Questions & Answers about Vira o leme para bombordo conforme eu disser!
Why is disser used here instead of the present tense digo?
The word conforme (as / according to) sets up an action that is yet to happen. Because the exact instructions I will give you are in the future and still unknown, Portuguese requires the Future Subjunctive (disser). If we were talking about a past or present routine (e.g., "You always turn the helm exactly as I say"), we would use the present indicative (digo).
Disser looks quite different from its infinitive dizer. How do we form the Future Subjunctive here?
For irregular verbs, the Future Subjunctive is built from the third-person plural of the Simple Past (Pretérito Perfeito). For dizer, that past tense form is disseram. Drop the -am to get the stem disser-. Since the subject in this clause is eu, no extra ending is added, so the final word is just disser.
Does the command Vira play a role in triggering the Future Subjunctive?
Absolutely. Commands in the Imperative mood, like Vira, inherently look forward in time because you are ordering an action that hasn't happened yet. This future-facing main clause strongly signals that the following conformity clause (conforme eu disser) needs the Future Subjunctive rather than a present or past tense.
Could I use the preposition a instead of para for the direction here?