Here are the ships I have:

http://www.heritagemint.com/jump.jsp?itemID=352&itemType=PRODUCT&RS=1&keyword=ship

http://www.heritagemint.com/jump.jsp?itemID=353&itemType=PRODUCT&RS=1&keyword=ship

Made of wood, no cannons, no holes, didn't sink, 18 inches long and I've filled them to overflowing with gold coins, real gold ingots and chinese coins. They seem to do the trick.