Wednesday, 30 September 2009
Laytime calculations in the spreadsheets
There has been a number of questions in the shipping community on a fast and most efficient way of laytime calculation. In addition to that it should be cost effective. In this short review we will address on how to make such a tool from the scratch.
A widely available vehicle to solve the problem is the spreedsheet application e.g. MS Excel or Openoffice.org Calc and etc. We will review an example of laytime calculation for a drybulk carrier on basis of one load- and one discharge port.
The key parameters to take into account include the following :
(*) the total cargo quantity in metric tons as stated in the bills of lading
(*) rate of loading (and discharge) in metric tons per weather working day of 24 consecutive hours
(*) rate of demurrage in US dollars per day. The despatch rate is half the demurrage rate unless otherwise agreed in the charter party.
(*) exact date and time stated in the Notice of Readiness (NOR) and tendered by the Master on arrival port ( or berth ).
(*) the statement of facts (SOF) , also known as the time sheet, with accurate recordings received from the port agent.
Normally, this data will suffice to derive the final despatch or demurrage, the balance due to the charterers or the shipowners.
The logic behind the laytime calculations is quite straightforward. Firstly, unless already known from the charter party, calculate the time allowed to complete the loading or discharging.
Secondly, find the commencement of laytime by adding the turn time to the time of Notice of Readiness. Also remember that laytime may not be commenced before commencement of laycan period, unless otherwise agreed in the charter party.
Then, sum up all the time-used intervals to find the total time-used. In the spreadsheet you may prefer to get a floating point value of the days used.
Finally, measure the difference between the time-allowed and the time-used, and multiply the obtained difference by the rate of despatch or demurrage depending on whether the difference is negative or positive respectively.
In the spreadsheet, the time intervals are properly summed up after adjustments of the properties of the cells to the time format. Make sure that the accuracy is properly set to your satisfaction.
Our IT-department has done a very good job. Click the picture to see the results obtained at the end.
It's easy, is not it! And there is no need to overpay for the ad-hoc software! Please note that you can easily request a copy of a ready-to-use laytime calculator from us against a small remuneration remitted to our PayPal account just to cover a glass of beer and a printer cartridge :) We can also render you our assistance in case you are completely lost with your laytime calculus. Either way, just contact me at : firstname.lastname@example.org , best regards, Maris.
PS: You are most welcome to visit our Laytime Calculations pages for discussions, review and analysis of hard cases.