In portu classis magna paratur, et nautae naves diligenter gubernant.

Because in can take two different cases depending on the meaning:

• in + ablative = in / on / at a place, with no motion
• in + accusative = into / onto a place, with motion toward it

Here, in portu means in the harbor, describing location, so portu is ablative singular.

If the sentence meant into the harbor, Latin would use in portum instead.

Classis is nominative singular, and here it means fleet.

It is the subject of paratur, so the basic structure is:

• classis magna paratur = the great fleet is being prepared

A common point of confusion is that classis may look plural to an English speaker because it ends in -is, but here it is actually a singular noun of the third declension.

Because magna agrees with classis.

In Latin, adjectives must agree with the nouns they describe in:

• gender
• number
• case

Classis is:

• feminine
• singular
• nominative

So the adjective must also be feminine singular nominative: magna.

That is why Latin uses magna classis or classis magna for great fleet.

Because paratur is present passive singular.

It comes from paro, parare = to prepare.

Its forms work like this:

• parat = he/she/it prepares or is preparing
• paratur = he/she/it is prepared or more naturally is being prepared

Since classis is singular, the verb is also singular: paratur.

So:

• classis magna paratur = the great fleet is being prepared

Because Latin grammar follows the grammatical number of the noun, not the real-world number of things inside it.

Classis means fleet, but grammatically it is a singular noun. So Latin treats it as one unit:

• classis ... paratur = the fleet is being prepared

This is similar to English using a collective noun such as the army is marching.

Because nautae is nominative plural, which is the case normally used for the subject.

In the second clause:

• nautae = the sailors
• naves = the ships
• gubernant = steer / pilot

So the structure is:

• nautae naves gubernant = the sailors steer the ships

A learner may wonder whether nautae could mean of the sailor or something else, but in this sentence its role is clear because it matches the plural verb gubernant.

Because nauta is one of the common first-declension nouns that refer to male people and are therefore masculine.

So:

• nauta = sailor
• nautae = sailors here

This is not unusual in Latin. Other common examples are:

• poeta = poet
• agricola = farmer
• pirata = pirate

They decline like first-declension nouns, but their natural gender is masculine.

Naves is accusative plural here, and it is the direct object of gubernant.

The verb guberno takes a direct object: you steer or pilot something. So:

• nautae = subject
• naves = object
• gubernant = verb

Thus:

• nautae naves gubernant = the sailors steer the ships

It is true that naves can also be nominative plural, but here the sentence structure and the verb make it clear that it is functioning as the object.

Diligenter is an adverb, and it modifies the verb gubernant.

It means carefully, diligently, or attentively, depending on context.

So:

• nautae naves diligenter gubernant = the sailors carefully steer the ships

A helpful pattern to notice is that many Latin adverbs are formed from adjectives, often with endings like -e or -ter.

Latin word order is much more flexible than English word order because Latin uses case endings to show grammatical relationships.

English depends heavily on position:

• the sailors steer the ships
  not
• the ships steer the sailors

Latin can move words around more freely because endings show which word is the subject and which is the object.

So this sentence could be rearranged in various ways without changing the basic meaning, as long as the forms stay the same. The given order is perfectly natural Latin, but it is not locked into English-style subject–verb–object order.

Yes. Et simply means and.

It joins the two parts of the sentence:

• In portu classis magna paratur
• et nautae naves diligenter gubernant

So it connects two related actions happening in the same scene.

Yes. In this sentence, classis means fleet, especially a naval fleet.

A learner might recognize the form classis and think of the English word class, but that is misleading here. Latin classis has several meanings in different contexts, but with portu, nautae, and naves, the nautical meaning fleet is the natural one.

A simple breakdown is:

First clause

• In portu = prepositional phrase, in the harbor
• classis magna = subject, the great fleet
• paratur = verb, is being prepared

Second clause

• nautae = subject, the sailors
• naves = direct object, the ships
• diligenter = adverb, carefully
• gubernant = verb, steer

So the sentence is built from two coordinated clauses joined by et.