This is how much sailing yachts cost.

[Guillermo]

Originally Posted by Eric W. Sponberg

Gross tonnage is never published in listings of boats or their designs, so it is not a readily available number on which to rely.

You're right, but maybe you could use the Cubic Number (L*B*T). We use this to figure out costs/value for fishing vessels in a first design stage or when appraising, based on a similar vessel's cost. It works. Maybe it could work here too.

[Eric Sponberg]

Guillermo,

For what it is worth, I plotted Cost vs. LBD and attach the plot. It does give a reasonable trend which might be of use to some, although the scatter is similar to Cost v. Length or Cost v. Displ. LBD is related to Displacement so one would expect a similar sort of plot. The trouble with using Cost v. LBD in a cursory way is that you have to calculate LBD for any given vessel before entering the plot, and LBD is harder to visualize than simple Length or Displacement. Also, to be more accurate and more indicative of the volume of the vessel, one should use Lwl x Bwl x Draft, or Loa x Boa x Depth (preferred, I think). Unfortunately, Bwl and Depth are almost never published, so the data is not readily available. Within one design house or for a single manufacturer where this data is readily available, then it could be quite useful.

Thanks to Brian Eiland for your chart. You and I have talked about it in the past privately. For building in a cheaper labor market in a faraway place, one should include the cost of monitoring construction which is a real and direct cost. As I mention in my article on my website "How to commission a yacht design and have it built", not every design detail and spec can be covered in the design documents. Many things are left up to later decisions on the shop floor. And human nature being what it is, we all make mistakes, we change our minds, and we think of improvements along the way.

These all have impacts on other parts of the design, and decisions have to be made to build the boat correctly, on time and on budget, or as closely thereto as possible. That requires that the owner, his/her naval architect, and/or the project manager be on site to handle the decisions. To be there costs money, real money added to the cost of the project, and oftentimes this comes out to more money than is saved by cheap labor.

One also has to think of equipment, and locations of cheap labor do not necessarily have sources of the proper grades or brands of equipment. These have to be imported to the locale, and that too adds to the overall cost.

Every boat building situation is different and should be analyzed accordingly for the best possible combination of cost, time, and quality. That, as I say in my article, is part of the adventure after all.

Eric

[Vega]

I have been looking for prices of boats for sometime, and it seems to me that The Koopmans look pretty accurate to me, but I don’t think it applies to the majority of boats sold in the market (up to 50ft in length).

Koopmans’s boats are expensive, with very good interiors. I think that those prices apply to the Top of the range production boats (Halberg-Rassy, Najad, Southerly, Island Packet, Malo, Arcona, Cabo Rico etc.).

It seems to me that custom boats cost a little bit more (including the project), but I believe that most of the boats sold in the market are Beneteau, Dufours, Jeanneau, Bavaria, Hunter, and the like, and these cost a lot less than the average in the graph.

[Eric Sponberg]

Hi Vega,

The data in my spreadsheet includes many production boats sold in the US, including Halberg-Rassy, Najad, Island Packet, Cabo Rico, Hunter, Beneteau, Jeanneau, Bavaria, Oyster, Moody, Kanter, J-Boats, Tartan, X-Yachts, Catalina, Caliber, Cigale, Shannon, Hanse, Morris, Santa Cruz, Pacific Seacraft, Amel, Wauquies, Saber, and Saga, to name most of them in no particular order. So there is a full range of quality and price, production and custom in the list.

Eric

[Vega]

Hello,

Eric, I think that I was misunderstood. By the way, I have appreciated your Graphs. It is an interesting piece of information and thanks for making it available.

What I mean, is that if you take the number of all boats from each brand sold in the USA last year, the number of Cigales, Santa-Cruz or Cabo-Rico, is minimal regarding for instance the number of Beneteaus. I do not know well the USA market, but probably, Bavaria, Hanse, Hunter, Beneteau Group and Dufour have probably sold more boats than all the others put together (and those are relatively inexpensive boats). What I mean is that this is not showing in the graph, regarding the average price of a boat.

[Guillermo]

L*B*H (Not T, or D in your notation, sorry) takes into acount the total volume of the circunscribing parallelopiped to the upmost continuous deck, not to floatation. It works well only when comparing quite similar vessels, this is, of the same type and not very far away dimensions.

Thanks for the plotting you've done with this. Dispersion is quite the same than for the other data, as you state, so of not better use. I agree with you that not having better data, LOA is the easiest way of facing the issue.

Anyhow, could it be possible (and useful) to categorize your boat's database packaging boats by types (or qualities) to try to find out if dispersion is less?

[Stephen Ditmore]

As Guillermo knows, I've been writing a fishing boat optimization spreadsheet based in part on the work of my teacher, Cyrus Hamlin. Cy always used CUBE (cubic number = LWL x Beam x fairbody depth amidships), as the dimensional corrollary of hull/deck construction cost, and in early versions I did the same.

More recently I've been using:

(LB + LD + BD) * Displ^(1/3) * 1.275

where:
L = LWL
B = Beam (max)
D = fairbody depth amidships (rabbet to top of deck at side)

This is derived from the surface area of a box of these dimensions, which would be:

(LB + LD + BD) * 2

Since static pressure and therefore panel strength/thickness vary with displacement, I multiply by displacement^(1/3). The result scales as a cubic value. Since the result gets multiplied by a cost per cubic unit factor anyway, I changed the constant, 2, to a value that would give a similar result to the cubic number for the heavy displacement fishing vessels I was considering (allowing me to use the same cost per cubic unit factor).

Do you see any problem with doing it that way, Eric?

[Alik]

[quote=Stephen Ditmore;112175]
...
This is derived from the surface area of a box of these dimensions, which would be:

LB x LD x BD x 2

...
[quote]

But why 'area' is cubic from this formula?

[Stephen Ditmore]

Oops. I made a mistake, Alik. I've now edited my previous post so the expression is correct. It's a sum of areas multiplied by displacement^(1/3). The logic is that, when buying material, it's a sum of the areas you are generally using. Multiplying the sum of the areas by displacement^(1/3) makes the result cubic.

I've read several places that doubling the freeboard adds less cost than doubling the length. That made me think there was something not quite right about CUBE = LBD as the function correlating with cost.

There are some previous postings that I'm still reading through. If I have not yet understood something said previously, please forgive.... I'm working on it.

Retired U.S. Naval Academy professor Bruce Johnson has tried to persuade me I should be using T instead of D for fairbody depth. I've been using D because the versions of ABS I've used use upper case D for depth, and lowercase d for draft. T means time to me.

Cheers,
Stephen

[Eric Sponberg]

Originally Posted by Stephen Ditmore

Do you see any problem with doing it that way, Eric?

Stephen,
Your formula probably has some merit. The overall dimensions LB, LD, and BD, necessarily set the equation to rectangular areas, which is then influenced by the multiplier 1.275. To my thinking, I would probably put some kind of block coefficient into the equation to reflect actual surface areas, and then I might expect the multiplier to go up. If you seem to get reliable trends with your collected data, then it probably works. The point of the exercise is to have a reliable estimating tool for future boat designs, so that you can estimate closely what a boat will cost based on arbitrary given numbers.

Vega,
You are correct, my graphs do not reflect the average prices of boats over the whole population of boats on the market. It is nearly impossible to get those numbers, and I would suspect that the data would be pretty suspect, biased, and not at all uniform. But that is not the point of my graphs. What I want to show is the variance of price to boat size for one example each of each design using overall and readily available dimensions. It goes so far as to include boats from all over the world, both custom and production. As one would refine the data, for example, doing custom boats and production boats separately, one might find a further refinement and narrowing of the graphs.

Eric