5 Steps to (NOT) Build a Boat

No matter what, building your own yacht will always require more than you anticipated. Before making the commitment to build your own boat, take time to seriously consider all the hidden costs and extra effort required. The best yacht for you is the one you can finish.

Planning for DIY Yacht Construction

1.0 Introduction

How to build a new boat in 5 easy steps.  Step 1:  DON’T.  In my work at DMS, I encounter many ambitious clients that want to build their own boat.  I love that ambition and optimism, and a regular part of my job requires me to interpret that raw ambition.  I work with my clients to refine their goals and translate the initial dream of boat ownership into a set of technical definitions.  And I discovered several repeated themes as clients consider DIY construction.  So today I want to share several steps of self-discovery that help before embarking on any boat construction project.  Because I think the dream of boat ownership is wonderful, but the reality of a completed boat is even better. 

2.0 Step 1:  Training for Yourself

The first requirement for any ship is a competent crew.  Ships do not work autonomously (yet).  They require a trained crew that understands the safety features and limits of the ship.  Remember that taking a ship to sea brings you into the wilderness, and safe enjoyment of that wilderness requires a crew that can anticipate the dangers.  That preparation only comes with training and experience.

Many people who dream of building their own ship start with years of boating experience.  But if you approach this dream as a beginner, with minimal expertise handling larger vessels, invest in yourself first.  Purchase training courses and learn how to safely pilot a larger boat of 12-15 m. size (39 – 49 ft.).  The American Sailing Association offers several courses to progress from complete novice to bareboat chartering and beyond. [1]

Don’t stop with the minimal training; gain some experience.  Try chartering a ship for a week.  Get exposed to the good and bad of boat ownership.  This initial investment in your crew greatly improves the success of building your own boat. 

These sample experiences also expose your personal preferences.  Boats come in all shapes and sizes, appealing to different people.  And what looks important on paper doesn’t always translate to real life.  Do you really know your preferences without ever experiencing a boat firsthand?  These sample experiences illuminate your priorities.  Because when building your own boat, it should be more specific than a simple hull that floats.  It needs to be the one boat that fits your specific needs.

3.0 Step 2:  Pick Your Priorities

Generally, clients ask about custom yacht designs for two major reasons:

• Custom design
• Cost savings

These two motivations dictate very different approaches for do-it-yourself (DIY) yacht construction.  For clients seeking a custom design, the dream is to obtain a yacht that exactly matches every expectation.  These clients frequently seek a naval architect to provide custom designs.  Custom engineering is wonderful, but it can cost tens of thousands of dollars to fully engineer a new custom ship.  My baseline cost estimate is somewhere between $40,000 – $80,000 USD for a complete yacht design.  For some clients, that cost is justified.  But for the more thrifty, you may want to identify what really matters for a custom yacht.

For those that seek cost savings, look for ways to reduce customization.  Engineering a new hull design requires the largest cost.  (It requires the engineer to consider arrangement, weight, structure, power, etc.)  Instead, consider a more focused customization.  Do you really want a completely new hull design, or just a different interior arrangement?  A new hull involves concerns for safety.  But interior arrangements rarely require engineering.

On the subject of safety:  avoid sacrificing safety for budget.  The first rule of yacht construction:  accept that even a DIY yacht will be expensive, and that cost is justified when safety becomes an issue.  Out at sea, this yacht becomes your life support system.  It provides warmth, food, shelter, transportation, and basic flotation.  These are all essential capabilities that must always work.  Safety sets the minimum price.  Any luxuries beyond that depend on your goals, why want the custom yacht.

4.0 Step 3:  Choose Your Material

What material will you use to build your ship?  The common choices are steel, aluminum, or composite (fiberglass).  Your material selection governs the complexity and shape of the hull design.

Steel and aluminum are more conventional, with a lot of advantages.  It can be easier to inspect the construction quality, local hull stresses are less of a concern, and the material costs are cheaper than fiberglass.  The strength for these materials largely depends on the metal mill and not your own technique.  The major concern for metal fabrication lies with weld quality.  Welds are easier to inspect than fiberglass.  With fiberglass, reliable strength inspections require destructive testing of a sample.  But there are several non-destructive techniques for weld inspection.  From the perspective of construction quality, steel and aluminum are far more reliable.

But these advantages come with drawbacks.  Steel and aluminum require more infrastructure to work with.  Due to simple weight of the metal members, cranes are almost essential.  And any curvature in the hull will require a hydraulic plate bender, which is only half a truth.  Hydraulic plate benders only curve the plate in one direction.  The term for this is developable surfaces, and you can do a lot within that limit.  But most complex ship hulls require non-developable surfaces, curvature in two directions on the same plate.  Not easy.  It requires advanced machinery, a very skilled welder, or both.  For most of us, metal construction limits us to very simple hull shapes.  If you want to build in metal, I hope you already have the infrastructure for it.  And accept that complex hull shapes are not feasible.

On the other hand, fiberglass allows more advanced construction, and that entails a higher risk for construction quality.  The strength of fiberglass depends on the skill of the person laying it.  Like all composite materials, the final fiberglass structure starts as two separate materials:  raw fibers and a resin glue.  And the ratio of fiber to resin drastically alters the strength of your final hull.  With fiberglass, you control the hull shape and the final strength during construction.  Table 4‑1 shows the relative tensile strength for fiberglass and epoxy, with comparison to steel for reference.  The strength of your final hull lies somewhere between the fiber and resin; this can range from well above the capabilities of steel to well under.  Getting the correct balance is critical for hull strength.

But the average DIY builder uses hand layup techniques, which are notorious for inconsistent ratios of resin to fiber.  Rather than a uniform hull strength, you get a patchwork of weak spots.  Professional shipyards use advanced techniques and equipment, called resin infusion, to minimize the human element and provide more reliable construction.  (Figure 4‑1)  Without that advanced equipment, the DIY boatbuilder should plan to compensate for lower build quality by overbuilding the hull.  Perfectly acceptable, but don’t expect high performance from an overbuilt hull.

5.0 Step 4:  Time Commitment

Feasibility becomes very important when considering the time commitment.  Many of my clients drastically underestimate the time and effort required to build a boat.  Whatever your estimate, it will almost certainly take more.  More time.  More effort.  More money.  I tried to develop a rough heuristic estimate for construction time, based on the total internal volume of the boat. [4] [5]  This was reasonable because you need to create structure around that volume and fill it with outfitting and machinery.  Construction time was estimated in two steps:

1. Calculate the total internal volume of the boat, including all hulls and cabins.
2. Estimate 46.0 people-hrs/m³ of internal volume for the construction time.

For large yachts, that translates into a lot of working time.  Say goodbye to holidays.  Table 5‑1 applied this estimate to several yachts for some examples.  Notice how the time commitment rapidly expands with larger yachts.  If you plan to manage a day job while building the boat, that only leaves 3 weekends a month on average for construction time.  The moral of this story:  any boat that you construct yourself will not be a gigantic palace.  Most likely, you should select the boat size based on construction time, rather than any design characteristics.

6.0 Step 5:  Alternatives to Blank Slate Construction

The moral of the story:  DIY construction requires many compromises to start from scratch.  Before making that leap, consider three alternatives:  refitting an old boat, buying a salvage hull, or using a kit boat.  These options save massive amounts of effort on construction, lofting, and staging.

6.1 Refit an Old Boat

Too often, we overlook the potential of older boats, but these older hulls hide major finds.  Over time, the market value of a boat depreciates.  A million-dollar boat from 1970 may only cost $100,000 today.  Don’t confuse market value with vessel capabilities.  Yes, you can expect that most of the machinery and electronics require updates.  But a well-maintained fiberglass hull can still endure for many more years.  I especially like older boats for the following reasons:

• Old boats already provide the hull, in good repair, with only minor defects.
  • There are always exceptions to this rule.
• You get the chance to carefully inspect the vessel before purchase.
• Many of the mechanical systems, like deck winches, can be rebuilt and reused.

Of course, these boats also hold numerous headaches and surprises.  Older boats require a careful eye towards the previous ship maintenance and upkeep.  Hire a surveyor to carefully examine the boat before purchase and double any estimate for refit costs. 

6.2 Buy a Salvage Hull

Every year, hurricanes and typhoons batter our shores around the world.  The ensuing destruction can be tragic, but it also presents an opportunity for you.  Those shores were full of yachts now subject to insurance claims.  When the dust settles, the insurance companies try to sell these “salvage hulls” and recover some of their costs.  Salvage hulls present the entire array of hull conditions.  Everything from mild scrapes to giant holes in the hull.  And the price varies accordingly.  Consider each salvage hull carefully and get assistance from an expert in yacht brokerage (that is not me).  Anticipate the following general conditions:

• The interior was likely flooded. You will need to clean and bleach every surface.
• Electronics will likely be ruined
• Engine may need to be rebuilt
• Some cosmetic hull damage at a minimum

The salvage hull offers an opportunity for those who are good at repair work and willing to take a risk on a boat.  This will take patience to find the combination of boat characteristics and tolerable damage.  Salvage hulls become very appealing if you already intended to completely renovate the interior.

6.3 Kit Boats

Still have your heart set on building from scratch?  There is a third option:  kit boats.  Kit boats feature a partnership between a yacht designer and a composite manufacturer.  The manufacturer creates the hull of your boat as a series of flat panels all cut to the exact correct shape.  They ship you a giant container full of these panels (Figure 6‑1), and you glue the pieces together.  “Glueing” requires you to join each panel with resin and fiberglass tape. 

Kit boats still require major construction, but they avoid many of the concerns with quality control.

1. The manufacturer creates all the panels under ideal circumstances
2. Glueing still requires hand layup of fiberglass, but over a much smaller area. With smaller surface area, you can safely overbuild the joints, with less impact on performance.
3. You do not need to perform extensive lofting
   1. Lofting requires careful dimensions and precision cutting to create the hull shape at each frame
   2. Kit boats come with the panels pre-cut to the correct shape. The hull shape evolves from assembly.
4. Kit boats also provide all the supplies you will need for the hull assembly.

One disadvantage is the simplicity of the hull design.  In a kit boat, everything starts as a flat plate composite, which limits your hull shape.  Don’t expect to create a racing hull with a kit boat.  For more information on this construction method, here are some example designers that offer options with kit boats:

Grainger Designs:  https://www.graingerdesigns.net/contour-systems/

Schionning Designs:  http://www.schionningdesigns.com.au/our-kits

7.0 Conclusion

DIY yacht construction is not for the faint of heart, or for the overly-ambitious.  No matter what, building your own yacht will always require more than you anticipated.  Before making the commitment to build your own boat, take time to seriously consider all the hidden costs, extra effort required, and the alternatives.  The best yacht for you is the one you can finish.

8.0 References