Performance of a three layer floating absorber based solar still (FASS) is compared with a traditional solar still (TSS) by carrying out experiments at outdoor conditions of NIT Calicut campus, at a daily average solar intensity of 580 - 630 W/m² during the test days. The floating absorber consists of Cu based spectrally selective solar absorber as the first layer, cotton fabric for feedwater transport as the second layer and extruded polystyrene for thermal insulation and structural support as the third layer. Two extreme vapour space heights (H_vs), viz. 0.1 m and 0.3m for the given specific height of the solar still were considered for the study. It was found that the surface temperature which indicates the solar thermal conversion was better for FASS, with the highest recorded enhancement of 94% for H_vs = 0.1 m. Also, FASS displayed enhanced productivity compared to TSS with its quick response to solar radiation as evident from its superior evaporation potential. For the small vapour space height of 0.1 m, FASS showed productivity enhancement factor greater than 200% when compared to H_vs = 0.3 m. Therefore, multifunctional floating structures in solar stills significantly enhances its performance with small vapour space height favouring enhanced productivity.