Proportions of an adult female orca.
Now, I don't know if this is perfect, but I think it works pretty well and it definitely helps me draw decently proportioned orcas.
I specify it to work for adult females, because from what I've noticed, calves are more 'compact'. I don't know how well it would work for males. I can't imagine drawing boys would be too different, they would just be bulkier.
But anyway, this helps me, so I thought it might also help other orca artists out there