I hope someone can give me some advice, I have recently been asked to take on a group of workers who deal with checking and unloading boats which transport gasoline. I have to teach them just the english that they need for their work, no grammar, reasons why etc, nothing. Im finding it very difficult reason being, my experience although some what varied does not include this type of teaching are there any good books out there or any tips you could give me?

thanks in advance