Sail Simulator

Realistic sailing simulation game. Many adjustable variables (weather, boats, scenery, and crew). Can be played multiplayer on the internet. Demo's and online forum available.
http://www.sailsimulator.com/

SimHarbor

Offers downloads, screenshots, game information, and a description.
http://www.geocities.com/simharbor/

Virtual Passage

Voyage planning software. Offers program information, screenshots, system requirements, and online ordering.
http://www.virtualsail.com/

Posey Yacht Design

Offers several sailing simulators for racing, navigation, tactics. All programmes run on mac or windows. Demos available.
http://www.poseysail.com/

21st Century Publishing

Sailing simulation games with realistic graphics and complete control over your boat. Can be played multiplayer on the internet.
http://www.21stcenturypublishing.com

Motorboat Simulator 1

Realistic motorboat simulator by Stentec Software. Includes screenshots, information, and specifications.
http://www.stentec.com/motorboatsimulator_i/

GameZone: 21st Century Sailing Simulator 2.0

[2/10] Review by John Brandon. "I would recommend this game to anyone who has been stuck in an isolation chamber for the last fifteen years and wants to ease into modern day game design and graphics."
http://www.gamezone.com/gzreviews/r13919.htm