Marine propulsion – Means to control the supply of energy responsive to a sensed...
Patent
1993-05-12
1995-02-14
Avila, Stephen P.
Marine propulsion
Means to control the supply of energy responsive to a sensed...
440 61, B63H 512
Patent
active
053890167
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an arrangement in a steering and propulsion system for a planing type motorboat having an engine and a trimmable drive.
BACKGROUND OF THE INVENTION
Planing motorboats are normally driven at relatively high speeds. The difference in speed compared to sailing boats and other non-planing motorboats is therefore appreciable. Since the steering characteristics for planing boats differ somewhat from conventional boats, inexperienced helmsmen experience difficulties at such high speeds. Near-accidents can have many different causes within the common expression "poor seamanship". It would however be desirable if the steering characteristics of planing motor boats were more similar to those of conventional boats.
When executing a turn with a planing boat, what normally happens, without going too deeply into the hydrodynamic factors which come into play, is the following:
If the rudder is moved to e.g. the right, the bow of the boat does not immediately turn towards the desired direction. The rudder blade, or the propulsion unit in the case where steering and propulsion are integrated, generates a side force to the left. The stern is not however moved immediately out to the left since the boat's inertia provides resistance. During the start of the turning manoeuvre it can be said that the rudder skids in the water. The side forces gradually start to take effect so that the stern is drawn to the left, whereby the longitudinal extension of the boat begins to deviate from the original course. The angular deviation implies that water pressure is exerted on the head of the boat from the side so that the bow and the stern move in different directions, i.e. the turn has now commenced. The effect of this procedure is normally that the boat first moves a little to the left of the original course before the right turn occurs.
It is easy to recognise that two fast moving, planing boats on a direct collision course can meet with problems if avoiding manoeuvres are not initiated in time. These steering problems arise on many planing boats, irrespective of whether they are provided with propeller or waterjet drive, integral or separate rudder and propulsion.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an arrangement which offers improved steering characteristics on a boat of the planing type.
This is achieved in accordance with the present invention by means of an arrangement in a steering and propulsion system for a planing type motorboat having an engine and a trimmable drive, said arrangement comprising: positions; motorboat; sensor being connected to said means for adjusting said trimmable drive, and arrangement, the water when a certain steering displacement is exceeded.
This arrangement is applicable to most planing-type boats, irrespective of whether the adjustment means for the trim position is separately located on the boat or integrated with the propulsion unit.
In a preferred embodiment, before a turn is commenced, the motorboat presents a prevailing trim angle which is recorded by the microprocessor, the microprocessor being further adapted to cause the boat to readopt this angle when the displacement of the rudder arrangement returns to a neutral position after execution of the turn.
Advantageously, the microprocessor is also connected to means for recording the speed of the boat to thereby take into account the speed of the boat when effecting trim adjustment during a turn.
The invention also provides for a similar arrangement for motorboats having a combined steering and propulsion unit.
BRIEF DESCRIPTION OF THE DRAWINGS
One embodiment of the invention will be described in greater detail in the following by way of example only and with reference to the annexed drawings, in which
FIG. 1 schematically illustrates in a sequence of pictures from left to right how a conventional planing boat normally reacts during a turn, and
FIG. 2 shows schematically the arrangement according to the invention applied to a so-called aquamatic dr
REFERENCES:
patent: 3581696 (1971-06-01), Ilon
patent: 4318699 (1982-03-01), Wenstadt et al.
patent: 4787867 (1988-11-01), Takeuchi et al.
patent: 4931025 (1990-06-01), Torigai et al.
patent: 5167546 (1992-12-01), Whipple
Avila Stephen P.
Volvo Penta AB
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