Segui lo skipper, altrimenti non puoi attraccare.

Segui is the tu form of the verb seguire and, in this sentence, it is being used as an informal singular imperative: Follow.

Italian informal commands for tu often look like the normal present-tense form, and for seguire that form is segui.

• tu segui = you follow
• Segui! = Follow!

So the sentence is addressing one person informally.

Italian usually omits subject pronouns unless they are needed for emphasis or contrast. The verb ending already tells you who the subject is.

So instead of saying:

• Tu segui lo skipper

Italian normally just says:

• Segui lo skipper

If you did include tu, it would sound more emphatic, like You follow the skipper.

In Italian, definite articles are used more often than in English. Here, lo skipper means the skipper.

The form lo is used because skipper begins with s + consonant (sk-), and nouns with that kind of beginning usually take lo in the singular masculine:

• lo skipper
• lo studente
• lo sport

So Segui lo skipper literally means Follow the skipper.

Here lo is definitely the definite article meaning the.

You can tell because it comes directly before the noun skipper:

• lo skipper = the skipper

If it were a direct object pronoun, the structure would be different, for example:

• Lo segui = You follow him/it

So in your sentence, lo belongs with skipper.

Altrimenti means otherwise or or else.

It is used to introduce the consequence of not doing what was just said:

• Segui lo skipper, altrimenti non puoi attraccare.
• Follow the skipper, otherwise you can’t dock.

It is a very common word in both spoken and written Italian.

Non puoi attraccare literally means you cannot dock or you are not able/allowed to dock.

Using potere + infinitive focuses on possibility, ability, or permission:

• non puoi attraccare = you can’t / you’re not allowed to dock

If you said:

• non attracchi

that would mean more literally you don’t dock or you won’t dock, which is a bit different. The original sentence is stressing that, if you do not follow the skipper, docking is not possible or not permitted.

After the modal verb potere (can / to be able to), Italian normally uses an infinitive:

• puoi attraccare = you can dock
• puoi entrare = you can enter
• puoi parlare = you can speak

So attraccare stays in the infinitive because it depends on puoi.

Attraccare is a nautical verb. It means to dock, to moor, or to bring a boat alongside a dock/quay.

So this is not a general everyday verb like arrivare. It belongs especially to boating, sailing, and harbor situations.

Examples:

• La barca attracca al porto. = The boat docks at the harbor.
• Non puoi attraccare qui. = You can’t dock here.

Italian often uses the present tense in situations where English might also use the present, especially in instructions and real, immediate consequences.

• Segui lo skipper, altrimenti non puoi attraccare.

This means something like:

• Follow the skipper, otherwise you can’t dock
• If you don’t, you won’t be able to dock

Italian does not need a future tense here. The present sounds natural and direct.

It is a loanword used in Italian, especially in nautical contexts. Italians do use skipper to mean the person in charge of a boat, especially in sailing or recreational boating.

Because it is treated as a masculine noun here, it takes masculine articles:

• lo skipper
• gli skipper (plural)

So even though the word originally comes from another language, it behaves like a normal noun in Italian syntax.

Yes. Since segui is the informal tu command, a more formal version addressed to one person would use Lei:

• Segua lo skipper, altrimenti non può attraccare.

Changes:

• segui → segua
• puoi → può

That version would be appropriate in more formal service or professional situations.