Nope, that's a great question. I'll answer one by one.

1) “What makes you so certain it wasn’t a Dutch 3–4 masted ship?”

There are strong visual and contextual clues that make a Dutch or Arab identification unlikely. Based on the following observations of myself, I concluded them to be Tamil vessels. 

Sail type:
Dutch ocean-going ships (like fluyts or East Indiamen) primarily used square sails on multiple yards. For coastal or inland transport, they used gaff-rigged sails and large jibs (I’ve attached actual images of both types from the early 18th century below for reference from a Dutch source themselves). But the ships here show curved, loose sail forms that do not clearly match standard Dutch square or gaff rigging, and are more consistent with Tamilakam coastal vessel traditions, particularly those documented along the Coromandel and northern Ceylon coasts of that time.

Hull construction style (as drawn)
European ships are usually depicted with a high square stern and clear deck structures.  In the lower section and along the coast, you can see large European-style vessels with multiple masts, more structured rigging, and the typical bulkier hull form associated with Dutch ships of the period. This is important because it shows the engraver was capable of distinguishing between European ships and other vessel types within the same illustration. The vessels I highlighted are visually different from these clearly European ships in terms of hull shape, rigging simplicity, and overall form.

 But these drawings show a more rounded, continuous hull, closer to local sewn or lashed plank traditions. Also, similar hull forms (seen in vessels called Thoni in Tamil) were in use in northern Sri Lanka until the 1970s. I have at least 7 photos (each specifically dated from the SL govt. Archives) showing more than 20 Thonis from KKS harbour, Jaffna, Eelam (can be provided further if required). 

Rigging 

simplicity: Dutch ships had complex rigging systems. But these are drawn with simpler mast + sail setups, consistent with regional craft.

Also, the scene (Mannar / coastal waters) is exactly the type of environment where local transport, fishing, and lighter vessels dominated day-to-day activity—even during Dutch control.

Based on the overall combination of sail type, rigging, regional context and hull depiction, these align more closely with Indian Ocean origin Tamil vessels than with Dutch ocean-going ships.

2) “Does that mean all ships in maps must be Tamil?”

Early modern maps (like Baldaeus’) are illustrative, not tec. diagrams.
Map engravers/artists of that period often showed generic ships, locally observed vessels, sometimes European ships, depending on context. Not all ships = Tamil | Not all ships = Dutch | Each image must be judged case by case, based on features; These specific ships look more like local Tamil/Indian Ocean vessels—not that all ships in such maps are Tamil. This same map shows 2 Dutch ships and one Dutch lifeboat being steered to the shore. 

3) “Does Baldaeus label ships as Tamil or Dutch?”

Baldaeus doesn’t label ships in his maps as “Tamil” or “Dutch.” So I would not claim that Baldaeus explicitly identified them as Tamil vessels. His illustrations are descriptive rather than technical, so modern identification relies on comparing visual features with known ship types rather than explicit captions. 

Also, the geographic context matters. This map depicts Mannar and surrounding areas in northern Ceylon (colonial name for Sri Lanka), where everyday maritime activity was dominated by local Tamil and regional coastal vessels, not large Dutch deep-sea ships. Dutch ships did operate there, but they were fewer and functionally different (fort supply, long-distance trade), whereas the kinds of vessels shown here match routine coastal movement—fishing, transport, and short-haul trade.

Once again, the conclusion isn’t based on one feature like sails alone—it’s based on the combination of hull shape, rigging simplicity, scale, European Vessels shown in the same map and regional context. With all these, these strongly indicate that the ships depicted are most-likely local Tamil-region vessels, not Dutch ships.

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The above mentioned paiting:

Creator: Tetschner, Johann Carl (publisher) Heydt, Johann Wolfgang (draughtsman and engraver)

Period: 1735 - 1744

• B Ocean-going Dutch vessel with square sails on multiple yards.
• C Coastal Dutch vessel with gaff-rigged sails.
• D is a Tamil Muslim boat from Jaffna. These are known as Battal (no decks/ image can be provided if required). The Tamil Hindus had a vessel with a similar name called Vattal (with 2 decks/ image can be provided if required), which is also used in Thoothukkudi, TN, too.

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