The coffin you use must be made of solid softwood and must not contain any plastic, lead, copper or zinc. It must have:
- between 40 and 50 50mm (2 inch) holes drilled throughout
- corners butt-jointed and strengthened with mild steel right angle brackets screwed internally, or substantial wooden bracing struts 50 x 38mm
- about 200kg of iron, steel or concrete clamped to the base of the coffin with brackets of 10mm mild steel bar, or blocks of weak concrete mix
- weight distributed evenly to prevent the coffin from turning to the vertical
- 2 long mild steel bands running from the top to the bottom of the coffin
- several mild steel bands across the coffin at about 30cm intervals along its length
The coffin and any inner box or liner must be made from natural, non-toxic and biodegradable materials. They must both be able to withstand any impact and be able to carry the body quickly to the seabed.