Si Clauses - Indicative
 

How would you know when to use either present and present or present and future for indicative si clauses?

Por ejemplo:
Los marineros ____ (contar) con un faro si ______ (haber) niebla.

Can't it mean both: "The sailors will rely on a lighthouse if it is foggy" and "The sailors rely on a lighthouse if it is foggy"?

Ok, I am not sure of what you are talking about gramatically, however, consider this: :)

Los marineros cuentan con un faro por si hay niebla.

-Los marineros cuentan con un faro por si hubiera niebla.

-Los marineros contaban con un faro por si habia niebla.

-Los marineros contarian con un faro por si hubiera niebla.

I think I covered the posibilities...

If I missed you question- then write the phrase in correct english, and I will translate it. :-)

Could you also use the subjunctive?

The subjunctive was used in two of chileno's examples, in the secondary clause. The subjunctive wouldn't be used in the main clause.

Rusty, would this be right for subjunctive?

Que los marineros contaran con un faro, por si hay niebla, sería bueno.

Correcto?

Probably not what is being asked, though... :(

Yes, it's correct. You're still using the subjunctive in a secondary clause, however. Sería bueno is the main clause.

I mentioned that the subjunctive can't be used in the main clause, but meant that comment for the types of sentences posted. You can, of course, have a main clause with a subjunctive. For example: ¡Ay! ¡Que lloviera!

Interesting!

What about? : ¡Ay! ¡Si lloviera!

You know I like this, and it makes me want to delve more in grammar, but now that I am, more or less, bilingual.

Thanks Rusty! :)

¿Me preguntas si sirve? Claro que sí. He oído las dos.
Both phrases can stand alone. Both can sport a main clause.
If it were to rain ... (then what)
Would that it rain ... (when, for what purpose)

Entiendo que las dos sirvan, mi respuesta/pregunta era por saber mas sobre lo que esta en rojo.

Eres genial explicando estas cosas! :)

Gracias.

Algo así:
¡Ay! Si lloviera, ¡podríamos aliviarnos del calor que hace!
¡Ay! !Que lloviera para regar las flores que se ponen mustias!