How did you go about to encapsulate the boot disk?
If you used vxdiskadm menu (option 2) to encapsulate it would have prompted for a reboot and convert the volumes during the boot process. /etc/vfstab is also updated.
It would've done another reboot to boot from the rootvol and swapvol.
I cannot refer you to online manuals, since VxVM 3.5 is no longer supported.
This URL will guide you through the process: