The paper outlines an experimental procedure devised to assess the strength of top-hat-stiffened panels under uniform pressure load. Structural stiffness issues and their dependence on lay-up have been explored. The nature of the failure, from matrix cracking through the final collapse, is detailed. Included in the discussion is the nature of failure modes and their linkage to lay-up design. Numerous strain and digital dial gauges were used to collect important information.The experimental work described in this paper has demonstrated the flexural behavior of the FRP (Fiber Reinforced Plastics) top-hat-stiffened panels. Experimental investigation has exposed the areas of weakness within the top-hat-stiffened panels and their failure mechanisms under in-service loads. Damage of the panels started with matrix cracking followed by delamination at the curved part of the overlaminate near the support region. The panels failed by fiber-matrix breakage at the cross-sectional region.This highlights the importance of choosing appropriate lay-up and geometry for the overlapped patch. The continuity of the longitudinal stiffeners in the present panels was maintained with appropriate cutouts in the transverse stiffeners. This way of constructing the panels produced higher strain values in the x direction than ones in the y direction. It has been understood that the final failure in the junction area of the crown took place at the discontinuous region. All the strain-gauge values at the loaded surface were negative (in compression), whereas they were positive (in tension) on the unloaded surface. The strain distributions lacked symmetry in the warp and weft directions due to the discontinuity of the transverse stiffener. The experimental load/deflection and strain/load plots would allow a designer to select a limiting load for a given lay-up sequence. The existing rules and codes for marine applications rely primarily on theoretical closed-form solutions with little experimental backup.