Lifeboat capacity plates

[Bob Read]

The fourteen wooden lifeboats on Titanic had capacity plates fixed to their forward inboard sides. The plates showed the nominal dimensions and capacity of the boat. By nominal I mean "as designed" not "as measured". The image below shows an actual photo of one of the 30 ft. lifeboat capacity plates and a drawing of both the 30 ft. and 25 ft. capacity plates. The numbers on the plates show the length, breadth, depth and cubic foot capacity of the boat.

 

[Mike Spooner]

Hi Bob,
In the book "The Ship Magnificent." It show a different lifeboat plates
The 14 main lifeboats :Load Plates 30.0 9.0 x 4.0. 64P.
The 2 cutters lifeboats: Load plates. 25.0 7.0 x 3.0. 33P.
The 4 collapsible lifeboats: Load Plates 28.0 8.0 x 3. 40P
So which one is right?

 

[Bob Read]

Hi Mike: That’s why I posted this. I think those were corrected in the revised edition of TTSM. The capacity was never expressed as a whole number with a “P” after it. Even Cameron’s “Titanic” had the plates with the capacity expressed that way and that was one of our major influences because there just weren’t clear photos of the plates until the one I posted surfaced. Also, the Engelhardts had no capacity plates that we have ever been able to prove. Titanic has a habit of giving up her secrets grudgingly.

 

[Mike Spooner]

Hi Bob,
I have say the plate for Engelhardts might of been a bit tricky on a canvas side boats!
I believe you have done some research into the lifeboats? Looking at the quoted seating capacity there doesn't seems to be not enough room for all to be seated! Or do you know if the figures has included standing to?

 

[Bob Read]

The Engelhardt capacity was found using different methods than the wooden boats. Since it was a “decked” boat they determined the passenger capacity by calculating the surface area of the deck using Stirling’s Rule. Then that area in square feet was divided by the 3.8 square foot allotment for each passenger. The measurements of Titanic’s Engelhardt’s resulted in a Board of Trade certification of a capacity of 47 passengers. Though these boats had Board of Trade ratings for passenger capacity, it was up to the officers who were loading the boats to determine what loading was safe for conditions. The capacity ratings do not mention standing or seated.

 

[Mike Spooner]

Hi Bob,
I am now starting to wonder if that figure quoted of 1,178 persons lifeboat capacity is reliable, and could well be less!
Has ever a modern practical demonstration have taken place to prove the figures are realistic?

 

[Bob Read]

The problem is that capacity is really the water-borne capacity not the davit-borne. On Titanic they didn’t have a plan for loading the boats once they were water-borne. So they only load just over 700 in boats certified for nearly 500 more. Yet they always talk about “not enough lifeboats”.

 

[Mike Spooner]

Looking at the lifeboat capacity base on 125cu ft per person. Has anybody put this to the test beforehand?
If one looks at the photos of the lifeboats in New York with a man standing inside one. As a guide line for the physical size, then try work out how many can seat in the boat. As for the big boats suppose to take 65, I can only work out there is room for 42 seating plus a further 2 at each end. Total 46. I see much the same story for the 2 cutter boats as room for only 32 for seating. Or are some required to seat on the floor deck of the boat?

 

[Bob Read]

Hi Mike: I'm not sure where you got that 125 cu. ft. per person. For the 30 ft. lifeboats passengers were allotted 10 cu. ft. per person. In the cutters they were allotted 8 cu. ft. per person. If the rated capacity per person couldn't be achieved I don't think the Board of Trade would have used the figures they did. They tended to lean toward the conservative side with their figures.

 

[Mike Spooner]

Hi Bob,
The 125cu.ft. figure came from RMS Titanic book Owners Workshop Manual. Now re reading the figure that was based on passenger capacity also dictated the size, with 125cu ft being bare minimum. The cubic capacity divided by 10 on the number of people that could be safety carried in the boat! So the figure of 10cu.ft., that sounds correct per person. But one has to ask why only 8cu.ft.for the cutter boats? Are they for the small back sided person?
I still think the quoted figures for capacity just look too small for the boats!

 

[Bob Read]

Hi Mike: Only two boats of Section D (the emergency cutters) were rated at 8 cu. ft. per person. There could only be two boats under davits of this type. These were more crew work boats than passenger lifeboats. For crew use they would only have a small crew. In the event that they were to be used as a lifeboat, it was up to the judgment of the officer loading the boat to judge how many could be safely loaded. Plus you have passengers of all sizes and children so the passenger capacity ratings were there to provide a guide to how many could be loaded in a water-borne boat. These capacities were not hard and fast rules.

 

[Jim Currie]

Hi Bob,
In the book "The Ship Magnificent." It show a different lifeboat plates
The 14 main lifeboats :Load Plates 30.0 9.0 x 4.0. 64P.
The 2 cutters lifeboats: Load plates. 25.0 7.0 x 3.0. 33P.
The 4 collapsible lifeboats: Load Plates 28.0 8.0 x 3. 40P
So which one is right?

Hello Mike.

The figures shown in that book are rounded-up to be practical. In fact, the BoT Rule for determining the capacity of a boat was to allow 10 cubic feet per individual. The plates simple showed arithmetic capacity...hardly practical.

Boat capacity rating was 10 cu ft/person. Hence a boat with the cubic of 648 was rated at 64.8.

The capacities in the Book are rounded up and practical. In practice, the capacity is found by multiplying the length x breadth times depth times the Coefficient of Fineness and dividing it by 10.
The C of F was the ratio of the boat's shape to a rectangular boat of the same dimensions. In the case of Titanic's big boats, it was 0-633.
The inside volume of a rectangular boat of the same dimensions is 1080 cubic feet, therefore, such a boat would hold 108 persons using the BoT Rule.
The fact that Titanic's boat was rated for 64.8 persons tells us that her boat was 0,633% the shape of a rectangular boat. These were what was termed "fine" boats. fatter boats would have had a C of F of closer to 0.75%.


Hope this helps.

 

[Mike Spooner]

The point I am trying to make the capacity figures for the lifeboats does not look very reliable. As I see from the boats in New York with the men standing in as a guide for size. It just not look possible that many can certainty be seated in the boats. As only two boats No 12 & 15 did exceeded the number of 65 persons. Were they standing or seated?
Then there is the case in rough weather what would the figure be then?
I just get the feeling Board of Trade rules seem rather slapdash and not to much practical thought has been put into. As that figure of 1178 persons for the boats could of well be less. Not looking too good for the Board of Trade!

 

[Bob Read]

Hi Mike: I have never heard anybody complain about the Board of Trade’s regulations about how cubic ft. capacity and passenger capacity were calculated. Most of the complaints are that they didn’t require lifeboat space for all aboard. But with Titanic having no plan for efficiently loading the boats you can see the greater problem. Even with not enough lifeboat capacity for all aboard, they still were only filled to about 60% total capacity. Add to that the fact that they were not able to load and launch all of the boats safely in the time they had and you see how there are much bigger problems than inaccurate passenger ratings.