Over a few years I've bought a couple of boat trailers for a Norman and a couple of Shetland Boats that I've been restoring and I realised that boat trailers and towing law is an absolute minefield.
I've spent months researching and making a comprehensive towing guide which I've uploaded onto my YouTube account. [With your permission Trev I'd like to share it with other members]. It is also relevant for caravans or other trailers such as horseboxes.
I've made a series of 5 x videos regarding all aspects and video 2 is especially useful if you are buying a boat with a trailer as the information I've outlined in this video can help you tell straight away if the trailer with the boat is legal and not a bodge job.
Good handy little films, but remember the max towing weight with an unbraked trailer is 750kg or 50% of the kerb weight of the tow vehicle whichever is the lower. So most small hatchbacks cannot tow the full 750kg weight. Also most tow bars have a weight reduction applied when towing a 4 wheel trailer, typically a 20% reduction. Peter G