Holland continued to improve his designs and worked on several experimental boats, prior to his successful efforts with a privately built type, launched on 17 May 1897.
واصل هولاند سعيه لتحسين تصميمه و عمل على عدة قوارب تجريبية ، حتى كلل جهوده بنجاح عندما أطلق أول غواصة في 17 مايو 1897 .