Jak tylko wodujemy kajak, zaczynamy wiosłować.

It is a fixed expression meaning as soon as, once, or the moment that.

Even though jak by itself often means how, in jak tylko you should treat the whole phrase as one unit.

Because Polish often leaves out subject pronouns when the verb ending already shows who is doing the action.

Here:

• wodujemy = we launch
• zaczynamy = we start

The ending -my tells you the subject is we. You could add my for emphasis, but it is not necessary.

It comes from the verb wodować, which means to launch a boat or kayak into the water.

It is a fairly specific boating verb. In less technical everyday language, people might also say things like wkładamy kajak do wody depending on the context.

Because kajak is the direct object of wodujemy, so it is in the accusative case.

But kajak is a masculine inanimate noun, and for that type of noun, the accusative singular usually looks exactly the same as the nominative singular.

So:

• nominative: kajak
• accusative: kajak

That is why the form does not change visibly.

After zaczynać or zacząć (to start / begin), Polish normally uses an infinitive.

So:

• zaczynamy wiosłować = we start paddling
• zaczęli śpiewać = they started singing

This is a very common pattern.

Wiosłować means to paddle or to row, depending on context.

In a kayak context, paddle is the best match. It focuses on the physical action of using the paddle, not just moving on the water.

Both wodujemy and zaczynamy are present-tense forms.

In this sentence, the present tense works well for a general or habitual sequence of actions:

• Jak tylko wodujemy kajak, zaczynamy wiosłować. = whenever / as soon as we launch the kayak, we start paddling.

If you wanted to talk about one specific future event, many speakers would more naturally use perfective forms:

• Jak tylko zwodujemy kajak, zaczniemy wiosłować.

So the original sentence sounds especially natural as a regular pattern or standard procedure.

This is mainly a question of aspect.

• wodować is imperfective
• zwodować is perfective

Very roughly:

• wodować can describe the action in progress, repetition, or a general/habitual action
• zwodować presents it as a completed single event

That is why wodujemy fits a general statement, while zwodujemy often fits a one-time future result.

Because Jak tylko wodujemy kajak is a subordinate clause, and Polish normally separates a subordinate clause from the main clause with a comma.

So the structure is:

• Jak tylko wodujemy kajak, = subordinate clause
• zaczynamy wiosłować. = main clause

Yes. Polish word order is flexible.

For example, you can also say:

• Zaczynamy wiosłować, jak tylko wodujemy kajak.

That is still correct. The original version puts the time condition first, which sounds very natural.

No. There are other natural options, for example:

• Gdy tylko wodujemy kajak, zaczynamy wiosłować.
• Kiedy tylko wodujemy kajak, zaczynamy wiosłować.

All of these can mean as soon as. Jak tylko is simply one of the common everyday ways to say it.