A few scenarios to help explain intentions:
I want to be able to log a maintenance time and date, associate it with the closest engine hours date, then calculate the engine hours time difference and check to see if the engine part service cycle is below or above that difference in time detected.
Or put another way: log maintenance, reference engine hours to find nearest date of most recent maintenance… then yes or no if service is needed based on service cycle of boat inventory item.
I hope that makes it more clear!
I currently have a database for engine hours (records time and hrs), boat inventory (connected to user) and maintenance log (records time and connected to boat inventory).