Glad to see after all these years since it was abandoned, people still are praising it and asking about it.
I'm still using it right now on my Galaxy S5. And it mostly still works and still gets better HTML5 support scores than Chrome despite having been abandoned 100 years ago (I guess another testament to just how great Boat was that it's still 99% working, though I am stuck on Android 6.0).
I actually came here to see if anyone knew a legitimate alternative to Boat. At some point this year, I finally am going to have to get a new phone I think, and that means I can no longer get Boat, unless I can find a safe third-party hosted copy of the apk.
I tried several browsers so far, and not a single one even comes remotely close to Boat. The handful that have the option of having actual tabs, are all horribly implemented.
Dolphin, for example, in full screen with tabbed browsing is jittery and doesn't work right. For one, the full screen randomly breaks and shows the status bar. Then, rather than having a neat little button that disappears after a few seconds that you can tap once to bring back and tap to open the tab bar, you have to drag down from the top to get to the tabs, which are all too big, and the design is ugly and unclean, never mind that it's jumpy, you can't re-hide the tabs once revealed, it doesn't allow fullscreen keyboard override in landscape mode... (I could go on forever about how crap it, and others, are) Like, if Boat was Legos, then Dolphin is like a cheap knock-off of Mega Bloks (in terms of UI/looks and how buggy it is).
So far, not a single browser is, for me, a suitable replacement. I almost thought about trying to learn coding and revive it myself, but then I remember how I tried making an app before for personal use way back in the Android Gingerbread days and it took a year just to get the basics down and a working menu, and I ultimately abandoned the app I was trying to make at that time because I couldn't keep up with how rapidly everything kept changing.
I wish I was rich, I would pay someone to revive Boat, as well as revive the best soft keyboard ever that also is abandoned can't find anything that even comes close to as a replacement: Thumb Keyboard.