Depreciation is a nightmare most owners have to contend with. But there is the added nightmare of having very little data when it comes to boats, meaning there is no easy way to calculate average boat depreciation. 

The type of boat you have, as well as its age, will naturally affect its depreciation. Roughly, any vessel will lose around 50% of its initial cost in the first decade of ownership, with the majority lost within the first couple of years.

Vessels older than 25 years will typically see little in the way of depreciation regarding their physical hull and structure. Still, the onboard equipment will undoubtedly be out of date unless upgraded. 

This can have a dramatic effect on the depreciation of your vessel. Even if you do upgrade your onboard equipment, you will only recoup a fraction of their initial cost on selling.

The mooring you choose for your boat will typically account for a higher proportion of your annual costs, depending on where you choose to moor your boat. 

Whether you go for a marina berth with all the facilities you need and walk access ashore or are happy with a mooring that will require a water taxi, tender or boatyard launch to reach. There is a breadth of choice that all affect your annual costs. 

At the extreme end of the scale, you can find yacht moorings for boats over 40 feet in marina berths that will cost you £10,000 a year. You can find mid-river moorings in the right location for around £1,500 to £2,500 a year in the middle. The cheapest option would probably be sailing club moorings. 

These are primarily used for smaller boats and can be as cheap (relatively) as £300 per year. Quieter moorings in your local area are also far cheaper, even for larger vessels. 

Most boats in these locations are kept on cheap, swinging moorings, which will be far more economical than those costing £1,000+. 

A common routine is for boat owners to have their craft kept at a swinging mooring during the summer when sailing and boating become more popular. Then, boat owners store it at a marina over the winter, where there are better care facilities and cheaper off-peak rates.

Again, coming up with a reliable cost for undertaking regular maintenance can be tricky, with many variables affecting what you can expect to pay. However, the maintenance processes you need to undertake every year are fairly standardised. 

Each year you will need to haul out your boat, apply fresh antifouling, conduct engine servicing gear tests and replace some underwater elements such as sacrificial anodes and bottom paint.

For sailing boats, you should have all of your spars and rigging inspected and checked along with your deck equipment, such as windlasses, winches and life jackets. 

Older boats will naturally require a greater level of maintenance, with repairs and replacements being eventually inevitable. Again, the boat's length will affect this, too, with smaller, simpler boats being cheaper to maintain than larger ones.

Gadget lovers will find that equipment replacements, upgrades and renewals can become quite an expensive part of boat ownership. 

Those who want all of the home comforts and latest tech when out boating can expect to pay much more here, while those who are happy with the simple life will be able to save money.

Your fuel costs will vary greatly depending on your boat's size, overall length, and engine. How often you use your boat and how far you travel will also naturally affect your fuel costs. Researching your engine type and its combinations with different boats and hull types can give you a rough idea of your fuel costs.

Unlike most other factors in this list, boat insurance is a relatively easy cost to work out. So long as you aren't doing anything overly risky, such as racing or solo long-distance sailing, then your insurance costs should be reasonable. 

For more expensive boats, such as pleasure yachts, your boat insurance costs are likely to be around 0.4% to 1.0% of your boat's value. Many owners opt for third-party policies for smaller boats, which can easily cost as little as £100 a year.

Of course, there's always the unexpected to account for, especially if your journeys take you far away from your mooring. Therefore, it is a prudent move to leave a little headroom in your annual costs budgeting. Typically, adding another 20% on top of what you think you should budget is a safe target to aim for. 

Again, the initial cost of your boat will determine how much this 20% figure will be. This may put some boats outside your price range, but you can find great enjoyment in boats of any size, so don't let contingency costs dissuade you from buying a boat; simply choose something you can afford.