A seismic streamer includes a jacket covering an exterior of the streamer. At least one strength member extends along the length of the streamer and is disposed inside the jacket. At least one seismic sensor is disposed in a sensor spacer affixed to the at least one strength member. An encapsulant is disposed between the sensor and the sensor spacer. The encapsulant is a substantially solid material that is soluble upon contact with a void filling material. A void filling material is disposed in the interior of the jacket and fills substantially all void space therein. The void filling material is introduced to the interior of the jacket in liquid form and undergoing state change to substantially solid thereafter.