What drives the cost of a multihull?

If you have a 20 ft beach cat and you scale it up to 40 ft, my first thought was that a boat is mostly surface area so maybe the cost should go up by 4 times. Searching the threads here, I found an post by Eric Sponberg who said that actually the cost is proportional to the cube of the length. Other posters have said that cost is roughly evenly divided between materials, labor and equipment. I can see that if you go from 20 ft to 40 ft you might want to exchange the paddle for an engine so that would drive up the cost. But let's go another doubling to 80 ft. The engine has to be bigger, but is it enough to make the cost follow a cubic?

The real reason I'm asking is, are there things that boat builders add in to longer boats to appeal to high end markets as the boat gets longer? A sort of feature creep? If the goal is to have a sturdy and safe boat does the cost still go up with the cube of the length?

 

Yes, 20X2X4 is eight times less than 40X4X8, ie. doubling linear dimensions. So the weight (materials) is eight times as much.

 

I would guess the real difference is in the production numbers.

It doesn't cost a lot more in materials to build a 40' cat than it does for a 20' cat - if you could build 5,000 40' cats. The labor would probably be less than double. The problem is that the molds and all the manufacturing hardware are expensive and if you only get to use them 5 times the cost apportioned to each boat gets a lot more expensive.

 

The old F40 was essentially a scaled up Tornado. So sail area was 4 times a Tornado. However the weight was more than four times greater. That's because a Tornado is built using 4mm ply. You wouldn't build a 40ft boat in 4mm ply, maybe the wood will be 8mm thick, as QAB and Nick Baileys boats were. So the shell weight tends to go up by the cube. You use heavier sail cloth on a bigger boat, so again its not just area that affects the price

Then bigger boats suffer more extreme loads than a beach cat. Which also tends to increase scantlings

And of course many big boat owners want a "pretty" interior, never mind air conditioning, generators, electric anchor winches etc. That all adds to weight and a bigger hull volume to hold it all, which means the hull has to be relatively bigger than strictly necessary. So scantlings go up, as does the surface area.

And you are right, the more you build the cheaper things become

Also remember that much of the final price that an owner pays goes to dealers and middle men

How much does GM or Ford get for each car they sell to a dealer? what's their mark up??

One big advantage of having a one off built is you don't pay the middle men

Richard Woods of Woods Designs

www.sailingcatamarans.com

 

Richard has summed it up well, the main driver of the extra cost is the extra weight of the boat (which is basically unavoidable due to the extra loads) and the heavier equipment required to deal with the loads. On my KHSD Formula40 trimaran project for example the main hull is 9mm and the floats 6mm all reinforced with glass on an equivalent small trimaran or cat you could get away with 3 or 4mm ply with just a fibreglass tape running down the centre of the hulls and reinforcement with bulkheads. Also peripheral gear such as winches, clutches, cleats, travellers all have to increase in size and strength. a 60' mast carries much greater loads and the sails themselves are more heavily pressed by a boat with much greater righting moment. So the cost is much greater even for a fairly basically equipped boat. Even very simple boats like Wharram catamarans cost a lot to build due to their weight they are not very structurally efficient for the weight of material that you use in their construction.

 

Thanks everyone for your feedback. If we ignore the fixed costs (mold building, manufacturer's property and equipment, etc.) and the middleman markup, there are three broad categories:
1) Material - hull, deck, cabin and other things the builder actually builds
2) Equipment - masts, engines, electronics and other things the builder buys to install in the boat
3) Labor.

To summarize your points, #2 causes a feedback in both extra material to support the equipment and labor to install it, and perhaps material costs increase at a somewhat greater than cubic rate due to expected extra loadings. Structural efficiency also feeds back on the overall weight and cost.

Are costs roughly evenly divided between these categories? Does labor rise at slightly less than cubic because it becomes more of a surface area dependency? Of course, there is the labor required to install more equipment that comes with larger boats. It seems that even when considering the purchase of a used boat, all of this is important because someone once bought it new and the sale price partly reflects the original price.

 

Surface area increases to the cube. The large boat is normally longer wider and taller. And the other factors noted really make it go up to some part of the fourth power.

One of the common ideas designers come up with is to design boats that are longer without making them all that much bigger in the other two dimensions. Recent example I saw of this was with some Oram designs, but many, many designers have tried it. However if it were such a good idea it would have actually caught one.

Larger boats are a whole other environment, you can't just lean into them and glass the keel, you may have to build stagging just to get in there, etc... You can't move the parts, you need materials handling. Also people want nice detailing. There aren't 3 molds when making a boat, there are like 30 or 100. You also have financing costs, and you have run size. Just imagine the electrical harness... How many Hobies get sold from the same mold vs larger yachts.

Also I think the middleman's mark-up is a red hearing. It costs something to sell something. Lets say you do a small business, and you have to design and keep up to date your own website. Big commitment. Or you pay someone to sell the boat for you at like 15% margin. As far as plans are concerned you do sidestep these costs, but you end up with something that probably has a poor resale. If I could spend 15% of project cost, but have an actual market to sell my homebuilt into, it would be well worth it.

 

One of the main reasons home built boats can be cheaper is because we settle for stuff like lousy finish, comparatively; interior like a gut. You can have more boat, for less, but really large boats are huge investments and the financial issues become more important as you get larger. You have to use what the market wants or eat it on resale.

 

Very true, I'm happy with basic and functional for an interior millions wouldn't be. It's strange though when you consider that multihulls used to be the simplest of boats and the most sparsely equipped now most production catamarans are virtually gin palaces. I guess all that extra volume is just too tempting to fill with equipment.

 

Longer but lean has always been a harder sell compared to room for length....most boats spend more time at the dock and are designed accordingly. I think Wharram called it the boat show syndrome. Many multihull sailors are different than they used to be too. Instead of the cutting edge the conservative element with fewer skills and larger funds have the money to keep the on the water condos developing.

 

Home built boats seem cheaper because you don't count you labor. If you work the same hours at your regular job, you could buy a production boat and have money left in the bank to go cruising. Amateurs typically take several times longer on every step of the job and end up with a lesser quality product. Also, the resale value is often nil.

 

if you work the same hours flipping burgers or delivering pizzas you usually come out money ahead, never mind a regular job that pays real wages.

you do not build to save money, but because you like to build, or to get something you can not buy.

 

I try to tell everyone that comes on here this same mantra.

I've seen seemingly intelligent guys with degrees,give up $80k and $100k+ a year careers to spend 3 miserable years building a boat- that ends up costing them $500-600k with lost wages.
Or they can buy slightly used and 10x nicer ones for $200k-and be boating instantly via cheap bank loans-wisely invest the difference and pay off the boat in 10 years and still have the $400k. And then live off the interest.

 

Eric Sponberg is right; on similar boats the cost goes at the cube of the length. No escape from this hard truth. It's even more sometimes higher as "big" boats tend to be more "luxurious" with more and more amenities, gadgets, and so called high tech.

Some gave pretty good explanations of the general principles.

West Van Han described very well the bad mantra of a lot of home builders. The result is often awful and often impossible to sell. Unless you are a very skilled guy making a very specific working boat (like a catamaran charter), that means that your capital and investment is lost. Plus the wasted years you'll never get back. Tahiti is full of destitute beggars who began with a romantic dream. There is also a pretty collection in Belize.

Do not forget that a boat needs a lot of maintenance (and thus money). Sail boats are the most expensive on this painful chapter with all this delicate hardware like furlers.

 

Good thing so many people are happy buying things off the rack......Most wage slaves though can't save up much of a down towards those bank approved molded jobs. Thank goodness the handy have alternatives..... Of course they could also make one offs for the bank loan guys. We've found furlers to be very durable....