Due to the problem with ingot loading, a trial with the PTs fully fitted out was conducted on 12 August 1941. Four boats - "PT-8", "PT-69", "PT-70", and MRB - returned and Elco sent two new boats, "PT-21" and "PT-29". During this trial, boats faced heavier seas, as high as . All except the Huckins ("PT-69") completed the run. The Huckins withdrew due to bilge stringer failure. The Higgins 76-footer ("PT-70") completed the entire run but also suffered structural failures, attachments between planking and web frames pulling loose, and deck fastenings in the neighborhood of engine hatches showing extensive failures. "PT-21" suffered minor cracks in the deck in the same location, but not to the same extent, as previously observed in "PT-26", "PT-30", and "PT-33". "PT-29" was assigned as a pace boat with "PT-8" in order to generate a pounding comparison.