Mobs focusing on your boat instead of eachother.

[Konerak]

 

Trying to get to the shore, but the hounds & spiders won't attack eachother. 

 

I died 3 seconds later when I found out a spider warrior could jump up & down the shore and still hit me in my boat. 

[JYM]

That is normal. The the spiders only are hostile towards the player. They attack other mobs only when they are attacked first. And in case of the hounds, their priority is to attack the player; it may take a while before they lost interest on you and attack another mob.

 

The only mobs that are hostile against hounds are wildbores (pigs).

 

edit: Snakes may be hostile against hounds, too, but it may be a bit tricky to make them fight each other.

[Devon Aster]

You need to go further out from shore to get them to break their focus on you.  It's much the same as trying to outrun them on land.  The key is putting enough distance between you and them, though with how low your raft was I understand not wanting to go so far you can't come back.

[Lacost]

Hounds only loose aggro after attempting to bite you. There is a chance it starts to bark around a little bit and after that the hound is looking for a new foe to aggro. So you would have to bait the dog into biting and then eventually it will attack the spiders.