US2257405A - Hydroplane - Google Patents

Description

Sept. 3 4 H. F. s. VON IBURTENBACH 2,257,405

HYDROPLANE Filed April 7, 1957 2 Sheets-Sheet 1 Patented Sept. 30, 1941 HYDROPLANE Hanns Frciherr Schertel von Burtenbach, Wiesbaden, Germany Application April 7, 1937, Serial No. 135,592 In Germany July 16, 1934 9 Claims.

The present invention relates to hydroplane boats having lifting planes fitted below the hull and adapted to lift the body of the boat out of the Water when in motion. The invention relates more particularly to the shape of the hull, and the disposition of the lifting planes with relation to certain features of the hull, to the supports of the lifting planes, and to the manner of connecting the said planes and supports to the hull.

In the past, the effect of the shape of the hull and the desirability of shaping the hull on special lines have not been realized in the case of hydroplanes provided withlifting planes, and it has been assumed that the hull does not affect the travelling qualities of the hydroplane. For this reason, hull shapes were usually applied that had no relation to the lifting planes, and which hardly contributed to the stability of the hydroplane. When boats of such hull shapes struck the water at full speed, for example in rough sea, they produced resistances of such force that, in consequence of the sudden drop of speed, the lifting planes were not able to support the hull any longer, and the latter dropped back again into the water.

The hydroplane boats according to the present invention are constructed on entirely novel lines,

in that a reciprocal cooperative efiectis established between the hull and the lifting planes in such a manner that the hull assists the stabilizing action of the lifting planes and increases the total raising power when the hull strikes the waves; or, vice versa, and also so that the flow of water at the hull is favorably influenced by' the lifting planes. This effect is obtained by a novel disposition of the lifting planes in combination with the hull, which owing to its shape will produce great dynamic lifting forces when coming into contact with the surface of the water and small resistances opposing the forward run of the craft, such lifting forces tending to lift the hull out of the water in starting or when travelling slowly or through the waves, thereby preventing the hull from being immersed excessively in the wave crests, and the said forces also tending strongly to right the hydroplane again when the craft is in .an inclined position. The hull of the hydroplane according to my invention is provided in the ordinary Way with steps or sharp edges extending transversely to the travelling direction and adapted to force the flow off the bottom of the hull and to permit Wetting ofthe bottom only at portions provided with gliding surfaces inclined forwardly against the flow. Contrary to the existing arrangements, the gliding surfaces are disposed relative to the axial direction of the boat, as Well as transversely to the axis, with considerable spacing, one section being positioned so far towards the bow that on contact with the water surface it will produce the greatest possible moment for stabilizing the longitudinal position with a ,minimum of frictional resistance, and also separate gliding surfaces are positioned at such distances laterally one from the other that the greatest possible moment for stabilizing the transverse position is produced. These lateral steps, which are preferably positioned at the stern but may also be positioned amidship, may even project beyond the greatest width of the hull. Owing to the fact that all other sections of the bottom are positioned high up or are arched so as to obviate frictional resistances by avoiding wetting, lifting forces and stabilizing moments are set up with lowest resistances to forward motion.

According to myinvention, the lifting planes are positioned directly below the above-described gliding surfaces, so that their lifting resultant coincides in position as much as possible with the position of the lifting resultant of the re-, spective gliding surfaces, whereby the gliding surfaces can supplement the lifting effect without causing a displacement of the combined lifting resultants. The hydroplane remains, therefore,

in its trimmed position. The lifting planes are steps, which are the most stable sections of the hull. Theencls of the lifting planes may pref erably be made to pass over to the gliding surfaces (at the steps) in such manner that the lifting effect of the lifting planes is supplemented by the lifting effect of the gliding surfaces without any interruption of flow. As a result the lifting planes (or lifting surface sections in continuous, i. e. uninterrupted surfaces) are themselves positioned at the greatest possible longitudinal and transverse spacings from one another, so that their own stabilizing moments ated, in the case of fracture or failing of a lifting plane, to compensate this loss and keep the machine from capsizing.

For the purpose of still further reducing'lthe resistance of the hydroplane when cutting through the waves, steps may alsobe provided at the side walls of the hull, which will force' off the fiow and will prevent areas of considerable length of the side walls from being washed' The gliding surfaces at the bow are hit by the full force -of the rising waves, whereas the gliding surfaces astern move in waves subdued by the action of theforwardgliding surfaces and lifting planes. According to the invention, the gliding surfaces are shaped differently, corresponding to their position at the forward or rear part of the hull. The forward gliding surfaces are provided with a more pronounced keel; and while travelling are placed higher above the water level by means of longer plane supporting stays than the rear gliding surfaces To obtain a powerful dynamic lifting effect near the stem, the forward gliding surface is provided with an increasing keel-shape and forwardly increasing transverse arch towards the stem in such a manner that this side-arch on the bilge edge terminates at all points in the horizontal or below same. The effect may be increased by means of a liaring portion near the stem in the shape of a fin,

which mayalso be arched concavely in the longitudinal direction and, in that case, will operate as a lifting plane. The said fin may extend towards the rear and pass over in smooth transition to the surface of the lifting plane. The same effect is obtained also by means of gliding surfaces which toward the center have the form of an inverted V, i. e, upwardly roof-shaped or concavely transversely arched, in which case the ends of the lifting planes may be properly fixed to the bilgeand a good transition can be obtained into the gliding surface.

Furthermore, in order to ,prevent excessive immersion of the bow into the wave-crests, a

lifting plane may also be fixed at the stem which,

if strongly keeled andarrow-shaped, will produce aflow of water spreading strongly to the sides and thus protect the lifting planes lying behind it from objects floating in the water. .It may also be arranged in the usual-way so as to be positioned above the Water level during normal travelling on the water. The keel (V) shape of thisauxiliary lifting plane can be .made similar to that of the gliding surface lying behind it in such a way that the lifting planes will produce a trough in the water having a shape similar to the cross-section of said gliding plane.

In order to separate the laterally spaced gliding surfaces, the portion of the hull between the said surfaces has an elevated position produced by two longitudinally extending vertical walls. This bottom section can also be arched upwardly or be shaped like an inverted V. This central section is thereby prevented from coming into contact with the water. The lateral gliding surfaces may extend beyond the sides of the hull and, in such case, areincreasingly more sharply V-shaped towards the stem until they pass over entirely into the sides of the hull. The lateral gliding surfaces thus formed will correspond to two-halves of the known wave-collecting form fixed laterally to the sides of the hull, the keel of which is formed by the edge of the bilge of the hull, and the stem of which is formed by the side wall. The keel-shape may also be transformed towards the stern into an inverted V- shape, 1. e. an upwardly directed roof-shape.

Also in this case the gliding surfaces may be extended laterally into fin-shape as described above, and the flaring section may be made to pass over gradually to the lifting planes.

1 A preferred modification of this general disposition producing a good effect is obtained by having a V-shaped bow-gliding surface and gliding surfaces at the stern with inverted V-shape at the center.

Water craft fitted with lifting planes offer quite special difficulties in starting. In most cases the head-resistance of the hull of the boat is greater in starting than the resistance of the supporting surfaces at full speed, when the hull has been lifted from the water. In the boat hull, according to the invention, the forward gliding and lifting surfaces produce a trough in the water, by which sections of the hull are increasingly laid bare as the travelling speedincreases. For this reason the boat hulls described, particularly those of larger hydroplanes, are designed so that the water thrown off the forward gliding surface and returning again to the midship section of the boat is again forced away from the hull of the boat so as to lay it bare again. For this purpose one or a greater number of auxiliary or intermediate steps are provided between the principal steps or between the lifting planes, or merely edges adapted to throw off the flow may be provided, whichedges are positioned sufliciently high so as not to be wetted at normal travelling speed. According to the invention, auxiliary lifting planes are also provided, which are preferably situated directly below the auxiliary steps and which cannot be wetted at normal travelling speed. At low speed and will trim the boat stern downwards, thereby increasing the setting angle of the principal planes. ThlS trimming is performed, for example, by means of the above-described auxiliary plane positioned adjacent to the stem at the start. In

case a greater number. of auxiliary planes are used, those positioned forward are designed so that with the reduction of speed they will be submerged sooner, deeper and with a greater area 'or a higher auxiliary lift than the auxiliary planes positioned at the rear, so that the lifts developed at the foreship will exceed those detance of the rear auxiliary planes behind the center of gravity, whereby the. moment of the forward auxiliary planes exceeds that of the rear auxiliary planes.

forward gliding surface from the stemlooking aft.

Figs. 9 to 12 are diagrammatic sectional views of the hull from astern, on the line :c--x of Figs.

.3 and 4. The gliding surfaces are of the sepa rate laterally positioned type.

Figs. 13 and 14 are side and bottom views respectively of a larger size hydroplane with five single gliding surfaces and three continuous lifting planes.

In the hydroplane illustrated in Figs. 1 and 2,

the characters a, b1 and be denote the three for-' wardly inclined gliding surfaces. The rear edges of the gliding planes are formed by steps, the foremost one of which is designated d in Figs. 1 and 2. Beneath the aftermost portions of the gliding surfaces adjacent the steps, lifting planes j aresecured in spaced relation to said surfaces.

In the example shown in the drawings, the lifting planes at the bow and stern are constructed as continuous or uninterrupted planes extending across the entire width. The ends of the lifting planes are in this case secured to the hull at the bilge. According to the invention, the step of the gliding surface a is located so far forward that when the hydroplane strikes the water surface, the opposed stabilizing moment resulting from the lifting force, which is defined by the shape and size of the gliding surface, and the lever arm at the point of attack, is at its maximum value with a minimum of frictional resistance. The after portion of the gliding surface a is terminated by the side wall of step d, which is widest at the bottom and disappears toward the edge of the deck, as indicated by dotted lines in Fig. 5. The bow gliding surface is set at an angle of such size, that an angle 7 is formed with respect to the Water line shown in dotted lines in Fig. 3, when the hydroplane careens on this surface. The lateral glidingsurfaces In and 112 are, in the example illustrated in Figs. 1 and 2, situated at the stern and extend over the maximum width of the boat. From Fig. 2 the great distances of the gliding surfaces In and be from one another are apparent.

In order to. produce the supporting effect according to the invention, the shape and size of the gliding surfaces as compared to the lifting planes should be arranged so that they will gradually produce about the same lifting effect as the lifting planes. If the lifting effect is too small, it is natural that only an insufficient auxiliary effect will be obtained, while if the lifting effect were excessive, shocks to the gliding surfaces could easily occur if the sea were running high.

In Figs. 3 and'4 a modification of the hydroplane is illustrated. The laterally spaced gliding surfaces In and be have been located amida the stem is visible.

ship, and a fourthgliding surface 0 has been provided at the stern. This stern gliding surface may be constructed similarly to theother gliding surfaces shown in Figs. 9 to 12, V-shaped, concavely or convexly arched transversely and also with an upwardly directed roof-shape. Below the gliding surfaces adjacent to the edges of the steps, three lifting planes 1 are provided. It is to be noted that at midship two divided planes 1 may be provided instead of a single plane. This division makes it possible that each lifting plane may be positioned in an undisturbed flow, the stern lifting plane being at such a distance from the bow lifting plane that no injurious influence is exerted. The hull of the boat is shaped as nearly on stream-line principles as possible. The side steps are preferably placed near the center line of buoyancy or center line ofgravity S-S at the widest section of the hull, where a large useful space may be provided. This position of the lifting planes precludes strong bending moments in the hull. Also in this case, the lateral gliding surfaces may be provided with fin-shaped flaring portions e. In Fig. 4, the outer ends of the middle lifting planes engage the fin-shaped flaring portions e, this being also illustrated in Fig. 9. As shown in Figs. 1 to 4, the spacings between the steps and the water level while in motion, and also the keel-shape tendency, decrease towards the stern end of the boat. The gliding surfaces themselves may be arched longitudinally, as shown in dotted lines in Fig. 3, and in this way their gliding coefficient is improved.

In Fig. 5 the section lines indicate the progressive increase of the keel-feature and of the transverse arch-feature of the forward or how gliding surface towards the stem, the said transverse arching terminatingin this case below the horizontal, and the hull of the boat lying behind the forward gliding surface has been drawn in dotted lines so that the step and the lateral or side step d, which decreases in width towards the top, are apparent. In Figs. 2, 4 and 7, the fin-shaped flaring portion e" near the point of In order to increase the lifting effect of the gliding surface, the auxiliary lifting plane g (Figs. 1, 2 and 7) may be fitted, which in this case is strongly keeled and extends towards the stem in the shape of an arrowhead and, with its ends, engages the flaring portion e", whereas the middle area portion of plane g has been fixed to the stem or its extension in the shape of supports. In the example shown,

this auxiliary lifting plane lies above the water.

level at normal speed. In Figs. 1, 2 and 7 is shown a further-fin-shaped flaring portion e, the profile or cross-section of which may be in the shape of a supporting plane at its extreme parts and passes over directly to the lifting plane. The fin-shaped flaring portions of the gliding surfaces possess the great advantage that the forepart of the boat is narrow and can be built on slender lines, and will yet produce sufficient dynamic lifting force due to the enlarged portions or fins at the gliding surfaces, which may be submerged in the flow of the waves. In Fig. 6 the lower middle gliding surface portion has no keel, whereby strong lifting forces may be generated even with small submersion, a feature desirable in many cases. In Fig. 8, showing intersecting lines, the inverted V-shaped or roof-shaped, forward gliding surface is shown, to which the lifting planes are fixed at the edges .of the bilge or protrude therefrom.

- In Figs. .9 to 12 the lateral gliding surfaces are .shownwith various profiles and transverse arch forms; As the lateral gliding surface, the particular bottom portion .will be considered which is washed at low speeds, i. e. when the hull is still gliding on the water. The water lines of a the gliding hull are denoted by WLI in the illustrations, whereas the Water lines at'full speed are those denoted by WLU. Consequently, the

lateral gliding surfaces of Figs. 9 and are .gliding surfaces is prevented from being wetted during the run in various ways. In Fig. 9 it has been arched upwards, a longitudinally extending step being also provided. In Figs. 10 and 12 the portion intermediate the gliding surfaces is made roof-shaped and may be provided here also with longitudinally extending steps or edges. In Fig. 11 the middle bottom section has been placed considerably higher than the gliding surfaces by means of longitudinally extending steps.

As shown in Figs. 2, 4, 9 and 12, also the lateral gliding surfaces may have roll-shaped flaring portions c with which the ends of the lifting planes engage and where the transition can take place in continuous course.

The shape of the lateral gliding surfaces, which evolve from the side walls, is shown in Fig. 5. Again a few cross-sectional views have been outlined. It is apparent that these gliding surfaces have substantially the same shape as the bow-gliding surface, and said lateral gliding surfaces are attached to the side wall in such a way that a bilge keel is formed by the edge of the bilge. The cross-sections disclose the V- shape as it increases towards the forward. section of the boat, and how the gradual transition into the side wall takes place. The lateral rear gliding plane illustrated by intersecting lines in Fig. 8 is in the shape of a reversed V or roof-shaped.

It is gradually incorporated as it sweeps forto a craft, the bow of which is designed as in Figs. 5, 6 or 7.

In Fig. 1 an auxiliary step or edge It is shown, which, if the craft is travelling at a low speed, will force away from the hull the water streaming off the forward gliding surface a in the shape of a trough Ml (shown in dots and dashes). Below the auxiliary step is found, for example the auxiliary lifting plane 2', which is shown as not submerged in the water at normal speed. In this embodiment is also shown the manner in which the auxiliary plane 2', in. case troughs of sufficient depth and area are produced (by the principal plane), can supplement the loss of lifting force of the principal plane 1 in consequence of slowing down. M2 is the trough at normal travelling speed. If the speed is reduced, the trough shortens, whereby the auxiliary plane is increasingly forced to advance from the trough valley into the trough hill due to the forward movement of said hill so as to enter,

at the minimum speed, wholly into the hill of trough M3, where it attains its maximum lifting force. In the embodiment of Fig. 1, the boat, at starting, will be immersed to a greater extent at the stern, because the auxiliary lifting plane 9 is situated considerably further ahead of the center of gravity of the craft, than the auxiliary lifting plane 2' is positioned to the rear of this center. The auxiliary plane 9 may also be of a greater surface area and may, for example, be set at a greater angle of attack than the auxiliary plane 2'.

The supports or stays s, engaging the steps, are fixed, as shown in Figs. 5 to 7 and 9 to 11, either at the keel or at the edges of the bilge, which may be drawn down very far at these points, especially as indicated in Figs. 7 and 9. The attachment of the stays directly to the steps and keels or bilge edges, respectively, involves the advantage that the supports are of short lengths, because the steps and keels are the lowest and also the firmest points of the hydroplane.

In Fig. 1 the driving means comprising. a propeller z is shown.

Figs. 13 and 14 illustrate, by way of example, a craft of larger size with three consecutive lifting. planes j, with their width of span increasing towards the stern. The maximum width and the minimum height over the water-level while in motion is again at the stern.

While I have herein shown and described certain preferred embodiments of my invention, I wish it to be understood that I do not confine myself to all the precise details herein set forth by way of illustration, except as specified in the appended claims,

Having thus described my invention, what I claim is:

1. A hydroplane boat comprising a hull having lifting planes secured thereto in spaced relation therebeneath. said hull being formed with 'a plurality of forwardly inclined gliding surfaces, said gliding surfaces extending respectively to the foremost, aftermost, and extreme side portions of the hull so as to exert the maximum righting moment when contacting the water, the bottom of said hull being formed-with laterally extending upward steps, considered from fore to aft, at the after end of each of said gliding surfaces for aiding in throwing the water off from the hull behind said steps to decrease water resistance, said lifting planes being located beneath the after portions of the gliding surfaces adjacent the steps, the ends of said lifting planes being secured to the hull at the bilge edge, whereby in operation the gliding surfaces assist the lifting planes in their stabilizing action and supplement the lifting effect of the planes at low speed and in a heavy sea.

2. A hydroplane boat comprising a hull having lifting planes secured thereto in spaced relation therebeneath, said hull being formed with a plurality of forwardly inclined gliding surfaces, said gliding surfaces extending respectively to the foremost, aftermost, and extreme side portions of the hull so as to exert the maximum righting moment when contacting the water, the bottom of said hull being formed with laterally extending upward steps, considered from fore to aft, at the after end of each of said gliding surfaces for aiding in throwing the water off from the hull behind said steps to decrease water resistance, said lifting planes being located beneath the after portions of the gliding surfaces adjacent the steps, the ends of said liftingplanes being secured to the hull at the bilge edge, stays extending between the hull and intermediate points of the lifting planes whereby in operation the gliding surfaces assist the lifting planes in their stabilizing action and supplement the lifting effect of the planes at low speed and in a heavy sea.

.3; A hydroplane boat comprising a hull hav-' ing lifting planes secured thereto inspaced relation therebeneath, said hull being formed with a plurality of forwardly inclined gliding surfaces, said gliding surfaces extending respectively to the foremost, aftermost, and extreme side portions of the hull so as to exert the maximum righting moment when contacting the water, the bottom of said hull being formedwith laterally extending upward steps, considered from fore to aft, at the after end of each of said gliding surfaces for aiding in throwing the water off from the hull behind said steps to decrease water resistance, said lifting planes being located beneath the after portions of the gliding surfaces adjacent the steps, the ends of said lifting planes being secured to the hull at the bilge edge, whereby in operation the gliding surfaces assist the lifting planes in their stabilizing action and supplement the lifting effect of the planes at low speed and in a heavy sea, the lifting effects produced by the shapes and dimensions of said planes and adjacent gliding surfaces producing substantially equal lifting force.

4. A hydroplane boat comprising a hull having lifting planes secured thereto in spaced relation therebeneath, said hull being formed with a plurality of forwardly inclined gliding surfaces, said gliding surfaces extending respectively to the foremost, aftermost, and extreme side portions of the hull so as to exert the maximum righting moment when contacting the water, the bottom of said hull being formed with laterally extending upward steps, considered from fore to aft, at the after end of each of said gliding surfaces for aiding in throwing the water off from the hull behind said steps to decrease water resistance, said lifting planes being located beneath the after portions of the gliding surfaces adjacent the steps, the ends of said lifting planes being secured to the hull at the bilge edge, whereby in operation the gliding surfaces assist the lifting planes in their stabilizing action and supplement the lifting effect of the planes at low speed and in a heavy sea, the side walls of the hull also being provided with steps in continuation of the steps of the hull bottom for forcing the water off from the sides in rear of said steps.

5. A hydroplane boat comprising a hull having lifting planes secured thereto in spaced relation therebeneath, said hull being formed with a plurality of forwardly inclined gliding surfaces, said gliding surfaces extending respectively to the foremost, aftermost, and extreme side portions of the hull so as to exert the maximum righting moment when contacting the water, the bottom of said hull being formed with laterally extending upward steps, considered from fore to aft, at the after end of each of said gliding surfaces for aiding in throwing the water off from the hull behind said steps to decrease water resistance, said lifting planes being located beneath the after portions of the gliding surfaces adjacent the steps, the ends of said lifting planes being secured to the hull at the bilge edge, whereby in operation the gliding surfaces assist the lifting planes in their stabilizing action and sunplement the lifting effect of the planes at low speed and in' a heavy sea, said gliding surfaces being V-shaped and the forward gliding surfaces havingsharper V-shape than theafter surfacesand being spaced farther from the adjacent lifting planes than the after gliding surfaces. r

6. Ahydroplane boat comprising a hull having lifting planes secured thereto in spaced relation therebeneath, said hull being formed with a plurality of forwardly inclined gliding surfaces, said gliding surfaces extending respectively to the foremost, aftermost, and extreme side portions of the hull so as to exert the maximum righting moment when contacting the water, the bottom of said hull being formed with laterally extending upward steps, considered from fore to aft, at the after end of each of said gliding surfaces for aiding in throwing the water off from the hull behind said steps to decrease water resistance, said lifting planes being located beneath the after portions of the gliding surfaces adjacent the steps, the ends of said lifting planes being secured to the hull at the bilge edge, whereby in operation the gliding surfaces assist the lifting planes in their stabilizing action and supplement the lifting effect of the planes at low speed and in a heavy sea, said gliding surfaces being V- shaped and the forward gliding surfaces having sharper V-shape than the after surfaces and being progressively laterally arched concavely towards the bow, the arches thereof ending in the bilge edge of the hull at all points substantially in a horizontal plane.

'7. A hydroplane boat comprising a hull having lifting planes secured thereto in spaced relation therebeneath, said hull bein formed with a plurality of forwardly inclined gliding surfaces, said gliding surfaces extending respectively to the foremost, aftermost, and extreme side portions of the hull so as to exert the maximum righting moment when contacting the water, the bottom of said hull being formed with laterally extending upward steps, considered from fore to aft, at the after end of each of said gliding surfaces for aiding in throwing the water off from the hull behind said steps to decrease water resistance, the portion of the hull bottom between some of the side gliding surfaces having longitudinal steps raising above the level of the central portion above the level of the side gliding surfaces so that the central portion of the hull between said side gliding surfaces will not be contacted by the water while the gliding surfaces are immersed, said lifting planes being located beneath the after portions of the gliding surfaces adjacent the laterally extending steps, the ends of said lifting planes being secured to the hull at the bilge edge, whereby in operation the gliding surfaces assist the lifting planes in their stabilizing action and supplement the lifting effect of the planes at low speed and in a heavy sea.

8. A hydroplane boat comprising a hull hav ing lifting planes secured thereto in spaced relation therebeneath, said hull being formed with a plurality of forwardly inclined gliding surfaces, said gliding surfaces extending respectively to the foremost, aftermost, and extreme side portions of the hull so as to exert the maximum righting moment when contacting the water, the bottom of said hull being formed withlaterally extending upward steps, considered from fore to aft, at the after end of each of said gliding surfaces for aiding in throwing the water off from the hull behind said steps to decrease water resistance.

some of said gliding surfaces beingconcave in the transverse direction, said lifting planes being located beneath the after portions of the gliding surfaces adjacent the steps, the ends of said lifting planes being secured to the hull at the bilge edge, whereby in operation the gliding surfaces assist the lifting planes in their stabilizing action and supplement the lifting effect of the planes at low speed and in a heavy sea.

9. A hydroplane boat comprising a hull having lifting planes secured thereto in spaced relation therebeneath, said hull being formed with a plurality of forwardly inclined gliding surfaces, said gliding surfaces extending respectively to the foremost, aftermost, and extreme side portions of the hull so as to exert the maximum righting moment when contacting the water, the bottom of said hull being formed with laterally extending upward steps, consideredfrom fore to aft; at the after end of each of said gliding surfaces'for aiding in throwing the water off from the hull behind said steps to decrease water resistance, said lifting planes being located beneath the after portions of the gliding surfaces adjacent the steps, the ends of said lifting planes being secured to the hull at the bilge edge, whereby in operation the gliding surfaces assist the lifting planes in their stabilizing action and supple ment the lifting efiect of the planes at low speed and in a heavy sea, and a V-shaped auxiliary lifting plane fixed to the hull at thestem'for supplementing the lifting effect of the forward gliding surface and the lifting plane beneath the after portion of the forward gliding surface.

HANNS FREIHERR SCHERTEL VON BURTENBACH.

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