Equipment is related to Machine. Machine is related to Engine. Engine is related to Boat. 
Son is related to Member. Member is related to Beam. Timber is a type of Beam. Timber is related to Wood. 
Equipment <--RelatedTo--> Machine <--RelatedTo--> Engine <--RelatedTo--> Boat 
Son <--RelatedTo--> Member <--RelatedTo--> Beam <--IsA-- Timber <--RelatedTo--> Wood 