DIY Cruising Catamaran: Complete Building Guide

A brand-new cruising catamaran can set you back a hefty amount of money. However, a DIY cruising catamaran provides a more affordable way to own your own boat. While building a large boat can be an extremely challenging and time-consuming experience, nothing beats the pleasure of bringing your own boat to life. 

To build a DIY cruising catamaran, buy good design plans, determine your budget and find a working space. Next, choose your hull material, buy supplies and start building the mast beam. Build and sheathe the hull, install bulkheads, the interior, and finally, launch the catamaran boat.

In this article, you will find a complete guide to building your own catamaran. You will also find detailed information on why you may want to consider building your catamaran and approximately how much this project would cost. Finally, we will explore the advantages and disadvantages of building a catamaran from scratch.

Why You Might Want To Build Your Own Catamaran

Most people might think that purchasing a used boat to repair and fix it up would be cheaper than a DIY cruising catamaran. But while building your own catamaran could be an enormous undertaking, it also comes with many advantages over buying something used. 

Other than the unique opportunity to create beautiful memories and experiences while cruising, sailing, and exploring beautiful coastlines, there are a number of benefits that come along with the DIY approach.  

Knowing Your Boat

Building your own catamaran provides you with intimate knowledge of your boat. You will know every corner, including where to find every bolt, wire, bulkhead, rib, hose, and support as you installed them yourself. This knowledge will enhance your confidence while at sea since you will have entrusted your life to a boat whose history you are aware of and deeply connected to.

Pride of Ownership

The satisfaction you get from crafting something with your own hands is immense. As a result, the knowledge that you built your boat from scratch will fill you with absolute pride and an immense sense of achievement. Furthermore, as an owner-builder, you get to keep and enjoy the boat for as many years as you wish.

Substantial Cost Savings

Building your catamaran will work out cheaper than buying a new or even gently used boat. Though you will likely require some additional labor since doing some things will require an extra pair of hands, if you are particularly good at DIY, you will save a significant amount of money on labor costs as a whole. 

Freedom To Create Your Own Designs

If you decide to buy a catamaran boat, it might not be easy to find one that meets your unique needs. However, instead of choosing from production boats that bear traditional and outdated designs, you can come up with an ultra-modern design or style for your catamaran. You also get to pick your layout, size, and equipment based on your taste and budget.

Great Learning Experience

Building your own boat will help you pick up numerous skills that will come in handy later when sailing your boat. As much as you might still require an expert to help you with specialized skills like carpentry or wiring, your new skills will serve you well. This will also be beneficial when it comes to your boat’s maintenance and fixing things for yourself. 

What To Look For in Catamaran Boat Designs

When deciding on the type of catamaran boat to build, you may want to choose a design that’s simple and easy to build. This is because doing so will allow you to spend a shorter time building the boat. 

You also need to have a set of requirements to guide you in choosing your design or what you might call an ideal cruising catamaran wish list. This is essential because, ultimately, you want to build a boat that offers outstanding qualities such as:

• Delivers good speed
• Affordable to own and operate
• Agile, strong, and easy to maintain
• Has a high resistance to capsizing
• Great for sailing and cruising
• Delivers a comfortable and easy motion underway
• Good handling ability and high performance under sail
• User-friendly embarking and disembarking
• Provides ample living and accommodation space 
• Presents a reasonable resale value

It’s worth noting that, in general, catamaran boats tend to offer a fair resale value mainly because of scarcity and the high price accorded to production models. So, if you build a well-constructed catamaran, you are bound to get a return that’s much higher than the cost of materials upon resale.

It’s also good to consider whether the design you settle on is from an established designer. This is significant because documentation of the building process is just as valuable when it comes to selling the boat.

How Much Would It Cost To Build Your Own Catamaran?

The cost of building your cruising catamaran will depend heavily on the size of the boat you plan to build and the skills you bring to the table. To give you an idea of probable costs, a professionally built 40 foot (12.1 m) long cruising catamaran could go for up to $300,000. 

Though building it yourself will undoubtedly be cheaper, most DIY boatbuilders tend to underestimate the expected costs. Your final costs should cover not only the cost of material and equipment but also the labor and time it would take to come up with the final product. 

If you were to build a 40-foot (12.1-meter) catamaran, your cost of materials would range between 20-30% of the total cost. Therefore, for $300,000 total, the boat’s materials would range between $60,000 and $90,000. The hull tends to range between 15-35% of the total build. Again, this depends on the finish and furniture.

But before you even start working on the DIY project, you will need to figure out where to do the work. If your home has ample space, then you can opt for a backyard building. But if you live in a small apartment, then you might want to consider renting a small garage at first and then move on to a boatyard later. This is one of the significant costs involved in building your multi-haul.  

What You Will Need

To get a clearer picture of how much the entire project would cost, let’s have a look at what else you will need to purchase.

• Good design plans
• Working space
• Wood 
• Glass
• Epoxy
• Plywood
• Resin
• Fiberglass
• Foam 
• Paint
• Ground tackle
• Matting and roving
• Equipment such as the engine, windows, rudders, deck fittings, mast, and rigging

In addition to the above, you also need to install plumbing and electricals. You may also want to consider going electric rather than using diesel. Not only will this drastically reduce your maintenance costs, but you get to use the regenerated power for all of your housing needs while sailing. 

Some catamaran boat designs help you save costs by advocating the use of less expensive corpus materials. Most of the material goes directly into making the boat, which means there is hardly any wastage on vacuum bagging. With this method, there are few molds and temporal building forms and fewer fillers to grind off as waste. All these factors reduce the time and cost it takes to build your catamaran boat.

That said, building a boat of any kind is a huge financial undertaking. As such, you still need to have the financial ability to keep building; otherwise, your project will stall or take much longer than anticipated. Instead of enjoying yourself and making memories cruising to faraway lands, you might end up spending all your time building a seemingly never-ending boat.

To reiterate, this project is more of a labor of love, given that it involves a tremendous amount of manual work. Calculating an hourly rate on the time spent building the boat and adding this cost to that of materials may make it seem a very pricey exercise. However, it is vital to understand that your time matters, and every hour you spend working for “free” should be included. 

With that in mind, you need to ensure that you are fully devoted to the boat construction project and are sure you want to do it before you begin. Stopping halfway because it seems like too much work would be incredibly costly.

How To Build a Catamaran

When it comes to building a cruising catamaran, you have 3 main options:

• You can buy an old boat and refurbish it.
• Purchase a bare hull plus deck molding for a home-boat building.
• Start from scratch and build everything, including the hull, on your own. 

As mentioned above, renovating an existing boat may end up being more costly than starting from scratch. To build a catamaran boat from scratch, follow the below step-by-step guide.

Prepare the Essentials

Before you jump into such a large project, there are several important aspects to consider:

• Buy your plans from an established catamaran designer. You can also get inexpensive, easy-to-build catamaran designs online.
• Get access to a large working space or build a shed. Depending on your climate, you may need to opt for climate control to avoid an excess of moisture in humid areas. 
• Decide on your choice of hull material. This could be fiberglass, aluminum, steel, wood, or ferroconcrete. 
• Start working on a bill of materials estimate. Include everything that you think you need to get a better idea of the initial costs.

Build the Mast Beam

Using wood and epoxy, cut and glue together the pieces of wood that will form the mast beam. Most of the work at this stage can occur in a garage since it involves building small parts. Still, the work could take up to 4 months, so be prepared to put in long hours.

Build the Boat Hull

Now, it’s time to build the boat’s hull. A catamaran comprises two hulls which are connected with a deck. Below is a short video showing how to build a hull mold:

This work requires a larger facility, so you might need to move out of the garage and into a boatyard. If you don’t have access to a larger workshop, consider building a shed where you can work as you do the construction. Make sure there’s enough room to fit the boat and also allow you to work comfortably. To cover the shed, you can use opaque white tarps. 

Sheathe the Hull

Get all the materials you require for this stage in the construction, such as lots of resin, fiberglass, and foam for use in the hull cores. You’ll also require matting and glass roving to sheath the hull. 

Sheathing helps to make the hull impervious to water and other marine borers. But first, you need to prepare the hull using a rotary sander. To make it as smooth as possible, use light, sweeping strokes. This is a very dusty task so be prepared to wear a facemask and safety goggles. 

Install the Bulkheads

Next is installing the plywood bulkheads. You might need to call in friends to help turn the hulls or use a crane. In this step, you will need to laminate the hull sides on the molded hull panels and bond them above the bulkheads. Ensure the bulkheads are snug and sealed in place.

Construct the Interior Structure

Over the next couple of months, the boat work will involve joining the hulls together with the beams that you had made back in the garage. Then, install the cuddy cabin, decks, and the cockpit. Soon the boat will start to take the shape of a catamaran.

Next, proceed to construct the major structural components such as stairs, hatches, mini-keels, and the interior. Then comes the work of fairing the boat, which is quite labor-intensive. 

Finally, it’s time to apply primer on the catamaran boat and start the paintwork. Before painting the boat, you will need to do additional sanding to finish off the two layers of primer as well as fill all the pinholes. Since it’s a large boat, the catamaran has lots of surface area; thus, the sanding could get extremely exhausting—mentally and physically—at this point.

The painting can take a while, too. The hulls are the easiest to paint, but the topsides, non-skid, as well as masking and prepping could seem never-ending. 

The final stretch involves working on the center bridge deck cabin and other final touches like installing the engines, electricals, and plumbing. This is also the time to fix the rudders, rigging, mast, windows, and deck fittings.

Launch Your Cruising Catamaran

After many months or years of hard work, your cruising catamaran is finally ready to test the waters. After lowering the boat into the water, check carefully in case there are leaks. If none, you can set up the sails and take your catamaran out for your first cruise. 

Below is a short video that takes you through the entire boat-building process:

If you don’t have deep pockets, don’t despair. It’s also possible to build an inexpensive catamaran boat, as shown in this post from the coastal passage.

The Pros of Building a Catamaran

Though it will be a costly endeavor, there are so many things to look forward to should you decide to build your own catamaran:

• It can be lots of fun.
• You get to have a new boat.
• It’s an excellent hobby for DIY enthusiasts.
• The effort is rewarding.
• It offers a great learning experience.
• You get the exact kind of boat you want.
• You can alter building plans and tailor the boat to suit your specific needs.
• It might be cheaper than buying a new boat.

The Cons of Building a Catamaran

Though there are a number of positive aspects to a DIY build, it is just as important to keep in mind that it won’t always be easy:

• Maintenance costs can be quite high.
• It’s both mentally and physically exhausting.
• It might require some technical know-how.
• It can take many months or even years to complete.
• It requires a lot of commitment to finish the DIY project.
• It might be challenging as well as expensive to get insurance.  
• You will spend almost all your free time building the boat. 

DIY Cruising Catamaran Tips and Tricks

If you are new to boat building, it would be a good idea to build a small boat first. This would give you a good indication as to whether you’d enjoy tackling a more extensive project like building a catamaran. Again, if you are the handy type, fixing your own electronics could also save you a significant amount of money. 

Here are more tips and tricks to get the most out of your DIY cruising catamaran:

• Lower your costs. Bring down your costs even further by sourcing for parts and supplies at marine surplus outlets, Craigslist, eBay, or wholesale suppliers. 
• Enhance your resale value. Most home-built boats are not easy to sell since they tend to be too customized. To enhance your resale value, it’s advisable to work with a standard design from a well-established naval architect.
• Follow the design instructions. Make sure to follow the designer’s instructions regarding the type of materials and tools to use during the build to avoid making costly mistakes.
• Maintain your original budget. Avoid any additional customizations once you have started building the boat. Using good plans and sticking to them ensures that your budget doesn’t spiral out of control.

Final Thoughts

Building a catamaran is about more than saving money. It’s fun, exciting, fulfilling, and can be a great learning experience. While it might take many months of back-breaking work, comparative shopping and sourcing for materials will help you save a lot of money. Still, at the end of it all, you’ll have a beautiful catamaran boat, all ready for your first cruising adventure.

However, if you have neither the time nor the energy to build your own catamaran from scratch, refurbishing an existing hull might prove faster and easier. It also works out much cheaper than buying a new boat.