Today I did my first search for "duplo" on this page, and got no hits! This is not right I thought. Duplo is the baby version of Lego, but it does not mean you can't build some quite grown up things with them. This is just a basic model of a boat, to teach some helpful techniques, and show how these bulky big blocks can make something cool to play with. (for your kid that is :-)
I've used different colors on each layer to show clearly how each layer is interlacing. It is essential to build this way to get a sturdy and stable construction. A sandwich construction of at least 3 layers is always the strongest solution and hardest to break apart.
The blocks are 2x4 and 2x2 standard duplos with exception of the three skinny yellow 2x4's at the bottom.
Hope this is just the beginning of many more instructables concerning one of the greatest toys for bonding time with my kids.
Build bold, build big!