In this paper idea of load and structural health monitoring (LSHM) system for assessment of composite powerboat has been presented. One of the structural health assessment method utilised in this system is electromechanical impedance (EMI). Authors have presented results related to influence of load and temperature on EMI method. EMI method is based on electromechanical coupling of piezoelectric transducer (PZT) with host structure. Due to this coupling, mechanical resonances of structure can be seen in electrical impedance characteristic of PZT. According to the literature EMI method is sensitive to change of loads in the structure and to changing temperature. Influence of changing operation and environmental conditions should be eliminated by compensation algorithms in order to reduce risk of false alarms in damage assessment system. Results of research related to simple specimen experienced the influence of changing temperature and transverse load and EMI method have been presented. Strains at bending condition for beam have been measured using fibre Bragg grating strain sensors. Some preliminary results of measurements related to powerboat have been also presented and discussed. Measurements have been related to self-diagnosis of piezoelectric transducers using EMI method and to measurements of accelerations using MEMS accelerometer.