Howard, Hull #316 has the tank under the cockpit sole. The volume is undetermined. I will be removing it as soon as I find nothing better to do on that fine morning. When I have dimensions I will forward them to you. Good Sailing Gary O. M-17 #316A M-7-11 #? C-21 Arizona Foothills 602 943-7252 Office 602 703-7245 Mobile 800 528-8962 Toll Free www.GaryOberbeck.com "Quality is never an accident; it is always the result of high intention, sincere effort, intelligent direction and skillful execution; it represents the wise choice of many alternatives." -William A. Foster