Jaccar Holdings, the main shareholder of Bourbon, said on Monday it will launch an offer to buy the French ship supplier on May 20.
Bourbon said in March that the offer, which is valid until June 23, would be conditional upon Jaccar securing 50.1 percent of the capital, as well as bank financing. It said at that time that the proposed bid was 24 euros per share.
Bourbon shares closed at 23.83 euros on Friday.
Jaccar currently owns 26 percent of the group, according to Bourbon's website.
Reporting by Maya Nikolaeva and Gilles Guillaume