GB2050656A

GB2050656A - A Tide Clock

Info

Publication number: GB2050656A
Application number: GB8016130A
Authority: GB
Original assignee: Riepe C W
Current assignee: Riepe C W
Priority date: 1979-05-16
Filing date: 1980-05-15
Publication date: 1981-01-07

Abstract

A tide clock has a dial 1 and a drive for an hour hand 2, a minute hand 3, and optionally also for a seconds hand 4 as well as a drive for a tide indication disc 5. The output shafts of all the drives are arranged coaxially. The tide indication disk 5 has the tidal range marked around its periphery and is rotated in 12 hours by an angle corresponding to the time difference between a normal tide cycle and 12 hours (e.g. about 25 minutes) so that the hour hand 2 always indicates the momentary tide status on the disc 5. As described the disc 5 is of transparent plastics and, in addition to HIGH and LOW markings, carries a curve 5' designating the intermediate tidal states by its relation to the rim of the disc and to an inner coloured circle 5''. The disc 5 is frictionally mounted on its drive shaft 9 so that a disc can be fitted to suit the local geographic area. <IMAGE>

Description

SPECIFICATION Improvements in and Relating to Tide Clocks The present invention relates to a tide clock and to a method of indicating the state of a tidal movement. The invention relates in particular, but not exclusively, to a tide clock with a dial and with a drive for an hour hand, a drive for a minute hand, optionally a drive for a second hand, as well as a drive for a tide indication, the output shafts of all the drives being arranged coaxially and the angular velocity of the output shaft of the drive for the tide indication being associated with the normal tide cycle.

In known tide clocks of this type (German Offenlegungsschrift 2,446,095, German Offenlegungsschrift 2,454,761) in addition to the usual markings for indicating the hours, minutes and optionally seconds, the dial has markings designating, for example, high and low tides, the high tide marking being displaced by 1 800 relative to the low tide marking. In addition, further subdividing markings can be provided between the high and low tide markings. A hand is fixed to the output shaft of the drive for the tide indication which, due to the construction of the drive and/or the selected transmission ratios in the case of a clock with a 12 hour indication requires 12 hours 25 minutes for a revolution, i.e.

it revolves once during a normal tide cycle. Thus, independently of the position of the hour, minute and optionally second hands, its hand indicates the momentary tide status and if corresponding subdividing markings are provided, the latter can be used to indicate in how many hours the next high and/or low tide will occur.

Quite apart from the fact that the invariable tide markings on the dial of the prior art tide clocks do not make it possible to take account of the fact that, in particular in coastal areas, the times for the rising and falling tides within a tide cycle are not equally long and can instead vary considerably, the known tide indication does not permit the direct reading off of the times at which future tide states will occur. Thus, the time at which a particular tide state will occur must be calculated from the information obtained through the momentary position of the tide hand and the hour hand, in conjunction with the tide markings.

A tide clock is already known (Swiss Patent 584,930) in which a ring defining the tidal flow is arranged concentrically with respect to the output shafts of the hour and minute hand drives and can be adjusted from the outside. Thus, by means of a conventional tide calendar, this ring can be so adjusted for a day which is of interest that the marking for the high tide is located at the corresponding time marking of the dial. The hour hand then gives the momentary tide state and the tide states occurring at other times of this day can be directly read off the corresponding time markings of the dial.

This known tide clock, which also does not permit a replacement of a ring defining the tidal flow by other means to take account of differing tidal flows, requires the manual setting of the ring to the time values relevant to the particular tide cycle, i.e. for each tide cycle a separate setting by means of the conventional tide calendar is necessary. Thus, for example, for an indication which is always to be available for a relatively long period a manual adjustment is necessary at the intervals of successive tide cycles.

One object of the invention is to provide a tide clock with automatically varying tide indication as a function of successive tide cycles and in which the tide indication is directly associated with the clock time indicated by the tide clock.

According to the invention, there is provided a tide clock of the type defined hereinbefore wherein a tide disk defining the particular tidal flow is fixed to the output shaft of the drive for the tide indication and wherein within 12 hours the output shaft of the drive for the tide indication rotates by an angle corresponding to the time difference between a normal tide cycle and 12 hours. Preferably, the output shaft carrying the tide disk is rotated substantially continuously corresponding to the output shafts carrying the hands.

Thus, in the case of the tide clock according to the invention, the tide disk defining the tidal flow is adjusted by the clockwork mechanism between individual tide cycles. Around the periphery of the tide disk is marked the tidal range, for example by corresponding dimensioning of the radii or by the course of lines in the marginal ares. Thus, the high and low tide markings are positioned at the corresponding point of the clock dial and the momentary tide status is indicated by the hour hand of the clock. This leads to a direct association of time and tide indications so that, without any calculations being necessary, the user can determine at what time and in how many hours high and low tide will occur.The resulting indication also makes it possible to estimate the momentary and future theoretical water depth, as well as the times of strong and weak currents, once again without any calculations being necessary.

It is pointed out in this connection that the tide clock according to the invention obviously only permits an estimate which is adequate for yachtsmen and the like. Thus, a certain imprecision results from the fact that a time of a normal tide cycle of approximately 1 2 hours, 25 minutes is applied to a 3600C circle (on a 1800 arc with a 24 hour indication) whereas the dial indicates a time of 12 hours on the 3600 arc (on a 1800 arc with a 24 hour indication). In addition, a conventional clock mechanism does not take account of the daily time fluctuations in the tide cycle, which is approximately +3 minutes.

The tide disk is preferably detachably fixed to the output shaft of the drive for the tide indication and can for example be in frictional engagement therewith. This makes it possible to replace one tide disk by another, so as to be able to take account of the differing times of rising and falling tides within a tide cycle, particularly in coastal regions. Therefore, the user can place on the output shaft of the drive for the tide indication a tide disk constructed for the geographical area which is of interest to him. Furthermore, when fixed by frictional engagement, the mounted tide disk can be very easily adjusted in order to adapt to the differing times at which the tide cycles start, as a function of the geographical position.

To enable the tide disk to be adjusted or changed as easily as possible, the output shaft of the drive for the tide indication can terminate further above the dial plane than the output shafts of the remaining drives, so that the tide disk is fixed above the hands and is therefore easily accessible.

In order that when the tide disk is arranged above the hand, there is a minimum parallax on taking the reading, the output shaft of the drive for the hour hand can terminate further above the dial plane than the output shaft or shafts for the drive or drives of the remaining hand or hands, so that the hour hand which serves as the indicator is located in the immediate vicinity of the tide disk.

So that the tide disk does not cover the figures on the dial, the minimum tide disk radius is preferably equal to or smaller than the radius of the circle which is tangent to the figures on the dial on the side facing the output shafts.

If the tide disk is made from opaque material, its maximum radius should be smaller than the length of the hour hand, particularly if the tide disk is positioned above the hour hand so that the latter remains visible.

There is also provided in accordance with the present invention a tide clock comprising a clock dial, an hour hand, a shaft on which the hour hand is mounted, a tide disc, a further shaft on which the tide disc is mounted and which is coaxial with the hour hand shaft, and drive means for driving the shafts at rates of rotation such that the hour hand indicates normal time at the clock dial, and the tide disc shaft rotates in a twelve hour period by an angle corresponding to the time difference between the period of a normal tide cycle and a twelve hour period, the tide disc having a shape or marking related to a particular cycle of tidal movement whereby in operation the juxtaposition of the hour hand and the tide disc indicates information relating to the state of the particular tidal movement.

There is yet further provided in accordance with the present invention a method of indicating the state of tidal movement, comprising driving an hour hand on a shaft of a tide clock to indicate normal time on a clock dial, driving a further shaft, which is coaxial with the hour-hand shaft, at a rate of rotation such that the further shaft rotates in a twelve hour period by an angle corresponding to the time difference between the period of a normal tide cycle and a twelve hour period, and mounting on the further shaft a tide disc having a shape or marking related to a particular cycle of tidal movement, whereby in operation the juxtaposition of the hour hand and the tide disc indicates information relating to the state of the particular tidal movement.

Preferred and optional features which have been set our hereinbefore may also be provided in accordance with the aspects of the inventions set out in the immediately preceding two paragraphs.

It is to be appreciated that the tide disc need not be circular, and indeed can be a member of any convenient form capable of being mounted on the said further shaft and of rotating therewith.

It is pointed out that the shaft referred to hereinbefore as the output shaft of the drive for the tide indication can also be a simple bearing shaft for the tide disk and that then, for example, the tide disk drive takes place on its periphery.

The invention is described hereinafter relative to a non-limitative embodiment and the attached drawings, wherein show: Fig. 1 in simplified diagrammatic form a plan view of a tide clock.

Fig. 2 a basic diagram of the dial and the parts of the tide clock located above the dial according to Fig. 1 in side view.

The represented clock has a clock mechanism 11 with corresponding reduction and/or transmission gears, as described e.g. in German Offenlegungsschrift 2,446,095 and German Offenlegungsschrift 2,454,761. From the thus formed drive, substantially continuously driven output shafts, 6, 7, 8, 9 extend concentrically to one another over the dial 1, output shaft 6 driving the second hand 4, output shaft 7 the minute hand 3 and output shaft 8 the hour hand 2. A tide disk 5 is detachably fixed by frictional engagement to output shaft 9. With this arrangement hour hand 2 is adjacent to tide disk 5, which prevents incorrect readings due to parallax. Thus, with the present clock, the arrangement of the hands is the opposite to that in conventional clocks in which the hour hand is adjacent to the dial and the second hand is furthest therefrom. The tide disk, the hands, the output shafts and the dial are covered by a diagrammaticaliy indicated casing 10.

Whereas output shafts, 6, 7, and 8 are moved at an angular velocity corresponding to the particular indication on a dial divided up into 12 hours, output shaft 9 is driven in such a way that a particular peripheral point of the tide disk fixed thereto within a 12 hour revolution of the hour hand traverses an area on the circle representing its movement path and which is concentric to shaft 9 which corresponds to the difference between the tide cycle and 12 hours, i.e.

approximately 25 minutes.

The tide disk, which in the present case is for example made from transparent plastic with a thickness of approximately 0.5 mm to approximately 2 mm, carries on its surface the markings "HIGH" for high tide and "LOW" for low tide, as well as a curve 5' designating the tidal range between high and low tide and between low and high tide, whereby the area between curve 5' and the inner circle 5" which intersects the curve at one point can be coloured to make matters clearer. It is assumed that in the present case the times for rising and falling tide are of the same length i.e. in each case half a tide cycle, i.e.

normally 6 hours, 12.5 minutes and that the tidal range is substantially symmetrical. However, it is immediately apparent that the duration of rising and falling tides, particularly in coastal areas can vary very widely and that the tidal range can also have some other configuration differing from that of curve 5' in Fig. 1. Therefore, the tide disk 5 for a geographical area fixed to the output shaft 9 by frictional engagement can be replaced by another tide disk appropriate for the new geographical area.

When using the tide clock, the user adjusts the tide disk 5 by corresponding rotation on output shaft 9 in such a way that the markings "HIGH" and "LOW" are located in the vicinity of those figures on the dial corresponding to the high and low tide times given in the relevant tide cycle given for example in the tide calendar. As Fig. 1 shows, in the present embodiment the setting is to the times 3.00 and 9.00. Thus, at any time, e.g.

at the time of just before 12.00 indicated by the hour hand in Fig. 1 the user can read off at a glance that in this case high tide will occur at 3.00 and that there is a little more than 3 hours until high tide occurs. On the basis of curve 5' he obtains information on the tidal range at the time of taking the reading, because this curve is intersected by the hour hand 2 and consequently information on the momentary state of the tidal range is obtained. On the basis of these tidal range readings, the user can also draw conclusions regarding the strength of the currents.

When the hour hand moves from the position shown in Fig. 1 in the direction of the indicated high tide time, the tide disk is obviously rotated slightly in a clock-wise direction, because during a 12 hour hour hand revolution the tide disk position changes by 25 minutes. However, within the tide cycle this position change is unimportant, because the tide clock is only intended to provide an estimate of the information based on the particular tide status.

When the hour hand has performed a complete revolution from the position shown in Fig. 1, i.e.

when 12 hours have elapsed, as stated hereinbefore the tide disk has rotated in the clockwise direction by 25 minutes, so that the indication "HIGH" is at 3.25 or 15.25 and the indication "LOW" is at 9.25 and 21.25. Thus, the change in the high and low tide times due to the standard tide cycle which differs from the 12 hour hour hand revolution is automatically taken into consideration on adjusting the tide disk. Thus, once again, the user can directly obtain the aformentioned information at the time indicated by the hour hand means of both the latter and the tide disk.

In the represented embodiment, the tide disk 5 is made from the transparent material and carries a curve 5' which indicates the tidal flow.

Obviously the tide disk can also be constructed in such a way that its periphery is shaped in accordance with curve 5' and can be made from an opaque material, such as cardboard. However, in the latter case it must be ensured that the hour hand 2 is not in any positions completely covered by the tide disk and the maximum tide disk radius must be smaller than the length of hour hand 2.

Claims

1. A tide clock with a dial and with a drive for an hour hand, a drive for a minute hand, and a drive for a tide indication, the output shafts of all drives being arranged coaxially and the angular velocity of the output shaft of the drive for the tide indication being associated with the normal tide cycle, wherein a tide disk defining a particular tidal flow is fixed to the output shaft of the drive for the tide indication and wherein within 12 hours the output shaft of the drive for the tide indication rotates by an angle corresponding to the time difference between a normal tide cycle and 12 hours.

2. A tide clock according to claim 1 wherein the tide disk is detachably fixed.

3. A tide clock according to claims 1 or 2, wherein the tide disk is fixed on the output shaft by frictional engagement.

4. A tide clock according to any one of the claims 1 to 3, characterized in that the output shaft of the drive for the tide indication terminates further above the plane of the dial than the output shafts of the remaining drives.

5. A tide clock according to claim 4, wherein the output shaft of the drive for the hour hand terminates further above the dial plane than the output shaft or shafts of the drive or drives of the remaining hand or hands.

6. A tide clock according to any one of the claims 1 to 5, wherein the maximum radius of the tide disk is equal to or smaller than the radius of the circle which is tangent to the figures on the dial on the side facing the output shafts.

7. A tide clock according to any one of the claims 1 to 6 for tide disks made from opaque material, wherein the maximum radius of the tide disk is smaller than the length of the hour hand.

8. A tide clock according to any one of the claims 1 to 7, wherein the output shaft of the drive for the tide indication is continuously rotated.

9. A tide clock comprising a clock dial, an hour hand, a shaft on which the hour hand is mounted, a tide disc, a further shaft on which the tide disc is mounted and which is coaxial with the hour hand shaft and drive means for driving the shafts at rates of rotation such that the hour hand indicates normal time at the clock dial and the tide disc shaft rotates in a twelve hour period by an angle corresponding to the time difference between the period of a normal tide cycle and a twelve hour period, the tide disc having a shape or marking related to a particular cycle of tidal movement whereby in operation the juxtaposition of the hour hand and the tide disc indicates information relating to the state of the particular tidal movement.

A method of indicating the state of a tidal movement, comprising driving an hour hand on a shaft of a tide clock to indicate normal time on a clock dial, driving a further shaft, which is coaxial with the hour hand shaft, at a rate of rotation such that the further shaft rotates in a twelve hour period by an angle corresponding to the time difference between the period of a normal tide cycle and a twelve hour period, and mounting on the further shaft a tide disc having a shape or marking related to a particular cycle of tidal movement, whereby in operation the juxtaposition of the hour hand and the tide disc indicates information relating to the state of the particular tidal movement.

11. A tide clock substantially as hereinbefore described with reference to the accompanying drawings.

12. A method of indicating the state of a particular tidal movement substantially as hereinbefore described with reference to the accompanying drawings.