tow, /tō/, verb, pull along with a rope, chain, or tow bar
So, why are they called towboats if they clearly pushing the barges?
Towboats
Towboats always push the "tow" of barges, which are lashed together with steel cables. The term towboat arises from steamboat days, when steamboat fortunes began to decline and to survive steamboats began to "tow" wooden barges alongside to earn additional revenue. Eventually, the railroad expansion following the American Civil War ended the steamboat era.
Towboats are characterized by a square bow, a shallow draft, and typically have knees, which are large plates mounted to the bow for pushing barges of various heights. Multiple barges lashed together, or a boat and any barges lashed to it, are referred to as a "tow" and can have dozens of barges. Many of these vessels, especially the long distances, or long haul boats, include living quarters for the crew.
Modern towboats can be from 35 to 200 feet in length, depending on the rivers they navigate, and can be from 21 to 55 feet wide with flat bottoms. Power from their diesel engines ranges from 600 to over 10,000 horsepower.
Barges
Coming through the Emsworth Locks you may see barges that are: 1) open hopper barges with coal or gravel; 2) covered hopper barges with cement products; 3) chemical and petroleum barges that are tanks; or, 4) flat deck barges that might be transporting equipment.
The dimensions of the barges that pass through the locks are:
standard barge
A standard barge is 175 feet long and 26 feet wide. The capacity is about 1,000 tons and when loaded has a draft (how far it sits in the water) of about 9 feet. A tow of 12 standard barges (4 wide and 3 long) could fit in the large chamber that is closest to Buzzie's Corner.
jumbo barge
A jumbo barge is 195 to 200 feet long and 35 feet wide. The capacity is about 1,600 tons and when loaded has a draft of about 9 feet. A tow of 9 jumbo barges (3 wide and 3 long) could fit in the large chamber.
super jumbo barge
A super jumbo barge is 250 to 290 feet long and from 40 to 52 feet wide. The capacity is from 2,100 tons to 3,300 and when loaded has a draft of about 9 feet. A tow of 4 super jumbo barges (2 wide and 2 long) could fit in the large chamber.
When empty the 3 barge types will have a draft of about 18 inches.
Buoyancy
Let's float some additional information by you: buoyancy. For these facts we will use fresh water (like in the rivers or what comes from the tap at home) as the medium.
Buoyancy (or floating) is achieved when the weight of the water that is displaced by an object is equal to the weight of the object. A cubic foot (12 inches by 12 inches by 12 inches) of fresh water weighs about 62.4 pounds and is equal to about 7.5 gallons but we will use the weight for this example. Let's say you weigh 187 pounds. If you divide 187 by 62.4 you will get about 3 cubic feet. So, if you are in the deep end of the pool your body will displace about 3 cubic feet of water and you will be floating with most of your head out of water. To demonstrate this take a deep breath and expand your chest as much as you can and your head will rise a little bit more out of the water. Your weight didn't change (except for the weight of the additional air in your lungs) but you body is bigger and displaces more water so you float a little bit higher in the water. Conversely, blow out as much air as you can and suck in your tummy and you will sink a little bit more.
If you have been to the ocean you learned that salt water is heavier than fresh water. A cubic foot of salt water is about 64.1 pounds, or 1.7 pounds heavier than fresh water. So, if you still weigh 187 after eating the salt water taffy and are floating in the ocean you only need to displace 2.9 cubic feet of water whereas 3 cubic feet was needed in fresh water.
So, how does all of this relate to barges? An empty jumbo barge (typical of most sizes that you see coming through the locks) weighs about 280 tons (560,000 pounds). To float, the barge must displace about 8,975 cubic feet of water (560,000 divided by 62.4). The barge dimensions are 35 feet wide and 195 feet long which is 6,825 square feet. So, 8,975 cubic feet divided by 6,825 square feet is a depth of 1.32 feet or about 16 inches. The barge will float in about 16 inches of water.
Towpaths
Before the railroads, canals were the efficient means of transportation for people and, mostly, cargo. The boats did not have any onboard power, instead, they were pulled through the canal by mules that trod a path that was beside the canal -- the towpath.
The history of the canals is fascinating and they extended the ports of commerce much further that you might imagine. Here are a few that you can explore:
In Pittsburgh and near the present day train station was the terminus of the Pennsylvania Canal that started in Philadelphia.
In nearby Roscoe Village near Coshocton, Ohio, you can find the remains of the Ohio and Erie Canal. Weekends you can ride a canal boat.
Travel to Paw Paw, West Virginia, (about 2 hours and 45 minutes away) to walk along the towpath of the Chesapeake and Ohio Canal through a tunnel. Yes, the canal is through a 3,118 foot tunnel,
When riding the Amtrak train between Pittsburgh and Washington, DC, your route will, in places, parallel the Chesapeake and Ohio Canal. Great scenery!
Today you can still find a mule beside the lock chamber that is closest to Buzzie's Corner. This is not a 4-legged mule but is used to pull barges out of the lock chamber. This mule is pulled by cables. It is the big yellow thing in the following image.