46' Post SF Sinks

HELLO!!!! Black Cloud indeed....why didn't he just name the boat "Please Sink On Me" or "Lucky No. 13" or "Unsinkable Molly"...I know there's more, Oh yeah "Davey Jones Locker" C'mon guys help me out here.

O.K. I feel bad for the guy, but better to sink at the dock than 20 miles offshore. I'd be willing to bet when his insurance agent hands over a check the conversation goes something like this, "Jim, I'm really sorry that this happened, but once you get her fixed up, you might want to re-think the name."

That looks like it's been stress cracked a long time.....almost like it was damaged previously from a poor winterization or something.....

I agree Capt J, that was years in the making, the serrated edges clearly make that case, if it was a back pressure explosion it would have been a much cleaner hole, that is a fatigued piece of pipe.

Looking at the pictures, I can't honestly say it was a long-standing problem or not, but the loud bang and "2 minutes" between up and down indicates a catastrophic failure whether there was a fault or not. This is scary stuff, and it seems indefensible against, except at the design stage. We all have plans in the backs of our heads for holes, but they all will take a few minutes to impliment. This indicates the possibility of an achilies heal that could exist on a lot of boats. I'd be curious to hear the opinion of some designers (NAs). In the mean time this indicates the clear need for an EPIRB and to keep your PFDs readily accessible.

Sure looks like a failed seam at the bottom.

Starting fluid ??

That's some hole! I keep a couple of mustang jackets on the back of my helm chairs just in case I have to go in the water in a hurry. I figure by the time I get them out from under some seat, etc. I'm already floating?

Still does not explain the "BANG "

My Wife and I have our personal life preservers on the bridge with us.
Not stowed but loose on the seat right with us.
Attached to each is a plastic whistle and a personal strobe light.

Any maintenance work done to the cooling system prior to the big bang ?

Marmot, Did you get my PM?

My theory is the exhaust was weak noticed by the old stress cracking on the inside of it. Something had floated into the exhaust causing excessive back pressure (dead animal, coconut, etc.). When the engine started there was excessive back pressure, and the bang was the side of the muffler exploding. There was no way a piece like that blew off without creating a bang noise.....sort of like when you fill a plastic bag or ballon with air and then smash it cause it to explode.

So re-reading the OP, this event occurred shortly after launch and preparing for a sea trial. Wonder when the last start up occurred. {later post says a few days earlier?} Was the boat stored on land or in the water, previously? Not an engineer, but that looks like an inside to outside failure. What else other than back pressure can do that? If it were in the water for a while, you'd think, ok, the engines hadn't been started for a while so something went up the exhaust and clogged it. On the other hand the boat had just been launched a few days earlier or at least started a few days earlier. How did they move it to the slip, if they did? No answers, just questions from here.

Tight set of facts, but theoretically possible. Interesting question about the diesel gen exhaust, if thru the same "hole" does that increase the back pressure theory possibility? Hope Jimbo can get us some more info....

"within in seconds they heard a loud bang". Doesn't sound like you'd have hot anything, much less "near flame". Back pressure makes the most sense.