As I have promised you, I write down this post to explain specimen of Calculation in Draft Survey. Please also refer to the previous post Draft Survey : Procedures and Calculation.
Ok, now we could directly go to the point. The vessel has alongside at the wharf in port to discharge the grain cargo. The Ship’s Particulars shown :
Name of Vessel : MV. OCEAN BALL, - Port of Registry (POR) : Panama, – Lenght Over All (LOA) : 182.00 M, – Lenght Between Perpendiculars (LBP) : 179.00 M, – Breath (B) : 32.20 M, – Depth (D) : 17.15 M, – Gross Tonnage (GT) : 28,342 MT, – Net Tonnage (NT) : 17,664 MT, – Summer Draft (SD) : 12.163 M, – Summer Deadweight (DWT) : 52,998 MT, – Light Ship (LS) : 7,780 MT, Constant (CS) : 320 MT, – Fore Distance to Perpendicular (Fd) : 1.70 M, – After Distance to Perpendicular (Ad) : 9.45 M. See Picture :
The Surveyor came onboard and made Draft Survey to determine the quantity of cargo on arrival. During inspection, she’s draft marks and others data finds as the followings :
- Fore Draft Port (FP) : 10.79 M / Fore Draft Starboard (FS) : 10.81 M.
- Mid Draft Port (MP) : 10.90 M / Mid Draft Starboard (MS) : 11.03 M.
- Aft Draft Port (AP) : 11.16 M / Aft Draft Starboard (AF) : 11.19 M.
- Density of Sea Water Sample (Den) : 1.021.
- Ballast Water (BW) : 265.00 Cubic Meter at Density 1.025, – Fresh Water (FW) : 183.00 MT.
- Fuel Oil (FO) : 612.00 MT, - Diesel Oil (DO) : 161.00 MT, – Lub Oil (LO) : 29.00 MT.
————————————————————————————————————–
The Draft Survey Calculation is described as below :Raw Draft Calculation
- Fore Mean (Fm) = (FP + FS) / 2 = (10.79 + 10.81) / 2 = 21.60 / 2 = 10.800 M.
- Mid Mean (Mm) = (MP + MS) / 2 = (10.90 + 11.03) / 2 = 21.93 / 2 = 10.965 M.
- Aft Mean (Am) = (AP + AS) / 2 = (11.16 + 10.19) / 2 = 22.35 / 2 = 11.175 M.
- Apparent Trim (AT) = Am – Fm = 11.175 – 10.800 = 0.375 M.
- Length Between Mark (LBM) = LBP – (Fd + Ad) = 179.00 – (1.70 + 9.45)
= 167.85 M
Draft Correction to Distance to Perpendicular.
- Fore Correction (Fc) = (Fd x AT) / LBM = (1.70 x 0.375) / 167.85 = 0.003798
= 0.004 M (rounded to 3 Decimals).
- Mid Correction (Mc) = (Md x AT) / LBM = (0.00 x 0.375) / 167.85
= 0.000 M (Not Available)
- Aft Correction (Ac) = (Ad x AT) / LBM = (9.45 x 0.375) / 167.85 = 0.021112
= 0.021 M (rounded to 3 Decimals).
True Draft and True Trim
- Fore Draft Corrected (Fcd) = Fm + Fc = 10.800 + (-0.004) = 10.796 M.
- Mid Draft Corrected (Mcd) = Mm + Mc = 10.965 + 0.000 = 10.965 M.
- Aft Draft Corrected (Acd) = Am + Ac = 11.175 + 0.021 = 11.196 M.
- True Trim (TT) = Acm – Fcm = 11.196 – 10.796 = 0.400 M.
Final Draft Calculation
- Fore and Aft Mean (FAm) = (Fcd + Acd) / 2 = (10.796 + 11.196) / 2 = 21.992 /2 = 10.996 M.
- Mean of Mean Draft (MM) = (Mcd + FAm / 2) = (10.965 + 10.996) /2 = 21.961 / 2 = 10.9805 M.
- Quarter Mean (MMM) = (MM + Mcd) /2 = (10.9805 + 10.965) /2 = 21.9455 /2 = 10.97275 M.
= 10.973 M.
- Or MMM = {(Fcd x 1) + (Acd x 1) + (Mcd x 6)} / 8 = {(10.796 x 1) + (11.196 x 1) + (10.996 x 6)} / 8
= (10.796 + 11.196 + 65.790) / 8 = 87.782 / 8 = 10.97275 M = 10.973 M.
————————————————————————————————————–
Hydrostatic Table
Refer to the Table, we could obtain :
Displacement (Disp)
- Disp at 10.970 M : 54,266.860 MT (DISP. FULL).
- Disp at 10.980 M : 54,321.070 MT (DISP. FULL).
- Disp at 10.973 M : 54,266.860 +[ {(10.973 - 10.970) / (10.980 - 10.970)} x (54,321.070 - 54,266.860)]
= 54,266.860 {(0.003 /0.010) x 54.210} = 54,266.86 + (0.3 x 54.210)
= 54,266.860 + 16.263 = 54,283.123 MT
Ton Per Centimeter (TPC)
- TPC at 10.970 M : 54.210 MT (Below TPC on Table).
- TPC at 10.980 M : 54.220 MT (Below TPC on Table).
- TPC at 10.973 M : 54.210 +[ {(10.973 - 10.970) / (10.980 - 10.970)} x (54.220 - 54.210)]
= 54.210 {(0.003 /0.010) x 0.010} = 54.210 + (0.3 x 0.010)
= 54.210 + 0.003 = 54.213 MT.
Longitudinal Centre Flotation (LCF)
- LCF at 10.970 M : 1.180 MT (Below LCF on Table).
- LCF at 10.980 M : 1.190 MT (Below LCF on Table).
- LCF at 10.973 M : 1.180 +[ {(10.973 - 10.970) / (10.980 - 10.970)} x (1.190 - 1.180)]
= 1.180 {(0.003 /0.010) x 0.010} = 1.180 + (0.3 x 0.010) = 1.180 + 0.003 = 1.183 M.
————————————————————————————————————–
Moment To Change Trim (MTC)
- MTC = MTC 1 – MTC 2.
- MTC 1 = MMM + 0.5 = 10.973 + 0.5 = 11.473 M.
- MTC 1 at 11.470 M : 709.910 (Below Table).
- MTC 1 at 11.480 M : 710.060 (Below Table).
- MTC 1 at 11.473 M : 709.910 +[ {(11.473 - 11.470) / (11.480 - 11.470)} x (710.060 - 709.910)]
= 709.910 {(0.003 / 0.010) x 0.150} = 709.910 + (0.3 x 0.450) = 709.610 + 0.045 = 709.955.
- MTC 2 = MMM - 0.5 = 10.973 - 0.5 = 10.473 M.
- MTC 2 at 10.470 M : 686.460 (Below MTC on Table).
- MTC 2 at 10.480 M : 686.770 (Below MTC on Table).
- MTC 2 at 10.473 M : 686.460 +[ {(10.473 - 10.470) / (10.480 - 10.470)} x (686.770 - 686.460)]
= 686.460 {(0.003 /0.010) x 0.310} = 686.460 + (0.3 x 0.310) = 686.460 + 0.093 = 686.553.
So, MTC = MTC 1 – MTC 2 = 709.955 – 686.553 = 23.402.
————————————————————————————————————–
**** From the above results, we collected the data as follows:
- Disp = 54,283.123 MT, - True Trim (TT) = 0.400 M, - LBP = 179.00 M,
- TPC = 54.213, – LCF = 1.183, - MCT = 23.402.
First Trim Correction (FTc)
- FTc = (TT x TPC x LCF x 100) / LBP = (0.400 x 54.213 x 1.183 x 100) / 179.000
= 256.35916 / 179.00 = 14.331615 = 14.332 MT.
Second Trim Correction (STc)
- STc = (TT x TT x MTC x 50) / LBP = (0.400 x 0.400 x 23.402 x 50) / 179.000
= 185.536 / 179.00 = 1. 045899 = 1.046 MT.
Displacement Corrected to Trim (DispT)
- DispT = Disp + (FTc + STc) = 54,283.123 + (14.332 + 1.046) = 54,283.123 + 15.378
= 54,298.501 MT.
Density Correction (Denc) <
- Actual Density (ADen) = Sample Sea Water Density = 1.021
- Denc = DispT x {(ADen – 1.025) / 1.025} = 54,298.501 x {(1.021 – 1.025) / 1.025}
= 54,298.501 x (-0.004 / 1.025)
= 54,298.501 x (-0.0039024) = -211.89947 = -211.899 MT.
Displacement Corrected to Density (DispDenc)
- DispDenc = DispT + Denc = 54,298.501 + (-211.899) = 54,086.602 MT.
Deductible Weight (Deduct)
- BW = 265.00 x 1.025 = 271. 625 MT, – FW = 183.000 MT, – FO = 612.000 MT,
- DO = 161.000 MT, – LO = 29.000 MT.
- Total Deduct = 1,256.625 MT.
Displacement Minus to Deductible Weight = Net Displacement (NDisp)
- NDisp = DispDenc - Deduct = 54,086.602 – 1,256.625 = 52,829.977 MT.
Estimated Cargo onboard (EstCOB)
- To estimated quantity cargo onboard, we need to know about Light Ship and Constant. Light Ship and Constant data is provided on the Ship’s Loading Manual. For the new ship, we could refer to the Constant on the Manual, but for the old ship it Constant may vary, please refer to the Chief Officer Constant Declaration or Draft Survey Previous Port, or we could calculate it in the final survey after the Ship completing to discharge her cargoes (empty Ship).
- Light Ship (LS) = 7,780.000 MT, – Constant (CS) = 320.000 MT.
- EstCOB = NDisp – (LS + CS) = 52,829.977 – (7,780.000 + 320.00)
= 52,829.977 – 8,100.000 = 44,729.977 MT.
————————————————————————————————————–
See the following Draft Survey Report Form..
We have completed the Initial Draft Survey, I hope it useful and see you in the next post.
Regards,
Surveyors
want the draft survey programm
Hello
This question is very urgently, I have quastion about tpc, why you don’t correct tpc to dock water density in the example, so you are used the tpc which versus to mmm on table, my knowledge the value of tpc on table according to salt water density 1,025.
I will be happy if answer and if can u send answer to my Emil many thnx
Best rgrds
This is amaging site for those who are related with this job.
Dear Eng. Yacout,
Thanks, I will inform you if any good program for load tanker.
Regards,
Surveyors
I am junior surveyor struggling to learn draft survey i need to know about correction of draft to keel deflection but i kwon to found the displecement so i don’t kwon calculete TPC , LCF and MTC.
Best Regards,
Paulo Ricardo.
Dear Sir
First, thank you loyal to the explanation of how to calculate the displacement, the quantity of goods loaded into the holds of the ship and when any draft of you easily, where I stopped for a considerable period for the exercise of inspections.
But life here in Egypt has become difficult and therefore resorted to the practice of examinations again, where I told the seventy-one years old.
I hope you have a modern program because I work now since 30 years, as well as price, and is there to explain and in the account to load tankers.
Finally, we thank you for your help I am waiting for reply.
Eng.Yacout
Dear Edgar,
Thanks, you have a sharp eye, this is very advantage for surveyor. Success for you.
Regards,
Surveyors
Dear Romy,
For common vessel draft survey, I do not find the rules as you are explained above.
But if the stability manual on board is stated it, you should be followed. Because the correct draft calculation of one ship is refers to the manual book available on that ship.
Regards,
Surveyors
Dear Riad,
There is no different between initial and final calculation.
Regards,
Surveyors
Hi Mr. Surveyor!
I am a Trainee Chief Officer. I really find your blog very helpful. Many thanks for posting this.
I just found a *typographical error in your calc.
===>
- Light Ship (LS) = 7,780.000 MT, – Constant (CS) = 320.000 MT.
- EstCOB = NDisp – (LS + CS) = 52,829.977 – (***7,780.000 + 320.00***)
= 52,829.977 – ***7,100.000 = 44,729.977 MT
*** should be 8100 (instead of ***7100). ***7780 + 320*** = 8100
Just a typo error. Answer is still correct. ***44,729.977.
Just corrected it for everyone’s info, so that they may not be confused when they follow the Calculations. ;-)
Again, Many thanks for posting this! Pls continue to educate us beginners.
Dear Surveyor,
Thank you for your effort in posting a detailed draft survey. I remember when I was still sailing as a Chief Officer, Trim Correction (the 2nd one) will be applied only when the Trin is 1% or more of the LBP( this is according to Stability Manual onboard), This means that if the LBP is 179m and the trim is 0.40m, 2nd correction is not applicable because it did not reach the criteria of 1% of LBP(1% of LBP is 1.79m trim). Please enligthen me regarding this matter.
TY
You have given a complete calculation of draft survey in a very clear and easily understandable manner even to a lay man. It is a wonderful job done.
Please explain the role of longitudinal center of floatation (LCF), tonne per centimeter (TPC) and moment to change trim (MTC) in the calculation of draft survey of bulk cargo vessels. Also how to correctly assess the weight of deductibles like fuel oil, diesel oil, lubricating oil, ballast water, fresh water etc. in a draft survey.
Best regards,
PR Reddi
the final survey mv : MV. OCEAN BALL
Draft Survey: Specimen of Calculation
plz
Mr.Surveyor
Good day. I am a junior surveyor
final survey for MV. OCEAN BALL plz
Dear Bheny,
Thanks for correction, have just changed the error.
Regards,
Surveyors
Dear Bheny,
I have answered some questions about ballast and sounding. You could check some comments in the post of Draft Survey and Bunker Survey.
Regards,
Surveyors
Thank for knowledge, but please check your MTC 1, I think there is wrongness input number because error in read table
Could you explain about Sounding also, I still confuse about that because there are also correction in there, Could u also explain about that?
dear all,
I am happy to meet you all.
I am a practising marine surveyor in Djibouti and I would like to be a part of your exchange network.
Our company name is Global Maritime Surveyors.
Thanks in advance
Waberi
Dear All,
It is a great pleasure for me to join your website. I am a new marine surveyor since the begining of this year. I started the draft surveys only at the beginning of the year.
For the moment, I am still practising the draft survey but i still have to learn the bunker survey and liquid surveys. If it is possible i would like to ask you help me on those topics.
Waberi from Djibouti
Pingback: Draft Survey: The Accuracy and Factors Effecting | Marine and Cargo Surveyors
Dear George,
The actual constant will be getting when the ship is empty by Net Displacement – Lightship.
Net displacement is the displacement after corrected by 1st and 2nd trim correction, density correction, and minus deductible (ballast, freshwater, bunker,etc).
Example : Net displacement 9,254 MT and lightship 8,888 MT
CS = 9,254 – 8,888 = 366 MT
In the initial survey when the vessel carried 50,500 MT cargo (as per B/L), net displacement 59,754 MT and lightship 8,888 MT, you could calculate constant as well, but it is the proximate constant (as we do not know the cargo declare is right or not).
CS = 59,754 – 50,500 – 8,888 = 366 MT.
Regards,
Faisal
Mr.Surveyor could you explain haw to found CONSTANT (CS).and I understood, that it should be found before loading, and till to discharging cargo, it not changeable.
Pleas, I’ll be very pricier.
Dear Nicolas,
I think is nothing wrong with your device, except the tiny one. My device was in the same range but it look bigger. It is Germany made and the temperature 27.5 C.
For temperature 20 C, it is industrial standard. Please check this link: http://pcdmiswiki.org/images/7/7f/NIST_History_of_Thermal_Compensation.pdf.
Regards,
Surveyors
I ve just got a hydrometer ranging 1.0-1.1, but what confuses me is very small and ranging temperature is 20C.
it s possible the calculate draftsurvey with negative trim
Dear Benny,
Wellcome..
Regards,
Surveyors
Thank you so much for this column!….It is highly appreciated, please oh please never stop this …you information is vital to the assistance of junior surveyours like my self …i look forward to more information about surveying ….it’s such a bonus to my training …thanks again!!!
Dear Capt,
Up to now, I can’t found another method for 2nd trim corrections as you are requested.
Regards,
Surveyors
Dear Budi Santoso,
The Trim is the different between the mean of After Draft and Fore Draft.
The calculation applied as follows :
Fore Draft Port side : 2.10 M
Fore Draft Starboard side : 2.12 M
Mean of Fore Draft : 2.11 M
After Draft Port side : 4.34 M
After Draft Starboard side : 2.36 M
Mean of After Draft : 4.35 M
So, the Trim = Mean of After Draft – Mean of Fore Draft = 4.35 M – 2.11 M = 2.24 M.
Best Regards,
Surveyors
dear sirs: i forget how i can foun 2em trim correction there 2 methode what is the second methode for 2 trim correction
best regards
I am junior surveyor struggling to learn draft survey . could u explain ”the trim calculation”.
thank’s
Thanks
Hi Elattar,
Thanks for appreciation.
Regards,
Surveyors
Dear Surveyor,
Thank you very much for the explanation.
It was brilliant and proves that you have incredible experience
Bro can u explain to me with chart how to get the formula 4 the pependicular correction and trim correction.
hello,
mean draft = 1.78 meters
TPC = 10.52 mt
how do we calculate her draft (in salt water) when she is loaded with 3000 mt of cargo please ?
thank you.
Hi Vishal,
Thanks, I will consider it. As now, my job volume is above normal, so I almost have no time to update this blog.
Best Regards,
Surveyors
Hi, I was going through the draft survey calucation sheet posted by you and it seems to be helpful for bingners… i would appreciate if you can post some litrature on trimming of bulk carriers too… thanks n good day
Dear Tun,
First, you could do separate the calculation (interpolation) to find the quantity at the trim and sounding easier. See the following steps how to find 2.46 at trim 3.578:
i. (3.578 – 3.000) : (4.000 – 3.000) = 0.578 : 1.000 = 0.578 = A
ii. (2.46 – 2.45) : (2.50 -2.45) = 0.01 : 0.05 = 0.20 = B
iii. 2.45 = 219.8 – {(219.8 – 216.8) x A} = 218.066 = C
iv. 2.50 = 226.0 – {(226.0 – 223.0) x A} = 224.266 = D
v. 2.46 = C + {(D – C) x B}
If you do the right calculation the result should be 219.306.
Regards,
Surveyors
Dear SIR,
i WILL WRITE AGAIN
3.0m 3.578m 4.0m
2.45 219.8 216.8
2.46 ????
2.50 226.0 223.0
Dear Sir,
I would like to know tank sounding calculation formular.
sounding 2.46 m and trim 3.578 correction is = 0
3.0m 3.578m 4.0m
2.45 219.8 216.8
2.46 – ??? -
2.50 226.0 223.0
So how to gat for value for 2.46 m ,trim 3.578m ???
Best regards,
Tun
Grateful if you could post a Draft Survey Calculation for a vessel with draft marks and hydrostatic tables in Feet & Inches.
Dear Tun,
Thanks for self-solving your previous two questions.
As Terms : Ton Per Cm Immersion (TPC) the number of metric tones required to change the mean draft of a vessel by 1 centimeter.
By means, every centimeter of ship’s draft going up or down on to the water will count by Metric Ton.
For example : Ship’s Mean Draft is 5.55 M, TPC is 49.00 MT. When the ship’s mean draft is change to 5.56 M, means the ship has received the load quantity 49.00 MT onboard.
Regards,
Surveyors
Dear Pankaj,
Thanks for your question. The Ship Beam is the same meaning with Ship Breadth or Ship Width.
Regards,
Surveyors
DDEAR SIR,
ABOVE TWO QUESTIONS,WE FOUND AND UNDERSTOOD,BUT WE DID NOT UNDERSTAND IS TPC CORRECTION ,SO HOW TO FIND OUT IT.
BEST REGARDS,
TUN
Dear Survyor,
Sorry sir We have one more question.
MTC 1 = MMM + 0.5 ( THIS 0.5 IS FROM WHERE,HOW TO GET IT?)
THANK YOU VERY MUCH FOR YOUR REPLY,WE ARE WAITING YOUR REPLY.
BEST REGARDS,
TUN
Dear Surveyor,
Please explain to me above calculation .We do not understand one point TRUE DRAFT AND TRUE TRIM
HOW GET (Fc is (_ 0.004m) ? From Draft correction to distance to Perpendicular calculation Fc is ( 0.004M)
Please explaine to me ( _ 0.004m)
Best regards,
Tun
I am junior surveyor struggling to learn draft survey . so please u tell me what is the meaning of ship beam.
Dear John,
I have explained it on last post “Draft Survey Procedure and Calculation”. Just take a look back.
Regards,
Surveyors
Good day. I am a junior surveyor struggling to learn draft survey
I would like to know the formula to calculate especially
LBM: length between mark
FD “ Fore distance to perpendicular:
AD : after distance to perpendicular:
Thank you very much indeed
Thanks Leyden,
I will post it once available. Keep in touch,
Rgds,
Surveyors
nice specimen , have any specimens on grain loading calculations . It wud be gr8.
Dear Surveyor,
Thank you very much for the explanation.
It was brilliant and proves that you have incredible experience.
I have used Draft survey Lt which is freely available in google and easily downloadable. Please try it and post your comment on this software.
Can you please let me know or post a specimen of calculation for
determining corrected sounding from the one physically observed on the
tank using a tank capacity table. I have never seen a tank capacity table.
Best Regards,
Sadanand
Dear Sadanand,
The VEF is a compilation of the Total Calculated Volume (TCV) measured on the vessel and adjusted for On Board Quantity (OBQ) or ROB (Remaining On Board), and then compared against the shore TCV.
The adjusted vessel TCV is divided by the shore TCV to obtain a voyage VEF for each voyage. The sum of all the qualifying vessel VEF’s are averaged to obtain the VEF.
A VEF(L – Load) should be developed at the load port using only load port TCV’s and discharge VEF(D – Discharge)’s should only use discharge port TCV’s. All voyages should be listed starting with the most current and working backwards.
Even voyages that do not meet the qualifying voyage criteria should be included. A minimum of five qualifying voyages must be used to obtain a workable VEF.
Voyages prior to structural changes that affected the vessel’s tank capacity should be excluded. Voyages with no shore side measurements should also be excluded along with any voyage that is not with in +/- 0.3% of the average ratio of all voyages listed.
I have put downloadable pdf file regards to this matter on the download box.
Regards,
Faisal
Source: John A. “Jack” Szallai – Orion Associates L.L.C.
Dear All,
Please can anyone brief me about V.E.F.(Vessel Experience Factor) ?
Regards,
Sadanand
Still waiting for the draft survey program.
Thanks Phlom,
You could send any materials related to marine survey and surveyor that you have to my email. I will published it on my blog.
Regards,
Faisal
I am back. If is any study material that i can send it to you just mail me and i’ll look for it. They are .pdf and .doc.
I was to my first draft survey. As observer…cause i am still learning :d But it was really interesting. And i used youre specimen as example and it was very good. So thx!
Dear Phlom,
Thanks, if you have any related articles you could send me one.
Best Regards,
Faisal
Dear Chistian,
Thanks, Yesterday I have discussed by email with my friend Ronald, he told me that he will launch the New Draft Survey Program. For pre-launching, he will be given the raw program in excel to attach on my blog for reviewing by the blog visitors.
On the last mail, he said that the download link will submit to me on the next 14 days. Then I will post it here. Hope it could be done.
Regards,
Faisal
Dear Joseph,
Welcome, the Draft survey is the same with others science, where everybody can do it as long as he/she has been wilfulness to learn it.
Draft survey would be more prefer for seaman or the person who has experienced with ship, cargo and port. Firstly, you should need more effort to learn about basic knownledge of the characteristics, specifications, descriptions and terms among them. Then practising the theory you have got is the best way to improve your skill.
Is there any feedback for Joseph? Just leave your comments!
Regards,
Faisal
Hy there! Thanks for this specimen. It is really useful. Hope it is more to come.
Ia’su!
Somebody has a basic draft survey programme (in excel for example)?
I am an Accountant. I want to study Draft Survey and Bunkers.
Any Special Help?
Dear Sadanand, will post it shortly.. Thanks.
Please give specimen report for survey of liquid surveys such as phosporic acid and also explain the derivation for Vessel Experience Factor(V.E.F.)