In plain words
Even if you were the greatest sinner among all sinners, you would cross all wrongdoing by the boat of jñāna alone.
Word for word
Even if you are the worst doer of sin among all sinners, you will cross over all wrong by the boat of knowledge alone.
The commentators
Bhagavadgītābhāṣyam
किञ्च एतस्य ज्ञानस्य माहात्म्यम् —
अपि चेत् असि पापेभ्यः पापकृद्भ्यः सर्वेभ्यः अतिशयेन पापकृत् पापकृत्तमः सर्वं ज्ञानप्लवेनैव ज्ञानमेव प्लवं कृत्वा वृजिनं वृजिनार्णवं पापसमुद्रं सन्तरिष्यसि । धर्मोऽपि इह मुमुक्षोः पापम् उच्यते ॥ ३६ ॥
In plain words
And there is more: the greatness of this knowledge —
"Even if you are" — even if, out of everyone who does wrong, you outdo them all: that is what "worst of sinners" means. Then "all" "by the raft of knowledge alone" — make knowledge itself your raft — and "the wrong," the whole ocean of wrong, the sea of sin, "you will cross" clean over. And here, for someone who wants liberation, even merit gets called sin.
Close to the Sanskrit
And what further — the greatness of this knowledge —
'Even if you are' — if you are, than all the sinful, the doers of sin, a doer of sin in surpassing degree, that is, 'the worst of sinners' — 'all' 'by the raft of knowledge alone', that is, having made knowledge itself the raft, 'the wrong', the ocean of wrong, the sea of sin, 'you will cross over' completely. Here, for one who desires liberation, even merit is called sin.