T-joints are typical structural elements in surface-effect ships. Seven different T-joint sandwich designs made of balsa wood cores and carbon fiber reinforced polymer (CFRP) facings have been compared under quasi-static tensile and compressive loading until failure. The T-joints differ in the details of the bond design between the horizontal and vertical plates. The performance of the designs is assessed based on failure loads and deformations, acoustic emission (AE) data and visual inspection. The design improvements yield an increase of the failure load from around 50 kN to at least 140 kN (corresponding to the failure of the horizontal plate). Preliminary results have been obtained for one repaired T-joint. AE monitoring indicates an early onset of damage and significant damage accumulation at loads around 70% of the ultimate failure load. For some T-joints there are indications for significant damage in zones outside that where final failure occurred.