On our 40ft boat, when we came up the canal this past May, we created 3 X's out of 2x6's (could have gotten away with two) and a square frame for the stern (also 2x6's). The three X's were placed: 3 feet or so from the bow, over the mast boot, over the companionway (we would get rid of this one in the future) and the square stern brace was, well, on the stern. We heavily strapped the X-braces and the square frame to the boat (anywhere solid) and we also did the same with the mast (from the spreaders). You can leave the spreaders on.
I'll differ from Vasco here. Don't be casual about this. Even with everything tied down, we hit some rough square waves on Champlain on the way up and our mast still shifted slightly. Make sure the stick is very secure. Put your boom down below. Leave the mainsail on if you want. Also, make sure you remove your genoa from the furler. The extra weight of the sail makes a big difference (at least it did for us - it was huge, and we almost damaged the sail by leaving it on). Also, prior to leaving (so you don't have to deal with it the day of), catalog, mark, etc. all the wires going through the mast boot as well as all of the rigging. Put tape around turnbuckles where each of the standing rigging connects so you know how far to screw it on. Get extra cotter pins for when you reattach everything. Make sure all antenna wires and other wires can be disconnected from the mast (or the backstay too, in our case). Know the path your running rigging takes.
By the way - if you leave in early May (right when the canal opens) there is little traffic. It took us about a day and a half to get through the entire canal. Tell the first couple of operators that this is your first time and they will help you out.
A few recommendations:
Each lock will have a flag. Look at the way the wind is blowing. Go to the side of the canal opposite where the wind is blowing. If the flag is out to the right, pick the left side. The wind does a loop when it enters the canal. On one side, the wind will push you towards the wall (preferable). On the other side, you will be pushed away from the wall (and will have to hold on for dear life).
Don't underestimate the number of bumpers you need. Always have extra. You will be pushed up against the wall. We bought fenderboard adapters allowing us to put a 2x4x10 over the side. A bunch of bumpers would have been fine.
Have port and starboard bow and stern lines ready - long ones that can reach up the (sometimes) 20' walls of the locks. You won't need them unless there is an emergency (except for the very last lock - the federal lock), but you'll be glad to have them just in case.
The federal lock in Troy (the first or last, depending on upstream or downstream) is a pain. All of the state locks have lines hanging down that you can grab a hold of. The federal lock has long vertical bars every 15-20 feet. You'll be lucky if you can grab just one of them. Run a line from the stern to the inside of the bar. Run a line from the bow to the inside of the bar. Then pull on the lines using the bar as a pivot point. This is the only lock that is really a pain.
Make sure you have AT LEAST two people on board. Someone will be focusing on the engine play while another person will have to be forward to grab a hanging line (with the boathook). If your stern starts drifting away from the wall while you are working the engine, you'll be in a closed area with a huge stick hanging over your bow and stern, and you will need to figure out a way to get back to the wall. It's not tough, but just takes some teamwork.
Most lockmaster's don't monitor the radio. The Lake Champlain/Hudson River cruising guide has a list of telephone numbers for all of the locks. Most often, the lockmaster's are hanging out outside by the lock itself. They call from lock to lock to let them know you are coming up. At the end of the day, they'll start asking you how far you intend to go.
Lock 9 (I believe) has a huge tie up area on the south side of the lock. That's where we overnighted. A few of the other locks also have places to overnight. The NYS Canal Authority (http://www.canals.state.ny.us
) has a cruising guide to the entire canal system. It's a bit helpful, although the charts don't mark depths.
Take a look at your mast while it's down. Replace lights (even if they work - and keep the working ones as spares). Clean the spreaders and the boots. Take advantage of the timing.
Lots of stuff, but I figure other's may be looking to do the Champlain Canal system and this MAY help them out a bit. If we don't sell our boat over the winter, but DO buy a new boat in Annapolis, we'll be bringing our one boat south to Annapolis and picking up our new boat to bring back north... should be a good month!
Have fun, and let me know if you have any other questions!