Dear Jfei,
you can get some general knowledge on ship design eg from the "Practical Ship Design, Elsevier Ocean Engineering Book Series, Volume 1, by D.G.M. Watson", ISBN 0-08-043921-7.
Also looking at the rules of various registries is very helpful.
For example ABS Rule Requirements for Materials and Welding both for Steel and Aluminum Vessels are very detailed.
Those you could download for free from the ABS website
http://www.eagle.org/ Good Luck,
Valoman