TIDAL CALCULATING WHEEL

Abstract: A tidal calculating wheel for determining times and/or heights of high and/or low water at secondary ports with reference to a standard port, comprising at least two disks placed on top of each other, secured together through their centres (0) by a central fastener (4) which allows the disks to rotate. Each face of the inner disk (1) is divided into divisions (S), which contain secondary port differences. The time or height at a secondary port being determined by relatively rotating the disks (1, 2, 3) until the desired secondary port tidal difference is visible through the appropriate window (A, B, C, D or E).

Description: TIDAL CALCULATING WHEEL This invention is a mechanical calculating device, which relates to the area of navigation concerned with determining times and heights of High and Low water at secondary ports. Predictions for secondary ports are made by applying time and height differences referred to a Standard Port The term "Secondary Port" does not imply that the place concerned must be of secondary importance Standard ports and Secondary ports, are the terms used in the U.K Hydrographic Office, Admiralty Tide Tables for European ports. Non European ports use the same procedure, but also include other different port types That is, "Secondary Port"(Semi-Diurnal), "Secondary Haven" (tides with large diurnal inequality) and "Secondary Harbour" (diurnal tides). Other Authorities may use other terms, however, for simplicity throughout the specification, drawings, claims and abstract the terms "Secondary Port" and "Standard Port" will be used to represent both European and Non European port types, for all authorities predictions which involve applying time and height differences to a reference port There already exists a whole family or genre of patented calculating devices of the rotating disk type For instance, The VMG Comparator - John Christopher Hirst - publication number GB 8816428 0 A device for measuring the speed of yachts Navigational and Yacht Racing Calculator - Phillipe H Mclain US patent no 4855577 References cited 2433984 1/1948 DeVries 235/78 N 3803389 4/1974 Yelverton 235/78 N 4149068 4/1979 Simon 235/78 R 4652728 3/1987 Galiana 235/61 NV X Wind and Course Calculator for Navigation-Patrick Galiana US patent no 4652728 References cited 3231188 1/1966 Warner 235/84 X 3361346 1/1968 Warner 235/84 X 3497681 2/1970 Warner 235/78 N 3625417 12/1971 Slauter 235/61 GM X 3876866 4/1975 Kaspar 235/88 R Pattern and Threshold Speed Calculator -Charles D Rathbun • US patent no 4251721 References cited 2076242 4/1937 Marquis 235/88 RC 2943789 7/1960 Parigini 235/88 F 2996242 8/1961 Bannister 3010650 1 1/1961 Aubert 235/88 RC 3929279 12/1975 Dibley 4011987 3/1977 Cheek 4134006 1/1979 Gordon 235/78/ N Musical Chord and Note Calculator • Felix Hector Garcia Lorenzen US patent no 4037518 Bra-Size Calculator -Seheres Lynn - US patent no 4454409 References cited 3050249 8/1962 Awramik, Jr. et al 235/88 R 3106030 10/1963 Pelosi 235/88 G 4137448 1/1979 Smith 235/78 G Circular Calculator for the Solution of Problems Connected with Electro-Magnetic Radiation Penetration - Gaggero et al - US patent no 3700162 References cited 1609972 12/1926 Sherrer 235/70 241 1491 1 1/1946 Williams 235/64 7 Improvements in and Relating to Slide-Rules UK patent application no 53578/69 patent no 1306946 on 23 06 73 and US number 3685727 Index at acceptance was G4B 5A 5B 5G38 Device for Assisting a Computer Operator in the use of Computer Programs - Michael F Churchill US patent 4918412 References cited 896002, August 1 1, 1908 Free Scale 1453100 April 24, 1923 Fulgora Calculating Device 2042615 June 2, 1936 Maxson Indicator 2834123 May 13, 1958 Knight Interpreting Converter 3572584 March 30 1971 Weaver et al Weight Reduction Calculator 4181090 January 1, 1980 Calise Dial-a-metric As regards the state of the art in the field of such calculators, concerned with tidal prediction, there does not exist a disk-type manual calculator, which determines the times and heights at secondary ports, with reference to an associated Standard Port. The state of the art at present is summarised by the following documents US patent no 5731573 Tide Calculator Predicts tide times and moon phases based on the semi diurnal tide cycle and moon phases US patent no 41941 1 1 Tidal Depth Calculator Tidal depths over bottom structures may be determined as a function of the time of the tide or time of calendar day GB 574743 is different to the "Tidal Wheel", in that it is not a manual disk-type calculating wheel, but a straight slide-rule mechanism, which uses "rollers" and its technical function does not involve calculating secondary port tides with reference to an associated Standard Port None of these is based on Admiralty published data, that is, the differences applied to secondary ports with reference to a Standard Port Because the Tidal Wheel uses Admiralty data it is able to show with great accuracy the times and heights, referred to chart datum, of high and low water for secondary ports It is also possible to make tidal wheels, which determine the time and height differences between large Standard ports For instance, between Dover and say Liverpool, Devonport, Holyhead and so on In fact, any port can be chosen as a reference port, but as Nautical Almanacs already publish tide tables for large Standard Ports and tidal differences between Standard and Secondary ports it is easier to construct wheels for these calculations At present, to calculate the tidal heights and time differences between large Standard ports (such as Liverpool, Holyhead, Vancouver, Le Havre) and their associated smaller Secondary ports (For instance, Holyhead has seventeen secondary ports) involves locating and copying data from nautical almanacs, interpolating/extrapolating this data with calculations or by constructing graphs Below is a description highlighting the problems involved in finding out times and heights of High and Low water For instance, consider the Standard Port of Holyhead TIME DIFFERENCES HEIGHT DIFFERENCES (IN METRES) High Water Low Water MHWS MHWN MLWN MLWS HOLYHEAD 0000 0600 0500 1100 and and and and 5.6 4.4 2.0 0.7 1200 1800 1700 2300 Bcaumaris +0025 +0 10 +0055 +0035 +2 0 + 1 6 +0 5 +0 1 Menai Bridge +0010 +0010 +0100 +0015 + 1 7 + 1 4 +0 1 0 0 Bardsc\ Island -0220 -0240 - 145 -0140 -1 2 -1 2 -0 5 -0 1 - earlier/before, + after MHWS = Mean High Water Spring, MHWN = Mean High Water Neap MLWS = Mean Low Water Spring, MLWN = Mean Low Water Neap If High Water Holyhead is at 0600 or 1800 then High Water at Bardsey Island will be -0240, that is, 2 hours and 40 minutes earlier If High Water Holyhead is at 0000 or 1200 it will be 2 hours and 20 minutes earlier at Bardsey Island When there is a tidal height of 5 6 metres at Holyhead, there will be 2 0 metres more at Beaumaris When there is a tidal height of 4 4 metres at Holyhead there will be 1 6 metres more at Beaumaris A problem arises when times and heights of high and low water are between these published fixed times As an example, What is the time and height of High Water at Beaumaris if time and height of High Water Holyhead is 1600 and 5 0 metres 7 To calculate Time of Beaumaris High Watet The time of 1600 lies somewhere between the fixed times of 1200 and 1800 This in-between time can be found by interpolating between the differences From time differences table 1200 = Beaumaris has a time difference of +0025 1800 = Beaumaris has a time difference of +0010 Interpolating 1600 = Beaumaris has a time difference of +0015 Therefore, Beaumaris High Water is 15 minutes after High Water Holyhead answer is 1615 To calculate Height of Beaumaris High Water The Holyhead height of 5 0 metres lies somewhere between the fixed Mean High Water Spring Height of 5 6 and fixed Mean High Water Neap height of 4 4 From height differences table Holyhead MHWS of 5 6 has a height difference at Beaumaris of +2 0 Holyhead MHWN of 4 4 has a height difference at Beaumaris of +1 6 Interpolating Holyhead HW of 5 0 has a height difference at Beaumaris of +1 8 Therefore, Height of Beaumaris High Water is 1 8 metres more than Holyhead High Water answer is 5 0 + 1 8 = 6 8 metres It is easy to appreciate the difficulty interpolating these differences and the possibility of making a mistake. Possible consequences could include running aground or being unable to enter/leave harbour. This was a simple example, chosen for ease of explanation, whereas some ports are far more complex, having large time and height differences, that is, hours instead of minutes and height ranges of many metres. It is because of this difficulty that many authorities recommend the use of graphs for accuracy. The U K Hydrographic Office, Admiralty Tide Tables, explain how to create a typical line graph For example, +0010 1200 1300 1400 1500 1600 1700 1800 Time at High Walcr at Holyhead The height differences can be plotted in the same way. The graphs below show a simpler method of plotting the Time and Height differences for the above task by offsetting the graph axes by an acute angle and joining the scales with parallel lines Values are interpolated between the times 1200 to 1800 and between heights MHWN 4 4 and MHWS 5.6 _ Λ° * α> Secondary' Port Secondary Port (Beaumaris) (Beaumaris) High Water Time J& High Water Height Differences Differences Λ 1200 1300 1400 1500 1600 1 700 1 800 4 4 4 6 4 8 5.0 5 2 5 4 5 6 Standard Port (Holyhead) Standard Port (Holyhead) High Water Times Axis High Water Height Axis (metres) The graph angle and the length of the parallel lines can be any chosen size. In fact, the angle can be reduced until the scales align, as shown below: Secondary Port Secondary Port (Beaumaris) (Beaumaris) High Water Time High Water Height Differences Differences )025 +0020 +0015 +00 10 + 1 6 + 1.7 + 1.8 + 1 .9 +2.0 I 1 - t 1 ' - J- -1 - ! 1200 1300 1400 1500 1600 1700 1800 4.4 4.6 4.8 5.0 5.2 5.4 5.6 Standard Port (Holyhead) Standard Port (Holyhead) High Water Times Axis • y High Water Height Axis - (metres) The values between the times value ; must always be interpolated, but the heights scale can be further improved by extrapolating ouπide the MHWN and MHWS values, as shown below. This is useful when a height difference is required for a Standard Port height, which falls outside the given range of 4.4 to 5 6, for instance for a Holyhead height of 6.2 metres would give a difference of +2.2 at Beaumaris. Secondar Port (Beaumaris) High Water Height Differences + 1 4 -1 .5 +1.6 + 1.7 + 1.8 + 1.9 +2.0 -2 1 3 6 3.8 4.0 4.2 4 4 4.6 4.8 5.0 5.2 5 4 5.6 5 8 6 0 6.2 6.4 i_ '-^ 3 Standard Port (Holyhead) § High Water Height Axis (metres) The same procedure is used for finding Low Water times and heights, but using the Holyhead (Standard Port) Low Water tide tables and associated secondary ports Low Water time and height differences. For semi-diurnal ports, heights obtained by applying the height differences are those for the Mean Spring and Neap levels. For the diurnal ports, heights obtained by applying the height differences are those for Mean Higher and Mean Lower, High and Low Waters. Some standard ports only have one calculation for their times, such as Vancouver (Canada) where one time is given for the secondary port difference + or - HHW and one time for the secondary port difference + or - LLW Therefore, graphs/scales could be replaced with the difference figures/simple sentence. For example, Waddington Inlet HHW +0010 to Vancouver HHW (Zone + 0800) Waddington Inlet LLW -0008 from Vancouver LLW (Zone + 0800) For greater accuracy Seasonal Variation should be allowed for. Admiralty Tide tables and the Tidal Wheels time calculations are based on the Zone Time of the Standard Port. When the secondary port time has been calculated Daylight Saving Time, if necessary is allowed for Drawing graphs can be a tedious problem, especially if at sea, on a bouncing vessel. It involves referring to almanacs, tide tables, copying down data and then constructing a graph. It is an unpleasant, time consuming task, which can lead to mistakes, which could be fatal to both vessel and crew. Also, another problem is the large number of graphs required for particular Standard ports, that is, for the Holyhead example, every Secondary port requires four separate time graphs to calculate High Water time differences and four separate time graphs to calculate Low Water time differences (For Holyhead-High Water is from 0000 to 0600, 0600 to 1200, 1200 to 1800 and 1800 to 0000. Low Water is from 0500 to 1 100, 1 100 to 1700, 1700 to 2300 and 2300 to 0500). Every secondary port also requires a graph to calculate High Water heights and a graph to calculate Low Water heights. For the Standard Port of Holyhead, which has differences for only seventeen secondary ports published in the U K Hydrographic Office, Admiralty Tide Tables Vol 1, this means a total of 170 graphs are needed to cover the North Wales coast There are Standard Ports, which have large numbers of associated secondary ports and, therefore, would require many more graphs For example, St Malo - (France) 24 secondary ports, Immingham (England) - 26 secondary ports, Oban (Scotland) - 33 secondary ports, Cobh (Ireland) - 38 secondary ports, Milford Haven (Wales) - 33 secondary ports The main object of this invention is to make it easier, quicker, more accurate and safer to determine times and heights of high and low water at secondary ports This, in turn, will make the plotting of tidal curves far simpler The main principle of the Tidal Wheel is aligning standard port times and heights with secondary port differences The Tidal Wheel consists of at least two disks Standard Port times and/or heights, printed on the outer disks are rotated to align with scales/data of Secondary Port differences printed on the inner disks The inner disks are viewed through cut-out or transparent windows in the outer disks If the outer disk windows are transparent the Standard Port times/heights can be printed anywhere on the window surface or along an edge of the widow The windows can be any chosen shape or size, providing they allow for viewing of the secondary port differences printed on the inner disks Another option is to print Standard Port scales/data on a rotating cursor/arm The differences can be represented graphically in any of the forms described above and printed in any chosen radial position on the inner disk In fact, the difference figures may even be shown without the graph/scale lines Another possibility is lines joining standard port scales to secondary port difference figures being printed on the transparent window surface Also, the scales do not necessarily need to take a straight linear form, they can be along a curved line and plotted on the disks circumferentially, as below Secondary Port (Beaumaris) High Water Height Differences ^ 5 , 4 5 0 5 , *-> 0 - . . S4 Standard Port (Holyhead) ^ - High Water Height Axis ~? (metres) Standard Ports with large numbers of secondary ports would require extra inner disks to be inserted (the outermost inner disks having cut-out or transparent windows to allow for viewing of the disk beneath) Disks are the preferred shape for calculating wheels, disks could, however, be replaced by any chosen shape, for example, hexagonal As such there are possible different embodiments of the invention In fact, the inner disk can be replaced by any surface, for instance, the tidal differences can be printed onto a plastic board that has other useful tidal information on it, or if using only two disks the inner disk could be self adhesive on one side. Also, the blank spaces on the wheel may be used for printing extra information such as Lat, Long of ports, Mean Levels and so on Accordingly, There is a tidal calculating wheel for determining times and/or heights of high and/or low water at secondary ports with reference to a standard port, comprising at least two disks secured together through their centres by a central fastener to allow relative rotation of the disks, a first disk having at least one window with standard port tidal times and/or heights printed on a scale on the transparent window surface or along an edge of the window, a second disk having predetermined values representing secondary port tidal differences printed thereon, the tidal time or height at a secondary port being determined by relatively rotating the disks until the desired secondary port tidal difference is visible through the window Preferably, the disks are made of a thin plastics material, but they may instead be made from card or a combination of these materials The central fastener or pin/rivet should preferably be made of a non-ferrous metal or plastics material to stop corrosion A preferred embodiment of the invention will now be described by way of examples with reference to the accompanying drawings in which 1/8 FIGURE 1 Shows construction of Tidal Wheel 2/8 FIGURE 2 Shows extra inner disk with window, required when there are many secondary ports 3/8 FIGURE 3 Shows face of Tidal Wheel inner disk with Secondary Port Time Differences 4/8 FIGURE 4 Shows face of Tidal Wheel inner disk with Secondary Port Height Differences 5/8 FIGURE 5 Shows outer Times disk with Standard Port (Holyhead) High Water time scales (0000 to 0600, 0600 to 1200, 1200 to 1800 and 1800 to 0000) and Low Water time scales (0500 to 1 100, 1 100 to 1700, 1700 to 2300 and 2300 to 0500) 6/8 FIGURE 6 Illustrates how to find time of High Water at Bardsey Island if Holyhead High Water is 1440 U T (G M T) in the afternoon and how to find time of Low Water at Trearddur Bay if Holyhead Low Water is 1530 U T (G M T ) 7/8 FIGURE 7 Shows outer Heights disk with Standard Port (Holyhead) Low Water and High Water heights scales 8/8 FIGURE 8 Illustrates how to find height of High Water at Beaumaris if Holyhead High Water is 5 0 metres Tidal data for creating the Tidal Wheel is derived from the U K Hydrographic Office, Admiralty Tide Tables, Vol 1 Holyhead will be chosen as the Standard Port Holyhead has seventeen secondary ports covering the North Wales Coast As shown in Figure 1, the Tidal Wheel consists of three disks - An inner disk 1 and two outer disks 2, 3 Each face of the inner disk is divided into divisions, in this preferred embodiment as sectors, S There is one sector for each secondary port Therefore, the Holyhead Tidal Wheel has seventeen sectors on each face of the inner disk If Holyhead had a large number of secondary ports extra disks 5 could be inserted, depending on the number of secondary ports (As shown in Figure 2, the outermost inner disks, 5, having at least one cut-out or transparent space/window, W, to allow for viewing of the disk beneath) The disks lie on top of each other being held together by a fastener 4, which may take the form of a clip, pin, rivet, or small nut and screw The fastener should hold the disks firmly in place whilst allowing them to rotate about the central point 0 The outer disks are slightly smaller than the inner disks, but if the disks are made of transparent plastic they could all be the same size Figure 1 shows outer disk 2 having four windows A,B,C,D, for viewing secondary port time differences and outer disk 3 having one window E, for viewing secondary port height differences printed on the faces of the inner disk, 1 If the outer disks are made of card or opaque plastic the windows are cut-out If the outer disks are made of transparent plastic there is no need to cut out the windows Standard Port Times and/or Heights differences could be printed on this transparent window surface, but in the case of this preferred embodiment the Standard Port scales are printed along the radial edge of the windows The size of the windows A,B,C,D,E match the size of the inner disk sectors allowing for clear viewing of secondary port differences Within the sectors are the secondary port differences Some secondary ports have only one time/height difference for all Standard Port times/heights This can be shown with a simple sentence, for example, the secondary port Caernarfon -0030 from all Holyhead HW Times Different combinations are possible for plotting secondary port differences within the sectors For example, the sectors could contain High Water Times/Heights and/or Low Water Times/Heights differences In this preferred embodiment, figure 3 shows secondary port Low Water and High Water times differences printed on one face of the inner disk 1 Figure 4 shows secondary port Low Water and High Water heights differences printed on the other face of the inner disk 1 By rotating the outer disks 2,3 the windows can be aligned with any of the secondary port sectors for tidal information Figure 5, shows outer disk 2 Standard Port (Holyhead) High Water Time divisions F,G,H,1 (0000- 0600,0600-1200, 1200-1800, 1800-0000) and Low Water Time divisions J,K,L,M (0500-1 100, 1 100- 1700, 1700-2300,2300-0500) printed adjacent to the window radial base lines When one of the four window base lines is rotated to match one of the secondary port sectors the tidal differences for that time division can be read from the aligned scales This means only one scale is needed for the four time divisions For instance, what is the time of High Water at Bardsey Island if Holyhead High Water is 1440 U T (G M T) in the afternoon? The answer to this is illustrated in Figure 6 The time face of the Tidal Wheel is used The window base line time division, H, of 1200 to 1800 is rotated to the Bardsey Island sector The Holyhead High Water Time 1440, Q, gives a time difference of -0229 Therefore, the time of High Water Bardsey Island is 1440 - 0229 = 1211 U T (G M T ) Finally, if in British Summer Time (B S T ) add 1 hour What is the time of Low Water at Trearddur Bay if Holyhead Low Water is 1530 U T (G M T ) in the afternoon? The answer to this is illustrated in Figure 6 The window base line time division, K, of 1100 to 1700 is rotated to the Trearddur Bay sector The Holyhead Low Water Time 1530, R, gives a time difference of -0015 Therefore, the time of Low Water Trearddur Bay is 1530 - 0015 = 1515 U T (G M T ) Finally, if in British Summer Time (B S T ) add 1 hour The Tidal Heights outer disk is slightly different to the Tidal Times outer disk Figure 1 shows outer disk 3 having one window E, which matches the size of the inner disk sectors allowing for clear viewing of the secondary port height differences In the case of this preferred embodiment, Figure 7, shows the Standard Port Heights for High and Low Water printed along the radial edges of the window By rotating outer disk 3, the Standard Port Heights can be aligned with secondary port differences printed within the sectors For instance, What is the height of High Water at Beaumaris if Holyhead High Water is 5 metres The answer to this is illustrated in Figure 6 The Height face of the Tidal Wheel is used The Standard Port, Holyhead High Water Height scale is rotated to the Beaumaris sector The 5 metre height ,S, gives a height difference of + 1 8 Therefore, the height of High Water Beaumaris is 5 0 + 1 8 = 6 8 metres

Claims: CLAIMS A tidal calculating wheel for determining times and/or heights of high and/or low water at secondary ports with reference to a standard port, comprising at least two disks secured together through their centres by a central fastener to allow relative rotation of the disks, a first disk having at least one window with standard port tidal times and/or heights printed on a scale that is adjacent to an edge of the window, a second disk having predetermined values representing secondary port tidal differences printed thereon, the tidal time or height at a secondary port being determined by relatively rotating the disks until the desired secondary port tidal difference is visible through the window A tidal calculating wheel as claimed in Claim 1 where the window is either transparent or a cut-out slot A tidal calculating wheel as claimed in Claim 1, Claim 2 where standard port tidal times and/or heights are printed on a scale that is printed on the transparent window surface A tidal calculating wheel as claimed in any preceding claim where lines joining standard port scales to secondary port differences may be printed on the transparent window surface A tidal calculating wheel as claimed in any preceding claim where standard port scales/data may be printed on a rotating arm/cursor A tidal calculating wheel as claimed in any preceding claim where the disks are made of a thin plastics material or card, or from a combination of these materials A tidal calculating wheel as claimed in any preceding claim where the central fastener is preferably made of a non-ferrous metal or plastics material, or a combination of these materials, to stop corrosion A tidal wheel as claimed in any preceding claim which can be mounted on any chosen surface A tidal wheel substantially as herein described and illustrated in the accompanying drawings

Inventors: WIDDERS PETER, WIDDERS, PETER
Applicants: WIDDERS PETER, WIDDERS, PETER
Application year: 2000
Main classification: G06G1
IPC codes: G06G1