A little background: while recently perusing the About page of the Below the Boat website, I noticed that the Johnsons punned that they "side launched" the site in December, with a link to this YouTube video:
Wikipedia, the source of the images at top and below, is uncharacteristically uninformative on the topic of side launching, but the Internet, being the oceanic expanse of data that it is, has turned up a quasi-encyclopedic account from a contemporary shipbuilder. As 11th generation Master Shipwright Harold Burnham of Essex, MA, relates in his exhaustive but otherwise enlightening account of his first side launch:
The way a side launch is executed is as follows: First, the vessel is leaned over so that her bilge rests on a short plank and wedges which will ride on the one groundway down into the water. Then a number of greased slabs (the barked edges of logs that are discarded when squaring off timber) are wedged up under the vessel's keel in the spaces between the blocking she was built on. Finally, as the tide rises, starting aft, the vessel's blocking is split out from under her keel. When enough of her weight rests on the greased slabs, the gravity pulling her down overcomes the friction holding her back. It is hard to guess which block will start her. Sometimes it takes a little jacking and jerking to get the vessel going, but once she starts things get really interesting...
This image dates back to 1751
Exactly who developed this method of launching is lost to history, but it is almost unquestionable that the draft restrictions of the Essex River spawned its use. Likewise, it was probably the horrendous angle of the vessels as they entered the water that limited the adoption of the side launching technique despite the fact that it was far easier and less expensive than a cradle launch.
As launchings became more and more infrequent, they went from being regular occurrences to exciting events. People came from miles around to watch. It is amazing how some people find mystery in the most basic of arts, and I am sure that many builders were entertained by the aura of uncertainty they created. I have heard educated people who witnessed the old launchings comment, "You never know what was going to happen"...
A nice short compilation of side launches
As I mentioned earlier, the old Essex launchings had only three basic elements: grease, gravity, and momentum. However, by their very nature there is a fourth element: complete lack of control. Form the moment the vessel starts until her drag brings her to a stop, there isn't anything anyone can do but wait and watch. If her builder has laid a proper path, she will follow it; otherwise her momentum will probably carry her.
In his prologue, Burnham notes that "The truth is that of the approximately 3,300 vessels launched in Essex, we know of none that was seriously damaged in a launching accident. Further, there is no record of anyone being seriously hurt or killed at one of our launchings, either." However, it so happens that 20 spectators were injured during the 1997 side launch in New Orleans, Louisiana. The USCGC Healy, a 420-ft, 16,000-ton icebreaker, reportedly kicked up a mean backsplash when it landed in the Mississippi River, sending a wave of muddy water and debris into a nearby viewing stand. Another longer compilation (boasting ship launches "good and bad") illustrates this 'side effect,' wrapping up with comparatively less spectacular slipway launches:
Unfortunately, I was unable to find much information regarding the launches themselves... anyone happen to know which vessels are depicted in the videos, or superlatives such as largest vesel ever side launched, etc.? It goes without saying that I'd like to witness a side launch in my lifetime...