In my opinion...absolutely YES! Think about what will happen sooner than later when that battery gets bounced around and tips over allowing the pos/neg terminals to short against your aluminum hull dumping tons of current... Not a pretty sight to say the very least and most dangerous as well. If you have ever seen a battery short out, you would never have to ask that question again! Not only do you need a battery box but you should have it attached securely as well. Think boating safety all the time...
IDK about Canada, but at least where I am battery box's cost little of nothing and even Walmart carries them. you'll have more in wood than buying a proper marine battery box..
...I found one at "Canadian Tire" very basic but only for 14.99$, I will buy one tomorrow ...