Sailing Visitors Blown Away By Help

[arsenelupiga]

Originally Posted by daletournier

Is the hull in that area balsa or solid glass, I assuming balsa? Sorry if this has already been answered.

i checked for you: not easy access at that point but with mirror I managed to see where balsa starts and I believe balsa starts above that level.

boat holed at that point should not sink. as front water tight compartment and engine room provide support.

However there are 2 tubes leading to bilge pump and factory default is access to front is closed, access to engine room is open. I suspect water flew back from bilge into engine room thru that tube and filled engine room with water and then this water reached other engine room. Not easy to remember to close after scary hole nearby, high winds other boats and probably already lots of water ingress.

[tuskie]

Originally Posted by arsenelupiga

However there are 2 tubes leading to bilge pump and factory default is access to front is closed, access to engine room is open. I suspect water flew back from bilge into engine room thru that tube and filled engine room with water and then this water reached other engine room. Not easy to remember to close after scary hole nearby, high winds other boats and probably already lots of water ingress.

I agree that this is probably what occurred. I'm sure that the owner had other priorities when the damage happened rather than shutting the valves on the tubes that connect engine compartment to the central bilge area.

It would have probably been far better to have these valves closed, so that water could not enter the engine compartment from the flooded central hull. Alternatively, a non-return valve could be fitted, but these are prone to blockage. The best solution IMHO, is to permanently seal off the engine compartments and fit separate automatic bilge pumps in each one. This arrangement is not done by Lagoon and many other CE certified yachts because EU pollution control rules forbid it. It seems an obvious improvement that I shall make to my Australian registered Lagoon in the light of this event.

[JPA Cate]

^^^^^
Great idea, tuskie.

Ann

[44'cruisingcat]

So CE certification results in a boat being more likely to sink. Nice.

Actually, on reflection, I recall it being illegal to leave bilge pumps on " auto" in marinas, due to the possibility of oil being pumped out. Disregarding the amounts of oil, fuel, battery acid etc that could be discharged if boats sank as a result.

[fxykty]

Originally Posted by tuskie

I agree that this is probably what occurred. I'm sure that the owner had other priorities when the damage happened rather than shutting the valves on the tubes that connect engine compartment to the central bilge area.



It would have probably been far better to have these valves closed, so that water could not enter the engine compartment from the flooded central hull. Alternatively, a non-return valve could be fitted, but these are prone to blockage. The best solution IMHO, is to permanently seal off the engine compartments and fit separate automatic bilge pumps in each one. This arrangement is not done by Lagoon and many other CE certified yachts because EU pollution control rules forbid it. It seems an obvious improvement that I shall make to my Australian registered Lagoon in the light of this event.

If the engine rooms are aft of the last bulkhead in the habitable spaces then yes, no reason not to have them completely sealed and with their own bilge pumps. That’s exactly how my French built cat is arranged. But I guess it was outfitted prior to EU pollution rules about pumping engine bilges?

But a boat that has the engines under the rear berths or otherwise inside the habitable spaces is not going to be able to create a sealed area. Especially if as with Felix the design of the steering and/or engine controls is such that one hull is connected to the other. On the other hand, aren’t there still void spaces or compartments right aft? I guess not, as the photo shows the boat completely down by the sterns.

Regarding flotation, as others have rightly pointed out, the point of the flotation, typically in the bridgedeck and/or main beams, is to keep the boat afloat as a rescue platform, whether inverted or not. Right side up, the salon is a much nicer space than a liferaft, even with water sloshing up from the hulls or from outside. The guys in the Kimberly grounding were certainly able to live in their salon for some amount of time with a lot more supplies and safety than in a dinghy or life raft.

Inverted, the bottom of the bridgedeck is awash and the escape hatches provide access to the mostly empty hulls. I’m guessing that pulling the mattresses from their berths and placing them on the ceilings will be enough to get above the water level. Still a better home than a life raft. The key for comfort would be to close the salon door to keep waves from surging through.

I hope I never have to verify these assumptions in real life.

[Paul L]

It was the belief of the owner that the engine room was a sealed bulkhead and that the water ran over the steering cable run between the hulls. It did not look like there was much flotation coming from the stern, so the bulkhead may not have been water tight as expected. Clearly the forward sealed bulkhead did its job.

[tuskie]

Originally Posted by Paul L

It was the belief of the owner that the engine room was a sealed bulkhead and that the water ran over the steering cable run between the hulls. It did not look like there was much flotation coming from the stern, so the bulkhead may not have been water tight as expected. Clearly the forward sealed bulkhead did its job.

Arsenelupiga and I have described the standard Lagoon 400 bilge pump set up. That is; tubes connecting the forward and aft compartments to the bilge areas of the hull centres. These tubes are sized to prevent bilge pumps being overwhelmed by water flow from these compartments and are fitted with shut off valves in the bilge area. It is normally the fore and aft sections of hulls that sustain damage leading to water ingress. The central bilges in each hull is fitted with an automatic and a manual bilge pump.

"Felix" may have been altered from original. Owners may not have understood the set up and hence, how it should have been operated. In standard configuration, water level in engine compartment of a L400 would need to be approximately 1 metre deep before it would flow across to the other hull. By then the bridgedeck is "uphill".

Until the photos of the damage were posted, it wasn't clear whether the water in the engine compartments came from a breach in the hull in this area or from back flow through the open valves of the connection tube. From the limited photos we are guessing and speculating that it was the latter. Guesswork and speculation is often proven wrong.

[Paul L]

Tuskie
Not sure your description contradicts what I heard. The question I asked was how did the water get from the starboard hull to the port hull. And the answer was through the steering cable area that connects both sides. Does this channel connect the engine compartment or the center hulls?

[tuskie]

Originally Posted by Paul L

Tuskie
Not sure your description contradicts what I heard. The question I asked was how did the water get from the starboard hull to the port hull. And the answer was through the steering cable area that connects both sides. Does this channel connect the engine compartment or the center hulls?

No contradiction, Paul. And BTW, thanks for your informative posts.

The steering cable and the aluminium rudder stock connection bar runs on top of the bridgedeck, just below aft deck level. As previously mentioned, water must be quite deep before spilling over. There are numerous athwartships connections in the Lagoon 400. There seems to be no design or construction attempt to make watertight separation between hulls on top of the bridgedeck. I'm not sure if any other designs or makers do this differently.

A possible senario could be. (Speculation warning!) Large hole below waterline in centre of starboard hull allowing the hull central section to flood. The bilge pumps overwhelmed, connection tubes with open valves to engine compartment allowing water to enter and fill starboard engine compartment . Loss of bouyancy in aft section allows water to flow over bridgedeck to enter and fill port engine compartment. Water then flows through port bilge connection tube (valve open) into port central hull section. Because vessel by now has a severe aft down attitude, quite a volume of water lies against port aft bulkhead before water level rises to port bilge pumps. Automatic bilge pumps no longer operate due to battery bank under aft rear bunk flooding. Vessel relies on bouyancy remaining in unflooded central hull sections and bow compartments to stay afloat.

Closed valves on tubes to engine compartments could hypothetically have prevented engine compartments on each side flooding. This bouyancy would have ensured a starboard listing but higher and much more level floatation.

[arsenelupiga]

see pic of underside, water has to reach dotted area for water to flood left hull. I would say this happens when right hull is already fully submerged.

Based on this experience I will close tube connecting engine room and bilge and add flooding alarm to engine room and also bow compartment. Thinking of buying powerful pump that runs on portable generator - this feels more flexible and usable.

[daletournier]

Originally Posted by 44'cruisingcat

So CE certification results in a boat being more likely to sink. Nice.

Actually, on reflection, I recall it being illegal to leave bilge pumps on " auto" in marinas, due to the possibility of oil being pumped out. Disregarding the amounts of oil, fuel, battery acid etc that could be discharged if boats sank as a result.

If that's true it's just stupid. These new rule pumps that can sense oil in your bilge and won't turn on are just as crazy.
I had dripless seal start leaking badly on my last boat. I was by myself motoring down the malacca straight and that stupid thing wouldn't operate properly, I spend 48 hrs sleep deprived because I had to activate the pump manually every 30mins. It turned out it was a slight oil coating on the sensor.
As you said if I'd sunk there would be alot more oil in the water.

[Seaslug Caravan]

Originally Posted by arsenelupiga

see pic of underside, water has to reach dotted area for water to flood left hull. I would say this happens when right hull is already fully submerged.

Based on this experience I will close tube connecting engine room and bilge and add flooding alarm to engine room and also bow compartment. Thinking of buying powerful pump that runs on portable generator - this feels more flexible and usable.

So to make this perfectly clear, is there only one bilge pump servicing the supposedly isolated Engine Room, Accommodation, and forward collision void spaces?

Is this correct?

[tuskie]

Yeah, but then again many of us have been to places and worked on boats where it is common practice to drain engine oil into the bilge and pump it overboard. If it wasn't for such there would be no need for these "crazy" rules.

[Paul L]

Originally Posted by tuskie

No contradiction, Paul. And BTW, thanks for your informative posts.

The steering cable and the aluminium rudder stock connection bar runs on top of the bridgedeck, just below aft deck level. As previously mentioned, water must be quite deep before spilling over. There are numerous athwartships connections in the Lagoon 400. There seems to be no design or construction attempt to make watertight separation between hulls on top of the bridgedeck. I'm not sure if any other designs or makers do this differently.

A possible senario could be. (Speculation warning!) Large hole below waterline in centre of starboard hull allowing the hull central section to flood. The bilge pumps overwhelmed, connection tubes with open valves to engine compartment allowing water to enter and fill starboard engine compartment . Loss of bouyancy in aft section allows water to flow over bridgedeck to enter and fill port engine compartment. Water then flows through port bilge connection tube (valve open) into port central hull section. Because vessel by now has a severe aft down attitude, quite a volume of water lies against port aft bulkhead before water level rises to port bilge pumps. Automatic bilge pumps no longer operate due to battery bank under aft rear bunk flooding. Vessel relies on bouyancy remaining in unflooded central hull sections and bow compartments to stay afloat.

Closed valves on tubes to engine compartments could hypothetically have prevented engine compartments on each side flooding. This bouyancy would have ensured a starboard listing but higher and much more level floatation.

One thing that was really odd and unexplained was the way the boat dewatered. The bows were pushed up on the sand, but the forward end of the keels were just touching the drop off. (The beach looks like a gentle slope, but the water in front had been dredged.) The starboard hole had been stuffed with foam footballs and plugs, plus an unsuccessful attempt to use underwater putty. Two petrol crash pumps were put into the port forward hatches. As the water was pumped out of the port hull the starboard hull started to rise while the port hull fell. It just kept going down for a long time, maybe dropped .75m or more. It didn't make sense as the pumps were on the port hull and the starboard hull came up relatively quickly. Eventually the starboard hull started to come up. Once it was up fairly far, a front-end loader was tied to the cross bar and the boat was pulled up to the high tide line.

[tuskie]

Originally Posted by Seaslug Caravan

So to make this perfectly clear, is there only one bilge pump servicing the supposedly isolated Engine Room, Accommodation, and forward collision void spaces?

Is this correct?

No, two. But both in central bilge area of each hull. Explained in post#84