on ships engine power is rated at bells, on the Coast Guard ships I was on, we had diesel bells and bird bells (turbines), answering a flank bell on the diesels would yield 16-17 knots, on the birds a flank bell was around 35-38 knots. we also had a war emergency flank where we bumped the N-1 speed of the turbines up and injected water, we could pick up another few knots (classified) to catch a go fast. when all the crap would start shaking off book shelves we knew the Capt aksed for WEF, affectionately know as When Everything Flys apart.