Assuming you narrowly dam up the canal near the ship to contain the brine, no I don't think so. Seawater is 3% saline and saturated brine is 26% saline, so you'd probably have sufficient mixing within the canal itself once you open the dams. The canal is 120 miles long and I can't imagine you'd dam up more than a third of a mile at maximum. But it would take a whole hell of a lot of salt.