Performance and survivability of totally enclosed motor propelled survival craft (TEMPSE) in ice and open water conditions

Lifeboats are a necessary fixture on all commercial vessels and fixed and floating offshore installations. They are the crew\u2019s last line of defense in the event of an emergency. These craft are depended upon if vessel/installation abandonment is required. Despite this reality, there are no special design regulations if the intended area of operation of the craft experiences some level of ice coverage. This poses navigational and structural challenges since lifeboats operating in ice are exposed to higher loading then ones operating in open water. The majority of lifeboats built today are typically built from a combination of chopped strand mat and heavy woven roving. This results in a structure that is easy and economical to build but may not have sufficient mechanical strength to provide a safe haven during emergency evacuations in ice covered water. The ice trials showed that the conventional lifeboat tested is capable of operating in ice concentrations to a limit of between about 6 and 7 tenths concentration. Either way, the utility of the lifeboat was severely restricted by ice cover. The basic performance limits of this type of evacuation craft show the basic design requirements for any craft that is meant to complement or replace a conventional boat system. A simple impact model relating impact energy to the lifeboat hull material and temperature indicated a safe operating speed for the lifeboat at 482.0 knots. During the ice trials 2007, 2009 and 2010, this safe operating speed was exceed regularly without damage to the hull. This can be attributed to the conservative nature of the model plus a couple of other factors, namely ice strength and lifeboat bow area reinforcement. In the 2007 and 2009 the ice was relatively weak and in 2010 the lifeboat entire bow area was reinforced during the impact panel dynamometer and sea-chests installation.NRC publication: Ye