We have also been through a few times in a retractable
keel monohull. We also snorkeled back through once anchored to take a look (what a ride
). The waterfall is not very wide, but it wider than it looks from the surface and I would not think the beam of 38 foot cat would be a problem at the right time. But our
monohull was narrower, so I have never done a practical test.
Coral is very unforgiving.
The
water at the outer
reefs is not particularly clear but it is clearer than the Whitsunday islands, so after cruising the islands the impression from the
boat is that the depths in these
offshore reefs is less than it is in reality.
I have never seen another
boat anchored inside or attempt the waterfall, but most of our trips were prior to
GPS and the lack of acurate fix discoraged attempting an unmarked narrow entrance with no landmarks, still I would be surprised if even largish cats cannot enter.