Costs assessment in admiralty jurisdiction is done in accordance with the Federal Rules of Civil Procedure and other applicable statutes.  Provisions of some statutes are expressly made applicable to admiralty proceedings.  Requiring prepayment of a deposit to cover initial expenses for services in keeping of property attached or arrested is one such provision that is expressly made applicable to admiralty proceedings.  However there is disagreement over application of such provisions.

Congress has granted seamen some preferential treatment over other litigants in admiralty.[i]  Accordingly, seamen can institute wage, salvage, health, or safety suits without prepayment of fees or costs.

Although seamen are specifically exempted by Congress from making prepayment of deposit for obtaining arrest of a vessel, many courts have found that a relevant controlling statute may require seamen to make prepayment of expenses before the marshal executes an in rem process.[ii]

Admiralty courts can award costs and expenses by interlocutory order, final judgment, or order of appellate court on appeal.  In such circumstances, admiralty court can require the plaintiff, defendant, claimant, or other party to give security or additional security.  Such security or additional security shall be the amount sufficient to pay all costs and expenses awarded against him/her.   Such security amount can be ordered to be made on filing of the complaint, on appearance of any defendant, claimant, or any other party, or even at a later time.
[i] Solomon v. Bruchhausen, 305 F.2d 941 (2d Cir. N.Y. 1962).

[ii] Lindsey v. Solutions Exch. (In re Lindsey), 178 B.R. 895 (Bankr. N.D. Ga. 1995).