Displacement weight versus actual weight

D_1: Estimated Displacement

D_2: Displacement when leaving the shipyard

D_3: Displacement equipped, ready to sail and with minimal crew sailing

D_4: Displacement at half load or with a load estimate for the intended sailing which can be several, e.g. regatta and cruising, or coastal cruising and large ocean crossing.

D_5: Displacement at Maximun load

In my opinion D_1 can and often is a funny number, and D_2 is not very useful, and D_5 does not seem useful either because it is not a precise boundary.

D_3 and D_4 is what corresponds to the real world.

 

Displacement "MOC", "Minimum Operating Condition", would be what i have called D_3

And then it would be necessary to point out for example two Displacements of type 4

The D_5 must be indicated, even if it is a somewhat arbitrary figure, i mean ... would be

D_3
D_4_A
D_4_B
D_5

(putting the accent in 4 and not the two extremes 1 and 5)

 

mOC is the minimum necessary to be able to handle the boat. It is the typical situation of taking the boat to the dock for repairs or inspections. Minimum crew, no payload, minimum fuel, minimum liquids on board: as close as possible to the lightship but still allowing the ship to be driven.
D5 is, in effect, what the designer indicates, a weight that complies with all the regulations required of the ship, the maximum weight with which the ship will be allowed to sail, even if it could be capable of more.

 

I prefer D_2 and D_5. With these two numbers, I can calculate just how much stuff I can safely stow aboard.

 

Personally I'd prefer D2. The others appear to leave a lot of space for subjectivity.

For example what is "ready to sail"? For the belt-and-braces guy with a taste for luxury it can mean a full set of engine spares, an air conditioner and heater, generator, dingy with big engine on davits, four anchors, life raft, bimini with solar panels etc etc etc and perhaps six crew. The person with the same boat on the same trip but with a taste for minimalism may just go singlehanded with perhaps two engine spares, two light anchors and and inflatable kayak. So they have the same design of boat but very different subjective opinions on the definition of "ready to sail" on the same voyage.

 

It is possible that D.2 is very objective, in my opinion it is not, but in any case, there is no regulation, as far as I know, that indicates which items should be included in it and what requirements the boat should meet in that condition. So I wonder what the purpose of studying that condition will be.
I'm not questioning your opinion, absolutely not, I'm just trying to be practical.

 

Yes

Yes, there are different points of view, all reasonable.

The issue from my point of view is to explicitly express the Displacement.

For example

I don't know exactly what the MOC (Minimum Operational Condition) Displacement includes in ISO

Loading conditions for ISO-12217-1 https://www.boatdesign.net/threads/loading-conditions-for-iso-12217-1.49173/

but one can indicate what one considers "MOC" on a case-by-case basis, facilitating communication

Also as Sharpii2 says, you can indicate the two ends and the rest is left blank to the client-user.