The easiest thing you can do is create an XML sitemap listing all of the available pages on your site and submit it to search engines. See Build and Submit a Sitemap | Google Search Central | Documentation | Google Developers.
An XML sitemap will get search engine bots to come crawl all your URLs and it may even get them to index a few of your pages that are available only through site search. Unfortunately, XML sitemaps are not a great solution for SEO. Google usually chooses not to index pages that are only found through an XML sitemap. Furthermore, an XML sitemap doesn't help with rankings the way that links do. Even if Google chooses to index unlinked pages from an XML sitemap, they won't rank well for anything competitive. See The Sitemap Paradox for more details about that.
In the end you may need to re-evaluate your desire for minimal site compared to the SEO benefits of getting links into all your pages. There are ways to implement lists of links that are far less intrusive than big lists of links on your home page:
- Have a single link on your home page that leads to list pages
- Have a links behind a drop down menu that takes up little space on pages
- Rather than creating list pages, link every page about a boat directly to several other pages about different boats. Like the "related questions" links on this page.
You should NOT try to create invisible links in your pages. Google considers invisible links to be search engine spam. Creating content that is meant for search engine bots and hidden from users is called cloaking. Implementing that is against the Google webmaster guidelines and would run the risk of your site getting banned from the Google search results. You can make the links less conspicuous or require a click to show them, but they must be designed for users and not just for search engines.
You might also want to actually test your assumptions that users know exactly what they want to search for. For example you might want to observe users using your site using usability testing tools that give you session playback and even videos of test users. In my experience, a significant number of users have difficulty with search. Either they don't know what to search for, or they don't get the syntax and spelling right. My guess is that many of your users would benefit from navigation to pages in addition to search.