worth noting that with 'lazy tongs' there is a reaction force against the work, which might not suit a canoe.
Note also that pop rivets come in more than one flavour; they can be 'blind' or 'open'. Blind rivets are designed so that the shank fails in tension, leaving the hole in the centre of the rivet plugged with the stub of the shank. I'd imagine that you want blind rivets in a canoe since the other sort will let water in?
If the shank pulls clean through the rivet this can mean that the hole through which the rivet passes is drilled oversize (for that rivet size) and that the joint may not be properly secure.
Anytime you are riveting through something soft (plastic, fibreglass, many non-metals) you need to be mindful of the load on the rivet at the point at which the shank pulls out. If this is too high you can either get failure in the non-metal immediately, or enough stress that it then cracks later over time. Sometimes you can overcome this by using larger washers/fittings to spread the load, other times you need to use a rivet with a lower pull rating.
In extremis you can knock the pins out of the rivets, and make the notch in them deeper than normal, so that they pull out at a lower force, more in accord with material properties. Other times you can set the rivet to a given force so that the joint is secure, and then cut the pin off flush with the rivet top, instead of pulling it out (at higher force).
If you use a rubber washer and a steel washer in the back, you can use displacement as a proxy for load in the joint, and this may offer most control when making such joints in materials which might crack or be deformed at high force.
cheers
