493 (4)

Załącznik 11 493

SIMPL.IFIED HARMONIO METHOD OF Tl DAL PREDICTION - (roni i

(b)    As (a) bul using thc following rales:

M**

s₂*

Ki

O,

—    29.32 dcg/hr.

—    Half (his figurę i.e. 14 66 dcg/hr

(c)    Onm intcrpolation of F Hence omit Lines 13. 14. 15. 16. 24. 25 and 26 and insert l l=F (dircet from ATT Tab VII) in Linę 27.

5.    Inter/iolation Between Tabulaird Values of A and F.

The hourly rales of changc of A for each constitucnt can bc calculaled from conseculise tabulatcd valucs, carc bcing lakcn to apply sufficient multiplcs of 360" to the tabulatcd valucs to ensurc that thesc rates approximate to the astronoimcal valucs for each constitucnt - i.c. 30 dcg/hr for M; and S? and 15 dcg/hr for K i and O). This can bc donc as follows:

Daily Ratc (p)=(Al+360 n) - A2

where naoor the smallest integer which makes p>600tn the casc of M; and Si and p>300 in the ca.se of K| and 0|. Thcn for cach of thc four constitucnt v Al=AI - (T X p)/24

( The valucs of A in Table VII arc published in a form designed to simplify the arithmetic of the onginal graphical version of thc Simpltficd Harmonie Mcthod of Tidal Prediction (thc tabulatcd valuc is 360" minus the astronoimcal saluc). The sccond term in the above cxprcssion is. thcreforc, SUBTRACTED.)

The intcrpolalion for F for any givcn timc is simplcr Ft=Fl +(T x P)/24 where P=F2-F1

6.    Veciorial Addnion o/Sl) components

The SD tidc (R, r) at any timc consists of the sum of thc Mj and S2 lides. Thus:

R sin r=H Ft sin(Attg) for M2+HFl.sin(At+g) for S2 R cos r=H.FT.cos(At+g) for M2+ H.Ft.cos(At+g) for S2

and from Ihts R and r may bc obtained If nsing a programmed calculator POLAR/RECTANGULAR conscrsion musi bc used to avoid ambiguily of sign or quadrant, but tf thc calculatton is betng donc manually ordinary trig (and tnversc trig) fundions may bc used provided great carc is taken to rcsoWe (his ambiguity

Sliallow Waler Correitions

The quartcrdiumal tide has phasc ........ dj =2r+fj

and amplitudę ....................... Da= R² x F4

and thc hcight corrcction due to the

quarierdiumal cffcct...................... ha =Da.cos da

The sixthdiurnal tidc has pha.se........d₆ =3r+f_fc

and amplitudę ....................... Dt^R¹ x F&

and hence height ....................... h* =D(,.cos d^ h4 and h6 must be summed algcbraically to the combincd SD and D tidc to give a corrcctcd licight for the rcquircd timc.

ADDITIONAL NOTES MORĘ APPLICABLE TO PROGRAMMABLE CALCULATORS

7.    Although thc boxcs show a possiblc route through thc problem this may not be thc best routc for every calculator

8.    If storage is limited parameters can often be combincd and placed each sidc of thc dccimal place after appltcation of suitable multiplierse g g and H can lic stored together: thus ag of 312 and Hof 2 45 mightbc stored as 312.245. Strangcly in somc cases this not only rcduccs the number of Stores requtred but also the program sleps.

9 Given sufficient facilitics on thc calculator the following are rccommcndcd:

(a)    Automatic stepping of TIME at both fixcd and s ariable intcrvals

(b)    Ability to changc Start Time of a senes of prcdictions.

(c)    Prediction of succcssisc days without re-entry of Harmonie Constants for cach day.

(d)    Prediction for sccond port on same day without re-entry of astronomical data (A and F)

(e)    Recording of Harmonie Constants for any port. Stcps should be allocatcd for amendmcnl of cardcd dala to allow for any changcs

Although possiblc to program for the deri vation of a ti mc of H W or of LW this has bccn found to bc of Itltle valuc. In a large number of ports where this mcthod is of greatest use thc curve may bc so fiat at these poinls that the actual tune dcrivcd is mcaningless: at pons where a double HW or LW or intermediatc stand occurs thcrc may well he ambiguity as to thc point on thc curvc obtained In most cases U is prcfcrablc to plot a short ponton of thc curvc from thc results of successivc calculations.

10. It is somettmes morę convement to work in ccnumctres rather than metres pros ided thcrc arc no Shalloss Waler CorTections.

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