Marshalltown’s poised to take a plunge with a big summer entertainment complex.Voters needed to come up with a “super-majority” and they did yesterday, just over 67-percent favoring a big new aquatic center swimming facility. The four and-a-half million dollar bond issue includes both a city outdoor swimming pool and a big addition to the indoor pool and spectator seating at Marshalltowns’ YMCA. If voters hadn’t approved the bonds, the city would have lost a big “Vision Iowa” grant for the project. The issue failed in a November ballot, but city leaders now say they’re ready to get going. The new aquatic center should be ready to dive in by Memorial Day 2003.