No paint job is any better than its foundation – a good sub-surface is critical. Painting over peeling paint is pointless – the old paint will continue peeling, taking the new paint with it. New paint will not keep old paint from flaking, but will simply come off as the old paint keeps failing.
Is the old paint at the edges of the chipped-away areas really tight, or can the chipped areas be easily enlarged by lifting up the edges of the chipped areas? If you can chip paint away, can you get to an area where you can’t chip the paint? If the later, you
might be able to prepare the hull and apply paint that will be serviceable for a few years. But given that the chipping away of the old paint is scattered over most of the hull, and given that the crackling of the paint is very extensive, I expect that the old paint will continue to chip away and fall off.
Below are links to some discussion about this issue, and how you might proceed if you judge that the existing paint is sound enough. As you will see in these discussions, I have re-painted an old canoe and successfully gotten a few years of use from it. But your photos show much more missing paint than I had to deal with, and your paint seems to have come off in large pieces, indicating some sort of failure of the paint to adhere to the filler. A new coat of paint will not cure such a problem.
Your canoe well may not leak much even in its current condition -- if the filler is uncracked, it will keep water out even with the failed and failing paint. But something has caused that paint to come loose over a large area of the hull, and even if the hull is water tight, I would expect continued paint failure.
And as has been mentioned, if you do go ahead, do not use paint stripper to remove the old paint from the exterior .
http://forums.wcha.org/showthread.php?t=5790 see pp. 2-3 of this thread
http://forums.wcha.org/showthread.php?7769-Painting-over-existing-paint&p=41339#post41339
http://forums.wcha.org/showthread.p...t-Restoration-advice-please&p=32358#post32358
http://forums.wcha.org/showthread.php?7775-Temp-repair-to-bare-spot-on-canvas&p=41357#post41357
http://forums.wcha.org/showthread.php?7619-time-is-not-on-my-side!&p=40689#post40689
http://forums.wcha.org/showthread.php?8564-Smoothing-Canvas/page2 starting at post 12, on bondo spot putty
http://forums.wcha.org/showthread.php?6607-sanding-or-not&p=35286#post35286
http://forums.wcha.org/showthread.php?8906-Repaint-Tips