(1) An abandonment shall be unconditional.
(2) An abandonment shall be effected in respect of the whole subject matter insured: Provided, That if a cause for abandonment has arisen only in respect of its part, only that part may be abandoned.
(3) Where a part of the insurable value has been insured, abandonment may be effected only according to the proportion which the insured amount bears to the insurable value.