US3452704A

US3452704A - Engine mounted on a gimbal-like frame

Info

Publication number: US3452704A
Application number: US565319A
Authority: US
Inventors: Lucius D Watkins
Original assignee: Outboard Marine Corp
Current assignee: Outboard Marine Corp
Priority date: 1966-07-14
Filing date: 1966-07-14
Publication date: 1969-07-01
Anticipated expiration: 1986-07-01

Description

July 1, 1969 D. WATKINS ENGINE MOUNTED ON A GIMBAL L-IKE FRAME Sheet of 4 Original Filed March 25, 1964 M1 7.1.. I l

CENTER OF PEECUSS/O/V INVENTOR 4 1/6/05 0. War-Kw;

W. m m

A TTORA/EVS July 1, 1969 L. D. WATKINS ENGINE MOUNTED ON A GIMBAL-LIKE FRAME Original Filed March 23, 1964 Sheet of 4 l 2 5 x A 5 3 a 7 fr 7 a J o un 5 2 a V 2 5 1 1 B3 l 3 6 w 2 M11" i 1 I Q /I I v 7 w M 7 i f a .m m m H. w H HU 4 1 ,u flv F I W7 3 N 0 J5 W a I n 111s. N

ATfOlP/VE Y9 July 1, 1969 L. D. WATKINS ENGINE MOUNTED ON A GIMBAL-LIKE FRAME Original Filed March 23, 1964 Sheet .iilikl nallllh x INVENTOR. due/us D. Wan mi BY W, M YAM ATTOENEY$ July 1', 1969 WATKINS 3,452,704

ENGINE MOUNTED ON A GIMBAL-LIKE FRAME Original Filed March 23, 1964 Sheet 4 of 4 INVENTOR. lac/us D. Wane/M5 United States Patent 3,452,704 ENGINE MOUNTED ON A GIMBAL-LIKE FRAME Lucius D. Watkins, Hartland, Wis., assignor to Outboard Marine Corporation, Waukegan, 111., a corporation of Delaware Continuation of application Ser. No. 353,882, Mar. 23, 1964. This application July 14, 1966, Ser. No. 565,319

Int. Cl. B63h 21/26 U.S. Cl. 11541 22 Claims ABSTRACT OF THE DISCLOSURE This application is a continuation of application Ser. No. 353,882, filed Mar. 23, 1964 and now abandoned.

The invention relates generally to boat and marine propulsion unit combinations.

Generally speaking, the invention provides for the mounting of a marine propulsion unit in a boat in such manner as to obtain certain of the advantages of both a conventional inboard mounting and a conventional outboard mounting, as well as to obtain other advantages. More specifically, the invention provides for the combination of a boat which can include a substantially closed motor well adjacent the stern, together with a marine propulsion device which is mounted for dirigible steering movement on a supporting frame and which is pivotally mounted about a horizontal axis to afford upward and rearward marine propulsion unit tilting in the event the marine propulsion unit strikes an underwater object. The frame and the propulsion unit can be principally housed in the motor well if one is provided.

Preferably, the trunnions which pivotally carry the frame are located above the center of mass of the combined frame and propulsion unit so that the center of percussion of the combined assemblage is in the part of the lower unit which projects below the boat, i.e., preferably in the gear box. The invention also provides for the passage of steering cables through the trunnions which tiltably support the frame and marine propulsion unit, thereby permitting tilting of the marine propulsion unit without axial displacement of the steering cables.

Still further, the invention provides for vibrationally isolating the supporting frame from the bearings which afford dirigible movement of the marine propulsion unit, thereby substantially preventing vibration transmission .to the frame and to the boat. The invention also provides for releasable reverse tilt lock means connecting the frame and the boat, and shock absorbing means for controlling tilting of the frame when the marine propulsion unit strikes an underwater obstacle.

The invention also provides for a plate structure which is supported by the tiltable frame, which includes exhaust gas passage means communicating with the lower unit and with one or more discharge nozzles to afford passage of the exhaust gas into the propeller slipstream notwithstanding steering movement of the marine propulsion unit relative to the plate structure, and which, when the pro pulsion unit is in the running position, closes the opening in the motor well wall through which the marine propulsion unit projects into the water. In addition, when the marine propulsion unit is in its normal operating position,

the plate structure cooperates with a gasket to minimize water flow into the motor well and to substantially eliminate air flow from the motor Well into the water in the path of the propeller.

The invention also includes provision in the motor well structure of a hinged rear wall part which accommodates upward and rearward tilting movement of the marine propulsion unit, together with a linkage which opens the hinged wall part in advance of the tilting movement of the marine propulsion unit and which includes means biasing the 'hinged wall part for movement to its closed position.

Other objects and advantages of the invention will become known by reference to the following description and to the accompanying drawings.

In the drawings:

FIGURE 1 is a fragmentary side elevational view, partially in section, of a boat which embodies various of the features of the invention and which includes a marine propulsion unit shown in its normal, generally upright running position;

FIGURE 2 is a view similar to FIGURE 1 showing the marine propulsion unit in a rearwardly and upwardly tilted position;

FIGURE 3 is a fragmentary top plan view taken generally along line 3-3 of; FIGURE 1; I

FIGURE 4 is a fragmentary sectional view taken generally along line 44 of FIGURE 1;

FIGURE 5 is an enlarged view, partially broken away and in section, of the marine propulsion unit and supporting frame shown in FIGURES 1 through 4;

FIGURE 6 is an enlarged rear elevational view, partially broken away and in section, of a portion of the marine propulsion unit and supporting frame shown in FIGURE 5;

FIGURE 7 is a sectional view taken generally along line 77 of FIGURE 6;

FIGURE '8 is a view, partially broken away and in section and on a reduced scale, taken along line 8-8 of FIGURE 5; and

FIGURE 9 is an enlarged fragmentary view of the reverse tilt lock means embodied in the arrangement shown in FIGURES 1 through 5.

The boat 11 shown fragmentarily in FIGURE 1 can be conventionally constructed to include, adjacent to the stern or transom 1-3, a motor well 15 formed by a pair of spaced side walls 17 and 19 (see FIGURE 4), a front wall 21, a top wall 23, a partial upper rear wall part 25 connected to the top wall 23 and the

side walls

17 and 19, and a bottom wall 27 having therein an opening or aperture 29 through which extends a marine propulsion unit or device 31 still to be described. Supported in the motor well 15 and attached to the

side walls

17 and 19, are a pair of spaced thrust blocks 33 and 35 (see FIGURE 3). Also mounted by the

side walls

17 and 19 are a pair of spaced

trunnions

37 and 39. The motor well 15 is also defined by a lower, hinged rear wall part 41 which is pivotally connected to the upper rear wall part 25 by suitable hinge means. Preferably, the inside surfaces of the motor well Walls are lined with a sound absorbing material 42.

Carried by the

trunnions

37 and 39 for pivotal movement about a horizontal axis is a gimbal-like frame or support 45 including spaced side members 47 and 49 (see FIGURE 3), a top cross bar '51, and a bottom cross beam 53. As can be seen best in FIGURES 1 and 4, respective bores or passageways 55 and '57 extend along said horizontal axis through the

side members

47 and 49, through the trunnion supported studs 59 and 61 extending from the

side members

47 and 49, through the

trunnions

37 and 39, and through the

side walls

17 and 19 of the motor well 15 for purposes still to be described.

Carried by the frame 45 by support means affording pivotal movement about an axis transverse to the horizontal axis is the before mentioned. marine propulsion unit 31 which comprises generally an internal combustion engine 63 (see FIGURE a motor or engine cover 69 generally enclosing the engine 63, and a lower unit 65 which is connected to the engine 63 and which carries a propeller 67. Preferably, the cover is of two piece construction to afford easy removal and accessibility to the engine, and is preferably lined with a sound absorbing material 70.

The support means affording pivotal movement of the propulsion unit 31 relative to the frame 45 comprises, at the top of the propulsion unit, a vertically extending stud 71 (see FIGURE 5) which projects from the engine block 73 and which is received in a bearing 75 mounted on a bracket 77. In turn, the bracket 77 is supported by a pair of spaced arms 79 (see FIGURE 3) projecting forwardly from the frame cross bar 51. Interposed between the bracket 77 and the arms 79 are means for vibrationally isolating the propulsion unit 31 from the frame 45. In the disclosed construction, such means is in the form of elastomeric cushions 81 (see FIGURE 4).

Adjacent the bottom of the frame 45, the marine propulsion unit supporting means comprises ring shaped bearing means 83 (see FIGURE 5) on the outer periphery of the lower unit 65, which bearing means 83 supports the weight of the propulsion unit 31 as well as affording rotation thereof and is engaged by complementary ring shaped bearing means 85 carried by a pair of L-shaped arms 87 (see FIGURES 4 and 6). In turn, the arms 87 are respectively connected to a pair of U-shaped brackets 89 supported respectively by legs 91 (see FIGURES 1 and 2) projecting rearwardly from the frame lower beam 53. Interposed between the U-shaped brackets 89 and the arms 87 are means for vibrationally isolating the marine propulsion unit 31 from the frame 45. In the disclosed construction, such means takes the form of elastomeric cushions 93. Location of the

elastomeric cushions

81 and 93 above and below the center of gravity of the propulsion unit advantageously permits use of cushions having relatively low spring rates.

The engine 63 conventionally comprises, as seen in FIGURE 5, the before mentioned block 73, an output or drive shaft 95, a fly wheel 97, a starting motor 99, an ignition system including a distributor 101, a carburetor 103 including a throttle and a linkage 105 connected to the carburetor throttle for regulating the speed of the engine. As is also usual, the engine includes a cooling system incorporating a water jacket 107 and an exhaust manifold 109 having a discharge opening 111 communicating with the hollow interior of the lower unit 65, which hollow interior comprises an exhaust gas passage 113 including an outlet 115.

The lower unit 65 includes a pan 121 which supports the engine cover 69, a main portion 123 extending below the pan 121, a spacer portion 125 projecting downwardly from the main portion 123, and a gear box 127 connected to the lower end of the spacer portion 125. The gear box 127 includes clutch means (not shown) connected to the driveshaft 95 and to a shaft 96 which supports the propeller 67. Either a conventional mechanical reversing clutch or an electrically operated clutch such as disclosed in application Ser. No. 143,773, entitled Marine Propulsion Device With Electromagnetic Reversing Clutch, filed on Oct. 9, 1961, and assigned to the assignee of this invention, can be employed.

Also carried by the lower unit 65 in surrounding relation to the driveshaft is a water pump 129. Extending from the discharge of the pump is a conduit 131 connected to the intake of the engine water jacket 107. The water pump 129 includes an inlet in communication with a chamber or cavity 133 which is located in the bottom of the lower unit main portion 123 and which communicates with screened inlet openings 135 (see FIG- URE 6) in the bottom of the main portion 123 on each side of the downwardly projecting spacer portion 125. Also communicating with the chamber 133 is a recirculating coolant line 137 extending through the lower unit main portion 123 to a thermostatic valve 139 (see FIG- URE 5) supported by the engine block 73. The valve 139 operates to apportion discharge coolant flow between the recirculation line 137 and a conduit 141 communicating with the exhaust manifold 109. As a consequence, the coolant discharge which is not recirculated is passed overboard with the exhaust.

Also extending through the main portion 123 of the lower unit 65 is means for controlling the clutch in the gear box 127. Such means can take the form of a mechanical linkage. In the specifically disclosed construction which utilizes an electrically operated clutch, an electrical cable 143 extends through the lower unit 65 to the gear box 127.

The exhaust gas and non-recirculated discharge coolant water flows from the exhaust gas manifold discharge opening 111 through the exhaust gas passage 113 in the lower unit main portion 123 to the discharge outlet which is in communication with the inlet port of the hollow interior of a plate structure or member 151 which is supported by the arms 87 carrying the bearing means 85 and which encircles the lower part of the main portion 123 of the lower unit 65 below the bearing means 83. Because the plate structure 151 is carried by the arms 87, the propulsion unit 31 is rotatable relative thereto and a packing 153 (see FIGURE 5) is employed to prevent the entry of water into the lower unit 65.

The plate structure 151 serves to complete the motor well 15, having an outline generally as shown in FIG- URE 7, which outline corresponds generally to the aperture 29 in the bottom wall 27. Around the periphery of the plate structure 151 is a rubber gasket 155 which assists in sealing the plate structure 151 to the bottom walls 27 and to the bottom of the hinged rear wall part 41, thereby minimizing entry of water into the motor well 15 and avoiding air flow from the motor well 15 into the water in the path of the propeller 67.

Extending downwardly and rearwardly from the plate structure 151 are a pair of exhaust gas discharge ports or nozzles 157, which nozzles communicate with the exhaust gas inlet port 150 and are located rearwardly of and on opposite sides of the propeller 67. As a consequence, exhaust gas and non-recirculated discharge coolant water are passed overboard through the nozzles into the wake of the propeller 67.

If an idle relief is desired, the main portion 123 of the lower unit 65 can be provided with an aperture (not shown) which is preferably connected to a flexible conduit (not shown) which can be connected to a muffler (not shown) carried by the boat. Ordinarily, an idle relief is not necessary with engines of relatively high horsepower.

From the foregoing, it is apparent that the propulsion unit 31 is free for dirigible movement relative to the frame 45, and that the frame 45 and propulsion unit 31 swing as one about the

trunnions

37 and 39 when the propulsion unit 31 hits an underwater obstacle.

The thrust from the propulsion unit 31 is transmitted from the frame 45 to the boat 11 through the

trunnions

37 and 39 and through engagement of the lower ends of the

side members

47 and 49 with the thrust blocks 33 and 35 when the propulsion unit 31 is in its generally upright, operating position shown in FIGURE 1. Preferably, rubber pads 159 (see FIGURE 1)are mounted on the thrust block surfaces engaged by the frame 45.

When the lower unit 65 strikes an underwater obstacle, and the assemblage of the frame 45 and the propulsion unit 31 swings upwardly and rearwardly, such movement is controlled by shock absorbing means in the form of a shock absorbing unit 161 (see FIGURE 4) which is connected, at one end, to the side wall 17 and,

at the other end, to the adjacent side member 47 Various shock absorbing units including a co-operating cylinder and piston can be employed.

The upward and rearward movement of the propulsion unit 31 occurring incident to the striking of an underwater obstacle can be employed to swing the hinged wall part 41 upwardly and rearwardly due to direct engagement therebetween. However, the disclosed construction utilizes a linkage 171 (see FIGURES 1, 2, and 3) which serves to open the hinged door part 41 in response to movement of the frame 45 and in advance of movement of the propulsion unit 31, thereby avoiding direct engagement of the propulsion unit with the hinged door part.

The linkage 171 comprises a pair of spaced duplicate sublinkages each of which includes a control link 173 joined to the adjacent one of the

frame side members

47 and 49 through a lost motion pin and slot connection 175, together with a compound lever 177 which is pivotally mounted by suitable means on the forward surface of the upper rear wall part 25 and which carries the hinged wall part 41. Also connected to each compound lever 177 is a spring 179 and a control arm 181, both of which are pivotally connected to a rocker 183 pivotally supported by suitable means on the forward surface of the upper rear wall part 25.

More specifically, the compound lever 177 includes an arcuate leg 185 which is connected to the hinged wall part 41, a second leg 187 which is connected to the control link 173, and a third leg 189 to which is anchored the spring 179. The control arm 181 is pivotally connected to the compound lever 177 at a point spaced from the connection of the lever 177 to the rear wall part 25 so as to obtain control arm movement incident to pivotal compound lever movement.

When the frame 45 rocks in the counterclockwise direction as shown in FIGURE 1, as for example, in re sponse to the striking of an underwater obstacle, the connection 175 causes translation of the control link 173 to the left as shown in FIGURES 1 and 2, thereby pivoting the compound lever 177 in the counterclockwise direction to swing the hinged wall part 41 upwardly and rearwardly. Such movement of the compound lever 177 also extends the spring 179, which extension is limited despite the travel of the compound lever because of counterclockwise movement of the rocker 183 caused by the control arm 181. As a result, closing tension on the hinged part 41 is maintained at all times without necessitating use of a spring having a relatively large extension capacity. When the propulsion unit 31 and the frame 45 return to their normal running position, the spring 179 returns the hinged wall part 41 to its closed position in engagement with the plate structure 151.

As used herein the term center of percussion refers to that point where impact upon a pivotally supported body will cause no appreciable reaction force at the pivotal axis. In this connection, the center of gravity of as pivotally mounted body will always be located between the center of percussion and the tilting axis at which there is no reaction force. Any object which is subject to impact loading at a specific point which is not the center of gravity can be mounted on a pivot so located that the impact point is the center of percussion with respect to the pivot. Accordingly, in the disclosed construction the horizontal tilting axis defined by the trunnions 37 and 39 (see FIG. 4) is located above the center of gravity (see FIG. 1) so as to constitute a point on the lower unit adjacent to the axis of the propeller shaft as the center of percussion.

Accordingly, loading on the

trunnions

37 and 39 in response to the striking of an underwater obstacle is substantially reduced or eliminated by locating the trunnions as at center of rotation with the center of percussion of the combined frame 45 and propulsion unit 31, located in the part of the lower unit normally submerged in water below the bottom of the boat hull, i.e., in the spacer portion or in the gear box 127 of the lower unit 65. In the disclosed construction, the

trunnions

37 and 39 are located in spaced relation above the common center of mass or gravity of the combined frame 45 and marine propulsion unit 31 at such distance which places the center of percussion in the gear box 127. Consequently, when the gear box 127 strikes an underwater object, the

trunnions

37 and 39 are substantially free of any force component acting therethrough. In addition, the location of the center of gravity is considerably lower than in conventional outboard motor mountings, thereby providing additional stability. Reverse tilt lock means 194 (see FIGURES 5 and 9) normally connects the frame 45 to the front wall 21 of the motor well 15. When the engine 63 is operating in reverse, the resulting thrust tends to swing the propulsion unit 31 upwardly and rearwardly. The reverse tilt lock prevents such movement while affording release in the event of the striking of an underwater object by the lower unit when the engine is propelling the boat in the forward direction.

The reverse tilt lock means 194 is essentially the arrangement disclosed in the Hulsebus Re. Patent 25,048, issued Oct. 3, 1961, but is slightly modified in order to adapt the arrangement for use in the subject environment. This adaptation includes use of a cable 195 (see FIG- URE 5) connected to the cross link or yoke 197 (corresponding to pin 58 in said patent), instead of the control link referred to by the numeral 59 in said patent. This cable 195 is trained around a pulley 199 mounted on the cross beam 53 and extends to a control lever 201 (see FIGURES 1 and 3) mounted on the side frame member 47. Manual movement of the lever 201 in the clockwise direction about its pivotal mounting 203 from the position shown in FIGURE 1 serves to displace the cable downwardly as shown in FIGURE 9 to release the tilt lock.

In addition, the arrangement shown in the drawings utilizes a spring 205 to bias the yoke 207 (corresponding to yoke 45 in said patent) about the fulcrum 209, which spring 205 corresponds to the spring 46 in the beforementioned Hulsebus patent and is located in parallel relation to the cross beam 53, being anchored at one end to the cross beam, and being connected at its other end to a flexible cable 211 trained around a pulley 213 and connected to the yoke 207.

Steering of the dirigible propulsion unit 31 is provided by a pair of steering cables 221 and 223 (see FIG- URES 4 and 8) which respectively enter the motor well 15 through the

passageways

55 and 57 and which are connected to the pan 121 of the lower unit 65. Entry of the steering cables 22.1 and 223 through the

passageways

55 and 57 along the tilt axis avoids lengthwise cable displacement incident to movement of the frame 45 and propulsion unit 31 about the horizontal tilt axis.

Fuel is supplied to the engine by a flexible line 225 (see FIGURE 8) which extends through one of the motor well walls and is connectable to a fitting 227 on the pan 121. Electrical service is supplied by a flexible conduit 229 which extends through one of the motor well walls and is connected to a complementary fitting 231 on the pan 121. Throttle control is provided by a flexible push-pull cable 233 which extends through one of the motor well walls and is connected to a throttle control link 235 mounted on the pan 121.

Supply of combustion air to the motor well for use by the engine 63 can be provided by the incorporation of a butterfly valve (not shown) in the top wall 23 of the motor well 15. Air flow from the motor well 15 to the carburetor 103 within the engine cover 69 is provided by an enlarged opening 237 (see FIGURE 3) in the top wall of the motor cover 69 around the stud 71.

In operation, when the gear case 127 strikes an underwater obstacle, the propulsion unit 31 and frame 45 tilt about the

trunnions

37 and 39. Because of the location of the center of gravity of the combined frame and propulsion unit below the trunnions so as to locate the center of percussion in the gear case, the trunnions are substantially free of any force acting therethrough as a consequence of striking of an underwater obstacle, Upward movement and rearward movement of the propulsion unit 31 resulting from the striking of an underwater obstacle causes release of the tilt lock means 194, and opening of the hinged lower part 41 of the rear wall by reason of the linkage 171. Such upward and rearward movement is restrained by the shock absorbing arrangement connecting the frame 45 and the motor well side wall 17. Moreover, such upward and rearward movement does not affect the

steering cables

221 and 223 due to their passage through the

trunnions

37 and 39. The flexible lines providing electrical, fuel, and throttle control, permit tilting movement without disconnection.

Upon return movement of the propulsion unit 31 to its normal upright position, the reverse tilt lock 194 is again engaged, the motor well 15 is closed by the plate member 151, and the rear wall part 41 returns to its normal position closing the transom and engaging the plate member.

Transmission to the frame of vibrational excitations from the propulsion unit is effectively eliminated by the

cushions

81 and 93, thereby also effectively isolating the boat hull. The incorporation of the

sound deadening material

42 and 70 along the inside surfaces of the motor well walls and along the inside of the motor cover 69 effective 1y reduces engine noise level in the boat to a minimum.

The disclosed arrangement provides a propulsion arrangement including the performance features of an outboard and the appearance features of an inboard. Specifically, in the normal operating position of the propulsion unit 31, the propeller 67 is located immediately under the hull 11 in perpendicular relation to the hull bottom for thrust in a direction parallel to boat bottom. If the propulsion unit 31 should strike a submerged obstacle, means are provided for propulsion unit movement clearing the obstacle. The arrangement also affords mounting of the propulsion unit 31 so as to place the center of percussion in the gear box 127 so as to effectively avoid fracture or damage to the propulsion unit upon the striking of an underwater obstacle. Additionally, the propulsion unit 31 is dirigible to afford steering control, and the engine 63 is totally enclosed within the boat, thereby providing a low and clean silhouette and exceptionally low noise levels in the boat. Still further, the exhaust discharge is mufflcd by reason of discharge into the wake of the boat and lower unit. The disclosed arrangement also permits shortening of the length of the lower unit, thereby providing a stronger unit. Location of the propeller beneath the boat hull serves to reduce propeller ventilation and to retain the propeller in the water during heavy seas.

Various of the features of the invention are set forth in the following claims.

What is claimed is:

1. The combination of a boat, a support, hearings on said boat mounting said support for pivotal movement about a horizontal axis, said bearings each having a hollow passage extending along said horizontal axis, a marine propulsion unit, means on said support mounting said marine propulsion unit for pivotal movement about an axis transverse to said horizontal axis, and means extending through said passage and connected to said marine propulsion unit for pivoting said marine propulsion unit relative to said support.

2. The combination of a boat, a support, bearings on said boat mounting said support for pivotal movement about a horizontal axis, said bearings each having a hollow passage extending along said horizontal axis, a marine propulsion unit, means on said support mounting said marine propulsion unit for pivotal movement about an axis transverse to said horizontal axis, means extending through said passage and connected to said marine propulsion unit for pivoting said marine propulsion unit relative to said support, a shock absorbing unit, means connecting said shock absorbing unit between said support and said boat for controlling pivotal movement of said support and said marine propulsion unit about said horizontal axis, and reverse tilt lock means connectable between said boat and said support.

3. The combination of a boat, a frame, means on said boat supporting said frame for pivotal movement about a horizontal axis, a marine propulsion unit comprising an engine, a cover enclosing said engine, and a lower unit including a propeller attached to said engine, a pair of elastomeric cushions mounted on said frame, first bearing means supported by one of said elastomeric cushions and engaging said engine at the top thereof, and second bearing means supported by the other of said elastomeric cushions and engaging said lower unit whereby said propulsion unit is rotatably movable about a vertical axis relative to said frame.

4. The combination of a boat, a frame, a marine propulsion unit comprising an engine, a cover enclosing said engine, and a lower unit including a main portion and a second portion below said main portion, a propeller supported by said second portion and connected to said engine, a pair of elastomeric cushions mounted on said frame, first bearing means supported by one of said elastomer-ic cushions and engaging said engine, second bearing means supported by the other of said elastomeric cushions and engaging said main portion of said lower unit whereby said propulsion unit is rotatably movable relative to said frame, and means on said boat pivotally mounting said frame and said supported propulsion unit for movement about a horizontal axis, said means pivotally mounting said frame being located, when said propulsion unit is located in a generally upright, normal operating condition, above the common center of gravity of said frame and said marine propulsion unit.

5. The combination of a boat, a support, a marine propulsion unit comprising an engine, a cover enclosing said engine, a lower unit including a main portion and a second portion below said main portion, and a propellor supported by said second portion and connected to said engine, a pair of elastomeric cushions mounted on said support, first bearing means supported by one of said elastomeric cushions and engaging said engine, second bearing means supported by the other of said elastomeric cushions and engaging said main portion of said lower unit whereby said propulsion unit is rotatably movable relative to said support, and means on said boat pivotally mounting said support and said supported propulsion unit for movement about a horizontal axis, said means pivotally mounting said support being located so that said propulsion unit is movable relative to said support about an axis transverse to said horizontal axis and so that, when said propulsion unit is located in a generally upright, normal operating condition, the common center of gravity of said frame and said marine propulsion unit is below said means pivotally mounting said support, a hollow passage in said means pivotally mounting said support and extending along said horizontal axis, means extending through said passage and connected to said marine propulsion unit for pivoting said marine propulsion unit relative to said support, a shock absorbing unit, means connecting said shock absorbing unit between said support and said boat for controlling pivotal movement of said support and said marine propulsion unit about said horizontal axis, and reverse tilt lock means connectable between said boat and said support.

6. The combination of a boat having a motor well at the stern thereof defined by a pair of spaced side walls, a bottom wall extending between said side walls and having an aperture therein, a rear wall extending between said side walls and including a part, and means hingedly mounting said part for swinging movement about a generally horizontal axis, a frame, means on said side walls pivotally mounting said frame within said motor well for movement about another horizontal axis, a marine propulsion unit including a lower unit, and means on said frame mounting said marine propulsion unit with said lower unit extending through said aperture and below said motor well and for pivotal movement of said propulsion unit about an axis transverse to said horizontal axes.

7. A combination in accordance with claim 6 wherein said frame includes a member closing said aperture when said marine propulsion unit is in a normally upright runnmg position.

8. The combination of a boat having a motor well at the stern thereof defined by a bottom wall having an aperture therein, and a rear wall having a first fixed part and a second part, and means hingedly mounting said sec ond part to said first part for swinging movement about a generally horizontal axis, a frame, means on said boat pivotally mounting said frame within said motor well for movement about another horizontal axis, a marine propulsion unit including a lower unit, means on said frame mounting said marine propulsion unit for pivotal movement of said propulsion unit about an axis transverse to said horizontal axes, and for projection of said lower unit through said aperture and below said motor well, and means connected to said frame and to said hinged rear wall part for pivotally displacing said rear wall part upwardly and rearwardly about its horizontal axis in advance of similar movement of said propulsion unit.

9. A combination in accordance with claim 8 including helical spring means connected between said boat and said second rear wall part for biasing said rear wall part toward a position normally closing said motor well, and linkage means connected to said helical spring means for bodily shifting said helical spring means to limit extension thereof while constantly maintaining a biasing force when said rear wall part is displaced from said position.

10. The combination of a boat having a motor well at the stern thereof defined by a bottom wall having an aperture therein, a frame including a plate structure closing said aperture when said frame is in a generally upright position, said motor well also including a rear wall having a part, and means hingedly mounting said plate structure for swinging movement about a generally horizontal axis, means on said boat pivotally mounting said frame within said motor well for movement about another horizontal axis, a marine propulsion unit including a lower unit, means on said frame mounting said marine propulsion unit for pivotal movement of said propulsion unit about an axis transverse to said horizontal axes and for projection of said lower unit through said aperture and below said motor well, and gasket means on said plate structure and engageable with the periphery of said aperture and with the lower margin of said hinged rear wall part for sealing said motor well against fluid passage between said plate structure and said bottom wall and said hinged rear wall part.

11. The combination of a boat having a motor well at the stern thereof defined by a bottom wall extending between said side walls and having an aperture therein, a frame, means on said boat pivotally mounting said frame within said motor well for movement about a horizontal axis, a member on said frame closing said bottom wall aperture when said frame is in a generally upright position, said member including an aperture, an exhaust gas inlet port, and an exhaust gas discharge port, a marine propulsion unit including an engine having an exhaust gas discharge, and a lower unit including an exhaust gas passageway communicating with said exhaust gas discharge and having an exhaust gas outlet, and means on said frame mounting said marine propulsion unit for pivotal movement of said propulsion unit about an axis transverse to said horizontal axis, for projection of said lower unit through said member aperture and below said motor well, and for communication between said passageway outlet and said member inlet port, notwithstanding rotation of said propulsion unit relative to said member.

12. The combination of a boat having a motor well at the stern thereof defined by a pair of spaced side walls, a front wall connecting said side walls, a top wall extending from said front wall and said side walls a, bottom wall extending from said front wall and said side walls, said bottom wall having an aperture therein, a rear wall extending from said top wall to said bottom wall and between said side walls, said rear wall having a hinged part, and means hingedly mounting said hinged part for swing ing movement about a generally horizontal axis, a frame, means on said side walls pivotally mounting said frame within said motor well for movement about another horizontal axis, a marine propulsion unit including a power head and a lower unit, and means on said frame mounting said marine propulsion unit for pivotal movement of said propulsion unit about an axis transverse to said horizontal axes and for projection of said lower unit through said aperture and below said motor well.

13. The combination of a boat having a motor well at the stern thereof defined by a bottom wall having an aperture therein, a rear wall having a part, and means hingedly mounting said part for swinging movement about a generally horizontal axis, a frame including a plate structure closing said aperture when said frame is in a generally upright position, means on said boat pivotally mounting said frame within said motor well for movement about another horizontal axis, a marine propulsion unit including a lower unit, means on said frame mounting said marine propulsion unit for pivotal movement of said propulsion unit about an axis transverse to said horizontal axes and for projection of said lower unit through said aperture and below said motor well, and a single gasket on said plate structure, said gasket engageable with both the periphery of said aperture and with the lower margin of said hinged rear wall part for sealing said motor well against fluid passage between said plate structure and said bottom wall and said hinged rear wall part.

14. The combination of a boat, a support, a marine propulsion unit having a power head and a lower unit, means on said support mounting said marine propulsion unit for pivotal movement about a generally upright axis, means on said boat mounting said support for pivotal movement of said support and said marine propulsion unit about a generally horizontal axis, for locating said marine propulsion unit with a part of said lower unit below said boat when said propulsion unit is in a generally upright position, for locating the center of percussion of said support and of said marine propulsion unit in said lower unit part, and for locating the center of gravity between said horizontal axis and said center of percussion.

15. The combination of a boat having a hull including a motor well, a support, means on said boat mounting said support in said motor well for pivotal movement about a horizontal axis, a marine propulsion unit including a power head, and means on said support mounting said marine propulsion unit with said power head at least partially forwardly of said support mounting means when said propulsion unit is in a normal operating position and for pivotal movement relative to said operating position about an axis transverse to said horizontal axis.

16. The combination of a boat including a hull having a motor well, a support, means on said boat mounting said support in said motor well for pivotal movement about a horizontal axis, a marine propulsion unit including a power head, means on said support mounting said marine propulsion unit with said power head at least partially forwardly of said support mounting means when said propulsion unit is in a normal operating position and for pivotal movement relative to said operating position about an axis transverse to said horizontal axis, a shock absorbing unit, and means connecting said shock absorbing unit between said support and said boat for controlling pivotal movement of said support and said marine propulsion unit about said horizontal axis.

17. The combination of a boat having a hull including a motor well, a support, means on said boat mounting said support in said well for pivotal movement about a horizontal axis, a marine propulsion unit including a power head, means on said support mounting said marine propulsion unit with said power head at least partially forwardly of said support mounting means when said propulsion unit is in a normal operating position and for pivotal movement relative to said operating position about an axis transverse to said horizontal axis, and reverse tilt lock means con nectable between said boat and said support.

18. The combination of a boat, a support, means on said boat supporting said support for pivotal movement about a horizontal axis, elastomeric cushions mounted on said support, a marine propulsion unit including a power head, bearing means supported by said elastomeric cushions for rotatably mounting said marine propulsion unit for pivotal movement about an axis transverse to said horizontal axis, a first of said bearing means being located above said power head and a second of said bearing means being located below said power head.

19. The combination of a boat having a hull including a well, a support, means on said boat mounting said support in said well for pivotal movement about a horizontal axis, a marine propulsion unit including a power head, means on said support mounting said marine propulsion unit with said power head at least partially forwardly of said support mounting means when said propulsion unit is in a normal operating position and for movement relative to said operating position about an axis transverse to said horizontal axis, and means on said boat engaged by said support for the transmission of thrust therebetween when said propulsion unit is in a generally upright position.

20. The combination of a boat having a motor well at the stern thereof defined by wall means including a bottom wall having an aperture therein and a rear wall part hingedly mounted for swinging movement about a generally horizontal axis, a gimbal-like frame, means on said wall means pivotally mounting said frame within said motor well for movement about another horizontal axis, a marine propulsion unit including a lower unit, and means on said frame mounting said marine propulsion unit with said lower unit extending through said aperture and below said motor well and for pivotal movement of said propulsion unit about an axis transverse to said horizontal axis.

21. The combination of a boat, a gimbal-like frame, means on said boat mounting said frame for pivotal movement about a horizontal axis, a marine propulsion unit including a power head and a lower unit and means on said frame mounting said marine propulsion unit with said power head within said frame and for pivotal movement of said marine propulsion unit about an axis transverse to said horizontal axis.

22. The combination of a boat having a motor well at the stern thereof defined by wall means including a bottom wall having an aperture therein and a rear Wall part hingedly mounted for swinging movement about a generally horizontal axis, a gimbal-like frame, means on said wall means pivotally mounting said frame within said motor well for movement about another horizontal axis, a marine propulsion unit including a power head and a lower unit and means on said frame mounting said marine propulsion unit with said power head within said frame and for pivotal movement of said marine propulsion unit about an axis transverse to said horizontal axis.

References Cited UNITED STATES PATENTS 1,574,977 3/1926 Johnson et al -41 X 1,874,988 8/1932 Harvey 115-41 X 2,166,234 7/1939 Conover 115-18 2,209,302 7/1940 Johnson et al. 11541 2,605,734 8/1952 Watkins 11518 2,718,792 9/1955 Kiekhaefer 11534 X 3,003,724 10/ 1961 Kiekhaefer 2484 2,975,750 3/1961 Smith 11541 2,976,836 3/1961 Fageol 11535 3,094,097 6/1963 Ellzey 11535 X 2,235,140 3/1941 Clarke 115-18 X 2,441,000 5/1948 Armstrong 11517 X 2,755,766 7/1956 Wanzer.

FOREIGN PATENTS 567,567 2/ 1945 Great Britain.

TRYGVE M. BLIX, Primary Examiner.