My experience, and I have a lot of it now, is when selling a high ticket item privately, you are going to run into frustrations unless you price it well below your comfort level. It took me 1/2 a year to sell my 2013 R Class and not give it away. Consignment only works when the dealer would be satisfied with 2 to 5 percent. Most want 10 percent or more. If you're going to consign, find a friendly, well liked, local boat broker (yes they do exist) who advertises on Boattrader, and let them consign it, if they're rake is fair.
The thing I discovered about shoppers for high ticket used items is that they'll trust a dealer much more than a private party. Dealers can also offer services you cannot (like financing). Shoppers also assume a dealer's service department crawled all over that boat on a "search and destroy all problems" mission. Or maybe they picture oompa loompas singing while they slave away getting it ready for happy second home. People also believe, and it's totally false and misguided, that they have some recourse if the used boat they buy turns out bad. Outside of warranty you don't even have that recourse on a NEW boat! LOL! Yes, an educated shopper can pick up a phone and arrange their own financing, and they see through that dealer "aura" (or even halo) but people are lazy too and like the one stop shop.
This has been a record breaking banner year for boat sales but as someone pointed out there's still a lot of inventory that's starting to go stale. I've even found new 2014s out there. A lot of those boats are above $60k but I've seen a lot of S classes too in both 2015 and 2016 flavors. If what you're selling is on any of those lists then you're in for an even tougher time. The right buyer is out there. It's about reaching them and about waiting.
The funny thing about my situation, besides feeling like I made one massive mistake after another (a story for another thread) is that even though many shoppers and dealers tried to make me feel like I was expecting too much, I would have one hell of a time trying to buy my own boat for the so-called high price I sold it for - a very hard time. As for book values, consider those only with some salt and I don't mean grain of salt - you want that big, chunky sea salt stuff or even road salt if you can find it. Don't use the mag chloride though, you'll get sick (don't ask me how I know).
