I have a lifeboat question...didn't know where to post it.
What were the specifications or dimensions of the lifeboats? Maybe it is my perspective from just viewing pictures, but it seems hard to image that 70+ people could fit in one boat. Maybe it comes from seeing them only partially filled. I don't know.
The regular lifeboats were about 9 m length, 2, 77 m wide and 1,2 m deep, and could carry 65 people. They were the biggest at that time! The "emergency lifeboats" had 7,68 m length, 2,19 m wide, 0.91 m deep and could support 40 people. The collapsible boats were 8,34 m length, 2,43 wide, 0,91 deep, with a capacity of 47 people. Hope this helps!
Deborah, the dimensions of the boats are given differently in various sources. Harland and Wolff were not very fussy about decimal conversions and so we see 9' 1' and 9.1' for the beam. The length is always 30' and the depth 4'. The calculated capacities vary slightly as a result.
The dimensions actually marked on the large boats are 30' x 9' x 4'. The capacity was 65.5 or 64.8 persons.
For reasons explained in my book, the capacities were indeed unrealistic. This was known at the time by those experienced at sea. The supposed total capacity of 1,178 persons existed only in the imagination of the Board of Trade. The capacities of the two emergency boats were especially over-stated, making Sir Cosmo Duff-Gordon and company nowhere near as selfish as they are often painted.
I've just been carrying out some calculations on the buoyancy of the main lifeboats on Titanic.
According to this source the volume is stated as 655Â·2 cubic ft. Does this refer to the internal or external volume?
If anyone knows of a source for the weight of the lifeboats, this would also be useful
Wow thanks for the detailed information by Bob Read. It's obviously not a straightforward question due to the complex shape of the boat. (not simply a matter of multiplying 30' x 9' x 4' to get the external volume).
The reason why I am asking this is to work out how dangerous it would be to overload the lifeboats, and if there was a large factor of safety. Based on using the stated volume as internal (and therefore simply ignoring the weight of the wood due to its own buoyancy as a worst case scenerio) there seems to be a massive safety factor of about 4!
Stephen, if you are trying to do calculations based on the published volumes of the boats, don't bother. They were reached by a rather arbitrary calculation.
For the big boats, it was length x beam x depth, multiplied by .6. This gave a nominal volume, which was divided by ten to get the approved passenger load. Measurements were external.
The capacities calculated vary a bit, because there was no agreement on the measurements. The version you mention was based on 30' x 9.1' x 4' x .6 = 655.2 cubic feet.
The capacity plates on Titanic show 30' x 9' x 4'. This gives 648 cubic feet, or 64 persons, as shown in Bob's article.
Bob puts small discrepancies down to the use of tape measures and the fact that the boats were not precisely identical. Bruce Beveridge says that H & W were rather casual in converting feet and inches to decimals, so 9'1" might become 9.1'. Either way, the calculated volumes are only vague estimates.
The real problem with the boats was not buoyancy, but space. In my e-book I demonstrate that the passenger capacities were very nominal, a fact known to some in 1912. Many books have repeated them as fact, but they were highly imaginative.
By convention, boat dimensions are always external. The technical reason has to do with the shape of the "skin" (planking) over the internal framework. Although a plank's nominal thickness does not change, its projected thickness (a.k.a. "skin thickness") is different depending upon the angle at which it crosses the frame. This is one of those concepts that is complicated in words, but is extremely obvious if you actually build a wooden boat.
As to the way dimensions are given, I'm certain that H&W was NOT casual in its notation. Another boatbuilding convention is to give dimensions as feet, inches, and eighths. A single dimension is written as three numbers separated by dashes which in handwriting can look a lot like dots.
Example: 10-3-4 indicates a dimension that is 10 feet 3 and 1/2 inches long (4/8" = 1/2").
In this conventional notation zeros are always used. A dimension exactly 10 feet long would be written 10-0-0. Feet (') and inch (") marks are unnecessary in this notation and seldom shown except in plans intended for amateur builders.
Also, few wooden boat dimensions need to be more accurate than 1/8th of an inch. If more fineness is needed, the builders I've known will indicate and additional 1/16th with a plus (+) or minus (-) sign after the eighths digit. Thus, 4+ eighths indicates 9/16" (4/8 + 1/16 = 9/16). I've heard these signs spoken of as "plus a tick" or "minus a tick." It might seem a clumsy system, but it is based upon human memory and works quite well in the real world. The mind easily holds a "ten, three, four plus" dimension while crawling out of a boat and walking to the mill to "get out a plank. Whereas, "10 feet three and 9/16ths inches" is harder to recall accurately. You can't re-cut a plank that's already too short.
The three-digit convention starts with what is called the "table of offsets." This is not a list of dimensions for individual planks and frames. Rather, it is a table listing the measurements from specified baselines to places on the skin of the boat. No matter how carefully done, a hand-drawn set of plans had built-in errors of 1/8th of an inch or greater.
This built-in error was an accepted fact accounted for in the lofting stage. "Lofting" is the process of drawing the boat full-size on the floor (usually the actual loft over the building shed). The table of offsets would be corrected from the life-size drawing before building commenced.
The three-digit convention of expressing measurements used for offsets eventually became the standard for expressing the lengths of planks, beams, etc. On hull #1 these dimensions were "picked off" the full-size lofting by the same "loftsmen" who corrected the table of offsets. It was natural for them to continue using their familiar system for expressing dimensions.
Decimal dimensions are a misery to use in wooden boatbuilding. You can't divide 10 into thirds and even a quarter of something is hard to measure. The good ol' foot divides nicely into 1/2, 1/4, 1/3 because it is based on 12. Also, your folding rule is a highly accurate square if you remember the 3-4-5 formula for a right triangle.
Given the date of Titanic's construction, and the misery of decimals, I doubt that the H&W shop did anything in tenths when it came to wooden lifeboat construction.
>>The reason why I am asking this is to work out how dangerous it would be to overload the lifeboats,<<
The short answer to that is: Very dangerous. Especially when you're talking about a small open boat on the open ocean. As Dave Gittins points out, the assumptions upon which the rated capacity was based more on wishful thinking then reality, as if everybody everywhere takes up no more then a few cubic feet of volumn. Forget the sliderule mentality because in the real world, it's just not as neat as that.
If you follow the news stories I post, you can see the consequences of overloading and not just with large vessels, but with much smaller craft which make up the majority of the ferries in use around the world, especially on Asian inter-island routes. Small open boats don't even come close to having the same margins of stability that even some of these craft do, and with nothing to act as a shelter or break against the weather, are a lot easier to swamp.
I’m amazed at the level of knowledge that still exists from those times. Thanks for all your replies.
Could the stability of the lifeboats have been improved if some of the passengers were prepared to stay as low down as possible? Did the nominal capacity assume women and children, which should be a lot easier to accommodate in volume and weight terms? I recall reading in one of the articles that the feet of the seated passengers didn’t actually touch the floor of the lifeboat. That suggests there was some scope for an improvement in stability or that standing on the floor may not have worsened the stability by very much.
>>The short answer to that is: Very dangerous<<
Michael, somehow I knew you were going to say that! The problem I have with this is that if the calculation of the capacity is as arbitrary as suggested, could 65 have been too much? It seems to me that we don’t really know what a safe capacity of the lifeboat really was, the 65 is just a guide and perhaps it would be more than this in a dead calm sea and certainly less in a very rough one. It must have been temping to overload the lifeboats in the conditions, and in fact am I correct in saying that lifeboat 11 was overloaded to 70 persons and everyone was safely recovered? Titanic Lifeboat Lowering Sequence
I suppose I’m looking at this problem in a slightly different way. Yes overloading of the lifeboats is potentially dangerous, moving the ship is potentially dangerous, but the question is would doing either of these increase the net probability of saving more lives or lessen it in the specific situation? I don’t see why these rules have to be cast in stone in a desperate situation where people are likely to die anyway. Presumably what is acceptable or not in those days depended more on the judgement of the Captain rather than rules and lawyers?
>>The problem I have with this is that if the calculation of the capacity is as arbitrary as suggested, could 65 have been too much?<<
Yes it could have been. Even if you have a large margin for weight on your side, the issue is still one of volumn. The assumption that the Board of Trade was operating under was that a single person would take up about 10 cubic feet of space at an average of perhaps 160 pounds.
The catch: These are averages not absolutes and out on the open ocean, you find yourself operating with a lot of unpredictable variables.
Yes, as the night wore on, they took more chances. Lightoller himself testified to that effect and everyone involved would have been well aware of the fact that it was a calculated risk. They were lucky that this all happened in a flat calm. Had the seas been livelier, the story would have been very different.
>>Presumably what is acceptable or not in those days depended more on the judgement of the Captain rather than rules and lawyers?<<
Pretty much. In a life and death situation people would have been a lot less reluctant to tell the lawyers to go get stuffed, and in much ruder language. I'm not so sure that anyone would be as quick to do so today.
I am currently working on passenger capacity for one of my water taxi boats. The U.S. Coast Guard uses a variety of approaches to determine the number of passengers allowed. Each produces a different number, but in the end the lowest (think safest) number dominates.
For example, if the stability test allows 20 people, but if there are only seats for 18, then the maximum capacity is 18.
However, even if my boat has a 20 passenger limit for example, that is not carte blanche to always carry 20 people. If Two-Ton Tessie, the Fat Lady from the Circus shows up with her Three-ton Tom husband...as an operator I am supposed to take their weights into consideration and reduce my passenger load accordingly.
The 65 person capacity must have been a theoretical consideration in 1912, not one based on practicality. Quite obviously, a boat can hold more skinny girls than burley football players. Even today these are realities that cannot be handled by law, regulation, or rule. The officer in charge has to apply real-time good judgement.
The capacity number is really less a factor in determining the total weight of human beings than it is in determining the carriage of other safety equipment. For instance, it determines the number of life preservers on my boats. For Titanic it had more to do with the amount of water and ship's bread or biscuit carried.
As for lawyers, they have pretty much forced a halt to the age-old method of learning by experience. If you are involved in an "incident" you can't share what you learned because doing so will certainly result in having money extorted by a band of legal thugs. This is why modern regulations tend to be written by "never been there" experts as a sop to the general public. I know for a fact that better life preservers, life rings, and other equipment is available but not approved simply because of fear of lawsuits. Sleep well on your next cruise, the courts are on your side!?
Stephen, I found that the weight of a fully loaded 30' boat, with all equipment was 5Â½ to 5Â¾ tons. I couldn't find the weight of an empty boat, but it must have been a good 1Â½ tons.
I also found this gem in a report from Captain Alfred Young, of the Board of Trade. After explaining the capacity calculation he says, "Such a boat should allow three square feet per person at the gunwale, which should be ample if all sit on the bottom who cannot find seating room on the side benches or thwarts." Lawrence, in boat 13, which was possibly the most crowded, mentions passengers standing huddled together for warmth.
While I'm at it, boat 11 actually held about 49 people. The witnesses almost always exaggerated the numbers in the boats. Fred Fleet was an honorable exception.
In Mersey's court, according to the lowest estimates from witnesses, 836 people were in the boats, 642 of whom were women and children. The real numbers are 712 and 389. Lord Mersey was asked to determine how many were in each boat, but he had to give up because of the inaccurate figures. Modern researchers have managed to get the numbers fairly right.
I’ve had a go at estimating buoyancy and space in the Titanic lifeboats, together with a suggestion of how the extra passengers might have been accommodated without significantly compromising stability. Sorry for mixing imperial with metric, this is only to identify where the original data came from.
Working on the figures supplied in the earlier posts, and based on the nominal values of 160lbs per person and 64 people per lifeboat, the passenger loading amounts to 10240 lbs. or 4.655 metric tonnes. So if the laden lifeboat weighed 5.5 tonnes, the lifeboat would weigh 5.5-4.655=0.845 tonne. This would be reasonably consistent with a 1” thick yellow pine/elm hull.
The 14 main lifeboats each had an estimated capacity of 655 ft3; this is equivalent to a displacement of 19.05 metric tonnes of seawater leaving a theoretical 18.28 tonnes to support passengers. The gunwale of the lifeboat is lower in the middle than the ends, so the useful volume and capacity for the purposes of buoyancy calculations may be slightly less than the following calculation suggests.
I have assumed the likely average weight of persons in the lifeboats would be around 70 kg (154 1bs)*. Multiplying this by the theoretical capacity per lifeboat of 64 people brings the total weight of people, if filled to design capacity, to 4.55 tonnes. Therefore, the buoyancy safety factor to allow for waves and instability is 4.06 (18.209/4.48) or to put it another way, only one quarter of the available volume is submerged.
Would it have been possible to increase the number of passengers based on buoyancy alone? Lets initially take a target overload value of 12% or 7-8 people per boat, since this would have been enough to ensure all 1316 passengers could have been accommodated. This would bring the buoyancy safety factor down to 3.63 so there seems plenty of spare capacity on these grounds.
Regarding space, I have guessed how the seating arrangement would be, and assuming that some of the passengers have to stand in front of the rowers to achieve the design capacity of 64 (see plan view) although perhaps they could crouch, if not sit. There also seems to be about 2’ 3” of space (about the height of a table) below the rower’s seats, which probably wasn’t intended to be used. Adults could be accommodated below these seats by lying two people on the deck in opposite directions with the legs bent at the knees. (See side view). This would provide 8 extra places per main lifeboat totalling 112. Alternately, children below 4’6” height could sit in the same space, sitting 5-6 abreast, providing up to 22 extra places in each main lifeboat. This arrangement allows the extra weight to lower the centre of gravity and raise the centre of buoyancy, thereby generally improving the resistance to capsize.+
If this was how the 109 children were positioned, there would be space for 72 additional adults, totalling 1359 which makes room for all the passengers plus 43 staff leaving 853 back on the ship, ignoring similar arrangements for the smaller lifeboats. The buoyancy safety factor is in theory reduced down to 3.33 for this larger loading if we stick to the weight assumption of 70kg per passenger, although it might be nearer 3.63 in practice due to the higher proportion of children.
Is all this academic in view that the lifeboats were not filled anyway? I suspect the main reason for the slow loading of the lifeboats was the reluctance of the women to leave their menfolk and the reluctance of the officers to spell out the urgency of the situation to avoid a panic. However, if there was room and the men and women could be loaded together, this may have speeded up the loading procedure.
*People were lighter in 1912 than today and some of the passengers are women and children. As a guide, the average 19 old American male weighed only 139 lbs (63kg) in the 1900s. (Fat History: Bodies and Beauty in the Modern West - Peter N. Stearns). On the other hand perhaps many of the 1st class passengers were overweight!
+ Sailing boats, such as these should have been designed for greater capsize resistance than vessels powered by engines or rowers, so if the sail was avoided this should add a further factor of safety.
>>Is all this academic in view that the lifeboats were not filled anyway?<<
For the most part, yes. The history you see in this instance is what you get. We can only speculate on the might-have-beens. The problem I see here is that there are a lot of assumptions being made on the averages as far as weight goes but it's never really so neat as working that out on a slide rule. There were big people, little people, and tweeners and the catch is how do you even get organized enough to sort them all out and distributed when time is short and getting shorter.
The imparative was to get as many into the boats as they could (Not such a steller performance there) and get them away as quickly as they could. (Great job done on the latter) If people were unwilling to go if a place was offered, then Charles Darwin has the last laugh.
>>I suspect the main reason for the slow loading of the lifeboats was the reluctance of the women to leave their menfolk and the reluctance of the officers to spell out the urgency of the situation to avoid a panic.<<
I think you'l find that a lot of testimony is out there to support this. It's understandable too. Don't underestimate the fear factor either. It was plenty dark and cold and the ship was so warm. Why take a chance in a freezing boat going out onto the dark cold ocean in the missle of the night? Hell, why risk the fall which when climbing in? Especially if you're a society lady in one of those tight skirts which which do a lot to inhibet freedom of movement.
If you want to get a sense of what that was like, see
I was there for this little experiment. Even under controlled conditions, when those tables were moved only three feet apart, Lori Stone balked at making the jump. Now think about this from the perspective of a woman being asked to do the same while facing a 70 foot drop!
I guess a better strategy may have been to give women and children first chance but if they fuss ask them to stand aside then fill up with volunteers, or if possible allow the loading officer to pick the smallest first.
I didn't realise it was necessary to jump on a port list until the lifeboats were swung over.
Was there anything stopping them loading all the lifeboats simultaneously?
Perhaps similar situations could occur with modern ships, so it isn't entirely academic. For example could a significant list make half the lifeboats redundant?
>>Was there anything stopping them loading all the lifeboats simultaneously?<<
A lack of trained hands. The entire deck department of the Titanic included a grand total of 66 persons and not all of them were seamen. See https://www.encyclopedia-titanica.org/titanic-deck-crew/ for the list. Two of them were doctors, one of them a window washer, and one of them was the mess steward. Further, the trained hands they had were needed as much to crew the boats as to operate the davits. They ended up running out of effectives long before they ran out of boats and some had to be crewed by passengers and engineers who either volunteered or who were simply drafted.
>>For example could a significant list make half the lifeboats redundant?<<
Damned right it could, and it has happened. Ask anybody who was on the Andrea Doria. Fortunately, it wasn't so bad on the Titanic that the boats couldn't be launched from both sides.