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es egal the efficiency of the keel in “sagging,” a condition which is the most fre- quent and most dangerous, is materially reduced. This will be evident when the keel in compression is considered. To obtain the full value of this member when performing this function, metal must be in line with metal, plate in line with plate, hot in a zigzag plane as would occur when out of line; this is one of the principal objections. Another objection is that the keel plates being intercostal and secured to the transverse floors by the vertical clips, there is no metal to rely upon when in tension, except the rivets in these clips. This condition will obtain more or less. at all times, and especially when the boat is on the crest of a wave.. | This defect is remedied in the construction shown in sketch “B.” Here the rivets in the clips act as additional strengthening to the vertical keel plate when in tension and materially aid it when under compression, In this type of keel construction the floor plates are scored out for the depth of the keelson and lap above it in the machinery spaces, as shown by the dotted lines in this sketch. At the ends of the boat the floors are in two pieces and are secured to the vertical keel by the angle clips and flanges of the plates, as shown by the solid lines. This gives a continuity of metal in the longitudinal member at a point farthest away from the neutral axis—a condition much to be desired. _The increased stiffness of this arrangement can be seen at a glance, while the important additions to the longitudinal strength are very ap- Saeren ZT” Feel et ahae ie CESS RR | Seep aae, i ace sas rere ears oe a Bax I x Z. se ne MARINE REVIEW. — tt principal longitudinal member is brought nearer to the neutral axis, and so few connections to floors provided. As regards the various connections of the vertical keel to its adja- cent members and the connections at the butts of the different plates and angles there remains so much to be said that but little will be attempted in these columns. The fore-and-aft continuous angles at the top and bot- tom of the vertical keelson should be well strapped by a bosom angle, and a good shift of butts made with each other, as well as with the surrounding work. For a certain length forward, where the cross sec- tion at the keel assumes a U shape the bars at the bottom must necessarily be omitted. It is impossible to make a good riveting job in this case. In some cases nothing was substituted, but where it is desired a substitute can be made of a forging or light casting, shaped as shown in sketch “D.” This enables the vertical to be riveted to it, and the flat keel plates to be well tapped to it, thus insuring a good stiff connection. The butts of the vertical keel plate are connected by a double butt strap, treble-riveted and extending from the lower to the upper angle. This makes a rigid con- nection and guarantees the reinforcing of the longitudinal strength. As to the connections between the floors and keelson, they must be ‘of ample strength to insure the transmission of all the strains to the various members involved, and the angles or flanges forming these con- nections should be well fitted and driven up. FLare 2. * _Saercu C parent. The fore-and-aft angles at the bottom and top of the keelson, together with the keel plate, form this addition, whereas in the former case there was nothing in this direction. As in sketch “A,” the vertical clips form rigid connections between the keel and the transverse framing, while the connection to the hull is amply taken care of by the two fore- and-aft angles mentioned. Where the floor plates are not too large they can be in one piece and ‘a score made for the keelson by punching. In the larger plates it is cheaper to lap them above the keel, as shown by the dotted lines in sketch “B.” In sketch “‘C” is shown an entirely different style of keel construction, and while it is used on some types of boats it would hardly be available for the larger torpedo boats or destroyers. This method of construction has one feature to recommend it and that is its comparative cheapness. As can readily be seen, it is formed by running an I beam of varying sizes on top of continuous floor plates, to which it is connected by angle clips and by the reverse bar or flange of the floor plate. The size of this I beam section is 5x3x3 in. by 10 lbs. amidships, reduced at the ends to 4x954x254 in. by 74 lbs. At the extreme ends it was continued in an inverted T bar section 3x3 in. by 614 lbs. In the wake of the engine space this beam was omitted in the center of the ship, but its place was taken by two channel bars of 4x2x2 in. by 8 lbs., spread apart so as to form the boundary and supporting bars of the engine bed plate. The boats on which this type of keel construction was used had but one engine, thus enabling the employment of this method. This practice is no doubt very good for boats of this size and displacement, 100 ft. and 65 tons respectively, but it can hardly be called the best practice when the Of the three sketches shown it seems that the one marked “B” is the most favorable for consideration. As this type meets all of the theoretical requirements involved, and as it is undoubtedly the easiest in const:uc- tion (except sketch “C,” which will be disregarded), and consequently the cheapest to erect, it must necessarily be selected for future use. I would therefore suggest that this method of construction be followed in all boats of this type. Although only a small portion of the ground has been, covered, a very valuable and important feature has been discussed, and it remains to the following articles to build up as good structure upon the “backbone” which has been created in this. The article will be devoted to some com- ments upon the additional longitudinal framing used in these boats. On Wednesday and Thursday last New York harbor was almost closed to navigation. On the New York side of North river the thick ice and ice floes made it practically impossible to navigate’ side-wheel steamers and some of the paddle ferry boats were fast in the>ice for hours at a time. Few boats could reach their wharves.< The larges transatlantic liners had to be almost surrounded with tug boats and sonie: of the loaded steamers worked for hours before being able to make ‘a passage for themselves. While such great trouble was being experienced in New York harbor, it is surprising to know that hardly any ice was visible: on the Thames river, Conn., and the wonderful Kennebec river in Maine. These rivers never freeze over, and considering the location, especially the Kennebec river, this is a remarkable fact.