As you are on the student’s page, you can get the “Classes” Taxonomy Name really simple.
$classes = get_the_terms( get_the_ID(), 'Classes' );
Next step is to select the Class you want to use, I assume it is the first one listed.
$theclass = $classes['0']->name;
You can get the other Taxonomy like this:
$projectsterm = get_term_by( 'name', $theclass, 'Projects' );
This only works if both have the same term name! But now you just have to get the posts for the Boats:
$args = array(
'post_type' => 'boats',
'projects' => $projectsterm->slug
);
$boats = get_posts( $args );
Hope this works for you!