1, BC first, then make the AC side vertical at point B and cross at point Q;

2. It is easy to find out that ∠BAC=30 degrees, ∠CBQ=70-30=45 degrees,

3. Find AB=25×3=75 nautical miles, BQ=75÷2=75/2 nautical miles, BC=BQ√2=75/2×√2 nautical miles; So BC

4. It is not difficult to find that the water inflow of the ship is 48 tons per hour, and the water increase of the ship is 40 tons per hour if the water pump pumps 8 tons per hour.

5. How long will it take for this ship to sink? 75t ÷ 40t/h = 15/8h。

6. Find the ship speed, v = s/t = BC/t = (75/2×√ 2)/(15/8) = 20√ 2 knots.