I would suggest a little larger than 5" fenders. We took our 25' Oday though the locks and back (~60 locks on our trip), and most go uneventful, but every few locks something very weird happens to a fender and it renders it useless.
Some things to consider (all of which happened more than once).
(1) For a bow fender you need something MUCH larger than 5", as you not only need to keep your bow off the wall, but the mast that sticks another 5'+ off the wall too. Remember your bow is rounded, and your boat usually not be parallel to the wall. This points your mast to the wall, and even an 8" fender can be too small here. Same things happens in the rear, just not as pronounced because the stern is wider. We used a 15" ball and it was about right for our boat. Then again we have a shorter boat and mast.
(2) Most locks have flat walls, but the locks undergo a major reconstruction about every 40-50 years on a rotating basis. Thus some locks have "holes" in the wall that literally swallow up a 10" fender. On our trip Erie Canal Lock 6 "ate" two adjacent 8" fenders, and if we did not keep the boat off the wall with our hands/hooks, the boat would have suffered some major damage. This is far more likely with 5" fenders. Fortunately Lock 6 is currently being refit for this coming year, and a major reason for boards.
(3) When tied to a dock your boat moves forward and back a foot or so before being kept by spring lines. In the lock you can move several feet, and also lower. This "rolls" your fender up and onto your deck. A 5" fender is smaller in both diameter and length. The shorter length hurts you here.
(4) Some locks, depending on water height, etc., will require your fenders to be a foot off the water, otherwise when the lock is full, your fenders would be too high. When you start to drop the low fenders are too small to keep the upper, wider part of the boat safely off the wall. This can easily be fixed by multiple fenders, some high, some low. But if your going to buy two small fenders, why not buy one larger one that is both wider and longer. Be careful of this on some of the middle Mohawk River Locks (12ish), some have less than 2 feet of clearance.
Now, I have at least two dozen of these old 5" fenders sitting in my yard. Most have either been found or came with a boat that needed larger ones. We use some for keeping on the dock year round or attached to temporary moorings, but the stock pile has just got too large. They are old and ugly, but all functional. So if you go with the cheap Wal-Mart ones, don't sweat it, they will work. Just put lots out (I would suggest at least 8 on your boat to help prevent the above issues).
PM me (or anyone else who is interested), depending on when you come through, I could sell you a bunch at $5 each. I could meet you at the Troy or Waterford docks. Who knew there was so much to say about fenders?
Boat: O'Day 25 / Sea Ray 270 Flybridge
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.