sailboat building price increase with the size

Hello, I have another dumb question: how much does price of building a sailboat increase in percent going from 10 to 12 meters in length approximately?
I know that building a hull is lesser part of whole cost, but what about equipment?

 

I think that a rough approximation might be according to the square of the length?
So 10 squared is 100, 12 squared is 144, and it would be reasonable to estimate that the increase in cost could easily be 40%?

Bear in mind that the bigger boat will also need bigger equipment - taller mast, larger sails, larger anchors etc.

 

Yes, I get that; thank you very much!

 

Larger sails are,of course, more expensive, but they also require bigger winches and pulleys and line. There will be very little that is the same on a small boat and a big one.

While a salon table may be a salon table and a galley stove and refrigerator might be the same regardless of vessel size, head and radio and other equipment of that nature might be the same, most likely more room and expense of build means bigger, higher end equipment even when it isn't strictly necessary. Some of that will be up to the designer. However, in general, bigger boats have heavier anchors and chain and lines, which means bigger cleats and windlass and deck fastenings. Bigger boats usually have, not only more portlights, but bigger openings which means heavier lenses, etc.

It is difficult to quantify for a custom build, but I would check out a production boat catalog, such as Beneteau or J Boat and see what their pricing looks like, for a rough idea.

-Will (Dragonfly)

 

One method I have seen & used:
You can estimate the price of similar type boats(hull forms) using the "cubic number" which is L x B x D (length x beam x depth* moulded) *depth is sheer to keel hull depth measured at amidships... nothing to do with draft .
If you only use length, use length ^3 (L cubed). So comparing a 30' and 35' boat would be 27000 and 42875. The 35 would be 1.58 time the cost. About 60% increase
In your case 10^3= 1000, 12^3=1728... about 1.7 times
Another way is by weight but that's another story

 

What changes? Only the length of the hull? What are the differences between the boats? Does the interior layout stay the same or are there more accomodations? If the boat scales uniformly in all directions the 12 meter boat will weigh about 70% more.

 

I recall reading, though I can't now find it, that only a few Sigma 292s were built because it was found that they cost just as much to build as the 33. In effect the biggest chunk of cost was labour time to fit the interior and that didn't really scale with length or displacement.

For smallish yachts lines and winches are sized more for ergonomics than loads, and you still need just as many water pipes, electrical cables and skin fittings on a smaller yacht, albeit the actual wires and pipes will be shorter.

 

Some one once told me a story about how his father was up sold to a bigger boat by the boat builders; who told him that the ends of the boat are expensive labor wise and adding more frames to the middle would not cost that much more for a longer boat.

 

If only that were true for dockage.

 

Hahaha.

Yeah

 

Back in the seventies we used to say $1000 a foot, then in the 80's $2000 a foot. Who knows what its up to now.

 

A lot of variables for a rule of thumb.
As Will Gilmore said look at what came before. There is a chance the last guy lost his shirt.
Or estimate line items in spreadsheets.
Risky business predicting future.