Supplemental sailboat propulsion device

A supplemental propulsion device for a sailboat or sailboard type water craft including a pivotal centerboard. A pair of propulsion wings that are vertically hinged to one-another and mounted to the lower portion of the leading edge of the centerboard of the craft. Upon the application to the centerboard of a reciprocating pumping action each propulsion wing moves inwardly to a retracted position adjacent the centerboard during forward movement of the lower portion of the centerboard and moves outwardly to an extended position removed from the centerboard during rearward movement of the lower portion of the centerboard. Cables connect the free edge of each of the propulsion wings to the trailing edge of the centerboard to stop the outwardly movement of the wings at a point no more than 90.degree. from the centerboard during the rearward movement of the lower portion of the centerboard whereby the propulsion wings provide enlarged and effective surfaces to the surrounding water to forcefully propel the craft through the water.

FIELD OF THE INVENTION 
This invention relates to a device to be used as a supplemental or 
emergency means for propelling a sailboat or other water craft that is 
without movement power. More particularly, the invention relates to 
supplemental or emergency propulsion means for use in connection with 
sailboats or sailboards which have a pivotal or removable centerboard. 
BACKGROUND OF THE INVENTION 
For many years there has been a developing interest in the recreational use 
of small sailboats (accommodating 1-4 passengers) and sailboards (usually 
accommodate 1-2 riders). Many of such sailboats (particularly those with 
shallow draft) and sailboards (with literally no draft) are stabilized in 
the water when under sail against sudden or radical side tipping by 
centerboards. Centerboards extend downwardly through a longitudinal slot 
in the hull or body of the boat or sailboard and, beacause such water 
crafts are most frequently portable (capable of being carried or are 
trailerable), they may be detachably or pivotally mounted within the hull 
slot. 
In the field of recreational sailboats and sailboards it sometimes occurs 
that a sail or mast is lost or destroyed or there is a lack of wind power 
for propelling the boat or board. Under such circumstances it frequently 
becomes necessary for the sailor and/or a passenger (if any) to row the 
boat to shore by a pair of single-bladed oars pivoted to side oarlocks or 
to paddle the sailboard to shore by a double bladed paddle. 
It is an object of the present invention to provide a water propulsion 
device for sailboats and sailboards which is mountable to the centerboard 
of such boats and boards. 
It is another obJect of the invention to provide a water propulsion device 
mountable to the centerboard of a sailboat or sailboard for use in 
propelling such boat or sailboard during periods when wind propulsion is 
not available or when a sail or mast is damaged and wind power can not be 
utilized. 
It is a still further obJect of the invention to provide an emergency water 
propulsion device for sailboats and sailboards which is readily mountable 
to the centerboard of such water crafts and which does not interfere with 
the functioning of the centerboard during normal wind sailing procedures. 
Other objects and advantages of the invention will become apparent from the 
following summary and detailed description of preferred embodiments of the 
invention taken in conJunction with the accompanying drawing figures. 
SUMMARY OF THE INVENTION 
The present invention relates to a supplemental propulsion device for 
sailboats and sailboards which is mountable to the leading edge of the 
centerboard of such water crafts. The centerboards of small sailboats and 
sailboards extend downwardly below these crafts for stabilization purposes 
and extend upwardly through a hull slot and are either pivoted to the boat 
or board hull or are removably affixed in pivotal fashion to the hull. The 
propulsion device of the invention comprises a pair of propulsion wings 
which are vertically hinged to one-another with the wing hinge mounted to 
the leading edge of the centerboard. By reciprocating the centerboard at 
its upper end forwardly and rearwardly about its pivot point the 
propulsion wings are positioned outwardly during the push or thrust 
portion of the reciprocating cycle and are positioned inwardly adJacent 
the sides of the centerboard during the pull portion of the reciprocating 
cycle of the centerboard. During periods of wind sailing, when the 
propulsion device of the invention is not in use, the wings of the device 
are locked into closed position inwardly adJacent the sides of the 
centerboard. 
For assisting the sailor or passenger in utilization of the propulsion 
device of the invention, the centerboard has at its upper end a handle by 
which the centerboard (upon release from its fixed stabilizing position) 
may be pumped or reciprocated. Such handle may be positioned forward or 
rearward of the pivot point of the centerboard so that the person pumping 
the centerboard, and thus the propulsion device, may be seated in 
centerboard-straddling position facing forward toward the bow (front) or 
rearward toward the stern (rear) of the sailboat or sailboard.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring initially to FIG. 1 there is illustrated a small sailing craft 10 
with shallow draft. The craft 10 is comprised basically of a boat hull 12 
having a forward or bow end 14 and a rear or stern end 16. A mast 18 
projects upwardly from the hull and bears by well known means a horizontal 
boom 20. A simple triangular canvas sail 22 is affixed by well known and 
appropriate means to the mast and boom. The sailing craft 10 is provided 
with a centerboard 24 which extends downwardly through a central elongated 
hull slot 26 (terminates at a forward end 26a and at a rearward end 26b) 
and which during normal wind sailing periods is fixed in vertical 
orientation with respect to the hull. The centerboard 24 provides 
stabilization of the craft under sail against sudden or radical side 
listing or tilting caused by heavy wind force against the sail or by heavy 
wave motion against the craft's hull. 
The centerboard 24, when released from its fixed wind sailing orientation, 
is pivotal with respect to the hull 12 at pivot point 28. Affixed to the 
centerboard 24 is a supplemental propulsion device 30 in accordance with 
the invention. The propulsion device 30 is mounted to the leading edge 24a 
of the centerboard. As shown in the perspective drawing view of FIG. 2 the 
propulsion device 30 is comprised of two force wings 32a and 32b which are 
Joined at their leading edge portions 32c and 32d, respectively, to an 
elongated hinge 34 having hinge leaves 34a and 34b. The hinge 34 is 
provided with upper and lower mounting eyelets 34c and 34d, respectively, 
which receive mounting screws 36a and 36b, respectively, that are driven 
into the leading edge of centerboard 24 to mount the propulsion device 30 
thereto. 
The force wings 32a and 32b are connected at their trailing edges by cable 
38 which limits the degree to which such wings may spread during the push 
or thrust portion of each reciprocating cycle of the centerboard during 
use of the propulsion device 30. Cable guide bracket 40 is mounted to the 
trailing edge of the centerboard by bolt means 40a (see FIGS. 3 and 4) and 
presents a bracket eyelet 40b through which cable 38 passes. 
Affixed to the upper corner of the trailing edge of force wings 32a and 32b 
are wing lock brackets 42a and 42b, respectively. With the force wings 32a 
and 32b in their closed position adjacent the centerboard 24 (see FIG. 3) 
during periods within which the propulsion device is not being used the 
lock portions 42c and 42d, respectively, of lock brackets 42a and 42b 
overlap with their respective lock holes 42e and 42f coming into alignment 
so as to receive a locking rod 44 (see FIG. 1). The locking rod 44 extends 
downwardly along the centerboard's trailing edge from an upper lock 
bracket 46 affixed to the upper portion of the centerboard. The 
centerboard 24 is provided with a handle 48 for pumping or reciprocating 
the centerboard when the propulsion device 30 has been unlocked (locking 
rod 44 removed from brackets 42a and 42b of device 30 and upper lock 
bracket 46) and is to be used. As shown in FIG. 1, the sailor has 
straddled the centerboard and is facing the bow 14 of the sailing craft 
10. In such position, the sailor in pulling handle 48 rearwardly moves the 
underwater portion of the centerboard 24 forewardly with the surrounding 
water causing the force wings 32a and 32b into their closed position (FIG. 
3) adjacent the centerboard. When the sailor begins to push handle 48 
forwardly during the pumping or reciprocating cycle the underwater portion 
of the centerboard 30 moves rearwardly with the surrounding water causing 
the force wings 32a and 32b to open to the extent permitted by cable 38 
with the wings acting as paddle surfaces to propel the craft forwardly. 
The cable 38 is desirably of a length such that the wings 32a and 32b 
never are permitted to extend to near 90.degree. of angulation with 
respect to the centerboard so that they always move back to their position 
adJacent to the centerboard after the craft propelling portion of the 
pumping or reciprocating cycle of the centerboard. 
It is to be noted that the centerboard handle 48, for pumping such board 
and the propulsion device 30 of the invention, may be located at a forward 
position on the centerboard so that the sailor may sit in a reversed 
orientation with his or her pulling action (rather than a pushing action) 
comprising the craft propelling portion of the pumping or reciprocating 
cycle. 
The above described embodiments of the supplemental propulsion device of 
the invention is easily assembled and mounted to the centerboard of small 
sailboats or to sailboards. While the present invention has been described 
with reference to preferred embodiments thereof, it is obvious that 
modifications and alterations of such embodiment will occur to others 
skilled in the art upon their reading and understanding of this 
specification. It is therefore to be understood that the present invention 
includes all such modifications and alterations, and equivalents thereof, 
being only limited by the scope of the following claims.