*Form a chain from layer 1 on down that breaks when there is no longer just one hull. Perhaps count the number links, grouping where the chain has one hull or not, or require that the chain contain level 1... [https://jaxenter.com/10-sql-tricks-that-you-didnt-think-were-possible-125934.html]
We went with the first option. The base table for this approach is '''hcllayer'''. The variables are '''highest1hulllayer''', highest2hulllayer, and highest3hulllayer in the '''highesthulllayer''' table.
====Elbow on fraction of locations in hulls====