US1180194A - Method of increasing cargo-carrying capacity of vessels. - Google Patents

Description

F. L. SAWYER.

METHOD OF INCREASING CARGO CARRYING CAPACITY OF VESSELS.

APPLICATION FILED MAR- 9. I916.

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rm: COLUMBIA PLANDGRAPH co., WASHINGTON, n. c.

FREDERICK LEWIS SAWYER, OF NEW YORK. N. Y;

METHOD OF INCREASING CARGO-CARRSTING CAPACITY OF VESSELS.

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Application filed March 9, 1916.

To all whom it may concern: I 7

Be it known that I, FREDERICK Lnwrs SAwYnn, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Methods of Increasing Cargo-Carrying Capacities of Vessels; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as wlll enable others skilled in the art to which it appertains to make and use the same.

My invention relates to the method of preventing the increase of draft of vessels, due to inequalities between the temperature of the parts of the vessel below the water line, and those parts of the vessel above the water line.

The vessel may be considered as a hollow longitudinal box girder, comprising, mainly, the skin plating, the decks, the frames, and other parts connecting the two. Part of the ship when afloat is submerged below the water line, and part is above the water line. In certain times of the year, and in certain localities, the water is very much colder than the air, and again under other conditions the air is very much colder than the water. When the water is colder than the air, there is a tendency of the submerged parts of the girder to contract, and the parts of the vessel not submerged to expand, causing a depression of the two ends of the girder, or, as it is technically known, hogging of the vessel. On the contrary, if the air is colder than the water there will be a tendency of the upper part of the girder to contract, and of the lower part of the vessel to expand, causing a tilting up of the two ends of the vessel, which results in a bending down of the vessel amidships, or increasing the draft amidships, which is technically known as sagging. Either of these results tends to increase the draft of the vessel, either forward or aft, or amidships, as the case may be, above the normal mean draft of the vessel. Under ordinary harbor conditions, this may not be important, but where the vessel has to go through canals of a predetermined depth, or cross bars where the water is comparatively shallow, it is desirable to carry as much cargo as possible, and a slight change of draft may be very material.

The hogging and sagging of vessels, due

Specification of Letters Patent.

Patented Apr. 18, 1916.

Serial No. 83,147.

to temperature, is of more importance in the case of iron or steel vessels, and is particularly important in the case of long and shallow freighters, such as ore or grain carriers, or colliers, or the like, especially those which are designed to go through canals of limited depth. It has been known in practice that long steel vessels in summer cruising in cold water increase their normal draft as much as six inches by the bow and stern, which is entirely due to the upper portion of the vessel being of considerably higher temperature than the submerged portion of the vessel. This tendency to hog is more accentuated than the tendency to sag, be cause of the fact that the ends of the girder at the bow and stern are comparatively sharp, and displace far less water for the same draft than would result from any sagging effect due to the same conditions in temperature, where the upper portion of the vessel was at considerably lower temperature than the submerged portion of the vessel. This excess due to hogging is further augmented because of the fact that the air frequently reaches a temperature far higher than is ever reached in the water of flotation; and the differences in temperature between the air and the water of flotation are more apt to be greater in summertime than would be the corresponding differences of temperature in the winter.

According to my invention I purpose to obviate these objections by causing the exposed and the submerged parts of the vessel to be brought as nearly as possible to the same temperature, either when loading alongside dock, or when going through canals, crossing a bar, etc, where these conditions in draft might be of material importance. To secure this result I apply the water of flotation to the exposed parts of the vessel as far as practicable, as by pumping same through a plurality of hose, so that the entire girder may be brought to a substantially uniform temperature, and so that any previous hogging or sagging may be compensated for by the contraction or expansion of the upper parts of the vessel when so treated with the water of flotation.

Reference is had to the accompanying drawings, in which Figure 1 shows a side elevation of an ordinary ore carrier or collier; and Fig. 2 is a diagram showing'the effect of hogging and sagging on the f keel of the vessel due to corrected and uncorrected temperature changes.

Referring to Fig; 1, A B represents the keel line of the vessel, and in Fig. 2 this is shown in full lines when the vessel is loaded on an even keel by correcting for any" temperature difierences so that the vessel is neither hogged nor sagged at the time of loading. When the lower part of the vessel is'at a lower temperature-thanrtheparts of. the. hull above the water line, the keel. line:

would assume the position indicated by the:

dotted lines A B inzFi'g. 2; In. this case the keel would be-hogged up amidshipstas keel line would assume the position indicat ed at A 13 showinga sagvamidships, as:

at a and aliftingup of theends as at 6 Thus,, it will be seen that Whenthe. submerged portion of the ship is colder than the upper portion, therewill be a hogging Copies ot thii patent may be obtained tor five cents each, by. addressing. the Commissioner ot- Patents,

up of the amidships portion of the'keel, and a sagging down of the bow and stern portions, thus increasing the draft by the bow and stern; while if the upper portion of the ship is colder, there will be a sagging down of the amidships portion of the ship and a tilting up of the bow and stern; in both cases causing increase of draft which, in certain cases, isvery undesirable, as it reduces the amount of cargo that the vessel can carrying for-a predetermined draft.

Having thus described my invention what I claim and desire to secure by Letters Patent ofthe United States is The method of preventing, increase in draft of a vessel where there is a substan tial difference of temperature between the air and the water of flotation, which consists in .applyingthe water of flotation to th upper portions ofvthe vessel for the purpose of approximately equalizing the temperature of the hull above the water line with the temperature of the hull below the water line, thereby preventing or reducing hogging, or sagging.

In. testimony whereof, I aflix my signature.

FREDERICK LEWIS SAWYER.

Washington; D. 0.

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