How to find compass error

Azimuths are tabulated from North or South towards East or West. Amplitudes are tabulated from East or West from North or South.

Step 1 – Observe suns bearing on the celestial horizon note it with the time of observation.

Step 2 – We will have to find the time in GMT so that we can use the time in Nautical Almanac.

Step 3 – Find Declination, (if the value is increasing, the d correction is to be added otherwise subtracted.)

Step 4 – Find LHA

Step 5 – Compare observed azimuth to calculated azimuth. Compass Error is the difference between the two values.

Tan Z = (( Cos DEC ) (Sin LHA)) / ((( Cos Lat ) ( Sin Dec )) – (( Sin Lat) ( Cos Lat )( Cos LHA)))

If LHA is More than 180 than it is entered as negetive. If Dec and Lat are contrary name,Dec is entered as a negetive. If Z is negetive add 180 degrees.

Blog, 4th Dec 2019, MUMBAI

I am thinking of writing my day to day experience so that people know how it feels in merchant navy line. Yes making videos will be more convenient for you guys to watch but that is a bit time consuming but i will definitely start making videos.

It is very fascinating as it offers 6 month of job and 6 month of rest or free time. But the actual story is quiet different initially as a deck cadet i will get a contract of 9 Months (+- 1 month). And this is really a long time almost a year. So it is going to be difficult as i never stayed away from home for this long. Have stayed Maximum of 6 months and that felt long at the end.

There are so many Questions poping in my mind right now.

  1. Is Merchant Navy a Right choice ?
  2. Is it a good choice for long term like 10-12 years?
  3. How it feels on board?
  4. Work culture?
  5. Away from family & friends for 9 months?

Answering all these questions require Experience, So what i will basically do is wait & experience things.And put everything on this blog column of the website and even try putting videos for everyone.

Tool Box meetings

  • Tool Box meeting to be carried out prior commencement of every work.
  • All Risk and control measures associated with particular task should be discussed in tool box meeting.
  • Any Special Precautions to be taken, Procedure to be followed and who will do what, to be clarified.
  • Any Doubts with regard to the Job to be clarified
  • Permits required if any are should be identified and discussed.

What is DPA, CSO

DPA – Designated Person Ashore – Any Matters with regard to safety of the vessel, Individual or environment can be directly brought to the notice of the DPA.

When DPA is not reachable due to any reason, The Alternate DPA(ADPA) has to be contacted.

CSO – Company Security Officer – For any concerns in security of the vessel the CSO has to be contacted.

When CSO is not reachable, ACSO is to be contracted.

From the following details, Calculate the DWT available :- present free board: port 3.0m, starboard 2.9m in water of RD 1.020 FWA 200mm. TPC 30. Statutory summer freeboard 2.8m.

Solution :

For, Port Side = (3 -2.8)  = 0.2m
= 20cm (above )

For , Starboard side =( 2.9 – 2.8) =0. 1m
= 10cm above

Hence ,Mean freeboard can be calculated as
= (20+ 10)/2
= 30 /2 cm
= 15cm available

As we know:

Change in draft = 

(Change in RD )x(FWA)

= (1.025 – 1.020 ) x 20 /0 .025
= 4cm

Now, Total sinkage = (15 + 4)cm
= 19cm

TPC = 30( given)
TPC   =  (A/ 100) x density
30   = (A/100) x 1.025
A = 30/ 1.025
= 29.268m2

Again for calculating  ,TPC at RD 1.020
= (A/100) x ( 1.020)
=  29.85 t/cm

Now , Cargo can be load =( TPC x sinkage)
= (29.85 x 19)
= 567.15 t

A vessel is loading in a SW dock and is lying with her starboard winter loadline 60mm above and her port winter loadline 20mm below the surface of water. if her summer draught in SW is 7.2m and TPC is 20,, find how many tonnes of cargo the vessel can load to bring to her down to her tropical loadline in SW.


Starboard winter load line  = 60mm above
Port winter load line = 20mm below
Mean draft = ( 60 – 20)/2
= (40/2)
= 20mm
= 2cm

qes 18

Summer SW draft = 7.2m( given)

We know that:

Waterline (W) = (1/48 of summer draft)
=(1/48 x 7.2)
= 0.15m
= 15cm

Total sinkage available to bring the vessel to her tropical load  line  = ( 2+ 15 + 15)
= 32cm

TPC =20( given)
So, Cargo can be load = (TPC x sinkage)
=(20 x 32)
= 640t.