In portu gubernator feminae ostendit quomodo funis ad ancoram nodo firmo ligetur.

Because in takes different cases depending on meaning:

• in + ablative = location, in / at
• in + accusative = motion into

Here the meaning is location, so Latin uses the ablative: in portu = in/at the harbor.

Also, portus is a 4th-declension noun, so its ablative singular is portu, not porto. If the sentence meant into the harbor, it would be in portum.

Here feminae is dative singular, meaning to the woman.

It is the indirect object of ostendit: the helmsman shows something to the woman.

This form is a good one to watch out for, because feminae could also be:

• genitive singular = of the woman
• nominative plural = women

But in this sentence the syntax clearly makes it dative singular.

It is an indirect question introduced by quomodo, which means how or in what way.

After a verb like ostendit (shows), Latin can say what is being shown by using an indirect question:

• ostendit quomodo... = he shows how...

So the whole clause functions as the content of what the helmsman is showing.

Because indirect questions in Latin normally take the subjunctive.

So after quomodo in a clause dependent on ostendit, Latin uses ligetur, not an indicative form like ligatur.

This is a standard grammar rule. The subjunctive here does not necessarily mean uncertainty; it mainly marks the clause as an indirect question.

Because funis (the rope) is the thing being tied, not the thing doing the tying.

So Latin uses the passive:

• ligetur = is tied / be tied

That matches the English idea how the rope is tied. If the clause were active, the rope would be a direct object instead.

Because funis is the subject of the passive verb ligetur.

In a passive clause, the thing receiving the action becomes the grammatical subject:

• funis ligetur = the rope is tied

If the verb were active, you would expect the accusative:

• funem ligat = he ties the rope

So funis is nominative because it is the subject of ligetur.

Because ad takes the accusative case, and ancoram is accusative singular of ancora.

Here ad expresses the thing the rope is fastened to:

• ad ancoram = to the anchor

Even though English to does not always suggest motion, Latin commonly uses ad with the accusative for this kind of attachment or direction toward something.

Nodo firmo is ablative singular, with noun and adjective agreeing:

• nodo = ablative singular of nodus
• firmo = ablative singular of firmus

It is best understood as an ablative of means/instrument:

• nodo firmo = with a firm knot

Latin often uses the ablative without a preposition to show the means by which something is done.

By form alone, ostendit can be either:

• he/she shows (present)
• he/she showed / has shown (perfect)

That is because in ostendere, the 3rd person singular present and perfect are spelled the same.

So context has to decide. In this sentence, shows is usually the most natural reading, especially since the sentence describes a general act of instruction.

Latin word order is much freer than English word order because Latin uses case endings to show how words function.

So Latin can arrange words for emphasis or style rather than strict grammatical necessity. In this sentence:

• In portu sets the scene first
• gubernator is the subject
• feminae comes before the verb as the indirect object
• the quomodo clause comes after ostendit as the thing being shown

English depends much more on position, but Latin depends more on endings.

Because Latin has no articles.

So a noun like gubernator can mean the helmsman or a helmsman, depending on context. The same is true for funis, ancora, and the other nouns here.

When translating into English, you add the or a/an according to what sounds natural in the context.