Krengning 20". 
Observeret Fart. 
(Observed Speed.) 
(Actual Speed.) 
15 
Virkelig Fart. 
Angle of Heel 20°. 
V Kvartmil i Timen. 
(Miles an Hour.) 
Kvartmil i Timen. | Tike Oy Teal ie | Et 
(UM Go Fonn) | v Corr. Diff. f. 1 Kvartmil. | 
v | (Goan) (Diff. for 1 Mite.) v Jorr. v Corr 
12.0 | 11:60 0:4) 0 | Rid =04 | 11.8 - —0.2 
9.0 | 8.7 —0.3 8.5 —0.5 | 9.0 0.0 
6.0 | 5.8 —0.2 re eens 06 OQ AL©.a 
4.0 | 3.9 —O.1 er | 88 og 4.4 +0.4 
3.0 | 2.9 —O.I ane 2.0 —1.0 3.6 +0.6 
2.5 | 2.4 —0.I 008 12 5103 3.2 —+0.7 
BoP | 2.1 —0.1I O08 0.4" —1.8 3.0 -+0.8 
DETTE | 2 == DOK 0:0 | —2.2 3.0 +0.8 
1.0 1.0 0.0 2.3 1.3 
Man ser, at Krængningsfejlen, selv med en saa stor 
Krængning som 20°, for de større Farter kun udgjør Brok- 
dele af en Knobs Fart. Svinger Fartøjet om et Punkt i 
eller nær Vandliniens Flade, er Krængningstfejlene 1 ethvert 
Tilfælde meget smaa. 
Anderledes stiller Forholdet sig, dersom Stigerøret ikke 
staar midtskibs. Der kommer da under Krængning en ny 
Korrektion til, som bliver positiv for Krængning til den ene 
Side og negativ for Krængning til den anden, og hvis Stør- 
relse voxer med Stigerørets Afstand fra Diametralplanet. 
Efter vor Erfaring viste Vandloggen sig særdeles hen- 
sigtsmæssig og holdtes med største Lethed i Orden. Et 
Blik ned i Maskinskylightet var nok til at observere Skibets 
Fart i Øjeblikket. Maskmisten kunde under Skrabning og 
Trawling holde Skibet gaaende med den befalede Fart. 
Til Reduction af de observerede Vindretninger og Vind- 
hastigheder til sande kræves Skibets Hastighed i Observa- 
tionsøjeblikket. Denne observeredes paa Vandloggen, der 
saaledes er et udmærket nautisk-meteorologisk Apparat.” 
af det Stykke, Vandets Overflade har flyttet sig fra det oprindelige 
Niveau i Røret. Ligger Niveauet under Krængningen højere, det er 
over Nulpunktet (Loddet paa Tal paa Skalaen), er x positiv, ligger 
det lavere (Loddet ovenfor Nulpunktet paa Skalaen), er x negativ. 
Formelen er: 
Ex 7 =| 202 0 — O05, 2 = O17 7779) 
Den negative Verdi af x lig en hel Meter er medtaget som Regne- 
exempel for at vise Virkningen af en saadan, omendskjgnt den ikke 
vil forekomme i Praxis. 
It is evident that, with greater speed, the error in- 
volved in heeling, even at an angle of 20°, will amount to 
only a fraction of a mile. And if the point about which 
the vessel turns he in or near the plane of the water-line, 
the error will be generally very small. 
The case, however, is different in the event of the 
upper tube not being amidships. Another correction, posi- 
tive with a heel to the one side, negative with a heel to 
the other, will then be needed for computing the speed, and 
the effect of the heeling will increase with the distance of 
the upper tube from amidships. 
So far as our experience went, we had every reason 
to be satisfied with the water-log; it answered excellently, 
and was easy to keep in order. A glance down the engine- 
room skylight sufficed to tell the ship’s speed. Hence, in 
dredging or trawling the engineer could keep the vessel at 
the exact rate required. For reducing observations of the 
wind’s direction and velocity to their true value, the speed 
of the vessel at the moment of observation has to be found. 
Now, this we took from the water-log, which accordingly 
proved an excellent instrument for meteorological work 
at sea.” 
distance o, through which the water in the tube has moved from its 
original level. If the level in heeling be higher, i. e. above zero (the 
weight within the divisions of the scale), the value of x will be posi- 
tive; if lower (the weight above zero), The for- 
mula is as follows: — 
x will be negative. 
Balor å = 20% o == (PO, 2 == eng, 
The negative value of x put equal to a whole metre, is introduced 
merely by way of example, to show its possible effect, the case never 
occurring in practice. 
