Primary Info Flashcards
How long is the Mac
290 feet
How wide is the Mackinaw
74 feet, 4 inches (or 5 inches depending on the source)
When was the Mackinaw commissioned
December 20, 1944
Where was the Mac built
Toledo Ship Yard by Toledo Shipbuilding Company
Relevant dates of it’s construction
Authorized by US congress 10 days after Pearl Harbor
Keel laid in March, 1943
Launched March, 1944 ( had limited superstructure, which was added later)
Commissioned December 20, 1944
Why did the Toledo Shipbuilding Company go bankrupt, and who completed the construction.
The contract had a number of penalty clauses and completion bonds.
It was the largest icebreaker ever built with unique design and many new features.
The American Ship Building & Dry Dock Company completed the construction, with a contract that included no penalty clauses.
Final cost $10million .
Quarter deck docent topics
Built during WWII. Commissioned Dec, 1944
Decommissioned June 10, 2006. Served 62 years.
The same day it was decommissioned, the current Mackinaw was commissioned and took over her home port, her duties and her name.
Self paced tour. Follow yellow arrows. 20 numbered signs.
Will lead you to engine room, berthing areas, galley, captain’s quarters, pilot house, etc. There will be guides to tell you more about the ship.
First stop is Officer’s Ward Room where there is a video we would like you to watch with safety tips for being on board and info about why icebreaking is important to shipping on the Great Lakes.
Enjoy your tour!
Engine room topics
Welcome to engine space #2. The middle of 3 engine rooms.
Main job to break ice; 5 main things that enabled that
1. Shape, 2. Weight. 3. Power, 4. Bow propeller 5. Heeling System
Details of Diesel engines.
Connected to DC electric generators.
Send electric power to propulsion motors that are connected to propellor shafts.
Function of Bow Propellor.
Trim tanks and Heeling tanks.
Noise level and ear protection.
Temperature. Large fans blowing air in from the stack. Cold and snowing like the outdoors.
Smell of diesel.
Diesel engine details
6 Fairbanks Morse Diesel engines - vintage 1938
Same engine used for locomotives and submarines.
10 cylinders, 2-stroke, opposed piston engines.
20 Pistons. 8” bore.
Each piston with connecting rod weighs around 75 lbs.
No valves or rocker arms. Pistons act as valves.
Used compressed air to start engine and to force fuel/air mixture into cylinders.
2000hp -4 hour rating, 1750hp continuous
Advantages of diesel/electric propulsion system
- Engines can be placed at most convenient location, don’t have to be in direct line to drive shaft.
- Power from all 6 engines can be sent to which ever propellor needs it
- When change speed of propellor can do so at electric motor and keep the Diesel engines running at most efficient rpms.
Stern propellers
Two
14 feet in diameter
Weigh 10.7 tons
Bow Propellor
12 feet in diameter
7.2 tons
Purpose of bow propellor
Sucks water out from under ice up to 150 feet ahead of ship.
This creates a void under the ice.
So when the ship runs up on top of the ice there is nothing under the ice to support it, so the ship easily breaks through it.
The back wash from the prop also washes all the ice back along the sides of the ship
Ice breaking ability on sheet ice.
Typically 2 to 3 foot sheet ice on the lakes.
Using it’s bow propellor, the Mac could maintain a steady 3 to 4 mph crushing through the ice.
It would burn 600 gallons of diesel fuel in that hour.
So getting about 200 gallons to the mile.
Ice breaking ability on windrow ice
Where ice gets blown up in to high stacks. Often 12-15 feet thick, occasionally 38-40 feet.
Using trim system, can pump water to stern, which raise bow, then drive forward onto the windrow, then pump water back to bow to weight it, to crush through ice.
Can use heeling tanks to pump 112,000 of water in 90 seconds from one side of ship to other to help crushed ice and/or to back ship off ice and then repeat the process.
No one could be on deck when using the trim or heeling system. Relief valves (man hole covers) could pop up and flood deck.
The Mackinaw never met ice it couldn’t eventually break through.
How much water is carried in ballast, trim tanks and heeling tanks?
345,828 gallons
How much diesel fuel is carried?
346,910 gallons
in a number of different gas tanks
along sides and bottom of ship.
How much freshwater is carried?
40,200 gallons.
Top speed of Mac
18.7 knots or 21.3 mph
Typical speed and fuel usage.
13.5 mph
Would use 150 gallons of diesel per hour
Getting around 11 gallons to the mile.
Only needed 2 engines to manage this speed in normal conditions (no ice and calm sea).
What was weight of Mackinaw
5,250 tons
Over 10 million pounds
What was normal draft of ship when fully loaded
19’2”
Now it has no water and no fuel so current draft is around 13’6”, which is why the stern propellers and the rudder are visible from the dock.
How long would the Mackinaw be out?
It had to go into a port every 7-10 days.
To empty black water tanks and to take on more fresh food.
It might be away from it’s home port of Cheboygan for as long as 6 months in some years but more commonly not more than a month or 2.
Break out?
Happens every year around mid- March.
Soo Locks open around March 25.
Mackinaw would start breaking ice on St. Mary’s River, east of the locks a week to 10 days prior. Then would break out around locks and then into Whitefish Bay on Lake Superior. Also would break out through the Straits.
How far did the Mackinaw travel on the lakes.
The Coast Guard Office in Cleveland would decide where each of the icebreakers was most needed.
Mackinaw would commonly create a down bound and an up bound track to Duluth on Lake Superior, traveled to Buffalo on Lake Erie to help break out the harbor there, and to Chicago on Lake Michigan.
Once traveled to Montreal, on the Saint Lawrence Seaway for the 1967 World’s Fair.
Could the Mackinaw leave the Great Lakes?
When it was first built, it was too big to get through the Welland Canal connecting Lake Erie to Lake Ontario.
This canal was later widened so it could fit, with about 2.5 feet to spare.
But the engines require fresh water from the lakes to keep the engines cool, and salt water would damage this cooling system, so if it ever travelled in salt water it would not have lasted long.
Details of fueling the Mackinaw.
The Mackinaw holds 346,910 gallons of diesel fuel.
It was filled at the start and end of ice breaking season, only twice a year. Managed by the Fuel King and a duty crew of up to 29 people. Typical needed around 150,000 - 200,000 gallons at a fill up.
If it was filled using tanker trucks, which it was sometimes, and if was nearly empty (which it probably wasn’t) it would take 38 trucks each holding 9,000 gallons of fuel to fill her.
If filled by large on shore holding tank, would take over 5 hours to fill her, pumping at 650 gallons per minute.
At today’s prices of around $3.00 per gallon of diesel, it would cost over $1,000,000 to fill her.
When was the Mackinaw decommissioned?
June 10, 2006