In response to the developer's comment about continue after taking the boat: No, whenever I try to load my save, it just fades the screen into a full black screen and freezes indefinitely. I already tried to clear the cache and refresh the page. Currently using Google Chrome (61.0.3163.100).
When you continue a slot after sailing the boat, it should put you right next to the boat right before you sailed, and you can continue to explore the starting island (but the second island is not done yet). Is this not what happens for you?
Are there any errors in the developer console when it stops at full black (F12)? I'm also using chrome 61.0.3163.100 and it works fine for me.