The Hingham Harbormaster is requesting proposals to repair aluminum hull corrosion on its 31-foot Safe Boat. The affected areas are below the waterline in the forward bilge beneath a diesel engine, with two sections (about 6 ft x 6 in each) of 5/16-inch bottom plate needing cropping and replacement. Corrosion was caused by trapped water and sediment, per a town surveyor’s assessment.