US3371642A

US3371642A - Trim control device for boats

Info

Publication number: US3371642A
Application number: US496553A
Authority: US
Inventors: William M Joy
Original assignee: Individual
Current assignee: Individual
Priority date: 1965-10-15
Filing date: 1965-10-15
Publication date: 1968-03-05
Anticipated expiration: 1985-03-05

Description

March 5, 1968 Q w. M. JOY 3,371,642

TR IM CONTROL DEVICBFOR BOATS Filed Oct. 15, 1965 3 Sheets-Sheet 1 A///? /J K j'/;/

INVENTOR.

M77??? 2% Ja w. M. JOY

TRIM CONTROL DEVICE FOR BOATS March 5, 1968 Filed on. 15, 1965 3 Sheets-Sheet 2 March 5, 1968 Filed Oct. 15, 1965 W. M. JOY

TRIM CONTROL DEVICE FOR BOATS 5 Sheets-Sheet I5 INVENTOR.

United States Patent 3,371,642 TRIM CONTROL DEVICE FOR BOATS William M. Joy, 1615 N. River Road, St. Clair, Mich. 48079 Filed Oct. 15, 1965, Ser. No. 496,553 8 Claims. (01. 114-665) This invention relates generally to improvements in boat trimming stabilizers and, more particularly, to a new and improved boat stabilizer which is adapted to be attached or mounted on the stern of a boat and be selectively positioned for coaction with the water during forward movement of the boat to control the longitudinal attitude of the boat.

The attitude, stability and movement of a boat during its propulsion through the water is affected by various factors, such as the shape of the hull, the area and symmetry and surface of the hull which is in contact with the water and the draft or depth to which the boat extends beneath the surface of the water. The operation of boats may also be greatly affected by the amount of power which is used to propel them such that a boat which is designed to operate satisfactorily with a motor of one particular size will assume one attitude in the water under optimum operating conditions; however, the operational efficiency of this same boat will be greatly reduced when the boat is provided with a motor of increased power due to the boat assuming a much greater attitude in the water.

There has heretofore been proposed various methods of overcoming the above stability problems whereby a particular boat may be efliciently operated with motors of varying power capacities. One very popular method of over-coming these problems is by providing one or more rearwardly extending plates or brackets on the stern of the boat which form extensions on the bottom surface area thereof, these plates or brackets being arranged at a preselected position relative to the bottom and transom of the boat for coaction with the water, whereby the boat will move through the water at a proper attitude under particular loading and power conditions. It will be noted, however, that such heretofore commonly employed devices have the inherent disadvantage that they only operate efficiently under particular loading conditions, i.e., certain fuel and passenger loads. More recently, devices have been proposed which are capable of being adjustable to accommodate various loading conditions but such devices heretofore known and used have been relatively complex in operation and construction and are accordingly difiicult to install and operate, along with being relatively expensive to commercially produce.

It is accordingly a general object of the present invention to provide a new and improved stabilizing device of the above character which is extremely simple in construction and operation and which may be readily adjusted to accommodate various loading conditions to which a particular boat may be subjected.

It is a more particular object of the present invention to provide a new and improved boat trimming device of the above character which may be readily adjusted to accommodate relatively heavy or light bow loading of the boat.

It is another object of the present invention to provide a new and improved boat trimming device of the above character which obviates the necessity of providing relatively complex support brackets and the like on the bottom or transom of a boat for the support of the trimming device.

It is still another object of the present invention to provide a new and improved boat trimming apparatus of the above character that is adapted to be used on marine hydrofoil systems.

Patented Mar. 5, 1968 It is yet another object of the present invention to provide a new and improved boat trimming device of the above character which is of an extremely simple design, rugged construction, is easy to assemble and economical to commercially produce. Y Other objects and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings, wherein:

FIGURE 1 is a top elevational view of the boat trimming apparatus of the present invention, as shown operatively installed on a conventional motor boat or the like;

FIGURE 2 is an elevated perspective view of the stern portion of the boat illustrated in FIGURE 1;

FIGURE 3 is a fragmentary side elevational view of the boat trimming apparatus illustrated in FIGURE 1;

FIGURE 4 is an enlarged fragmentary cross-sectional view of the structure illustrated in FIGURE 3;

FIGURE 5 is a fragmentary cross-sectional view taken along the line 5-5 of FIGURE 4;

FIGURE 6 is an enlarged fragmentary side elevational view of the boat trimming apparatus of the present invention;

FIGURE 7 is a fragmentary cross-sectional view taken along the line 7-7 of FIGURE 6;

FIGURE 8 is an elevated perspective view of a slightly modified embodiment of the boat trimming apparatus of the present invention, as shown operatively installed on a marine hydrofoil system;

FIGURE 9 is an enlarged side elevational view of a portion of the structure illustrated in FIGURE 8, as seen in the direction of the arrow 9 thereof;

FIGURE 10 is a bottom elevational view of a portion of the structure illustrated in FIGURE 8, as seen in the direction of the arrow 10 thereof;

FIGURE 11 is a side elevational view of another embodiment of the boat trimming apparatus of the present invention; and

FIGURE 12 is a side elevational view of the structure illustrated in FIGURE 11, as seen in the direction of the arrow 12 thereof.

Referring now to FIGURES 1 through 3 of the drawings, the boat trimming apparatus of the present invention, generally designated by the numeral 10, is shown in operative association with a boat 12 of conventional construction, such as an outboard motor boat of the pleasure or racing type having a transom 14 at its stern to which a portable outboard motor (not shown) of the usual kind may be conveniently attached. The boat trimming apparatus 10 of the present invention comprises a pair of identical trim assemblies, generally designated by the numeral 16, which are adapted to be mounted on the port and starboard sides of the transom 14 and extend rearwardly therefrom to provide portions of considerable area extending rearwardly or aft of the bottom of the boat 12 and in the general plane thereof, whereby to resist lateral and longitudinal tilting of the boat as the same is propelled through the water under various operating and loading conditions. It may be noted that, together with the above described method of securing the forward portions 20 of the trim tab elements 18 to the boat bottom 25, it may be possible to bend the elements 18 approximately parallel to their transverse axes, whereby the elements 18 will be generally L-shaped. The upwardly projecting portions of the elements 18 defined by these bends may then be rigidly secured to the outer surface of the boat transom 14 in a manner such that the rear portions 26 of the tabs 18 project rearwardly or aft of the transom 14 in substantial coplanar relation with the boat bottom 25.

As best seen in FIGURES 1, 2 and 6, each of the trim assemblies 16 comprises a flat or planar plate-like element or trim tab 18 which is generally rectangular in shape and is preferably constructed of stainless steel or a similar strong, corrosion-resistant material. The trim tabs 18 are preferably of uniform thickness which is selected such that the tabs 18 are somewhat flexible about their transverse or lateral axes, as will be described. The trim tab 18 of both of the assemblies 16 is adapted to be mounted on the boat 12 by having the forward portion thereof, herein designated 20, rigidly secured by means of a plurality of countersunk screws, bolts or the like 22 to the exterior surface 24 of the bottom 25 of the boat 12, whereby the rear portions, herein designated 26, of each of the tabs 18 projects aft of the boat transom 14 and in substantial coplanar relation with the bottom of the boat 12, as best seen in FIGURE 6. By virtue of the flexible construction of the trim tabs 18, the rear portions 26 thereof are adapted to pivot or flex angularly upwardly and downwardly relative to the forward portions 20 thereof and thus relative to the plane of the bottom of the boat 12. By thus angularly raising or lowering the rear portions 26 of the trim tabs 18, the tabs 18 will serve to minimize both longitudinal and lateral tilting of the boat 12 such that the same may be propelled through the water at a desirable attitude under various operational and loading conditions, as will later be described.

Referring now to FIGURES 3, 4, 5 and 7, each of the trim assemblies 16 comprises an actuating mechanism 28 for independently raising and lowering the rear portions 26 of the associated trim tab 18 and thus for controlling the stability of the boat 12. As best seen in FIGURE 4, each of the mechanisms 28 comprises a reversible electric motor 30 of conventional design which is adapted to be actuated by electrical energy from any suitable source, such as batteries or an outboard motor powered generator or the like. The motor 30 of each mechanism 28 is adapted to be supported on the interior side of the boat transom 14 by an L-shaped mounting bracket 32 which has a downwardly extending leg section 34 secured to the transom 14 by suitable screws, bolts or the like 36, and an upper leg section 38 that is secured to the lower side of the motor 30 by suitable screws or bolts 40. The motors 30 may be housed within suitable covers 41 which are secured at their lower ends to the brackets 32 by suitable screws 42. The motors 30 of each of the trim assemblies 16' have a drive shaft 43 which is connected to a right angle drive unit 44 that is secured to the top of the associated motor 30 by suitable screws or bolts 46. The right angle drive units 44 include externally threaded output shafts 48 which, upon actuation of the motors 30, are adapted to move internally threaded shafts 50 that are threadably mounted upon the output shafts 48 in directions axially or longitudinally thereof. As seen in FIGURE 4, the shafts 50 extend through openings 52 in the upper end of the transom 14 and through central bores 54 formed in a pair of sealing collars 56 that are secured to the exterior side of the transom 14 coaxially of the openings 52 by suitable screws 58. Suitable O-ring sealing members or the like 60 are retained within semi-circular shaped grooves 62 formed around the bores 54 of the collars 56, the sealing members 60 serving to prevent any water from entering into the boat 12 between the outer periphery of the shaft 50 and the inner periphery of the openings 52.

The outer ends of the shafts 50 are formed with generally rectangular shaped end sections 64 which are adapted to be pivotably connected within bifurcated or yoke-shaped end sections 66 that are formed on the upper ends of a pair of actuating rods 68 by suitable pivot pins or the like 70. As seen in FIGURE 5, the pins 70 may be retained within suitable axially aligned bores 72 and 74 that are formed in the

end sections

64 and 66, respectively, by conventional cotter keys or the like 76.

Referring now to FIGURE 7, the lower ends of the actuating rods 68 are formed with rectangular shaped end sections 78 which are adapted to be pivot-ably secured between a pair of spaced parallel bosses and 82 that are secured to the tops of the rearmost portions of the end sections 26 of each of the trim tabs 18 as by welding or the like, the end sections 78 being pivotably connected to the bosses 80 and 82 by suitable pivot pins or the like 84 which extend through axially aligned bores 86 and 88 formed in the end section 78 and bosses 80, 82, respectively. The pins 84 may be retained within the bores 86 and 88 by suitable cotter keys 89.

The dimension of the shafts 50 and actuating rods 68 of each of the trim assemblies 16 are selected such that as the shafts 50 move axially away from the exterior surface of the transom 14, upon appropriate energization of the associated motors 30, the rods 68 will be biased upwardly and outwardly, as indicated by the phantom lines in FIG- URE 3, resulting in the rear end portions 26 of the trim tabs 18 being flexed upwardly relative to the plane of the bottom of the boat 12. In a similar manner, as the shafts 50 move axially in a direction toward the interior surface of the transom 14, the associated rods 68 will be biased downwardly, resulting in the rear end portions 26 of the trim tabs 18 being biased downwardly relative to the plane of the bottom of the boat 12, as also indicated by the phantom lines in FIGURE 3.

In operation of the boat stabilizing apparatus 10 of the present invention, assuming that the boat 12 is being initially propelled or accelerated, for example, when moving away from a dock or similar mooring structure, the bow of the boat 12 will tend to rise out of the water. At such time as any appreciable amount of waves are encountered, the boat will be subjected to substantial bouncing and pounding, resulting in unpleasant jarring of the boat 12 and its occupants. To overcome such unpleasant effects resulting from the improper attitude of the boat 12 moving through the water, the electric motors 30 of each of the trim assemblies 16 may be appropriately energized such that the shafts 50 are biased inwardly or toward the interior surface of the transom 14 resulting in the rear end portions 26 of the trim tabs 18 being biased or flexed downwardly relative to the plane of the bottom of the boat 12. As the end portions 26 are thus moved, the hydrodynamic effect of the water impinging against the lower surfaces of the portions 26 will tend to raise the stern of the boat 12 sufficient to attain a proper attitude and thus obviate the aforementioned bouncing and pounding of the boat 12 and unpleasant effects resulting therefrom.

When the load distribution in the boat 12 is such that the bow or front end thereof rides lower in the water than the stern or rear end of the boat, the motors 30 of each of the trim assemblies 16 may be energized such that the shafts 50 are biased outwardly or away from the outer surface of the transom 14, resulting in the rear end portions 26 of the trim tabs 18 being biased or flexed upwardly relative to the plane of the bottom of the boat 12. The hydrodynamic effect of the water on the end portions 26 disposed in their raised positions will cause the stern of the boat 12 to be lowered in the water as the boat 12 is propelled, whereby the boat 12 will attain a desirable horizontal attitude.

It may be noted that by virtue of the fact that each of the trim assemblies 16 is independently operable, it may be possible to raise the rear end portion 26 of one of the trim tabs 18 and simultaneously lower the rear end portion 26 of the other of the trim tabs 18, whereby to achieve lateral stabilizing of the boat 12 under various loading and operating conditions and thus prevent the boat from tilting toward one side or the other as the same is propelled through the water.

It will thus be seen that the boat stabilizing apparatus 10 of the present invention provides means for controlling both the longitudinal and lateral stability of a boat in the water, which apparatus, as hereinabove described, may be installed in a minimum amount of time and be controlled by relatively simple manipulation of any suitable control such as electrically operated switches or the like for appropriately energizing the motors 30 of the trim assemblies 16.

Referring now to FIGURES 8 through 10, a slightly modified construction of the boat trimming apparatus of the present invention is shown in operative association with a boat 100 of conventional construction including port and

starboard sides

102 and 104, respectively, and a bottom section 106. The boat 100 is provided with forwardly and rearwardly positioned

hydrofoils

108 and 110, respectively, which are disposed below the bottom section 106 of the boat 100 and extend transversely of the longitudinal axis thereof. The forward hydrofoil 108 is attached to the bottom section 106 by a plurality of substantially

vertical struts

112, 114 and 116. In a similar manner, the rear hydrofoil 110 is secured to the bottom section 106 of the boat 100 by a pair of laterally spaced

struts

118 and 120.

In accordance with the principles of the present invention, the forward hydrofoil 108 is provided with a pair of laterally spaced plate-like elements or trim tabs 122 which are preferably of the same general construction as the trim tabs 18 hereinabove described. It may be noted that during most loading and operating conditions, it is not necessary to provide the rear hydrofoil 110 with the trim tabs 122 since the rear hydrofoil 110 tends to seek the same level of submersion as the front hydrofoil 108 to maintain the boat 100 at a substantially level keel; however, it will be apparent that the rear hydrofoil 110 may be provided with such trim tabs when the design of the boat and the operating conditions therefor so warrant.

As best seenin FIGURE 9, each of the trim tab members 122 comprises a forward portion 124 which is adapted to be secured to the lowermost side of the hydrofoil 108 by means of suitable screws, bolts or the like 126, whereby the rear portions 128 of the trim tabs 122 project toward the rear end of the boat 100 in substantial coplanar relation with the bottom surface of the hydrofoil 108. By virtue of the flexible construction of the trim tabs 128, is hereinabove described, the rear portions 128 are adapted to pivot or flex angularly upwardly and downwardly relative to the forward portions 124 thereof and thus relative to the plane of the lower surface of the hydrofoil 108. By thus varying the angular relation of the rear portions 128 of the trim tabs 122 relative to the plane of the lower surface of the hydrofoil 108, the boat operator may control the attitude of the boat 100 as the same is propelled through the water, and may also maintain the hull of the boat 100 at a predetermined distance above the surface of the water.

Means for thus biasing the rear portions 128 of the trim tabs 122 angularly upwardly and downwardly is provided by a pair of actuating shafts 130 which extend upwardly from the rear portions 128 of the trim .tabs 122 and are secured at their lower ends to the upper surfaces of the portions 128 by means of suitable pairs of bosses 132 and pivot pins 134 that are substantially identical in construction and operation to the bosses 80 and pivot pins 84 hereinbefore described in connection with the trim tab 18 and shafts 68.

The upper ends of the shafts 130 extend through suitable openings 136 in the bottom section 106 of the boat 100 and are connected to suitable actuating mechanisms (not shown) adapted to selectively bias the shafts 130 axially upwardly or downwardly, whereby to pivot the rear portions 128 of the trim tabs 122 upwardly or downwardly, as above described. One suitable mechanism for selectively biasing the shafts 130 is the hereinbefore described actuating mechanism 28 which includes a suitable electric motor 30, drive unit 44 and externally threaded shaft 148. Suitable sealing means (not shown) such as O-rings or the like are preferably interposed between the outer periphery of the shafts 130 and the inner periphery of the openings 136 to prevent water from passing between these surfaces into the interior of the boat 100.

Referring now to FIGURE 10, the rear portions 128 of each of the trim tab members 122 are provided with generally rectangular shaped flaps or tabs 140 which are adapted to have their forward end portions secured as by spot-welding, screws, bolts or the like to the lower surface of the rear portions 128, the rear portions of the flaps or tabs 140 extending rearwardly of the trim tabs 122 and being adapted to be manually bent upwardly or downwardly in accordance with the operating conditions to which the boat is to be subjected. More particularly, the rear ends of the flaps are adapted to be bent upwardly or downwardly to compensate for drag, motor size and various other parameters.

Referring now to FIGURES 11 and 12, a slightly modified embodiment of the boat trim apparatus illustrated in FIGURES 8 through 10 is shown in operative association with a boat of conventional design and comprising a hull portion 152 which terminates at its stern end in a substantially vertical transom section 154. In accordance with the principles of the present invention, the boat 150 is provided with a trim tab support bar 156 which extends transversely of the bottom 158 of the hull 152 slightly forward of the transom 154. The bar 156 is supported at a position spaced from and substantially parallel to the bottom 158 by a pair of laterally spaced, generally U- shaped support brackets 160 which are secured at their upper ends by suitable screws, bolts or the like (not shown) to the boat bottom 158, the opposite ends of the bar 156 being fixedly secured within the lower ends of the brackets 160, as best seen in FIGURE 11.

The bar 156 is adapted to support a pair of laterally spaced trim tab members 162 which are substantially identical in construction and operation to the hereinbefore described

trim tabs

122 and 18. As best seen in FIGURE 11, the forward portions of the trim tabs 162 are secured by suitable screws, bolts or the like (not shown) to the lower side of the bar 156, the rear portions of the trim tabs 162 extending rearwardly of the bar 156 at positions spaced from and substantially parallel to the bottom section 158 of the boat hull 152. In a preferred construction of the present invention, the rear ends of the trim tabs 162 preferably terminate slightly forward of the plane of the boat transom 154. The rear portions, herein designated 166, of the trim tab members 162 are adapted to pivot or flex angularly upwardly and downwardly relative to the plane of the forward portions thereof, as described in connection with the

trim tabs

18 and 122, whereby to control the longitudinal tilting of the boat 150 such that the same may be propelled through the water at a desirable attitude under various operational and loading conditions, as above described.

Means for thus angularly raising or lowering the rear portions 166 of the trim tabs 162 is provided by suitable actuating shafts 168 that are attached to the upper surfaces of the portions 162 in the above described manner and which extend through suitable openings (not shown) in the bottom section 158 of the boat 150, these shafts being operatively connected to suitable actuating mech anisms (not shown) for selectively biasing the same axially upwardly or downwardly, as was hereinbefore described.

While it will be apparent that the preferred embodi ments herein illustrated are well calculated to fulfill the objects above stated, it will be appreciated that the present invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

What is claimed is:

1. In an apparatus for stabilizing a boat having a hull which terminates at its stern end in an upwardly extending transom section,

a pair of flat rectangular shaped trim tab elements constructed of a relatively flexible material and having a first portion secured to the underside of the hull at the opposite ends of the transom section and a 7 second portion extending rearwardly of the transom section and disposed in substantially coplanar relation with the underside of the hull,

a pair of actuating motors mounted on said transom section,

a pair of shafts aligned with said trim tab elements and extending through laterally spaced openings in said transom section,

drive means connected to said motors and adapted to move said shafts along the longitudinal axes thereof, and

a pair of actuating rods pivotably connected at their upper ends to said shafts and at their lower ends to the upper sides of said second portions of said trim tab elements,

energization of said motors being adapted to move said shafts longitudinally thereof whereby to vary the inclination of said second portions of said trim tab elements relative to the plane of the underside of the hull.

2. The invention as set forth in claim 1 wherein said trim tab elements are constructed of stainless steel.

3. The invention as set forth in claim 1 wherein said drive units are threadably connected to said shafts.

4. In a boat stabilizing apparatus,

means defining a substantially fiat elongated trim tab element having a first sect-ion rigidly secured to a portion of the underside of the boat which is in contact with the water as it is propelled through the water and a second section integral with said first section and extending rearwardly of said first section and disposed in substantial coplanar relation with said portion of the boat, and

means for varying the inclination of said second section of said trim tab element relative to said first section thereof including first shaft means pivotably connected at the lower end thereof to said second section and second shaft means pivotably connected to the upper end of said first shaft means and motor means for longitudinally biasing one of said shaft means.

5. In combination with a marine craft having a hydrofoil system,

means defining a substantially fiat elongated trim tab element having a first portion rigidly secured to the hydrofoil and a second portion extending rearwardly of the hydrofoil and disposed in substantial coplanar relation with said first portion, and

means for varying the inclination of said second portion of said trim tab element relative to the hydrofoil including first shaft means pivotably connected at the lower end thereof to said second section and second shaft means pivotably connected to the upper end of said first shaft means and motor means for longitudinally biasing one of said shaft means.

6. In an apparatus for stabilizing a boat having a hull which terminates at its stern end in an upwardly extending transom section,

a pair of flat rectangular shaped trim tab elements constructed of a relative flexible material and each having first and second portions,

a trim tab support bar extending laterally of the hull at a position spaced slightly below the underside thereof,

means including support bracket means for supporting said bar at said position spaced below the underside of the hull,

means for rigidly securing said first portions of said trim tab elements to said bar in a manner such that said second portions thereof extend rearwardly toward said transom below and substantially parallel to the underside of the hull, and

means pivotably connected directly to the upper sides of said second portions and including shaft means extending upwardly through the hull for varying the inclination of said second portions of said trim tab elements relative to the plane of the underside of the hull.

7. In a boat stabilizing apparatus,

a pair of trim tab elements constructed of a relatively flexible material and having first portions rigidly secured to the stern end of the boat and second portions extending rearwardly of the boat and disposed in substantial coplanar relation with the underside thereof;

means for independently varying the inclination of said second portions of said trim tab elements relative to the plane of the underside of the boat, said last mentioned means comprising first shaft means pivotably connected to said second portions of said elements, said second shaft means movably connected to said first shaft means, and power means for axially moving said second shaft means.

8. A stabilizing device for a boat having a bottom section and a transom section extending upwardly from said bottom section, said device including,

a trim tab element comprising an elongated, uniformly thick, relatively flexible member having a first por-' tion rigidly secured to one of said boat sections and a second portion extending rearwardly of the transom section in substantial coplanar relation with the bottom section,

an actuating element secured to said second portion of said member adjacent the rear end thereof and operable to bend said second portion both upwardly and downwardly relative to the plane of the bottom section,

upward bending movement of said member being operable to create a downward force on the stern of the boat during forward movement thereof whereby the bow of the boat will be raised, and downward bending movement of said member being operable to create an upward force on the stern of the boat during forward movement thereof whereby the bow of the boat will be lowered.

References Cited UNITED STATES PATENTS 1,237,7'15 8/1917 Smith 1l4-66.5 3,111,103 11/1963 Bennett 11466.5 3,120,829 2/1964 Chew et a1. 114-65.S X 3,208,422 9/ 1965 Schopmeyer 11466.5

ANDREW H. FARREIJL, Primary Examiner.

Claims

1. IN AN APPARATUS FOR STABILIZING A BOAT HAVING A HULL WHICH TERMINATES AT ITS STERN END IN AN UPWARDLY EXTENDING TRANSOM SECTION, A PAIR OF FLAT RECTANGULAR SHAPED TRIM TAB ELEMENTS CONSTRUCTED OF A RELATIVELY FLEXIBLE MATERIAL AND HAVING A FIRST PORTION SECURED TO THE UNDERSIDE OF THE HULL AT THE OPPOSITE ENDS OF THE TRANSOM SECTION AND A SECOND PORTION EXTENDING REARWARDLY OF THE TRANSOM SECTION AND DISPOSED IN SUBSTANTIALLY COPLANAR RELATION WITH THE UNDERSIDE OF THE HULL, A PAIR OF ACTUATING MOTORS MOUNTED ON SAID TRANSOM SECTION, A PAIR OF SHAFTS ALIGNED WITH SAID TRIM TAB ELEMENTS AND EXTENDING THROUGH LATERALLY SPACED OPENINGS IN SAID TRANSOM SECTION, DRIVE MEANS CONNECTED TO SAID MOTORS AND ADAPTED TO MOVE SAID SHAFTS ALONG THE LONGITUDINAL AXES THEREOF, AND