Throwing it past Childermass will absolutely give them a view of where they go. However, throwing it past Childermass and his chair this close also... means a puppy stampede, which encompasses not only Reira but also Childermass and his chair. The arcanines are about as aware of their size as the growlithes are, which is to say not at all.

Childermass begins to sit upright, out of the comfortable lounging angle of the beach chair, but it isn't fast enough. One leaps over him, back paw catching the edge of the chair and flipping him with it (he definitely shouts something not suitable for the ears of children with that). Naturally, a dog that large carries on unimpeded, wholly ignoring that they've just knocked someone over and spilled their drink.

There's also a lot of sand being kicked up, so have fun with that.