These are the trial exams which are very useful in taking the pressure off. I encourage you to develop some sibling rivalry between children as this will encourage them to strive for 100% success rate. The Boat and PWC Practice Test has a lot of the same questions you will be seeing in the exam and will get candidates used to the style of questions Transport NSW like to ask. I suggest you give this a go until you can consistently  obtain 100% accuracy consistently as the questions do change after each attempt. If you are wishing to also obtain you jet ski Licence the PWC will help you out too. For the GBL you will be required to get 80% out of section "A" and 100 % on Section "B". The questions can be multiple combinations from a bank of over 180 questions so it's best we adhere to the famous "7Ps" which was drummed into us in the military  to avoid any disappointment. The complete list of possible questions is here for GBL and PWC

Best of luck