Yacht Serena III sinks off Ft. Lauderdale

So does ABS. The rules for yachts follow the "standard" IACS wording that the stabilizer be fitted in a watertight compartment or if damaged cannot lead to flooding of auxiliaries or other necessary equipment or create progressive flooding.

If they tore a hole in the side because a stabilizer failed to shear off then it was their boat to lose ... they should have been able to contain the flooding to the single compartment. That might have gained them time to receive salvage assistance.

But ain't nobody talking ... as is usual in these affairs.

Yes but it does project out the side where you could clip something coming off the bottom or the side of a sloping channel.

One crew talked but still makes no sense. Thx for the insight above.

That doesn't look like a stabilizer fin to me to small, wrong angle; even yet from that angle does it doesn't look like it is beyond the hull side. I agree with Bill that finding one extending beyond the keel of an 11' draft boat is extremely unlikely. Think about how these things work; down low and close to the bottom (which means close to the centerline of the boat) makes them less effective. Now that certainly doesn't mean one can't hit something protruding in it's path, including an underwater ledge or channelside. I know this from personal scientific testing.. don't ask me how!

How large would the shaft be for the stabilizer fin? You would think the crew would notice the handling getting "sluggish" Sad to see a relatively new boat go to the bottom.

Here's an example of a stabilizer fin extending beyond the hull side:

That one could be knocked pretty hard and easily in that position if you were to pass a coral bombie or rock too close.

A Composite fin could be made to shatter but I have not seen any of those offered to my projects so far.

Most folks who operate vessels with Stabs manage to do so without any major life threatening incidents so it might not be a popular item even if available.

What should it look like? Considering those fins were designed and spec'd for satisfactory performance on that boat by people who "know big boats" it is a bit disingenuous to make the claim that they are too small and at the wrong angle.

There is a relationship between fin size, vessel speed, rudder size and power and the interaction between all those factors. A rudder alone can be used for roll stabilization but it is not very effective and creates a whole new world of issues so it is not common to find the rudder as part of the roll control system.

A fin sticking straight down would control roll but would also increase draft all out of proportion to the benefit. The angle fins are fitted is often related to the side clearance, some boats that use retractable fins place them parallel to the water surface, stick far out from the side, and work quite well, just as well as those at some angle intended keep them withing the box defined by draft and breadth.

Back to the topic, Serena was built by a commercial yard in Brazil that builds steel commercial vessels and small (up to 10m) composite recreational boats. It is fairly safe to assume the boat was steel and if they used fin stabilizers from the usual suppliers and they were fitted in compliance with class rules and manufacturer's recommendations, it is extremely unlikely that grounding a fin hard enough to hole the boat would have gone unnoticed by the crew or passengers.

I have seen a lot of fins damaged by grounding, groundings that were immediately and painfully obvious to all on board. Those fins were bent, broken, de-skinned, and/or shattered but none of them tore a hole in the hull or ripped the shaft from the actuator to leave a shaft sized hole open to the sea. It is very easy and fairly common to hit a fin and nothing else, docks, dredged channels, and coral heads are the usual suspects. Resting on a fin as the tide falls is another issue that may damage a fin (they are designed to fail - they are sacrificial to save the hull) but that doesn't sink the boat either.

Regardless of what the mate said might have happened, there is a lot more to this story.

This one broke off fairly cleanly. I need to dig through my pic files, there are a few showing fins that look like fish skeletons from the composites failing when the fin structure flexed during a grounding ... a grounding that everyone on board knew instantly but did not hole the boat.

"...I have seen a lot of fins damaged by grounding, groundings that were immediately and painfully obvious to all on board. Those fins were bent, broken, de-skinned, and/or shattered but none of them tore a hole in the hull or ripped the shaft from the actuator to leave a shaft sized hole open to the sea..."


The captain of this 61' steel trawler said he didn't know he hit something. He also didn't know how the razor blade marks got on the lucite cocktail table either. No water entry into the hull.

Is there any hint as to recent maintenance performed on vessel?

Larger boats don't normally have little DC bilge pumps in each compartment, there is a bilge system that uses one or more high capacity pumps drawing suction through a bilge manifold with separate suction valves and lines to strum boxes in each compartment. The bilge pump system can normally be cross connected to make it a "fire and bilge" system with the pumps taking a suction from sea to discharge into the fire main.

Surely you are not suggesting ...

Of course another cause may have been the boat reached a speed that simply ripped the fin apart!

This is true that they don't have automatic pumps, although many times there still is a high water alarm for each compartment on the larger boats. On larger yachts I've seen a few compartments which are a bear to visually inspect them, hidden under carpet/padding/hatch in a stateroom. I kind of don't know why they don't utilize a Rule 4700 in at least a few of these compartments with float switches.

I've also seen on some yachts and commercial boats where these pumps and manifold have been located in the engine room, so in some cases of fire or flooding, you can't access them without compromising the rest of the boat.

Ripping the stabilizer fin apart would not let water in. Now if the shaft for the fin got ripped out of the hull absolutely would sacrifice the vessel.

Now I can't understand how the Captain didn't notice anything in the running attitude of the boat or feel of it during this episode. No high water alarms going off. I cannot understand with 7 crew on a boat of this size, how nobody could find the problem before it became a major one, and how they couldn't mitigate it. Although a 6-8" hole from a stabilizer fin might've been pretty hard to stuff stuff in and have it stay there.....

I was on a seatrial on a larger Hatteras MY years ago with an extension and one of the rudders fell out and the surveyor sat on top of the rudder post stopping the flow of water as we went to the yard. LOLOLOL

Where do you suggest this pump discharge?

It is the rare boat that size that does not have the bilge pumps and manifold in the engine room. Larger boats might have an auxiliary machinery space with the pumps but even 60m boats typically have the fire and bilge pumps in the engine room.

I don't think anyone suggested such a thing.

The only place a bilge alarm is required is in the space with the bilge pump and fire pump. The bilge pump can be automatic with the high water alarm but it is not required.

It is very easy to understand. It is not "nice" to say why but examples abound.

If by some phenomenal impact or bizarre circumstance the fin shaft was pulled out, the hole it would leave on a boat that size is probably 3 or 3.5 inches and certainly not more than 4.

"Bigger" boats in the 80-130' range which this one falls into will typically have automatic pumps with a backup pump that has a central manifold, as well as a manual hand operated pump. The backup pump manifold is usually located in the engine room or a separate machinery space, typically it consists of 2 electric pumps that can also be used for fire fighting. The main engines will also normally be fitted with "crash pumps". Close the seacocks, turn a valve and then the main engine raw water intakes can be used to dewater the engine room bilge.

Not sure if it's a RINA certification requirement , but most of these vessels also have a portable gasoline powered emergency pump.

Take with a liberal grain of salt, going by what I've seen over the last 20 years.

On our 130', we have 13 automatic bilge pumps, float switches and alarms. Minimum of two in every bulkhead section. Then we have two emergency pumps (plus one backup) with lines to each compartment. And then we have an emergency engine driven pump. I may not have it all exactly right, but something like that.

In addition to meeting standards that wouldn't allow a stabilizer to compromise things you also have some form or forms of emergency repair kits, the biggest challenge being the pressure of water inflow.

I would suggest that the electric bilge pumps, discharge overboard just like they do on smaller yachts, perhaps with a check valve and seacock at the thru-hull.

The only bilge alarm required may very well be in the engine room, but it would be completely foolish not to have high water alarms in every compartment or at least in the lazarette compartment which would be most prone to flooding. A lot of the yachts 90-120' that I have run have both had high water alarms for most if not every compartment and also have had electric pumps added with a seacock and check valve at their thru-hull discharge. Larger than 120' that I've worked on....160-172' have also had an alarm system for every bilge compartment.

I also worked on a 160' MY that when it was virtually new, the 4" a/c discharge pipe broke off and it destroyed everything in the engine room and a lot of the rest of the lower level of the boat.

It's also foolish IMO to have your only bilge pumping capabilities in the engine room. There should be a secondary source of pumping bilges outside of the engine room. I like redundancy. If the engine room is flooding you might not be able to get into it without flooding the rest of the boat via the engine room door. If there's a fire in the engine room, and many other scenario's.

Now I have run some yachts (made from commercial boats) and commercial boats 80-110', that had no automatic pumping. They had a large bilge pump, and a manifold of valves of where to suck from. They also had a fire pump that you could use on this manifold in place of the bilge pump, and they had a crash pump on one engine that could also be valved to pump out the various bilges, but it was all manually activated and valved, and all in the engine room.

This was an expedition type yacht with 11' draft, I would imagine it had large stabilizers. A 4" hole will flow 700 GALLONS PER MINUTE or even a lot more. That would sink a yacht pretty quick if it can't be stopped.

A crew of 7, someone should've been wandering around and noticed water, or the boat riding funny or handling funny. Something.