If you are interested to work onboard ships, maybe you can join the marine engineering bridging programme offered in ALAM. The programme is open to degree holders, especially those from engineering related courses.

ALAM is more established and have been in existence longer than SMA. ALAM is also a maritime training centre owned by MiSC Berhad, so it's considered part of the Petronas group. SMA is owned by the Shin Yang shipping company from Sarawak if im not mistaken. Both can provide you the relevant certification to become a seafarer.

SPM result is good enough to be used for application purpose. You can insert your STPM result as well but Im not sure if it gives any advantage in application process. But once you are accepted into the DME programme, whatever you have studied before does not give any sort of fast track/carry over credit so everybody have to follow the programme regardless of previous learning background.
After entering ALAM, you will have the chance to get sponsors from shipping company such as AET and MISC.

The sponsor will pay for your course fee and provide apprentice placement onboard their ship for your cadetship onboard training.