Great question Bruce! And one that has been asked by many people many times . . . . with no clear answers.
Note, the pilot boat had no depth sounder, no GPS, and no compass.
Water depth was determined, WHEN it was actually checked, with a lead line.
I can't think of any way that the pilot boat could legitimately determine where the "deep" water actually was, and how they could possibly guide boats into that channel effectively.
They have stated that they have procured a depth sounder for the panga pilot boat, but without a chartplotter to plot the actual depths observed, in my opinion, just a depth sounder, while a tiny step in the right direction is of limited value.
Scot - Bill said they have purchased a Garmin depth sounder that actually looks like it could have much of the bottom scanning needed.......except my hunch is it requires a transducer that is likely very expensive versus the included transom hung transducer. But that's only a guess.
https://www.garmin.com/en-US/p/739042
I have no idea how you accurately map a bar with a lead line. Realize the bar is a half mile out from the channel opening so you're floating in the middle of nowhere so remembering where the deepest part is would be a memory meme far beyond my abilities.
One question that hasn't been asked is the channel is 12 feet deep. When? At the highest tide? MLLW which is traditional? Having viewed the Google Earth history, I sincerely doubt the 12 foot is consistent if it even exists. Given the number of boats that have recently broached or touched bottom, guessing this is not a 12-foot year.
At the very least, folks have to take more responsibility for a safe crossing. I would have left it to Bill and the pilot which obviously would have been a mistake. I probably would have gotten lucky but maybe not.
Here's my best thinking knowing what I now know
1. I am a displacement speed boat and cannot match the speed of rolling waves. If they break, I am at serious risk of broach. Kevin's Bayliner 4788 likely has the speed to ride a wave in so my decision might (might....) be different in his boat.
2. Panga drivers have no idea what it's like to drive a large slow vessel. Even Bill, reportedly an ex cruiser, has likely become complacent. According to accounts of VHF chatter during the event and his 4 incidents of 585 crossings' stat, what's an incident to him far exceeds my threshold for "incident." In short, you cannot outsource risk.
3. You have to really, really study tides. Not enough to just show up at high tide, but you need to pick a day with higher high tides.
4. Going in means coming out eventually. You simply must have the time to wait it out to avoid making a mistake.
5. Speaking of giving your self time, one of the issues with BDS and going in is anyone approaching from the north do so from Chiapas which is over 200 nms away. The urge to listen to the pilot/Bill and believe them must be overwhelming when a slip and cold beer with swimming pool is just 10 mins away and the alternative is not great. You simply must not put yourself in that type of decision matrix if you can at all help it. I don't know Mark on Rum Truffle, but he was clearly hesitant about going in and he went anyway, a decision I'm sure he regrets more than any other in his life. He didn't have great alternatives.
Bottom line is BDS is not for me. But the lessons learned are deeper than that.
Good discussion.
Peter