Today, the ships navigator is the final, & possibly, the weakest link in the chain of the production of the chart. The care & attention which is lavished on each chart continues until it leaves the Admiralty chart agent, after which all depends upon the competence of the end-user. Properly used & understood, How to Keep Your Admiralty Charts Up-to-Date should ensure that each expensive chart on board is as good as those ashore ready to purchase.