US2364064A

US2364064A - Centering device

Info

Publication number: US2364064A
Application number: US480879A
Authority: US
Inventors: John P Francesco
Original assignee: Individual
Current assignee: Individual
Priority date: 1943-03-27
Filing date: 1943-03-27
Publication date: 1944-12-05
Anticipated expiration: 1961-12-05

Description

Dec. 5, 1944. J. P. FRANCESCO 4 GENTERING DEVICE Fi'led March 27, 1943 INVENTOR Jblm 7. Francesca.

Patented Dec. 5, 1944 UNITED STATES PATENT OFFICE" CENTERING DEVICE John P. Francesco, Havel-hill, Mass. Application March 27, 1943, Serial No. 480,879

2 Claims. (Cl. 33-46) (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) In drydocking operations, it is usually necessary to maintain the ship over the centerline of the drydock floor so that the keel will drop on the keel line pier blocks as the water level goes down. After the ship is moved in position in the flooded drydock, centering lines are, stretched across the dock at the bow and stem to properly guide the ships downward course as the water recedes. A float or plumb bob is commonly used on this line as a marker over the center line of the dock, and as the ship is lowered the centering line is let out at both ends to more or less follow the drop in water level. i

Another method that has sometimes been used is to have a buoyant marker at the bow or stern attached to a line running down under a pulley fastened to a pier block properly located on the dock floor, the other end of the line being passed up to the top of the dock where it is taken up as the water recedes, so as to maintain it taut between the floating marker and the pulley while maintaining the marker on the water surface. This forms a virtual inverted plumb bob supported upward from the pulley, the buoyant force taking the place of the force of gravity in an actual plumb bob or rod.

The present invention is an improvement in the means heretofore used for centering and checking the ships position in a drydock by combining the two old devices and connecting them together to aid in maintaining the ship on its proper downward course as the water is drawn off, so that it will come to rest in proper central alignment on the keel line pier blocks.

The object of this device is to provide an improved means for sighting the bow or stem of a ship in drydocking to enable its proper guidance over the centerline of the dock as the water is withdrawn therefrom.

A further object is to combine the devices used to assist in centering a ship in drydock in such a manner asto obtain better results and eliminate any efiect of turbulent weather conditions that are sometimes met with.

A further object is to devise a centering means for ships in drydocking, which may be easily drawn out of the way of the ship as it is moved into place, and which may then be quickly and accurately adjusted and used from then on without any further adjustment.

Further and more specific objects of my device will appear as the description proceeds, having reference to the accompanying. drawing, in which:

Fig. 1 is a sketch indicating the, relative location of the centering means in connection with a particular shape of ship which comes to a point at one place at the bow and at two places at the stern;

Fig. 2 is a side view sketch of the ship and ceitering device shown in Fig. 1 from the port s1 e;

Fig. 3 is a sectional view of a portion of the drydock taken at 1-3 of Fig. 1, showing the relative positions of the parts of the device, the keel line pier block being enlarged for better illustration, and

Fig. 4 is another sectional view of a portion of the drydock taken at 3-3 of Fig. 1, showing the keel line block and another pier block, enlarged as in Fig. 3, but omitting the plumb bob line 9, and showing a buoy attached to the sight line used as a part of my device.

Like parts in the several views of the drawing are designated by the same numerals.

In the drawing, the ship I is seen moved into position over the drydock floor center line l2 (Fig. 1). The line 9 is stretched across the drydock at the bow and has a plumb rod I hung on a ring 8 fixed to the line 9', over the center line It. Similar lines 8' and 9" are stretched across the drydock and have plumb rods 1' and 1" adjacent the corresponding comers at the stern.

(If the stern comes to a point at one place, only one line would be used at the stem, with a plumb rod I at that point.)

The {pier block II is on the center line of the drydock floor and has a mark in on its top designating the line directly over the center line. The pulley 2 is mounted so that its groove on the port side is tangent to the vertical plane of this centerline. The sight line 4 is passed around the pulley,

as shown more clearly in Figs. 3 and 4, so that it runs to the starboard side of the pulley and is fastened to line 5 which is passed around a pulley 3 mounted on a block l3 at some distance from block II, and then passes up to the top of the drydock, where it is held or fastened to keep the line taut. The other end of the sight line 4 is connected to a buoy 8.

To prevent fouling of the sight line during maneuvers of the ship in moving it into position, the buoy may be pulled down out of the way by pulling up the line 5. When the ship is in place, line 5 is let out until the buoy comes to the surface. It is then picked up by some one in a punt, and the sight line 4 is removed from the buoy and attached to the ring 8 which is directly over the drydock centerline, as previously pointed out. The line 9 may thenbe drawn up as desired so that the ring 8 remains in the vertical plane of the centerline, and the line may be also drawnlisting the ship might have which would bring its keel off center even if one particular portion of the how were kept centered during the ship lowering operation.

Thus the device enables proper alignment of the keel on the keel blocks even if the ship lists. The device has the further advantage over previously used devices for this purpose in that it is more stable and needs no further adjustments once it is set up. The line 9 if used by itself with a plumb bob or even a plumb rod, which may be 2 or 3 feet long, would not be as accurate nor stable as my combined device. A high wind or heavy sea, if the rod extends partly into the water, would tend to sway it and make sighting difficult and inaccurate. The same is true if the buoy and sight line 4 is used independently for sighting purposes.

In addition to being unstable, these devices when used independently, require constant adjustment during the water evacuation. As the ship is lowered, they have to be accordingly lowered. Line 5 would have to be pulled up to keep the sight line 4 taut, with the buoy following the water level. In the case of the line 9, its ends would have to be let out proportionally to maintain the ring 8 and the plumb rod directly over the center line during the lowering operation.

In my device by attaching the sight line It to the ring 8, I obtain a stable device that is simpler to adjust, and once adjusted may then be left alone and used to better advantage, making sighting easier and more accurate, not only in determining the proper centering of the ship at the surface of the water, but also with respect to its keel.

Similar sight lines 4' and 4" are arranged in like manner at the stem at the corresponding points thereof, locating the ships stern over the centerline. It is to'be understood that a single sight line 4' may be used at a point of the stern which is directly over the keel line, if desired. In either case the sight lines 4" and/or 4' are connected to the corresponding line or lines 9" and/or 9' in a manner similar to the method used at the bow, as explained above.

(9 I may omit any one or all of the pulleys 3, 3' and 3" where conditions are such that the line passed directly up from the pulley 2 to the top of the dock would not interfere with the ship maneuvers, in bringing it into position. Pulley 3 (or 3' or 3") is used and placed 011 to one side only under conditions where it is necessary to do this to prevent fouling of the line.

It may therefore be seen that my device will save time to a certain degree and will give more satisfactory results in operation.

This device and method may be used by or for the Government of the United States for governmental purposes without the payment to me of any royalties thereon or therefor.

What is claimed is: 1. A ship centering device for drydocks comprising a line stretched across the drydock at either end of the ship having a plumb bob hung at a fixed point thereon adjacent the position of the ship to be sighted when the ships keel is properly aligned over the keel line pier blocks, a sight line having one end thereof tied to the plumb bob, the other end of said sight line being passed under a pulley located directly under said plumb bob and then to the top. of the drydock for fastening thereto.

2. A centering device for use in drydocks including a line stretched across the top of the drydock, another line extending from the top of the drydock and passed under a pulley mounted adjacent the floor of the drydock over its center line, and means at the point of the first-mentioned line directly over the centerline of the drydock floor to which the said other line is tied, so as to form a stable vertical sight line.

JOHN P. FRANCESCO.