Coronial Inquiry-Sinking of Eliza 1

[PierreR]

Actually, the roll test is most useful for when you have an unknown boat, not the other way around where you have design information. The roll test can tell you quite a bit about capsize risk and is used for that purpose when adding weight up high in a boat.
In thinking more about the roll test, I realized that the roll test results mean a whole lot more to someone knowledgeable about boat design. I may be assuming more simplicity in the test than I actually use.
When I first look at a boat, I want to know what was going on inside the head of the boat's designer. When I see a boat that is designed to a purpose and everything fits throughout the boat, I know that I am probably dealing with a tried and true naval architect and a good builder. If I see a boat with some things pointing towards one purpose and other systems aiming at another purpose I know I am likely dealing with a boat that has been altered by previous owners, the marketing department or the bean counters and I am skeptical of what that means for stability and fit for purpose. All boats are a big compromise designed for a purpose. some people just cannot live with some of those compromises and can't help but alter the boat to suit there dreams. If you cannot live with design compromises, you have the wrong boat, go buy the right boat.
Armed with some knowledge, I know pretty much where the stability curves should be and what to expect from a properly done roll test. On an unknown boat, I will put more faith in the roll test, than I will in original stability numbers when dealing with significant alterations. That is especially true for ultimate stability. If I am dealing with a boat I know is designed with high initial stability and low ultimate stability I am going to be erring on the side of faster roll rates than the comfortable 1:1 ratio. Its not easy to do a good roll test on a big boat with high initial stability. If I am dealing with a high D/L ratio deep draft boat intended for offshore work, I am going to be looking for numbers much slower in roll rate but probably not exceeding a 1:1.15 ratio.
One of the big draws for me to my present boat, was a lack of many alterations. Few alterations also meant a lack of updating, but that I can handle. At least most people on this forum are aware of the fact that they can screw up their boats with alterations. I have seen some beautiful boats destroyed by more money than common sense.

In the case of the boat in the report that capsized in Australia, you have a naval architect being paid to convince a bunch of laymen who are deciding a case. A simple roll test would be about as convincing in the court room as it is here in the forum. By the naval architects own words I don't think he got any better information than he could have with a simple roll test.

 

[sunchaser]

One also should consider the impact to stability when lead acid batteries are replaces with lighter LiFePo batteries. Use LifePo, add a bunch of solar panels up high....

Later,
Dan

This is a very smart post.

 

[Delta Riverat]

Went to the boat today and did a number of "steps on and off"

From what I saw when I stepped on and it went down and then back up, down to up was a second. Which seems to be the period of the oscillation. 230 pounds of me on a 7.5 foot lever arm (15 foot beam) took the boat down an inch.

I'm feeling confident. Half the beam at water line about 2 meters and 1 second period.

 

[Jeff F]

Armed with some knowledge, I know pretty much where the stability curves should be and what to expect from a properly done roll test. On an unknown boat, I will put more faith in the roll test, than I will in original stability numbers when dealing with significant alterations. That is especially true for ultimate stability. If I am dealing with a boat I know is designed with high initial stability and low ultimate stability I am going to be erring on the side of faster roll rates than the comfortable 1:1 ratio. Its not easy to do a good roll test on a big boat with high initial stability. If I am dealing with a high D/L ratio deep draft boat intended for offshore work, I am going to be looking for numbers much slower in roll rate but probably not exceeding a 1:1.15 ratio.

It sounds like you're gathering information about the boat's design in order to determine what an appropriate roll rate should be using your judgement and experience. I get what you're saying and appreciate your perspective.

But if you tell me that boat A has a roll rate of 1.1 and boat B has a roll rate of 1.0 the only thing I know without additional details is that boat A is going to have a less snappy ride. Without further details I don't think I can assume that one is more likely to capsize than the other.

 

[psneeld]

It sounds like you're gathering information about the boat's design in order to determine what an appropriate roll rate should be using your judgement and experience. I get what you're saying and appreciate your perspective.

But if you tell me that boat A has a roll rate of 1.1 and boat B has a roll rate of 1.0 the only thing I know without additional details is that boat A is going to have a less snappy ride. Without further details I don't think I can assume that one is more likely to capsize than the other.

It may not be as useful in 2 different boats, but I believe for the same boat or similarly designed boat hulls, it does point you in a direction.

Both conditions are easily noticed in the roll period and are telling you a lot about stability...but yes limited without some knowledge of the boats design or the delta in roll rate change.

Thus my previous comments that vessels used in icing conditions start trying to rid the upper decks and superstructures of ice when their "roll" becomes longer. It's an old rule of thumb for many.

Also a previous comment I made was free surface effect and how many inexperienced/clueless boaters drive around and never notice the "new" feeling of the boat. Until something happens, then they pullup the floor boards and are "shocked" at the amount of water down there.

 

[PierreR]

Went to the boat today and did a number of "steps on and off"

From what I saw when I stepped on and it went down and then back up, down to up was a second. Which seems to be the period of the oscillation. 230 pounds of me on a 7.5 foot lever arm (15 foot beam) took the boat down an inch.

I'm feeling confident. Half the beam at water line about 2 meters and 1 second period.

For a good test you need to get the boat rolling 20 degrees or more then average three tests in a row. The lines need to be very slack. On a boat your size it might take two people to do the test. It is a simple test but not necessarily easy.
Stepping on and off a few time is only testing initial stability.

 

[Nick F]

From what I saw when I stepped on and it went down and then back up, down to up was a second. Which seems to be the period of the oscillation.

Excuse me, but this is only half the period of roll.

The period is the time taken for a FULL cycle - that is, down to up and then to down again.

 

[psneeld]

I would hope a 44 foot trawler wouldn't roll 20 or more degrees with only 2 people stepping on a gunnel. A bit rusty thinking through this.... but wouldn't that take the gunnel dropping almost 2.7 feet?

Think that will take a bit of thinking to get that much weight on and off the boat quickly enough to make an accurate 20 degree roll.

 

[PierreR]

One also should consider the impact to stability when lead acid batteries are replaces with lighter LiFePo batteries. Use LifePo, add a bunch of solar panels up high....

Later,
Dan

This is a good point and one I have not fully addressed yet. In my case, initial stability, roll rate and ultimate stability are very big considerations. Stability in my boat is not easy to address. My wife is very balance challenged and not very strong. A quick snappy roll is far more dangerous for my wife than a comfy 1:1 beam to time ratio.
The problem is that I have an LRC with a huge range and fuel load. I have two main tanks outboard and forward of the engines totaling 360 gallons and I have two keel tanks totaling 390 gallons. I am constantly managing and moving fuel because the roll gets snappy if the fuel gets low in the main tanks and I have a full load in the keel tanks. 5,000lb of fuel is a lot for a 42 foot boat.
I have a snappier roll than I like, but I have not tested the mains being full and the keel tanks empty. I suspect she is marginal in that condition. Especially if the under bunk water tanks are full.
That brings us to the change in batteries and adding panels up high. I have not tested things in marginal conditions and I suspect they may be unacceptable with a change in batteries. The batteries and the galley are both on the port side and ballast (~1,100lb) are favoring the starboard side.
I have a lot to think about, Dashew solved these problems by starting with full fuel and low water tanks. A water maker added water to the tanks at about the same rate as fuel burn. That complicates the fuel management problem but I can carry 2,000lb of water and that might be a solution Water is aft but probably somewhere around the metacenter. Having a true long range cruiser is not for the uniformed. The compromises and complications are not acceptable to most boaters.
I have bigger fish to fry on the boat before I get to that point but, planning ahead is the key to not redoing something later.

 

[PierreR]

I would hope a 44 foot trawler wouldn't roll 20 or more degrees with only 2 people stepping on a gunnel. A bit rusty thinking through this.... but wouldn't that take the gunnel dropping almost 2.7 feet?

Think that will take a bit of thinking to get that much weight on and off the boat quickly enough to make an accurate 20 degree roll.

Its actually easier than you think. You have to act in unison and time your inputs. Think caddy dancers. You have to sing the tune with it.
Think yours is bad, try a 70' Pluckebaum

 

[psneeld]

Its actually easier than you think. You have to act in unison and time your inputs. Think caddy dancers. You have to sing the tune with it.
Think yours is bad, try a 70' Pluckebaum

I just don't think 500 pounds is going to drop the gunnel almost 3 feet on a 44 foot trawler or anything else.

2 large guys on my smallish 40 never made it list even a foot.

Any vertical motion of the people changes their mass (weight) due to acceleration and would affect the experiment.

Of course I think the whole precise thing is a bit moot because of so many other stability issues....it's just a rough guess anyhow.

 

[Pascall]

We have connected a GPS compass on autopilot, with this compass you can read the Pitch and roll.
It can also show a graph of how many heels the ship has made in the past hour.
This gives a good indication of how much the ship has actually heeled, to the feeling it always seems more.
In the picture below we made a turn of 43 degrees, it felt like we were capsizing!
The turning moment of our boat is 65 degrees so we were still miles away from that, which gives a certain feeling.

Greet,

Pascal.

 

[Jeff F]

.
Thus my previous comments that vessels used in icing conditions start trying to rid the upper decks and superstructures of ice when their "roll" becomes longer. It's an old rule of thumb for many.

Sure. I got that point when you posted it. But I don't see how that helps in capsize screening for a new/unknown boat. Without a meaningful target or baseline you don't know whether the observed roll period is within the safe range for that design or outside it.

Put another way, if I were able to successfully perform a roll test on my own one-off boat, what result should I be satisfied with? I don't see how anyone here can tell me what a safe number is for my boat without a detailed design review, and so I see little point in attempting the test.

OTOH, if I had a production boat that went through a rigorous design and build process I would assume that a roll test could confirm that the boat is still within design parameters, just as a tippiness test could. But I'd need a qualified NA to tell me what those measurement values should be for that design.

 

[psneeld]

Sure. I got that point when you posted it. But I don't see how that helps in capsize screening for a new/unknown boat. Without a meaningful target or baseline you don't know whether the observed roll period is within the safe range for that design or outside it.

Put another way, if I were able to successfully perform a roll test on my own one-off boat, what result should I be satisfied with? I don't see how anyone here can tell me what a safe number is for my boat without a detailed design review, and so I see little point in attempting the test.

OTOH, if I had a production boat that went through a rigorous design and build process I would assume that a roll test could confirm that the boat is still within design parameters, just as a tippiness test could. But I'd need a qualified NA to tell me what those measurement values should be for that design.

Reread and absorb the whole post.... please next time quote my whole post instead of a cherry picked section for the benefit of others.

The rule of thumb I learned for ice accretion did focus a bit more on hand time versus just roll period. So if a boat doesn't start to re-right immediately after reaching maximum roll, but hangs, things are reaching max loss of stability. How close? Does it matter if you are there at max roll and hanging uncomfortably long? Even for a new boat hang time should be near non-existent.

The reason I have used ice accretion as an example is to let others understand the effect of adding weight above the waterline. If you plan to add weight, using a roll test will let you know how much you can add and how much it affects your boat in gross measure.

 

[Jeff F]

Reread and absorb the whole post.... please next time quote my whole post instead of a cherry picked section for the benefit of others.

The rule of thumb I learned for ice accretion did focus a bit more on hand time versus just roll period. So if a boat doesn't start to re-right immediately after reaching maximum roll, but hangs, things are reaching max loss of stability. How close? Does it matter if you are there at max roll and hanging uncomfortably long? Even for a new boat hang time should be near non-existent.

The reason I have used ice accretion as an example is to let others understand the effect of adding weight above the waterline. If you plan to add weight, using a roll test will let you know how much you can add and how much it affects your boat in gross measure.

I think most folks reading this understand that adding weight above the WL is going to have an adverse effect on stability.

I'm still struggling to understand how to put this into practice. Here's a real world case: I'm considering adding ~1000 pounds of solar panels to the upper deck of my boat. How am I going to use a roll test to determine whether stability will be dangerously affected? I do a roll test before and after modifications. What then? I've got two numbers which without additional context tell me little about my risk.of capsize. Obviously ultimate stability and motion will be somewhat affected by the change, but is it dangerous? Maybe my boat is too stiff now and the mod will make the boat more comfortable and no less safe, or maybe it'll turn it into a death trap. How do I make an informed decision?

 

[psneeld]

One more time...the roll period when starting to hang is never a good thing unless it was there from the beginning and you are a ballasted boat and right at the edge where the ballast starts to have it's real effect (documented I believe in that one article).

To accomplish on a project adding weight aloft, simulate the weight by increasing weight at the gunnel then start rolling moments. There are formulas that allow you to calculate weights at different heights and offsets from centerline to have the same effect.

If you get to a point where there is a noticeable hang, you probably should rethink the whole project.

If you chance it and get those two points of info and there is no noticeable difference in roll or hang times you win. You still have to accept the facts of environmentals such as free surface, cargo weight shifts, live loading movement, etc...etc...

Me... I would be very hesitant to add 1000 pounds of solar on any vessel less than 50-60 feet. Unless it had a very wide beam and the ability to down ballast without sinking her too far. That just comes form generic experience with all kinds of commercial and recreational experience. So if not very experienced and contemplating adding higher up weights in excess of a couple hundred pounds.... I would hire a pro.

 

[Jeff F]

Me... I would be very hesitant to add 1000 pounds of solar on any vessel less than 50-60 feet. Unless it had a very wide beam and the ability to down ballast without sinking her too far. That just comes form generic experience with all kinds of commercial and recreational experience. So if not very experienced and contemplating adding higher up weights in excess of a couple hundred pounds.... I would hire a pro.

And.if I hire a pro, what steps will that pro take to give me hard numbers? Somehow I don't think that roll testing is going to play a prominent role in the determination.

 

[psneeld]

Think whatever you like.

I am not sure anyone thinks you are going to get hard numbers from roll testing as I believe I have posted several times. Calculated stability and even tested stability is rarely like the real test at sea. Dynamic and destructive testing is more accurate but how many times is it done? Especially with boats?

All it might show you is that you may roll back up temporarily from a severe knockdown or maybe not.... but the sea still calls the shots.

 

[Jeff F]

Think whatever you like.

I am not sure anyone thinks you are going to get hard numbers from roll testing as I believe I have posted several times. Calculated stability and even tested stability is rarely like the real test at sea. Dynamic and destructive testing is more accurate but how many times is it done? Especially with boats?

All it might show you is that you may roll back up temporarily from a severe knockdown or maybe not.... but the sea still calls the shots.

I don't think we disagree. I appreciate the discussion as usual.

My case is not contrived, and my boat is 50 x15 with high initial stability and the ability to add up to five tons of ballast in the flat bottom. And I don't go out in big waves. So I'm not going to lose sleep over capsize risk if I do it without consultation.
I trust my gut, and my suspicion is that it'll be a net positive in terms of handling and stability.

More broadly, my assumption these days is that modeling is pretty mature, and that if a computer has a 3d image of the boat the answers to a lot of these questions are very close. If you add in weight and weight distribution you're there. Both can be derived several ways. Roll testing in my mind can be a calibration input to the model for an existing boat, or a validation of build against design. It's certainly something the designers care about, and it can be derived or observed.

I'm still trying to get my head around this. I suspect that if PierreR came aboard Escapade and did a roll test it would come back snappy, which would green light the project if I understand his approach.

I'm going to go back and reread the thread.

 

[psneeld]

As built by a lot of manufacturers varies handsomely from the original design....maybe less so in the last 15-20 years as I have torn into less new boats.

Another aspect of stability is just sheer error at many levels of build....

What was the final outcome of that brand new, high priced expedition boat that rolled over when being launched in the Pacific Northwest a few years back? What would have happened if it hadn't rolled at this point? This was roll test #1 and it failed big time.

https://www.boatinternational.com/y...-the-northern-marine-85-launch-capsize--27573

The National Transportation Safety Board determined the probable cause of the capsizing of Baaden during its launch to be the "vessels low margin of stability due to the combined effects of a recording error during the final vessel weigh, which resulted in an incorrect assessment of the vessel’s centre of gravity, and an overestimation of the weight of installed ballast."

In other words, there were ballast and stability issues, caused in large part by a transcription error from the builder New World, which had acquired Northern Marine's assets and was operating under its name.

New World had supplied the stability naval architect with an aft starboard load value of 68,500 – a typo as it was really 60,550. But the naval architect used the incorrect measurement to calculate the vessels total weight, and the aft port load had 68,700 – an 8,000 pound difference caused by a typo that proved fatal for this yacht's launch. On top of this, New World also overstated the ballast weight as 23 LT when it was really 16.61, causing the architect to overestimate the yacht's stability.

 

[sunchaser]

My two ruble thoughts——

Some years when negotiating on a Nordhavn I posed the question to PAE regarding stability with an after build Stidd chair added to the FB. PAE’s in-house NA said the chair weight was barely within the limits but hold off on a larger dinghy.

Reputable builders will provide information and guidance on added weight and windage considerations. About a decade ago I was involved with a noted NA when working on keel and cockpit additions. The revamped keel was hollow thus about 400 gallons of AF we’re added to compensate for hydro dynamic changes.

This is a science and when contemplating serious cruising any material weight additions or deletions should should garner more than casual consideration.

 

[rslifkin]

Reputable builders will provide information and guidance on added weight and windage considerations. About a decade ago I was involved with a noted NA when working on keel and cockpit additions. The revamped keel was hollow thus about 400 gallons of AF we’re added to compensate for hydro dynamic changes.

The challenge is when the builder of your boat is no longer around, or has gone under and been re-incarnated a couple of times. Good information can be hard to come by in those cases.

 

[sunchaser]

The challenge is when the builder of your boat is no longer around, or has gone under and been re-incarnated a couple of times. Good information can be hard to come by in those cases.

Quite easy to find capable NAs who are familiar with the vessels I’ve been involved with. An interesting NA named Ed Monk and his still current organization is one. OA anyone? Many other NAs are out there with good qualifications. But yes, many vessels were and still are slapped together as visual copies of quality vessels, but lacking a few stability design details.

A boat search is by many a search for a specific brand with well established design parameters a highlight. But for this thread drift, it is hard to conceive that adding 1,000 lb high on the vessel is done without diminishing stability.

 

[BruceK]

The contrasting views above support the Coroner having the assistance of what appear to be expert testing by a qualified person carrying out a range of tests. The idea that some abbreviated form of test involving some people jumping on the gunnels would have sufficed rather than the test regime presented seems wrong to me.
Though it seems there were requests, neither the builder nor the original importer/seller/supplier of Eliza1 assisted the Coroner with any NA testing. Maybe there was none to provide, maybe not, but effectively he started with a blank page as far as the safety characteristics of the boat were concerned, and needed all the information he could get. That some of it rated "Pass" was only known in hindsight after testing was performed. Ultimately it was the tests graded "Fail" that helped guide the Findings.

 

[Delta Riverat]

I know nothing about naval arch or initial stability or long stability.

I know a little about small outboards. The smaller they are the more they dip when you board. Yeah that's pretty easy eh? And the smaller they are the more you slow down for wakes. You don't even want to go out if there's whitecaps.

My take on this is the "feels a little tender when boarding" in the report.

Don't know anything else about stability but my boat does not feel tender when boarding.

 

[PierreR]

I just don't think 500 pounds is going to drop the gunnel almost 3 feet on a 44 foot trawler or anything else.

2 large guys on my smallish 40 never made it list even a foot.

Any vertical motion of the people changes their mass (weight) due to acceleration and would affect the experiment.

Of course I think the whole precise thing is a bit moot because of so many other stability issues....it's just a rough guess anyhow.

Let me try this again. You don't stand on the gunnel and jump off. You use the same motion and principle as a swing set.
I wanted my boat precisely because when I stand on the rail it only goes down about an inch. Perfect for my wife to board.
I had little trouble timing pushes down on the rail to get that boat really rocking. It takes several rocks and timed pushes to get the rocking you need.

 

[PierreR]

The contrasting views above support the Coroner having the assistance of what appear to be expert testing by a qualified person carrying out a range of tests. The idea that some abbreviated form of test involving some people jumping on the gunnels would have sufficed rather than the test regime presented seems wrong to me.
Though it seems there were requests, neither the builder nor the original importer/seller/supplier of Eliza1 assisted the Coroner with any NA testing. Maybe there was none to provide, maybe not, but effectively he started with a blank page as far as the safety characteristics of the boat were concerned, and needed all the information he could get. That some of it rated "Pass" was only known in hindsight after testing was performed. Ultimately it was the tests graded "Fail" that helped guide the Findings.

I went back and re-read the coroners report and will stand corrected. Sometimes when you read something you remember details that are actually not there.
I had remembered them doing a roll test before conducting the CE test and assumed it failed and called for further testing. It appears the Peta Emma was not in the water at the time. The roll was mentioned by Allen Beebie. I am unfamiliar with the test they performed but assume that is probably the best test available to run in Australia. They do say the drew lines from the hull but do not talk about the weight and balance or top hamper measurements so I cannot comment on that. I do remember being shocked at the results.

My boat is currently in heated storage and is leveled. I am tempted to pull lines from it using a rotary lazier line and a grid pattern. The report got me to thinking of a way to simplify weight and balance. The travel lift that took me out of the water has four scales on it. One on each end of the two slings. I bet you could level the boat in the slings, take the measurements for the slings and record each scale. Now roll the boat as far as it will go in the slings, note the deck angle and record the weights each direction. I bet you can calculate everything from that more accurately that weight and lever arm for each piece of equipment. Big expensive pain the ars but I would know how to modify things for even better balance and ride. Probably not worth it because the roll test is accurate enough for solar panels and LiFePO4 batteries.

 

[Pascall]

My work has taken place on the water as a manager.
Until things went completely wrong in the Netherlands with the hoisting of a bridge, I never had any problems loading pontoons.

https://youtu.be/j83Euldj75I

After this accident, the government began to require a stability calculation for work on pontoons.
But my question, when are you going to perform a stability calculation, remained unanswered.
We had work on a bridge where we used a cherry picker on a pontoon, the pontoon was so big that you couldn't see the cherry picker, but the customer demanded a stability calculation.
Later at the same work they didn't ask for it anymore because they saw that it was ridiculous and a waste of money for this work.
But where is the limit, when do you have a stability calculation made, with so many percentages adding up the mass of the boat, common sense, when in doubt?
When placing the 25 kilo radar at a height of 4.5 meters on our boat, I had the stability recalculated, this did not affect the stability according to the calculations.
Briefly placed a solar panel of 15 kilos at a height of 2.10 meters, I did not calculate this, I based this on experience and common sense.
The weight of the boat plays a big role, if you place the solar panel on a 5 ton boat or on a 15 ton boat, the length/width does not have to differ much from both boats.

Remains a difficult story.

Pascal.

 

[Serene]

I think most folks reading this understand that adding weight above the WL is going to have an adverse effect on stability.

I'm still struggling to understand how to put this into practice.

[SNIP]

Same here!

All of this makes logical sense, but hiring a NA is easy to say, but costly and complex to execute just to decide whether to add solar panels, for example.

I have been reading this thread with interest and will try the roll test when my boat is back in the water, but still not sure whether this tells me if my vessel is seaworthy in 30knot winds and 2m swells.

If I install weight aloft, I understand this will affect stability, but can I now only go out in 25knot winds and 1.5m swells?

Then I wonder that wave action/effect will vary depending on the angle of how the waves hit the boat and also the wave period.

This is the sort of practical application I am missing.

 

[BruceK]

I see the issue Jeff F and Serene raise. Short of employing an NA, I suppose we have to use our commonsense. You`d hope that the builder did NA tests(not sure Eliza 1 had any) and designed the boat with a margin so that adding say 10kg of equipment or a fat friend to the FB did not "upset the apple cart" (so to speak).