RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^sales/([a-z0-9A-Z-]+)/?$ /sales/boatlist.php?folder=$1 [NC,L]

/sales/boatlist.php?folder=yachts

<Directory "/var/www/html">
    Options All
    AllowOverride None
    Require all granted
</Directory>