Company or personal asset?
If I had a fiver for every time a client has asked me about this I would have bought a Scorpion by now - but hey, what's wrong with the Ribeye - no, don't start!
If the company buys the boat for commercial purposes you're right in saying that it pays for it after tax - 19% if the company is "small" and the profits are therefore under £300k pa. The company can claim capital allowances on the boat but these are restricted if there is private use.
However, once owned by the company you need to take note of the benefit in kind issues. BIK's are chargeable on personal use of company assets and the Revenue can try to argue that the boat is solely for the personal use of the director/employee in which case a BIK of 20% of the cost of the asset is declared on the P11D (and the employee will pay tax at their marginal rate) and the company will pay Class 1a NIC on this at 12.8%.
The Revenue will also seek to disallow a large proportion of the running costs of the boat for tax purposes unless it can be proved that the commercial benefit of the company is the main purpose and that personal use is merely incidental. On sale the company will be able to claim for the business proportion of the loss on sale or if it is a profit this will be added back into the tax computations.
I have seen many situations where we have tried to claim that this is a marketing expense - we've dione it for aircraft and other assets too and it's quite difficult to get the Revenue to agree it - but then if it was easy everyone would do it!
If the boat is purchased privately and then made available to the company for corporate entertaining, marketing and other commercial purposes, a charge can be made by the owner. The company can claim that this charge is a trading expense and get relief for this against corporation tax.
The individual can, as explained in a previous post claim tax relief on the expenses as far as they relate to the commercial use of the boat and set the costs against the charge raised to the company. On sale, if you have used the boat as a business asset the commercial proportion of the loss or profit on sale will be subject to tax or available to set against your other income as a loss.
It's all a bit swings and roundabouts really but it depends on the funding structure of the business, whether you want to incur the wrath or interest of the Revenue - they will get involved where there is a boat! - and what you want to do eventually. I have clients who have boats in the company who just accept the BIK charge as a cheap way to boat and a cashflow advantage by having the company fund the asset.
For bigger boats we have used other methods of tax efficient funding that can also help to save the VAT etc - but that's not for here....