Ako je morska struja jaka, skiper neće pristati uz obalu.

Ako means if. It introduces the condition:

Ako je morska struja jaka = If the sea current is strong

In Croatian, ako is the normal word for real or likely conditions, just like English if.

Because struja is a feminine singular noun.

Both adjectives must agree with the noun in:

• gender
• number
• case

So we get:

• morska = sea / marine
• jaka = strong
• struja = current

All three are feminine singular nominative here.

No. Struja can mean several related things, including:

• current in water
• electric current
• sometimes flow or stream in a broader sense

Here, because of morska (sea), morska struja clearly means sea current.

Je is a clitic form of the verb biti (to be), and Croatian clitics usually appear very early in the clause.

So:

Ako je morska struja jaka
not normally Ako morska struja je jaka

This placement is very natural in Croatian. English speakers often want to place je later, but Croatian prefers it near the beginning.

Je is the 3rd person singular present of biti (to be):

• ja sam = I am
• ti si = you are
• on/ona/ono je = he/she/it is

So morska struja je jaka means the sea current is strong.

Skiper means skipper, especially the person in charge of a boat or yacht.

It is a loanword, and it is very common in nautical contexts. Depending on context, English might translate it as:

• skipper
• captain
• boat operator

Neće pristati is the negative future tense.

• će is the future auxiliary
• neće = will not
• pristati is the infinitive

So:

• pristat će / će pristati = will dock / will come alongside
• neće pristati = will not dock / will not come alongside

Croatian commonly forms the negative future with neće + infinitive.

No. Pristati can mean different things depending on context, such as:

• to agree
• to accept
• to dock / come alongside / land

Here, because of uz obalu (by/alongside the shore), it clearly means something like:

• to come alongside the shore
• to dock near the shore
• to approach the shore by boat

Uz here takes the accusative case, so obala becomes obalu.

• nominative: obala = shore, coast
• accusative: obalu

Uz obalu means something like:

• alongside the shore
• up to the shore
• by the shore

In this sentence it fits the idea of a boat approaching or docking near the coast.

Because uz obalu and na obalu are not exactly the same.

• uz obalu = alongside / by the shore
• na obalu = onto the shore / to the land itself

With a boat, pristati uz obalu suggests coming alongside the coast or shore.
Pristati na obalu would suggest landing on shore more directly, which is a different image.

Yes. Croatian word order is fairly flexible.

For example, you could also say:

Skiper neće pristati uz obalu ako je morska struja jaka.

This means the same thing:
The skipper will not come alongside the shore if the sea current is strong.

The difference is mostly about focus and style:

• starting with Ako... emphasizes the condition
• starting with Skiper... emphasizes the subject/action first

Because Croatian does not have articles like English a/an/the.

So:

• skiper can mean a skipper or the skipper
• obalu can mean a shore/the shore depending on context

Croatian relies on context, word order, and situation instead of articles.