Pitot tubes are used on submarines and surface ships to measure speed through water using Bernoulli's principle. A pitot tube has two openings - one facing the oncoming water to measure total pressure and one on the side to measure static pressure. The difference in these pressures is used to calculate water velocity and the ship's speed in knots. While simple and robust, pitot logs have errors at low speeds and from vibrations, debris, or mechanical issues. Alternatives for measuring speed include impeller logs, propeller RPM, GPS, Doppler velocity logs, and correlation velocity logs.

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APPLICATION OF PITOT TUBE IN
SUBMARINE
Presented By: -
ROHAN KUMAR -USN:1NT21AE065
PAWANDEEP SINGH -USN:1NT21AE054
SHRI ARCHITH -USN:1NT21AE071
NISHANTH R -USN:1NT21AE061

2. WHAT IS A MEASURING LOG?
 All nautical instruments designed to measure the speed of a
ship through water are known as logs.
 This nomenclature dates back to the days of sail when sailors
tossed a log attached to a rope knotted at regular intervals off
the stern of a ship.
 The sailors would count the number of knots that passed
through their hands in a given period of time.
 Though it’s precision and range capacity are comparatively
little, pitot tubes are modest, dependable, cheap, and suitable
for an assortment of ecofriendly circumstances, including
extremely higher temperature and a varied as assortment of
pressure.
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3. INTRODUCTION TO PITOMETER LOG
 Pitometer log (also known as pit logs) are devices used to
measure a ship's speed relative to the water.
 They are used on both surface ships and submarines.
 Pitometer log is based on the principle of the early
navigational method, dead reckoning.
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Pitometer Log from the Titanic

4. PRINCIPLE OF PITOMETER LOG
 In fluid dynamics, Bernoulli's principle states that an increase in the
speed of a fluid occurs simultaneously with a decrease in static
pressure or a decrease in the fluid’s potential energy.
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5. CROSS-SECTIONAL ANALYSIS
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6. WORKING OF A PITOT TUBE
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Formula to find delta H

8. HOW ARE KINEMATICAL MEASUREMENTS CONVERTED
TO UNITS OF MEASUREMENT?
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• RODMETER : -
Commonly called the sword.
It is located in the forward torpedo room.
It is a unit in which dynamic and static pressure
are produced and transmitted.
Under the water it extends unto 3 feet.
• SEA VALVE: -
The sea valve forms a support to the rodmeter and
provides support.
• CONTROL UNIT: -
It is a control unit which is mounted in the
forward torpedo room.
• ROTARY DISTANCE TRANSMITTER: -
It is located in the forward torpedo room and it
develops the force applied to equalize the dynamic
pressure produced in the rodmeter.
• MASTER SPEED INDICATOR: -
The revolutions registered on the counter converts
speed indicator into knots.
• SPEED AND DISTANCE INDICATOR: -
This is commonly called as repeaters.
It repeats the speed and distance of the master speed
indicator.

9. ANALYSIS OF FORMULA
 An expression can be derived for the velocity of water impacting
the ship as a function of the difference in dynamic and static
water pressure using Bernoulli’s principle. The total pressure of
the water in the tube with moving seawater can be described by
Equation 1.
 (Equation 1): pTotal = pStatic + pDynamic
 pTotal is the total fluid pressure.
 pStatic is the static pressure, which strictly depends on depth.
 pDynamic is the fluid pressure caused by fluid motion.
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10.  (Equation 2):
 vWater is the speed of the fluid flow.
 ρ is the fluid density.
 Equation 2 can be solved for the velocity of water in terms of the
difference in pressure between the two legs of the manometer.
Equation 3 shows that velocity is a function of the square root of
the pressure difference.
 (Equation 3):
Because the speed computed by the pitometer is a function of the
difference between pressure readings, the pitometer does not
produce an accurate result when the ship's velocity is low and the
two pressure readings are nearly the same.
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11. POSSIBLE ERRORS IN PITOMETER LOG
 Due to internal vibrations there can be unintentional
distortions in reference fluid.
 Loss of gear chip.
 Foreign material in a fluid can easily clog the pitot tube and
disrupt normal reading as a result.
 Malfunctioning control valve.
 Lag errors.
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12.  The main advantage of a
pitometer is that it can
provide accurate speed
without any fluctuations
even in the roughest sea
conditions.
 It is robust in construction
and has a rapid response
time.
 The disadvantage of this
principle is that changes
in speed or direction can
only be computed with a
delay, and that derived
direction becomes
inaccurate when the
distance traveled
between two position
measurements drops
below or near the random
error of position
measurement.
ADVANTAGE
DISADVANTAGE
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13. ALTERNATIVES TO A PITOMETER LOG
I. Impeller log
II. Propeller RPM
III. GPS-Global Positioning System
IV. Doppler Velocity log
V. Correlation Velocity log
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DVL IN A
SUBMARINE
CONCEPT OF GPS

14. HELMSMAN VIEW OF COCKPIT
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Nuclear submarine

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Research Submarine

16. UNITS OF PITOMETER LOG READINGS
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Readings from a Pitometer log are read in units of KNOTS
1 KNOT = 1 Nautical Mile Per Hour

17. THANK YOU !!
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