Hi Martin ,All above good advice, I have three Lowrance machines. A 9 t I 2. Now obsolete A f s 9 I am very pleased with and have just obtained the new eagle 9 live sight, suggest you check out videos , there is plenty on YouTube to study up, to get the best out of them you need to consider some good cards in them like platinum plus or equivalent, they come in around or just over Β£200 but if your buying new, lookout for deals, you can sometimes get them free in the deal so don't forget to ask. Also may be worth having a word with Ashley at seatronix, he is very knowledgeable and helpful, don't know where your boat is but he is near Poole and gets to mariners there regular. Hope this helps. Good luck, Colin.