The core sampler is designed to take geological core samples from a variety of locations including: the seabed, caves, and the floor of the blue hole. The core samples consist of cylindrical "cores" of up to 20 feet in length, which report data on the sedimentary formation of the ocean floor.
Because of the small amount of actual sampling being done in this mission, it is more cost-efficient to simply buy or rent a standard vibrocorer than to research and develop a totally new machine. Vibrocorers are manufactured by many different companies and are used in many geological expeditions. The cost of a vibrocorer is around $25,000.
Structure Overview The vibrocorer is made up of four separate sections: the core tube, the control box, the buoyancy system, and the vibrohead. The steel core tube ranges in thickness from 2.1mm to 3.1mm. It can be of any length, but is usually 6m long with a diameter of 10.5cm. The core tube can be lined with a separate tube of either aluminum or polyethylene. These inner liners have a wall thickness of 1.9mm. The core tube is vibrated into the seabed and then extracted with the core sample intact inside. The length of the core sample required determines the size and material of the tubes.
Control & Sample Collection
The control box contains the control circuits and the power supply. It is located above the vibrohead. The power supply provides power in a range from 8.5 KW at 9 A to 10 KW at 12 A. This powers the two 3 HP motors in the vibrohead. The motors rotate in opposite directions at 50 or 60 Hz, providing a force of 32 to 48 kN depending on the setting. This motion drives the core tube down into the sediment. The depth depends on duration of vibration and the composition of the seabed. This parameters will also help us determine the setting to be used.
The buoyancy system consists of a weight stand and a buoyant frame. These are designed to keep the vibrocorer vertical during vibration. The weight stand lies on the seabed and has adjustable legs. It can be filled with scrap metal or lead for ballast. The amount of ballast is determined by the environmental conditions. The buoyant frame is connected above the vibrohead and is connected to the weight stand by steel cables. The weight stand works in conjunction with the buoyant frame in providing a stable vertical support. The modular design allows ease of transport and a greater mobility underwater.
To the right is an earlier sketch of the Core Sampler.