Stages of the voyage

Trade Book

The trade book of The Unity begins with an enumeration of all the trade goods taken on board, the cargo. The cargo is followed by all the conducted trade transactions, first those on the coast of Africa, then those in West-India.

Captain and first mate

Together, the captain and first mate were responsible for all trade, and for keeping a good record of all conducted trade. They could be held personally accountable for any damages or losses, as can be read in Article 9 of the Instructions:

“The captain will be obliged to conduct trade with the consent of the first officer insofar as that all evenings he will meet with the second officer, telling him of the goods which were traded that day, what they were traded for and where they were put away. This should be done so that if the captain dies unexpectedly, the first officer will, on his return, be able to give a detailed memory of the day-by-day doings to the directors, giving a good report and accountability of the conducted trade. Therefore, the first officer is hereby ordered to strictly adhere to these, or, in case of mistakes, to forfeit his monthly salaries to this Compagnie. He is also strictly ordered not to provide any loan or such to anyone, whoever it may be, on the coast or in the colony. Any such will be for his own costs and moreover, as before, will forfeit all the monthly salaries and bonuses.”

The numbers

Two different trade books have been preserved from The Unity’s voyage. They are identical, apart from the currency used: one of the books uses guilders, the other Flemish pounds. This blog publishes from the book which uses the guilder. The final ‘currency’ used during the voyage is gold, based on standard gold weights.


The guilder prices were noted as follows: f guilder:shilling:farthing

1 guilder = 20 shillings
1 shilling = 16 farthings

For a price comparison between the 18th century guilder and the current buying power in Euros, see the calculator of the International Institute of Social History (ISSG).

Flemish Pounds

In Zeeland, many prices were also noted in Flemish pounds: £ pound:shilling:penning.

1 Flemish pound = 20 shilling = 240 penning
1 Flemish pound is 6 guilders.


Some areas along the coast of Africa set prices in gold. In those cases, the trade book first noted the value of the goods in gold, followed by the price in guilders. The gold was noted in weights of Once and Engel.

1 Once = 16 Engels = 40 guilders: f 40:0:0
1 Engel = ca. 2,5 guilders: f 2:10:0
8 Onces = 1 Mark (246 grams)

Weights and volumes in the trade book

The traded goods from the cargo were noted down in quantities or in weight. Goods which were noted by quantity include guns, trumpets, glasses, knives, padlocks and tin bowls. Goods which were noted by weight (lb., libra, pounds), include the copper kettles, Tobacco, beads, grease and gunpowder. The pound in questions is likely the Middelburg pound.

1 Middelburgse pound = 467,7 grams

Liquid goods were packed in a variety of containers, each with their own standard volume. These included the butt and the anker. The ankers consisted of 6 or 12 steckans. Liquor was packed and traded in boxes of 6 jugs or 6 bottles.

1 butt (large water barrel) = 563 liters (for the VOC)
1 Anker = 35 to 39 liters
1 Middelburgs steckan = 2,25 liter
1 Middelburgs jug = 1,12 liter
Bottle: an anker of 35 liters is equivalent to 45 bottles

Other goods traded along the coast of Africa include ivory, rice, mealie-meal (kind of grain), water and palm oil. Ivory was traded in libras (pounds). Rice was sold in baskets of a standard size (which remains unknown). Mealie is a type of grade which was traded per chest (volume also unknown). The water was bought per barrel (volume unknown) and the palm oil per aume.

1 aume = 4 ankers (about 155 liters)

Logbook and Trading Book

In this blog the trade is linked to the logbook as much as possible. When the first mate mentions a purchase of an enslaved person in his logbook, he or the captain was also supposed to note this down in the trade book. In the case of The Unity the log book and trade book often coincide, but not always!

Sometimes the differences concern the date of a transaction, or the number of persons bought, or the amount of provisions bought. These differences can be explained by one or more of the following:

  • The boarding of people and goods was not always done simultaneously to their payment. Payments could also be done a few days later, before the ship left the coast.
  • Trade was conducted simultaneously from the boat and the ship. The boat was often gone for a week or more, and could cover quite a large part of the coast. The boat could therefore sail back to ports which The Unity had already passed, or sail ahead.
  • The first mate made mistakes in keeping the logbook.
  • The captain and/or first mate made mistakes writing up the trade transactions in the trade book.
  • Contrary to the logbook, the trade was not put together on location, but on completion of the entire voyage. The book therefore does not order the transactions chronologically, but in kind.