sees him entirely against the sky.
Briefly, the theory of this thing that I worked on is this, that like everybody who has thought of painting ships, there was a time, some three years ago, when I thought it would be possible to make a ship relatively increase or decrease its visibility to a great extent, and that was at a time when a submarine was hardly thought of as a real active part in warfare, or likely to be as active as it has become, and it was a question of gunnery if you could more or less hide a ship to a point from a man behind a gun. You may, provided the other ship is not as well hidden as you are, be the first to get your shot in. With a submarine, I think the whole proposition is different. A submarine gets a ship always against a light sky and does not see it against a sea background.
Ships are generally seen from other ships from a bridge or from a shore station or some lookout of a mast, and the consequence is they get a darkish background behind the ship, and if the color of that ship synchronizes with the color of the sea behind, it will reduce the visibility of it to a great extent.
There are endless features which will always enable anyone to pick up a ship at any range. The submarine seeing that same ship against a low sky will probably see the whole of him at once. If it is a misty day he may not see him quite so well. The point is that a submarine is working almost entirely with a hydrophone now. He does not bother about looking for ships, he hears them long before they come up to him, and he not only hears them, but gets their relative course. He cannot get their actual course. If the hydrophone gives him the same sound for a long period, and is working at a resistance, he knows it is going away; if it increases, the ship is coming towards him, and it is after that he can come up to the surface and start visible work with the periscope, and if he knows that a ship is in the vicinity, no being on this earth is going to hide that ship from him. So that if you can, when he comes to the surface with a periscope, distort that ship so much, and into such a degree that it makes it a question of doubt on the part of the submarine officer’s mind as to the actual course of that ship, then you have done just about as much as you can possibly do with paint.
In this last week’s return of mercantile losses, due to submarines, they no doubt were making a concerted effort in connection with the drive on the Western front to generally terrorize people and the nations they are at war with, and I suppose they think by an extra effort it will probably frighten people, and so as a result they sunk twenty-eight ships in this last week’s returns, but, judging from the returns up to the present, I should think that that was an extra effort on their part to get more ships, but at the same time, they unsuccessfully attacked nineteen, and I think the fact that they missed nineteen shows that there is some factor which is worrying them pretty badly.
It may be painting and it may not, but a great deal is painting, and we also know from valuable sources that they do not like the painting at all. They have been sketching a number of these ships in neutral ports, but I do not think sketching is going to help them at all.
I do not know that there is very much to say, the rest really is simply a question of practice. You will find all sorts of questions will arise when you are painting ships which I cannot enumerate now. There are always questions arising from one source and another, but the chief thing to remember in connection with these ships is to see that you get your bow design well carried out and see that any lines of black crossing the bow are properly connected and not left three feet above the joint. They have a very favorite trick of doing that.
The fore bridge is very important and there you want to see that you get an excellent distortion and good variety of paint, and whatever other points occur to you when you are looking at her.
One question that has arisen a great deal at home is the side light screens. The red and green screen. In some cases we found those light screens to be very large, as in the standard ships I have noticed. For some reason, best known to the builders, they have made their light screen the full size of the end of the bridge, and the consequence was we had considerable difficulty with the Board of Trade.
The theory of the light screen has always been a mystery. I do not know what they are for, but I believe the reason, as far as I can gather, was simply to prevent mistake on the part of unskilled men in shifting the lamps in day time. These light screens are important, and if you find any ships fitting canvas along permanent decks, as they are sometimes, you will find an increased dislike to painting any of that canvas. There you have to override the captain or whoever objects to it, and carry your design right over the canvas.
There was the case of a ship which had a number of devices on her proposed by an eminent scientist. They cut her funnel down to about two feet above the deck; they cut her masts down, and they put a sort of bowsprit and poop stay with a long strip of canvas hanging down in the water to hide the stem, and I was told by a man who saw her, that the canvas poop stay carried away before they got through the Narrows. The canvas that went up over the deck structure, I know for a fact was never fitted because I saw the ship in Liverpool. The Captain did not fit it after he got to sea. The cutting down of the funnel meant the interruption of forced draft.
There are one hundred and one schemes which were never carried out.
There [i.e., The] whole business of camouflaging of the ships at sea rests more in the practical side of it than anything else.
In Boston it was proposed that a ship be painted like a cloud. It is astounding to me how people in their senses can talk like that. This is a case where on paper you have a wonderful scheme.
They came into one place in London and said it would be a good idea to paint a bow on a stern, and a stern on a bow. In theory it sounds rather good at first, but if you are at sea in a ship and you see another ship, or you will see a ship with a design on her, when that ships is three miles off when you first sight her, we will assume that you cannot see the bow painted on the stern, and the stern painted on the bow, but after two miles you cannot be such a fool as to think that the submarine if he sees that ship larger, no stern painted on the bow is going to show she is going away. If a ship is passing on the parallel course, a great distance, you might for a moment make people think she is going away. All you can do and what you can do is to make a ship appear to be going southwest when she is going southeast.
The limit that a submarine officer allows himself to be out in the estimation of a ship’s course, to make a successful attack is eleven and a half degrees, which is one point, so if you can fool him with two points, you can do something. If you can fool him with four, you can do a lot. If you can fool him with eight, you have done the trick.
Submarines have given up coming to the surface as they have been fooled to such a great extent.
I have been on patrol and I have seen friends of mine on patrol. One particular friend of mine was in an eighty foot motor launch. He had a six pounder and he saw a big German submarine on the surface at daybreak one day at about four thousand yards, and he started panting after him, doing his eighteen knots. When he sighted the submarine, the latter, much to this fellow’s annoyance, took no notice of him, and did not take the trouble to fire back at him, never getting near him. Personally, I do not think the gunnery question comes into it, it is all torpedo attack. There is the question of painting a ship. If you are stationed at shipbuilding yards where ships are about to be launched, if you have got plans for ships that are on the point of launching it is a great saving in time, labor and money to get those ships marked off while the staging is still around them. If you wait until the ship is launched, you have got to rig all kinds of material, boatswain chairs and endless trouble. The marking off is probably the most difficult, but the filling in is a simple matter if you can get them marked off; the marking off lines painted in with just a dead white line.
If you have a curve to make, they have all their different ways of getting curves, but if you get your ship marked off while the staging is round her it is very much simpler to fill it in afterwards. It is no good painting while she is on the launch ways. If you do paint her, for a couple of months she will knock about wharfs and docks and endless other dirty places and you would have to repaint her in a short time before the ship goes to sea.