Why a Weight Certificate Follows the Grain
A weight certificate records how a grain cargo was measured. Shore scales and draft surveys answer different questions.
Grain contracts are promises about quantity as much as about price. A weight certificate is the paper that says how the quantity was measured and what number came out. Without it, the invoice is an opinion. With a weak one, the invoice is an argument. The bill of lading will often recite a weight, and that recital is only as good as the method behind it. How to read the bill itself is covered at https://goodsandgrain.trade/bill-of-lading-bulk-grain.
Shore scales and the ticket they print
At a terminal with a certified bulk scale, trucks, railcars, or a loading belt are weighed and the weights are added up. The certificate should name the scale, the date, the commodity, and whether the figure is gross of something you did not mean to sell. A scale ticket for one truck is not a certificate for a vessel. Someone has to total the tickets, exclude the wrong crop, and sign the result.
Ask when the scale was last checked and what the certificate says about that check if a dispute is likely to be large. You do not need to become a metrologist. You need the document to point at a device and a procedure, not at a round number someone preferred.
Draft surveys are a different kind of number
A draft survey estimates cargo weight from the ship's displacement. Surveyors read the draft marks, measure ballast and bunkers, and apply the ship's tables. The result is an estimate with a method, not a scale printout of every kernel. It is widely used on bulk vessels because weighing an entire ship on shore is often impossible. Two competent surveyors can still differ by a modest amount. The contract should say whose figure governs, or how a gap will be split.
Do not treat a draft figure and a shore-scale figure as duplicates that must match to the pound. They are different instruments. A large gap is a problem. A small gap is the reason contracts have tolerances.
What the certificate ought to identify
A useful certificate names the vessel or the conveyance, the berth or the elevator, the dates of weighing, the commodity description, and the unit. Metric tons and short tons are not interchangeable, and a silent unit is how a price per ton gets applied to the wrong quantity. Tie the description to the contract words, the same discipline as on the commercial invoice at https://goodsandgrain.trade/grain-commercial-invoice-contents.
If the weight is provisional, say so. A provisional draft used to start the paperwork is not the final certificate. Marking it final because the ship is about to sail is how the later adjustment becomes a fight about bad faith instead of a planned true-up.
When two weights both look official
Loading weight and outturn weight often disagree. Some loss is ordinary in handling. Some is a calculation error, a draft misread, or grain left in a conveyor. The sale contract, not the louder surveyor, should say which weight is used for payment and what shortage is too large to ignore. If the contract is silent, you do not have a rule. You have two numbers.
Keep the raw notes. Draft readings, ballast soundings, and scale tapes are what a later review will ask for. A one-line certificate with no backup is a weak shield.
Put quantity in the same conversation as price
A price negotiated to the cent is wasted if the quantity can move by more than that cent is worth. Read the weight clause when you read the price clause. Decide whether you can live with a draft survey as the binding figure before you are staring at one beside a ship that has already sailed.
Methods and governing rules differ by contract and by port. This is a map of the document, not a claim that one method is always fairer. If the cargo is large, have the operator who will attend the survey read the clause first.
Frequently asked questions
Is a draft survey as exact as a truck scale?
It is a different method. It estimates weight from the ship's displacement. Expect a method and a tolerance, not a printout of every bushel.
Whose weight should the invoice use?
The contract should say. If it does not, shore figures and draft figures can both look official and still disagree.
What if the certificate has no unit?
Do not guess. Metric tons and short tons change the money. Send the page back for a unit before anyone pays against it.