More trouble for the Duck Boat.

[MossRoad]

I did, and IMO as an automotove engineer and a boat guy, it was way off base. Boats commonly have exhausts that exit below the water. In the case of these ducks, what they have done is bring the exhaust out through the hull high, and then pipe it down to the waterline, likely to keep the engine a bit quieter for passengers. The exhaust flow coming out is far more powerful than any wave action trying to follow backwards against the direction of travel and up into those exhaust outlets.


Wave action isn't going to stall the motor. It'll keep chugging happily along, just like my little Mercruiser, which runs happily with the exhaust exit well below the water line, and more than 4' below if I come to an abrupt stop. Heck, at that point, the top of the engine is better than a foot under, and it still runs happily. Same with my Jeep, which certainly isn't at risk of stalling simply because the tailpipe is underwater.

It may also be relevant to point out that although these ducks are based on the DUKW from WW2, they have been extensively modified. My understanding is that they are longer, and that the payload has been increased over the WW2 version. It also appears that they may have less freeboard, though that may simply be due to seeing DUKW's operated with light loads, while ducks are commonly operated very near capacity.

In the picture that BCP posted, you can clearly see the hood that I was talking about being propped up. In heavy seas, that's a water scoop. I still suspect that may have been a large part of the problem, especially since one boat negotiated the same heavy seas without sinking, or even taking on water as far as we know...

It is interesting to note that the thing that got the original DUKW program approved was using a prototype to rescue stranded sailors in very heavy seas.

Boat exhaust from inboard gas engines generally have an upturn in them at least a foot above the waterline, and the exhaust then exits at the waterline, not below the waterline. Did the DUKW that sank have this?

 

[1stDeuce]

Boat exhaust from inboard gas engines generally have an upturn in them at least a foot above the waterline, and the exhaust then exits at the waterline, not below the waterline. Did the DUKW that sank have this?

Yes. The exhaust exits the hull at the top of the tubes shown in the pictures, and blows out the bottom. The top of those tubes is probably 2' above the normal waterline, which compares well to a normal boat's upturn. Even if submerged, so long as the engine was running, water will not backflow and create issues. With the engine off for a long enough time, and the nose completely submerged, you MIGHT eventually get the exhaust to fill with water and get to the engine, but that's not related to anything that went on, and at that point, you're already fubar.

Look at that hood again... Big water scoop if it isn't sealing well. It almost appears that it can be raised and lowered remotely. Hopefully it wasn't something so simple as the driver or captain not noticing that it was still open...

 

[MossRoad]

Yep. That would be awful.

 

[Sigarms]

Life jackets are not always a life saver. In some circumstances they can kill you.

In the sailing community there is a great debate, that will not, and cannot be "won," over which is better/safer, automatic inflating life jackets or manual inflating life jackets. A self inflating life jacket has a good chance of saving a life if one is sent over the side of a boat which often happens when the sail boat is knocked down by a wave or has an unexpected gybe. When this happens there is a good chance the sailor would have a head injury and knocked out. A self inflating light jacket could save a life in those circumstances.

But, there always seems to be a but, in a capsize or knock down, which is going to be in heavy seas, the sailor is almost certainly going to be tethered to the boat. During a capsize the sailor is very likely to be trapped in the cabin or in the cockpit which is now over the sailors head. In this situation having an auto inflating PFD could get you killed since one will be pinned to the upturned boat. A manual inflating PFD would be better in this case. If the sailor is knocked out, well they are almost certainly going to die.

The sailor has to make a choice, flip a coin, etc., on what circumstances one would LIKELY find themselves in and pick the "correct" inflatable PFD.

In the case of the DUCK they had regular old PFDs, which in this accident, would be like having an auto inflating life jacket.

The key question to me is did the overhead structure on the DUCK trap people on the vessel? If so, the PFDs would not help the people but would in fact hinder their escape. On airplanes they tell you to put on the PFD, BUT DO NOT INFLATE it until you have gotten out of the aircraft.

Did that overhead structure meet Federal regulations and could people escape from under it? There are DUCKS in Dublin doing the same thing these DUCKS were doing. The Dublin DUCKS have an over head structure but from what I have seen it would be easy to swim off the DUCK if it started to sink. The Dublin DUCKS also appear to have the passengers wearing PFDs when the DUCK enters the water. I would be OK with wearing a PFD on a DUCK in Dublin based on what I saw, but on the DUCK that sank, I am not so sure. I have not seen a good photo of the top of the DUCK that sank, but from the photos I have seen, I would be concerned with wearing a normal PFD or an auto inflating PFD.

NTSB will answer the questions.

Later,
Dan

I've white water kayaked what some would consider to be some BIG water level rivers (on the east coast, the Upper Gauley is generally commercially run at 2-3k CFS and I've been on it over 10k, not to mention some insane runs at high levels in Idaho and Montana and Canada).

1- Life jacket will ALWAYS help you, not hurt you in moving water.
2 - although I have only sailed on a sail boat as a guest, and by no means know sailing in a body of water, I do know that you NEVER teather yourself to an object in MOVING water. You tie yourself onto something in moving water, you've just increased the odds that you will kill yourself.
3 - For a two bit ride on a duck boat, I highly doubt that the life jackets on the duck boat were auto inflating. Generally, auto inflating PFD's cost more money.

 

[Industrial Toys]

They probably came with the boat!

 

[k0ua]

The PFD's are not self inflating on the and they didn't "come with it in WWII" either

PICTURES: Sunken duck boat raised from Missouri lake

Note: the engine "hood" is NOT open. The PFD are evident, and the canvas top of the duck boat is opened up. Just when that happened I don't know.

 

[2LaneCruzer]

Was this unit manufactured for WWII or was it one of the newer models?

Good question; and I don't know the answer. My assumption was that it was one of the WWII vintage ducks. I was not aware that there were any manufactured after the war. In any case, it wouldn't make any difference, unless the safety standards had changed during that time. Still don't think the manufacturer had much to worry about.

 

[k0ua]

Good question; and I don't know the answer. My assumption was that it was one of the WWII vintage ducks. I was not aware that there were any manufactured after the war. In any case, it wouldn't make any difference, unless the safety standards had changed during that time. Still don't think the manufacturer had much to worry about.

One of the local TV stations reported it was an original WWII era DUKW. Whether that was true or not is anyone's guess.

 

[MossRoad]

Apparently, it was NOT a WWII era DUKW.

Read this entire article.... YIKES!

Branson duck boat: Amphibious vehicle designed by previous Ride the Ducks owner Robert McDowell - The Washington Post

 

[bcp]

The PFD's are not self inflating on the and they didn't "come with it in WWII" either

PICTURES: Sunken duck boat raised from Missouri lake

Note: the engine "hood" is NOT open. The PFD are evident, and the canvas top of the duck boat is opened up. Just when that happened I don't know.

Top view showing roof frame, from:

Lawsuit in fatal duck boat sinking seeks $1 million




Bruce