Photo credit: U.S. National Archives
The Titanic and Olympic (as built) each carried four collapsible boats of the Engelhardt type in addition to their conventional wooden lifeboats. The Titanic Engelhardts were responsible for saving many lives at her sinking, despite difficulties encountered in launching them.
Added 23 Dec 2017
Two articles describing Engelhardt boats were published in the German journal Schiffbau. The first article describes in considerable detail the construction of these boats. The second article has plans and several photos of a later version of the Engelhardt, as well as two photos showing the Olympic's enlarged boat outfit installed during her 1912-13 refit.
The original articles in German can be read online at the HathiTrust site:
(Due to copyright restrictions these may not be visible in all countries.)
"Rettungsboote für Seeschiffe"
I have translated them into English here:
"Lifeboats for Seagoing Vessels" 23 July 1913.
The images accompanying these articles were published in Germany over 50 years ago and as such the copyright is believed to have expired.
Added 23 Dec 2017
The Engelhardt boats for the Olympic and Titanic were built under license by R. McAlister & Sons of Dumbarton, Scotland. The order book page can be seen here at the Ballast Trust site:
R. McAlister and Titanic Lifeboats.