US2421145A - Method of building log rafts - Google Patents

Description

y 7, 1 947. .1. G. GIBSON 2,421,145 7 METHOD OF BUILDING LOG RAFTS Filed Feb. 28, 1945 l/VVEN 701a JAMES 'okoo/v 'leso/v under the finished raft.

Patented May 27, 1947 METHOD OF BUILDING LOG RAFTS James Gordon Gibson, Vancouver, British Columbia, Canada Application February 28, 1945, Serial No. 580,156

2 Claims.

My invention relates to improvements in log rafts and rafting methods. The objects of the invention are to provide a method of building log rafts which is particularly adapted for use in rafting such heavy logs as are regularly transported in deep sea along the coast of the Pacific Northwest. Hitherto the most successful log raft built for this work was the so-called Davis raft which relied on a mat fabricated by binding a plurality of logs in side by side relation to form a floor on which a bundle of logs totalling some millions of feet were bound and towing the entire structure to destination.

The present raft contemplates the use of the mat as a cradle on which the bundle of logs constituting the raft is formed and removing said floor for use in constructing other rafts after the superimposed load has been properly tightened up and bound into a substantially cylindrical unit.

Referring to the drawings:

Fig. 1 is a transverse view of the mat on which the raft is to be formed.

Fig. 2 is a transverse view showing the mat substantially immersed in the water and the raft formed thereon.

Fig. 3 is an end view of the finished raft with the mat portions removed.

Fig. 4 is a longitudinal view, part in section, showing the preferred method of cinching the raft lengthwise.

In the drawings like characters of reference indicate corresponding parts in each figure. With a view to clearly showing the ropes or cables binding the several parts of the mat and the raft together, the logs are shown somewhat spaced apart, but it will be understood that the logs are bound together as tightly as possible to withstand the working of the structure during towing, etc.

The numeral l indicates a mat which is formed in two sections 3 and 4. Each section is made up of logs 5 which are floated in side by side relation as shown in Figure 1 and are connected together by a plurality of wire ropes 5 preferably laid alternately over and under adjoining logs, across each section 3 or 4 and. back to starting point where the free ends of the ropes are clamped together as at l, leaving a free length 8 of said ropes lying in the water to be later used for the purpose of hauling the section to which it is attached from It will be understood that these mats and the rafts built upon them are greatly in excess of the length of any log used and that particularly in the making of the mat some logs may be joined together lengthwise by boom chains or other appropriate devices so that the mat when made 'up will not be liable to elongation due to some of the logs moving endwise with respect to adjacent logs, due to water movement or the action of loading the raft logs onto the mat.

When both sections 3 and d of the mat are completed, a plurality of lines [0 are attached to the innermost logs of the section d as shown in Figure l and are passed down and around the innermost boom of the section 3, the free ends of said lines being brought to the outer edge of the section 4 and clamped in position as at ll, so that both sections may be held together during the subsequent raft building operation.

A plurality of girth lines M are spaced at suitable intervals of the length of the completed mat and are extended transversely across the mat with their free ends 15 descending into the water.

When sufficient girth lines are so placed, rows of logs H are laid parallel to the logs of the mat over said girth lines, the logs being piled from the centre of the mat outwards, the end to end abutment of logs of one row being staggered with relation to the abutment of logs in adjacent rows so as to stiffen the ultimate raft against endwise flexure. As the logs are piled upon the mat, so will the central portion of said mat become concavely curved so that by careful placing of the logs the superimposed logs will assume a substantially cylindrical shape as shown in Figure 2.

' When a sufficient quantity of logs are assembled,

the free ends l5 of the girth lines M are brought over the logs and a tackle l8 secured between the ends of each girth line. The girth lines are then tightened up by winches hauling in each of the tackle ropes until the logs encircled by each girth line are brought into compact form. When all the girth lines are drawn up as required their free ends are clamped together by any suitable clamps as at l9, see Figure 4. The assembled and bound bundle of logs now becomes a complete raft indicated by the numeral 20.

In towing any bundle raft by a tow line attached adjacent the forward end there is a tendency to elongate the raft so with a view to preventing this condition and providing a continuous endwise compacting effort on the raft while being towed, a cable 22 is tightly bound around the raft adjacent its after end and is preferably clamped at the top of the raft as at 23, the free end of said cable is led forward and allowed to fall in between parallel logs adjacent the upper centre of the raft and is fitted with a single sheave block 24. A second cable indicated by the numeral 26 is securely bound around the forward end of the raft and is also clamped adjacent the top of the raft as at 21, the free end of this cable is passed through the block 24 and preferably led in between the logs and out forwardly of the raft to form a tow line 28 therefor. When the raft is completed, clamps holding the lines Hi to the outer edge of the mat section 4 are released, tugs or other suitable hauling devices are attached to the free ends 8 of the lines 6 and the sections 3 and 4 of the mat l are pulled from under the raft 20, leaving said raft ready for towing to destination.

The clamps l9 will preferably be ofsome approved quick release type capable of bein collectively disconnected by detonating or other means, so that when the raft is delivered, it is only necessary to open said clampsto allow the logs to settle and disperse over the surface of the booming ground.

The towing cables 22 and 28 and the girth lines l4 and their clamps only remain to be returned to the booming ground where further rafts are to be built.

While I have described the mat as being made up of logsand ropes binding said logs together, in side by side relation, it will be obvious that said mat may be made of sawn timbers spaced some reasonable distance apart and held in position by chains, cables or other means which would allow the mats to conform to the underside of the raft built upon it.

What I claim as my invention is:

1. The method of building a log raft which consists of superposing logs in side by side relation upon a flexible buoyant mat until the mat has become substantially concave in cross section, binding the superimposed logs together as a bundle raft and removing the mat from beneath the raft.

2. The method of building a log raft which consists of superposing logs in side by side relation upon a flexible buoyant mat until the mat has become substantially concave in cross section, binding the superimposed logs together as a bundle raft, dividing the mat longitudinally and removing the divided portions of said mat from beneath the raft.

JAMES GORDON GIBSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 392,691 Robertson Nov. 13, 1888 715,939 Ayres Dec. 16, 1902 800,263 Campbell Sept. 26, 1905 1,142,239 Davis June 8, 1915 1,488,664 Clancy Apr. 1, 1924

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