Crabbing and clamming don’t always go hand in hand. You want to have minus tide for good clamming so that the beds are exposed. For crabbing, ideally you want a small tidal exchange so that the current isn’t too great.
You will find the most low tides in May, June and July but twice every month there are minus tides, during the full and dark phases of the moon.
A common saying for crabbing is “any month that ends in a ‘R’ has the best crab.” The later into the fall the better. During the summer, crabs are available but it can be hit and miss. Also, there will be more soft crab in the summer. A soft crab is one that has recently molted its shell and will not have as much meat.
Nehalem, Tillamook, Netarts, Yaquina, Alsea and Coos Bay are all very popular crabbing spots. Nehalem, Tillamook nd Yaquina have some piers/docks you can crab from. Most bays also have boat rental places.