A private study has shown serious problems with Australia's new Collins-class submarines. The combat data system is already obsolete and unable to perform up to necessary standards. The diesel engines were poorly designed and built, resulting in frequent breakdowns. The hull design was not tested well enough in miniature, resulting in the full-sized submarine hull being too noisy as ocean water passes over its surface. A change to a more stealthy alloy for the propeller resulted in frequent cracking. The periscope has poor optical performance and vibration problems. The communications system, built to Australian specifications, is inadequate at best and does not have a satellite link.--Stephen V Cole