This paper describes experiments which comprise part of the UK joint SERC/industry-sponsored program on fluid loading. The experiments have been undertaken in a novel test rig which accelerates a cylinder from rest to a constant velocity in a still water tank and cover the Reynolds number range 105 to 106 . Results are presented for 30 cylinders ranging in diameter from 150 mm to 400 mm. The test program comprised: (a ) cylinders with different distributions of marine growth (mussels and kelp) and artificial roughness at low surface cover; (b ) fully sand/gravel-roughened cylinders with aspect ratios (L/D ) from 3.75 to 10 and relative roughness (k/D ) up to 0.025; (c ) cylinders covered in regular arrays of pyramids at (k/D ) up to 0.1. Based on the results, some tentative conclusions are drawn about the estimation of the effect of marine fouling on the fluid loading of offshore structures.