Aggie and Gull are actually shapeshifters who have access to three different forms. A human form, and animal form, and the hybrid of the two. While their human forms and their hybrid forms are pretty close to each other in size, Aggie is a whopping 80ft long sea monster, where as Gull is just a normal sea otter. (Though I realize that I draw him much more like a river otter)

So even though this doesnt accurately show just how small Gull is in his feral form when compared to Aggie, I think its pretty clear he is more then happy to ride this 'ship' into any sea battle.