Complex sentence: In stark contrast with the G7a steam driven torpedo, the T2 left no visible stream of bubbles to alert ships they were under attack, and was virtually silent; however, these were the T2's only advantages over the G7a torpedo.
Split into simpler sentences: In stark contrast with the G7a steam driven torpedo, the T2 left no visible stream of bubbles to alert ships they were under attack, and was virtually silent. However, these were the T2's only advantages over the G7a torpedo.