Maritime cabotage and IWT are reserved to Uruguayan-flagged vessels. Waivers permitting foreign-flagged vessels to perform cabotage services may be granted by the Executive branch on an exceptional basis when Uruguayan-flagged vessels are not available. Vessels entitled to provide cabotage transportation services are subject to the following requirements: if owned by an enterprise: (i) 51 percent of the owners of such enterprise must be Uruguayan nationals; (ii) 51 percent of the voting shares must be owned by Uruguayan nationals; and (iii) the enterprise must be controlled and managed by Uruguayan nationals. The captain of a merchant vessel flying the national flag must also be a Uruguayan citizen. Furthermore, half of all cargo transportation of Uruguayan foreign trade (imports and exports) is reserved to Uruguayan-flagged vessels meeting the above-mentioned ownership requirements. Waivers, however, may be granted on an exceptional basis to foreign-flagged vessels to carry the reserved portion of the foreign trade. 
"CHAPTER I - DOMESTIC VESSELS
Article 1
Navigation and cabotage trade, that is, that which is carried out between ports of the Republic, as well as port and beach services, salvage operations, cargo, and those carried out by tugboats, launches and other smaller vessels in waters of Uruguayan jurisdiction, are reserved for national flag vessels.
The Executive Branch may authorize, as an exception in these operations, the use of foreign-flagged vessels when there are no national-flagged vessels available.
Transport trailers and trailers for convoys of vessels that carry out international cabotage are excepted.
For passenger transport (unloading and boarding) of cruise ships arriving in our country, the ship's foreign-flagged auxiliary vessels may be used, as long as their number does not exceed 50% (fifty percent) of those necessary for said transportation. The other boats must be of national flag. (*)
In special situations and with proven reasons of general interest, duly authorized auxiliary vessels of the cruise ship with a foreign flag may be used, in a number that exceeds the percentage established above.
[...]
Article 4
For the purposes of this law, cabotage vessels will be considered those that are registered in the respective registration, are commanded by captains or employers who are natural or legal Uruguayan citizens, have at least one third of their crew made up of citizens and are subject to to the regulations on cabotage merchant shipping. [...]"(Law No. 12091 LAW ON NATIONAL NAVIGATION AND DOMESTIC TRADE  [google translation])
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"CHAPTER I - GENERAL PROVISIONS
Article 1
For the purposes of this law, a merchant ship is considered to be any floating construction, self-propelled or not, of a civil nature, whose purpose is the transport of goods or people for a commercial purpose, in the maritime, fluvial or lacustrine sphere. (*)
Article 2
Merchant ships that have been provisionally or definitively registered shall have the right to fly the national flag, within the conditions established in the following regulations. The ship will be considered for all purposes as imported, once the definitive registration has been obtained. [...]" (Law No. 16387 MERCHANT MARINE  [google translation])
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"CHAPTER II - RESERVATION OF LOADS
Article 2
The Eastern Republic of Uruguay reserves the right to transport, on its flag vessels, at least 50% (fifty percent) of the merchandise, goods or products that are traded abroad by sea, river or lake, for which it will regulate its traffic based on what is provided in the following articles.
A) IMPORTS
Article 3
The transport of merchandise, goods or imported products that is carried out by sea, river or lake without prejudice to the provisions of international agreements, must be done in national flag vessels that meet the conditions set forth in articles 9 and 10 of this law, except that none of them is in a loading position and with an available warehouse.
[...]
CHAPTER III - SHIPS OF THE NATIONAL MERCHANT MARINE
Article 9
National flag vessels that comply with traffic or services approved by the Ministry of Transportation and Public Works, and the merchandise, products and goods that they transport, will enjoy the benefits of this law, provided that they comply with the requirements listed. next: [...]
B) When their owners, participants or shipowners (article 1045 of the Commercial Code) are private, state or mixed legal entities (article 188 of the Constitution of the Republic), they must prove, as appropriate:
1) Its registered office in the national territory.
2) Control and direction of the company exercised by natural or legal Uruguayan citizens.
3) Have a duly accredited representative domiciled in the national territory.
4) Registration and justification of being up to date with the obligations established by social and tax laws corresponding to the company, to ships armed by it or owned by it.
For the cases in which the traffic or service to which the ship is destined must be carried out exclusively within the national territory, they must prove, as appropriate: [...]
B) When the owners, participants or shipowners are legal entities, state or mixed (article 188 of the Constitution of the Republic):
1) That half plus one of the partners is made up of natural or legal Uruguayan citizens, domiciled in the Republic.
2) By accounting and notarial record, that the majority of the shares, representing at least 51% (fifty-one percent) of the computable votes, is made up of registered shares, owned by natural or legal Uruguayan citizens.
3) That the control and direction of the company are exercised by natural or legal Uruguayan citizens.
4) Justification of being up to date with the obligations established by social and tax laws corresponding to the company, to ships armed by it, or owned by it.
In all the indicated cases, registration in the Public Registry of Owners and Shipowners and in the National Registry of Commerce will be necessary.
The benefits established in this law are subject to the resolutory condition of compliance with the requirements demanded above.[...]" (Decree Law No. 14650 NATIONAL FLAG MERCHANT MARINE - VESSELS  [google translation])
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"Article 2 (Integration of the crew). The crew of the national merchant ships will be integrated as follows:
A) 90% (ninety percent) of the officers, including captain, chief engineer and radio operator, by natural or legal Uruguayan citizens.
B) With no less than 90% (ninety percent) of the rest of the crew of natural or legal Uruguayan citizens.[...]" (Law on the Crewing of National Merchant Vessels (No. 18.498 of 12 June 2009), Article 2 [google translation])
Law No. 12091 LAW ON NAVIGATION AND NATIONAL CABOTAGE TRADE [google translation]
Law No. 16387 MERCHANT MARINE [google translation]
Decree Law No. 14650 NATIONAL FLAG MERCHANT MARINE - VESSELS [google translation]
Law on the Crewing of National Merchant Vessels (No. 18.498 of 12 June 2009), Article 2 [google translation]
[<a href="https://www.impo.com.uy/bases/leyes/12091-1954">Act</a>],[<a href="https://www.impo.com.uy/bases/leyes/16387-1993">Act</a>],[<a href="https://www.impo.com.uy/bases/decretos-ley/14650-1977">Decree-law</a>],[<a href="https://www.impo.com.uy/bases/leyes/18498-2009">Law</a>]