Q.Is there any exemption of Lifeboat carriage on a ship and can any vessel sail without Lifeboat?

Yes. There vessel may exempt of the lifeboats. All will depend of the convention, trading area, type of vessel, service and another matters. 

I'm working to Panama Maritime Flag Authority  and I issue exemption certificates (COLREG, SOLAS, Load Line, MODU Code 79,89,09, MARPOL etc) everyday. The exemption certificates are granted by this administration as long as it is permitted by the convention. 

If you require manage a exemptions certificates for your vessel, I can grant you my services and experience in Maritime flags and Recognized Organizations. 

Regards. 

SOLAS Chapter III Reg 2 - Exemptions; Gives Flag state the legal authority under this convetion to exempt an individual ship or class of ships to comply with any specific requirements of  Chapter III of SOLAS, if the vessel  does not proceed more than 20Nm from the nearest land and there are sheltered  anchorages in the vicinity.