Catamaran..

Sounds like a fun project. If possible I would use a wood that is more resilient to weather, such as cedar. Also consider finding logs that have had some time to season. A green or fresh wood still has alot of water in it and will not be so accepting to the sealer.Send pictures when it is done and let us know how it turns out.

 

i would consider finding some plans somewhere, i've built a couple of small dinghy's, from some plans purchased from http://glen-L.com designs, they are at least worth taking a look at (even if you are dead-set on doing it from scratch) and you can see pictures of what others have built on the site too.... i know there is at least 1 catamaran on there.

Another thing to consider when building boats is time and funding. It will take ALOT longer than you expect it to, and though you may start out super cheap, when it comes to buying things like sails and rigging, it can get REALLY expensive, really fast. A new hobie sail would probably start around 800, and you could easily spend 2 grand for full on racing sails. However... ebay usually has an assortment of old sails for good prices. Also check out http://apsltd.com, they are generally the cheapest for new parts, and are located in Annapolis.

Oh, and just a word about your hollowing out logs plan, ever heard of the Kon Tiki ?? The polynesians used this type of vessel to get to the south pacific... they used giant balsa logs (too bad they dont grow here), so it is possible to use this method, but i think your going to find that pine is unsuited to boat building. Also... the log method is going to be really heavy.

 

had almost the same idea, i would use cedar, and all you need is to build a skeleton and wrap it with thin cedar planks, and wrap it with a cheap thin layer of fiber glass, and the sail is going to be the most costly part. It is not a easy or weekend project if your going to go thru with it due it right, not worth putting all the effort to watch it sink like a rock.