explosive forces it is an expensive part of the vessel 5 as a result a system such as this one that permits an increased number of detonations per vessel top 10 is more cost effective although this example uses five trenches 110 arranged in parallel to each other and one vessel top 10 it is noted that the number and position of trenches 110 and the number of vessel tops 10 used would be optimized by taking into consideration the amount of time needed to empty and prepare a trench 110 and the amount of time required to unlock remove relocate and lock a vessel top 10 in position it is anticipated that the optimum combination of these factors would result in the vessel top 10 being continually moved from trench to trench being in position above any particular trench only as long as required to safely detonate the explosive charge while the example of the vessel bottom 20 shown in fig1 is resiliently held in position by top springs 90 and bottom springs 92 it is also possible to rigidly hold vessel bottom 20 in position so that it does not move relative to foundation liner 40 when subjected to.