Did customs officers have more search power than police?

Did customs officers have powers over ships and cargo that ordinary police did not?

Yes. They could board a ship and require its cargo to be unloaded and reloaded for inspection.

Customs officers could board a ship and require its cargo to be unloaded and reloaded. That inspection power could interrupt the vessel's work and force access to the goods it carried. The comparison with ordinary policing concerns those powers over ships and cargo.