While training (for any activity) it is important to fulfill your nutrition requirements. If you are training for a rowing competition, a good diet will consist of adequate calories, about 60% carbohydrates, 15% - 20% protein, and 20% - 25% fats. If you are a vegetarian training, make sure to get enough iron, vitamin B12, calcium, and calories. Some great snacks to fulfill your diets needs are: Jam or peanut butter sandwiches, fresh or dried fruits and fruit juices, fig bars, oatmeal cookies, ice lollies, low-fat fruit yogurt, and power bars. Good luck training!