Coronial Inquiry-Sinking of Eliza 1

[psneeld]

There ARE methods to see "ballpark" ideas of your vessels stability. They are discussed in this thread.

Predicted stability goes out the window when your bilge is half full of water or a rogue wave slams you....so a clear "woobie blanket" is really never really available to calm one's fears at sea.

Unless your boat exceeds about every safety feature available like the military ships I have been on.

 

[Delta Riverat]

Ah, yes, the "flybridge test", good point.

During the sea trial part of the process, we had 6 people up on the fly. My wife and I, the Captain and his trainee, the surveyor and the broker. Had to be a thousand pounds.

No problem.

 

[sunchaser]

Ah, yes, the "flybridge test", good point.

During the sea trial part of the process, we had 6 people up on the fly. My wife and I, the Captain and his trainee, the surveyor and the broker. Had to be a thousand pounds.

No problem.

No problem? Did you head out under the Golden gate into 4-6’ beam seas? Boating fatalities due to an overloaded upper deck are all too common.

 

[SteveK]

Ah, yes, the "flybridge test", good point.

During the sea trial part of the process, we had 6 people up on the fly. My wife and I, the Captain and his trainee, the surveyor and the broker. Had to be a thousand pounds.

No problem.

No problem? Did you head out under the Golden gate into 4-6’ beam seas? Boating fatalities due to an overloaded upper deck are all too common.

Exactly! That would be a test.

 

[waltini]

My Stability Report

My 1986 48' timber trawler came with a stability report. The boat is a one off. 27 tonnes lightship.

A naval architect used the line drawings, 800kg in weights and a pendulum.

There are 10 pages of calculations. The test was done with all tanks pressed up and tank crossovers were closed. The weights were moved from side to side in different combinations and measurements of heel and draught were taken. Slack lines.

A calculation for wind, turning and free surface are included. There are four compartments and stability with one compartment flooded is included.

And in enclosed waters I can have 16 people on the flybridge with a further 28 on the main deck!

If anyone is interested in the calculations let me know.

 

[Serene]

There ARE methods to see "ballpark" ideas of your vessels stability. They are discussed in this thread.

[SNIP]

yes have read all of the posts and will be giving these ideas a try once the boat is back in the water.

 

[Jeff F]

The test was done with all tanks pressed up and tank crossovers were closed. The weights were moved from side to side in different combinations and measurements of heel and draught were taken. Slack lines.

That sounds like the same process I've observed for sailboats. I forgot to mention the measurements of draught. Weight is calculated by observing how high the boat floats on its lines.

Am I correct in assuming that roll period was not part of the measurement process?

 

[Tad Roberts]

Roll timing was really useful in the days before the PC and easily available hydrostatic software. It gives only a vague indication of stability characteristics, and is too crude to give a exact idea of the effect adding weight might have. If your roll time is 1-1.1 times the vessel's beam in metres, the boat is safe and will be reasonably comfortable in a sea.

So if your boat's beam is 12'6" and roll time (all the down on port to all the way down on starboard and back all the way down on port is one full roll) is 3.7 seconds, 12.5/3.28 = 3.81 metres / 3.7 seconds = .97 .....close enough to 1.

If the roll time is shorter the boat is stiffer, it rolls more quickly and will be safe but uncomfortable, most planing boats will fall into this category. If the roll time is much longer than the beam in metres there is cause for concern and stability should be more seriously investigated.

Stability cannot be seriously assessed visually, the "Complex calculations" must be done. This involves either finding a hull lines drawing for your boat, which can be impossible for older production boats, or having a naval architect measure the hull out of water, and create a new hull lines drawing/computer model. It also requires taking floatation measurements to establish the boat's operating displacement, and doing an inclining experiment to establish the vertical centre of gravity. The NA will use all this information, plus data on size and location of tanks and crew and stores and cargo (if any) to create a real stability study and then the ISO CE (Category A, B, C, or D) stability worksheets can be completed.

 

[rslifkin]

For the roll time test, do we care about overall beam or waterline beam? There can be a significant difference on some hulls with flared sides. My own boat has an overall beam of 14 feet at deck level, but it's only about 12.5 feet at the waterline (and both taper in about 1.5 feet from the widest point to the transom).

 

[PierreR]

Tad, thank you for that confirmation.
Is a full assessment cost effective for adding something like solar panels and weight on the flying bridge?

 

[Tad Roberts]

For the roll time test, do we care about overall beam or waterline beam? There can be a significant difference on some hulls with flared sides. My own boat has an overall beam of 14 feet at deck level, but it's only about 12.5 feet at the waterline (and both taper in about 1.5 feet from the widest point to the transom).

Obviously it will make a big difference if there's significant flair, with most boats it's not really a huge factor so max beam can be used. Again, the roll-timing is a crude approximation, but will give you a basic idea to work from. In The Nature Of Boats, Dave Gerr mentions using 111% of the waterline beam if the difference between beam on deck and beam waterline is more than 10% (of deck beam). I don't know where this comes from and it's another fudge factor introducing inaccuracy......

 

[Tad Roberts]

Tad, thank you for that confirmation.
Is a full assessment cost effective for adding something like solar panels and weight on the flying bridge?

This is a question of degree. If you are adding 1000 lbs up high on a 15,000 lb boat, that's a big deal.....On the other hand if you're adding 1000 lbs up high on a 65,000 lb boat, it will raise the VCG possibly an inch or two, changing the LPS (Limit of Positive Stability) perhaps by a few degrees.

Here's a study I did on adding a dinghy up high....
https://blog.tadroberts.ca/2016/05/change-in-stability-with-dinghy-aboard/

 

[Kit_L]

This is an extremely interesting thread. Going back a bit to p.2–3:

And also that the draft is 13' - it must have quite a keel compared to Eliza 1. Brokers........

Here is the yachthub ad:
https://yachthub.com/list/boats-for-sale/used/power-boats/halvorsen-44/304197

I requested images of that Halvorsen out of the water, because I did not believe the quoted draft figure of 13'.

Here are the images:

My guesstimate for draft is 5–6 feet. What do you think?

 

[Insequent]

This is an extremely interesting thread. Going back a bit to p.2–3:



Here is the yachthub ad:
https://yachthub.com/list/boats-for-sale/used/power-boats/halvorsen-44/304197

I requested images of that Halvorsen out of the water, because I did not believe the quoted draft figure of 13'.

Here are the images:

My guesstimate for draft is 5–6 feet. What do you think?

Instead of 13' they may have meant 1.3m. That would be approx.4'3", which is believable.

 

[SteveK]

I think the ladder in the picture is 8 feet. he guy beside boat is kneeled. My guess is about 6 foot draft, no way 13below water line. But maybe they were talking about air draft, that could be 13 feet without mast.

 

[Kit_L]

I did ask to clarify the draft figure with the broker, and he came back with the images AND confirmation of the 13 foot draft figure (confirmed, he said, by the owner). Well, after this thread, this one is off the 'new boat' list anyway!

 

[Jeff F]

Tad, thanks for your explanations. It all makes sense to me.

I'm curious about cost. If I have line drawings for my hull and am able to perform incline and freeboard measurement tests according to instructions it doesn't have to be expensive, does it? I understand that you don't want to certify anything based on someone else's measurements, but for me such an advisory service might be really attractive, and a no-brainer if low cost.

 

[Delta Riverat]

That hull bottom looks tender to me.

 

[Serene]

This is an extremely interesting thread. Going back a bit to p.2–3:



Here is the yachthub ad:
https://yachthub.com/list/boats-for-sale/used/power-boats/halvorsen-44/304197

I requested images of that Halvorsen out of the water, because I did not believe the quoted draft figure of 13'.

Here are the images:

My guesstimate for draft is 5–6 feet. What do you think?

Yes that us the ad. but I don't think the pics you posted are the same boat.

 

[Kit_L]

@Serene: I have looked at all the images again, and I think that you are right. The safety rails are different, and the portholes in the forward areas of the hull are nowhere to be seen in the additional images. Thanks for pointing this out. Nonetheless, that is what the broker sent me when I asked for underwater images of hull and running gear. The mystery deepens.

 

[Tad Roberts]

Tad, thanks for your explanations. It all makes sense to me.

I'm curious about cost. If I have line drawings for my hull and am able to perform incline and freeboard measurement tests according to instructions it doesn't have to be expensive, does it? I understand that you don't want to certify anything based on someone else's measurements, but for me such an advisory service might be really attractive, and a no-brainer if low cost.

I guess everyone has a different idea of what "expensive" might be, I don't think of it as cheap, but also it's not wildly expensive. If the owner provides an accurate hull lines drawing, inclining and floatation measurements, and tank size and location data, then it's down to some hours in front of a screen. The NA needs to first create a reasonably accurate hull model, with simple hulls this can take a few hours, more complex forms (say a complex multichine catamaran) will take longer. Then I would create a weight sheet with the various load conditions, full load, light ship, and arrival (10% tanks, full crew) conditions, then put it into a simple report. It would be a matter of a few thousand dollars, which in hindsight we could say would have been a good investment in the Eliza case.....

 

[BruceK]

@Serene: I have looked at all the images again, and I think that you are right. The safety rails are different, and the portholes in the forward areas of the hull are nowhere to be seen in the additional images. Thanks for pointing this out. Nonetheless, that is what the broker sent me when I asked for underwater images of hull and running gear. The mystery deepens.

Imagine 1 was enough to realise it was another boat seen on the hard. Others show a keel very different to a normal Halvorsen. The 44 must have spent quite some time out of the water after visiting Balmoral Beach, there must be pics of it.
FWIW, I wondered if the design deficiencies could have contributed to it breaking its mooring. Bad weather and unexpected underwater wear can cause failure, but so can loading. Boats do best on a bow mooring sitting up in the traditional way.

 

[Serene]

It made the ABC News back in September;

https://www.abc.net.au/news/2023-09...tandards-dropped-halvorsen-cruisers/102851608

 

[Serene]

Here is a short video of the salvage;

https://www.facebook.com/mosmancoll...rsen-peta-emma-makes-it-to-t/175556293748623/

If you watch closely you can even see the crane knock the mast off!

 

[Kit_L]

Wow: just wow. I will be interested to see what happens with both the seller and the broker—the broker has not replied to my request for him to confirm that the Halvorsen for sale in the link above is, in fact, the repaired Peta Emma. Now we know for sure it is. It was sold as scrap, and re-birthed. Very disappointing.

 

[Serene]

Wow: just wow. I will be interested to see what happens with both the seller and the broker—the broker has not replied to my request for him to confirm that the Halvorsen for sale in the link above is, in fact, the repaired Peta Emma. Now we know for sure it is. It was sold as scrap, and re-birthed. Very disappointing.

If you look at the sixth photo in the ad. you can see the name on the transom;

https://yachthub.com/list/boats-for-sale/used/power-boats/halvorsen-44/304197

 

[Kit_L]

Well spotted. I just hope any potential buyer is a member here.

 

[Delta Riverat]

If the Broker pics are real (not before) whoever did the refit is pretty good.

 

[Hippocampus]

Most of us are on SD boats. As such they are mostly dependent upon form stability for their static stability. Their stability improves slightly with forward motion due to dynamic stability effects. However for capsize risk and recovery one needs to assess the entire Gz curve. Any roll timing test that’s even remotely doable only addresses initial stability.

The Gz curve gives you the AVS (angle of vanishing stability) but also allows you to see the area under null. This will determine the speed it will take the vessel to recover if inverted totally or even partially. For ocean going vessels that area of negativity should be as small as possible and for small boats generally a AVS greater than 120 degrees is required to enter ocean races.

Righting arm is achieved by form stability or weight under the waterplane. Weight must be greater than 65 lbs per square foot so denser than seawater to contribute significantly . The arm for weight is distance x weight. Hence the use of bulbs on sailboat keels. Weight offset from axial midline may improve comfort (how roll tanks work) if opposite direction of roll direction but if symmetrical and not substantially below waterplane contributes poorly to improve the Gz curve and may cause detriment. For the boats we are on the additional risk is downflooding. Few of our boats won’t downflood at angles as low as 30 to 45 degrees. Between that and dependency on form stability they will not be stable at very modest angles of heel.
Some designs for FD boats place engine room air intakes and exhausts to allow decent heel angles without downflooding occurring. Some place engines, batteries and other heavy components below the waterplane and as far down as possible to improve righting arm and decrease negative area in the Gz. They also add dense ballast as low down as feasible. They also remove what weight possible above the waterplane . What weight that remains is kept as close as possible to the waterplane.
Weight above the waterline may and usually does improve comfort as the inertia of that weight decreases snap roll. But it’s detrimental to static stability.
Similarly all forms of comfort stabilization (fins, fish, gyros, Magnus) have NO effects to improve the AVS nor Gz. They are just for comfort. They may have a modest initial effect on dynamic stability if stability is not significantly stressed.
My boat (and most SD recreational trawlers) have a limit on weight allowed on the flybridge . For me it’s clearly posted at the steps up to it. Most boas also have weight restriction on what weight is allowed on the boat deck. With a set of solar panels we have our dinghy on a freedom lift as to not contribute significantly to further instability.
Much of the posts above speak to initial static stability. Although of interest for comfort it’s of little importance to risk of downflooding, knockdown or inversion or sinking.

 

[BruceK]

If you look at the sixth photo in the ad. you can see the name on the transom;

https://yachthub.com/list/boats-for-sale/used/power-boats/halvorsen-44/304197

Doesn`t seem there was any attempt to disguise the name, it was openly referred to by the Coroner by name. One task for his staff was notifying its broker and owner of the Findings so they might consider their position.
The immediate clue something had happened to it was 22 hours on the rebuilt Cummins engine and the new Onan genset still under warranty.
My (?reliable/unreliable)TF memory is that Eliza 1 was purchased(and resold)by a TF member, who posted first in joy and later in great disappointment.