Aug 23 (Reuters) - Seaspan Corp SSW.N
* Seaspan provides vessel update
* Accepted delivery of MSC shuba B containership that will commence 17 -year fixed-rate bareboat charter with Mediterranean Shipping Company
* Announced that has entered into fixed-rate time charter contracts with a "leading liner" for two 10000 TEU newbuilding containerships
* Also entered into agreements to sell four 4250 TEU class vessels for gross proceeds of approximately $37 million
* Two TEU vessels currently scheduled to deliver in 2018 and, upon delivery, will commence three-year fixed-rate time charters