Jääkarhu was 78.5 metres (258 ft) long overall and 75 m (246 ft) at the waterline.
Her hull had a moulded breadth of 19.28 metres (63.3 ft) and was 18.50 metres (60.7 ft) wide at the waterline.
Her displacement was 4,836 tons at a draft of 6.5 metres (21 ft).
These main dimensions made Jääkarhu by far the largest icebreaker in service under the Finnish flag at that time – she was more than 10 metres (33 ft) longer and 4.5 metres (15 ft) wider than the second-largest icebreaker, Tarmo, and had more than twice the displacement.
Only the old Wäinämöinen, handed over to Estonia in 1922, came close with an overall length of 75.4 metres (247 ft), beam of 19.2 metres (63 ft) and displacement of 3,619 tons.
Her bow, which had slightly rounder lines than the previous Finnish icebreakers, had a stem angle of 23–25 degrees and her hull, protected by an ice belt up to 28.6 millimetres (1.13 in) thick, was divided into eight compartments by watertight transverse bulkheads.
With a crew of 47, Jääkarhu had the largest crew among the Finnish steam-powered icebreakers even though she required less stokers than the older icebreakers due to her oil-fired boilers.

Jääkarhu was also the most powerful steam-powered icebreaker ever commissioned in Finland.
Her three triple-expansion steam engines, two with a maximum continuous rating of 2,500 ihp driving four-bladed nickel steel propellers weighing about 11 tons each in the stern at 120 rpm, and one turning a third propeller of the same size in the bow at 130 rpm with a maximum continuous rating of 2,600 ihp.
However, for short periods of time during icebreaking operations, the combined output of the engines could reach 9,200 ihp.
Unlike the previous coal-burning icebreakers, Jääkarhu had eight oil-fired boilers with mechanical ventilation that consumed 2.5 to 4.5 tons of fuel oil per hour.
Although she was the most expensive to operate, and for that reason she was always the last one to enter service and first one to sail back to her summer moorings, her endurance and range were considerably better than those of the older icebreakers since she could hold nearly 1,000 tons of fuel and required refueling only two or three times during normal winters.

Like the old Wäinämöinen, Jääkarhu had a heeling system with two pumps capable of transferring 650 tons of ballast water per hour between side tanks, heeling the vessel up to five degrees in ten minutes.
In addition, she had six centrifugal pumps for moving 100 tons of water in five minutes between the fore and aft peak tanks to adjust her trim and release the icebreaker from compressive ice.
For escort operations she had a towing winch and a stern notch that was considerably larger than in the older icebreakers.
Her single piece cast iron rudder weighed 9 tons.
Jääkarhu was 78.5 metres (258 ft) long overall and 75 m (246 ft) at the waterline. Her hull had a moulded breadth of 19.28 metres (63.3 ft) and was 18.50 metres (60.7 ft) wide at the waterline. Her displacement was 4,836 tons at a draft of 6.5 metres (21 ft). These main dimensions made Jääkarhu by far the largest icebreaker in service under the Finnish flag at that time – she was more than 10 metres (33 ft) longer and 4.5 metres (15 ft) wider than the second-largest icebreaker, Tarmo, and had more than twice the displacement. Only the old Wäinämöinen, handed over to Estonia in 1922, came close with an overall length of 75.4 metres (247 ft), beam of 19.2 metres (63 ft) and displacement of 3,619 tons. Her bow, which had slightly rounder lines than the previous Finnish icebreakers, had a stem angle of 23–25 degrees and her hull, protected by an ice belt up to 28.6 millimetres (1.13 in) thick, was divided into eight compartments by watertight transverse bulkheads. With a crew of 47, Jääkarhu had the largest crew among the Finnish steam-powered icebreakers even though she required less stokers than the older icebreakers due to her oil-fired boilers.
Jääkarhu was also the most powerful steam-powered icebreaker ever commissioned in Finland. Her three triple-expansion steam engines, two with a maximum continuous rating of 2,500 ihp driving four-bladed nickel steel propellers weighing about 11 tons each in the stern at 120 rpm, and one turning a third propeller of the same size in the bow at 130 rpm with a maximum continuous rating of 2,600 ihp. However, for short periods of time during icebreaking operations, the combined output of the engines could reach 9,200 ihp. Unlike the previous coal-burning icebreakers, Jääkarhu had eight oil-fired boilers with mechanical ventilation that consumed 2.5 to 4.5 tons of fuel oil per hour. Although she was the most expensive to operate, and for that reason she was always the last one to enter service and first one to sail back to her summer moorings, her endurance and range were considerably better than those of the older icebreakers since she could hold nearly 1,000 tons of fuel and required refueling only two or three times during normal winters.
Like the old Wäinämöinen, Jääkarhu had a heeling system with two pumps capable of transferring 650 tons of ballast water per hour between side tanks, heeling the vessel up to five degrees in ten minutes. In addition, she had six centrifugal pumps for moving 100 tons of water in five minutes between the fore and aft peak tanks to adjust her trim and release the icebreaker from compressive ice. For escort operations she had a towing winch and a stern notch that was considerably larger than in the older icebreakers. Her single piece cast iron rudder weighed 9 tons.
Jääkarhu