Boat Design

Marsh Design offers a range of boat-related services, geared towards amateur builders with unusual or specialized requirements. Designer Matt Marsh is a lifelong boater, passionate about the water and the vessels that traverse it. 

Marine services offered by Marsh Design include:

Custom designs for power and sailing craft.

Stock plans for small craft, a slowly growing collection of designs I feel are good enough, and predictable enough, to offer to potential boat builders.

Design-assist services, for cases where a complete new design is not necessary (eg. redesigning the interior layout of an existing boat, or adapting a stock plan to include specific features).

Repair and retrofit planning, guidance and project management services are available for boatowners looking to re-power or re-wire their vessels, and for those looking to rebuild or restore older craft to meet their own desires. Systems integration and troubleshooting services are also available.


Custom Design

Sometimes, you just can't find the boat you need. Perhaps you have an unusual combination of requirements. Perhaps you have your heart set on building your own, but none of the stock plans you can find are quite right for you. Perhaps you're looking to save money and/or get a better quality boat, compared to what you can find at brokerages.

All of these- surprisingly, even the last one- are good reasons to consider a custom design. It's a long and intricate process, of course, and not for everyone, but if the idea of a boat that is exactly what you need sounds appealing, then read on.

Custom design is not a full time job for me. It's something I greatly enjoy, and I have decided to offer these services, one boat at a time, to a few clients who need a passionate, capable designer to address specialized or unusual requirements. For the moment, I'm interested only in small craft: runabouts, landing craft, tenders, launches, dinks, even models. If your tastes tend toward the big and fancy, of course, I'd be happy to help you find a suitable match from among the ranks of other designers.

The Design Process

Rather than charging by the hour, I offer custom designs on a flat-fee basis, broken down into three stages of design development. You're assured of getting what you want every step of the way, and there is no commitment to continue if you decide to abort or pause the project partway through.

Concept Phase

To start the concept phase, we need to agree on the basis of the Statement of Requirements. The SOR should include details of how the boat will be used, what range, speed and payload/crew capacity you require, the sea states in which the boat is expected to operate, a summary of any required interior accommodations, and your preferred building location and methods. Your sketches, scribbles, and references to other boats you've liked are very helpful at this stage. I will produce preliminary designs based on the SOR, and will revise the general arrangement and hull design of the boat until you are satisfied. Minor revisions to the SOR may be made during this stage, as your requirements develop along with the preliminary design. But a major design change (“I know I said powerboat, but can we give it a mast and sails?”) means going back to the start.

At the end of the concept phase, the design documentation will consist of, at a minimum:

  • Three-dimensional hull and general arrangement model in Rhino/OpenNURBS (*.3dm) format
  • Rough weight estimate
  • Rough performance predictions

Preliminary Design Phase

When you are satisfied with the general arrangement and preliminary hull design, and we both agree that the preliminary design is appropriate for the design requirements. I will then proceed with the structural drawings and detailed arrangement plans, consulting with you as the design progresses to ensure the design is true to your needs. The main goal of this phase is to develop the design to the point where we can be sure it will work as intended, and where you can take the design package to builders and equipment suppliers for cost estimates.

At the end of the preliminary phase, your custom design will include:

  • Final hull lines
  • Preliminary structural drawings
  • Detailed arrangement drawings
  • Accurate weight estimate
  • Equipment specifications and necessary data for build cost estimating
  • Updated performance predictions

Details Phase

When you are satisfied with the detailed drawings and calculations from the second stage, we can move on to the construction drawings. This phase includes the final structural calculations, the electrical and mechanical systems design, and all the remaining drawings necessary to build the boat.

Deliverables from the final stage may include:

  • Final construction drawings and details
  • Final materials list and construction specifications
  • CAD files from which CNC cut files can be produced, if applicable. (Note that this is not the actual cut files, just DXF drawings from which they can be made. The metal shop should generate and check the cut files.)
  • Electrical schematics, if applicable
  • Mechanical installation drawings, if applicable
  • Plumbing drawings, if applicable

Drawing Details

All drawings and calculations will be in SI units, but if your material suppliers work in US customary units, I can prepare the drawings so that inch-standard sizes can be used. The 3D models will be in the OpenNURBS (3dm) format used by Rhinoceros 4. The intermediate and final drawings will be delivered electronically in PDF format. The cost of printing the large-format drawing sets is not included in the design fee (it's usually cheaper to have a local shop print them). If you prefer, the plans for smaller boats can often be prepared as a somewhat thicker set of A (8.5”x11”) or B (11"x17") size sheets instead of large format drawings.

Ownership of Design

As is customary in this field, the design copyright is the property of the designer, with the client having the right to build one boat (or sometimes several) from the completed plans. At a later date, I may offer a variant of the design to other clients as a stock plan. If you're planning to mass-produce the boat, additional contract terms can be negotiated as necessary.

Class Compliance

If RCD compliance or the approval of a particular classification society is required, this can usually be arranged. Compliance with a particular set of rules tends to be easier when considered right from the start; even so, fully class-compliant boats do cost more to design than boats that- although equally safe and seaworthy- do not carry bureaucratic approvals. Practically speaking, though, the sort of small craft I am interested in do not tend to require class approvals.


The details of the design contract should be discussed and formalized early in the process. Although I like to think that everyone is honest, truthful and agreeable, part of working in our society is covering one's backside and protecting one's clients. A formal design contract, explicitly spelling out what work is to be done and what deliverables will result, helps to avoid misunderstanings and boosts everyone's confidence in the project. Since these details vary from project to project, I won't bore the reader with intricate legal details here.


The design process will progress at the speed of money; in other words, each stage of the design will begin on receipt of payment for that stage. Even if you're not sure that what you want is possible, it might be worthwhile to go through the concept phase, just to see how your ideas pan out. There is, of course, no requirement to continue with further phases of the design if you don't like the concept. The design process can go as slowly as you desire, but cannot realistically be shortened to less than one month, even for a small boat.


Preparing the Statement of Requirements

The single most important document in the design process is the Statement of Requirements (SOR). This is the document in which you, the client, write down exactly what you want the new boat to do. The needs and desires you lay out here will guide the entire design process.

The SOR can, on occasion, be very short: "I want it to be as similar as possible to my current boat, but with room for 4 to sleep on board" could be a perfectly good SOR. The trade-offs involved will come out for discussion during the preliminary design, but the goal is set- and all possible design options will be evaluated against that goal.

Usually, though, the SOR is longer and more detailed. If you want me (or anyone else) to design a boat that's ideally suited for your needs, I have to understand what those needs are- what you'll use it for, in what weather, for how long. And since boats tend to be a substantial emotional investment, I need to know what about them gets you excited- what you've looked at already, why you like or hate it, and what feelings you're hoping to capture in a custom design.

The following list of questions should get you thinking. You don't need answers to all of them at once, but working through them in the early stages of the design process should help you put your thoughts in order and give you a reasonable idea of what you're looking for. Honest answers help to ensure that your custom boat design will be a good match for your unique needs.


What will the boat be used for? (Short trips to the beach, or long coastal cruises, or big-game fishing, or watersports, or....)

How many crew? Any kids, seniors or disabled?

How much cargo?

For how many hours/days/miles at a time?


Describe the worst sea conditions (wind, waves and current) in which the boat will be used.

What's the coldest and the warmest weather in which the boat will be used?

How fast do you want to cruise? What about top speed, and how much speed are you willing to sacrifice when the boat is fully loaded?

Your current boats (if any)

What boats do you have experience on, or currently use?

Where have you cruised with them? What do you like about them?

What do you hate about them?

Why don't they meet your requirements for your new boat?


How much do you expect to spend building this boat? (Be realistic- the budget is the big deal-breaker for many people, but if it's accurately known in advance, the boat can be designed to stay under budget.)

Who will build the boat? (You, or you plus friends, or a local commercial yard, or a yacht yard somewhere else, or....)

If you're building the boat yourself, what materials are you comfortable working with? What sort of projects have you already completed? (e.g. if you like metal: can you MIG weld, can you form compound curves, can you cut and handle large sheets of half-inch plate. Or if you like wood: do you do rough carpentry, or cabinetry, or do you make violins, etc.)

Do you have a preferred construction material or technique?

How long do you expect the build to take?

Motive power

Sailboats- any preference for rig type?

Powerboats- do you have a particular preference for inboards, or I/O, or jet, or outboard?

Will you need an auxiliary engine or trolling motor? How far/fast do you need it to take you?

Layout & Styling

What boats have you already looked at?

What attracted you to them?

Are there particular design elements that you really like about certain boats? (The galley layout, perhaps, or the view from the helm station, or the way the rig controls are laid out.)

What did you dislike about these boats?

What about your personal tastes for styling and layout? Is there a particular look or feel you want to capture?


List all the gadgets, gizmos and fixtures you want on board. This could be a long list! (Include everything you think you'll want: head, sink, fridge, nav computer, microwave, power windlass....)

Make a note of things you might want to add in the future- perhaps you'll want that elaborate nav system a few years later, even if it's too pricey now. If so, we can ensure that there's enough space, power and places to run the cables.

Constraints & trade-offs

Are there limits on length, beam, draught, bridge clearance, or weight? (e.g. must fit through a certain canal, trailerable with a Dodge Caravan, etc.)

What traits do you want to prioritize? (e.g. speed trumps comfort, or rough-weather ability trumps living space, or long-distance efficiency trumps dockside handling, etc.)


Design Assist

Design assist services are meant for clients who have some unique requirements, but do not need a full custom design. These services are ideal for:

  • Experienced amateur builders who have a clear idea of what they need.
  • Professional shops that require advice on a few aspects of an otherwise in-house design.
  • Other engineers & designers who want to independently cross-check some assumptions, calculations or design ideas.

Examples might include creating a new interior for an older boat that is undergoing retrofits, or making modifications to a stock plan to suit a particular set of requirements. Systems design & specification, such as powertrain selection or DC electrical bus design for a builder whose expertise does not include those fields, is also fair game.

In cases such as these, there is no need to go through the full custom design process: the boat may already exist, or the design may be based on a stock plan for which most of the design work has already been done. This option is generally targeted at clients who already have a pretty clear idea of what they want, and just need a bit of help with drawings and calculations to make sure it'll work as expected.

There are a few things that I can't do under design assist contracts:

  • I won't "check over" or "review" an amateur-designed boat, or respond to questions like "I designed it myself, can you just do the stability and performance calculations?"  If you have the engineering knowledge to design a small boat (and I only deal with small boats), you either don't have much need for my help, or will have already done this work and just want it cross-checked. If you don't have the engineering knowledge, I essentially have to treat it as starting a custom design from scratch, as (1) there will be lots of scope creep as I find things that won't work and need to be changed, and (2) I can't take responsibility for work that isn't mine.
  • I won't make modifications to plans that are the intellectual property of another designer without his/her written permission to do so. All living boat designers provide some degree of support to clients who want to make modifications to their designs. If you already have plans, your starting point should always be the person who drew those plans.

Design assist services are unique to each individual case, and if you're interested in this option, please contact us for additional information. This kind of work is billed at our hourly rates, rather than the flat-fee schedule used for complete custom designs.


Retrofit, Repair & Systems Integration

Repairing, restoring or upgrading your boat can quickly become a complex, tedious endeavour. It's easy to get overwhelmed. How much can you do by yourself? What tasks are too complex and have to be farmed out? How do you decide between various suppliers, various equipment options? How do you even figure out what needs to be done to bring an old boat back?

We can help you make sense of it all. Whether it's a structural grid rebuild, an engine replacement, rewiring, or the addition of new electronics, I can help you to put together a logical, coherent and technically sound strategy for making sure things turn out the way you want.

We specialize in small boats- under ten metres or so. Most boatowners who would be looking for help in these areas are doing a lot of the work themselves, so we try to create repair and retrofit plans that are balanced for low cost and longevity- so you don't have to do it again in ten years- even if this means the work will take a bit longer to do.


Projects that might fall under the repair & retrofit umbrella could include:

  • Engine replacement (we can specify a new engine, redesign the engine mounts, and plan out the new wiring and plumbing runs)
  • Electronics upgrade (new network design, wiring schematics, systems integration & troubleshooting)
  • Structural rebuild (new scantling calculations, plan of work, shop drawings, quality control)
  • Leak tracing (identify the failed parts, plan the repair, test the repair)
  • Owner training (teach you how to repair and maintain something you're not familiar with)


Stock Plans

Click here to see all designs - stock, in progress and unavailable. The list below contains only those boats for which stock plans are currently available.

Stock plans are designs that are ready to go- you can get the complete plans immediately and start building tomorrow. Most of these boats are designed for amateur or advanced amateur construction; any professional yard familiar with a particular boat's construction method will also be able to build it.

Full construction plans and build instructions are available for all the boats in this list.


Design Prices

Stock Plans

Prices for our stock plans are listed at the bottom of each boat's page, if that plan is available.

Our stock plan model is a bit different than most. Drawings are delivered to you electronically, so we don't ship rolls of paper. This keeps the costs down, since you don't have to pay extra for shipping paper around the world (although we can print and mail drawings, at cost, if necessary).

We offer unlimited technical support to help you finish your project. If you can't figure out how something's supposed to go together, ask and we'll explain it. If you need some information that's missing from a drawing, we'll send it to you. If you're not sure whether a local wood is a good substitute for the specified one, ask us and we'll run the numbers to see if it's OK. It's all part of our carefully crafted scheme to turn frustrated, garage-bound builders into happy, lake-bound boaters.

Complete Custom Designs

Clients interested in a custom design are often worried about the cost spiralling out of control. Our solution to this problem is to define the total budget at the beginning of the project. The boat will be designed to stay well under budget if all goes well, leaving enough of a margin that a few late-stage change orders or builder delays won't break the bank.

Design services are billed as a percentage of the total estimated cost of the project. Depending on the size and complexity of the boat, the total design fee is typically in the range of 4 to 7 percent of the final cost of the boat.

When you consider the "extra" costs that go into a mass-produced boat (broker's fees, advertising, transportation costs, factory overhead) and the tendency of custom builders to run relatively lean operations, custom boats simply don't live up to their reputation as being unusually expensive. Plus, you get exactly what you want, designed to your own unique specifications.

Additional Boats

If you're commissioning a design for mass production, the design process and fee is exactly the same as for a one-off boat; additional boats produced will typically be assessed a small royalty on the order of 1% of their sale price.

Hourly Services

Design assist, repair & retrofit, surveying and other ad-hoc services are billed at hourly rates. Rates may vary depending on the complexity and risk involved in the project; contact us for details.