Ask the police how to protect your home they'll tell you to take reasonable precautions: lock up, don’t leave valuables on display and use your common sense and judgement. Ask the police how to protect your boat and they tend to say the same thing.
Keeping your home safe
In the past, most crime on boats involved letting your fire extinguishers off and taking a pack of bacon from the fridge - both extremely annoying losses. Times have changed and now some boaters have a few bits and bobs they care about, so make the obvious choices you would make for a house. Bear in mind that passers-by on the towpath might be just a couple of feet from your window, so can look right in if your curtains are open.
Local boaters can give you the rundown of any crime hot spots. Before worrying overly, though, don’t forget that people often remember that brief period of trouble years ago like it was yesterday. So ask a few people before you wake up thinking the blackbird in the bush is out to get you. Most of the canal's sights and sounds are a slice of heaven rather than anything to worry about. A parent letting their kid stand on your roof for that precious photo may take getting used to at first, but it's worth relaxing about. The first time you saw a boat, did you think it was someone's home, or did you shout 'Oooo look a boat!' and go look in the windows? A polite word and explanation with a smile for next time is seldom ignored.
Bikes, especially in inner cities, are a bit different for a boater as we don’t always have the room to put them inside. You wouldn't leave your bike badly chained up in the front garden, nor is it wise to leave it on the roof and hope for the best. Your local boat yard may be able to fabricate something more secure for your roof and deal with your other security concerns too. Many boaters living in cities opt for a fold-up bike to remove the issue completely. As they also fit on the train, car and bus, it’s a good reason to ask Santa for a Brompton if you’ve been good, and if he can afford one.
See this police web page including a video on bike security for bike security tips.