M.B. Marsh Design offers a steadily growing range of plans for small watercraft. Our services include custom design, refit planning, condition surveys, failure analysis, systems integration and more.

Our designs hit what we think is an ideal balance between performance, capabilities, cost and ease of construction. Most of them are suitable for amateur or advanced amateur construction. These are boats that you can build in your garage, needing only patience, common tools, basic carpentry and fibreglass skills, and a willingness to learn. The resulting vessels are stylish, capable boats that will serve you well for many years.

From The Drawing Board

New designs from our drawing board, and assorted thoughts on boat design in general.

A cruising yacht that won't break the bank

Submitted by Matthew on

Let's face it: Boats are EXPENSIVE.

Assuming you want to own a yacht of an appropriate size for long-term cruising- say 12 metres (40 feet) LOA- you currently have four options:

  • Buy a new, ready-to-go cruising yacht, often with a price tag north of \$350,000.

  • Buy a new day-sailing boat and upgrade it to offshore cruising standards. The basic boat may be under \$200,000, but the design will often be inappropriate for offshore work and may require substantial hardware and systems upgrades.

Outboard motorboat power calculations

Submitted by Matthew on

Every year, mixed in with the usual chatter around the boatyards, I hear at least a few comments along the lines of "I beefed up the transom of my 14-footer so it can take 60 horsepower!"

Er, no. That's not how it works.

Maximum power ratings for small outboard vessels are calculated according to the size and design of the boat, taking into account the following factors:

  • Length of hull (longer = higher power rating)

  • Beam at transom (wider = higher rating)

Understanding monohull sailboat stability curves

Submitted by Matthew on

One of the first questions people ask when they discover I mess around with boat designs is: "How do you know it will float?"

Well, making it float is just Archimedes' principle of buoyancy, which we all know about from elementary school: A floating boat displaces water equal to its own weight, and the water pushes upward on the boat with a force equal to its weight. What people usually mean when they ask "How do you know it will float" is really "How do you know it will float upright?"

Length matters

Submitted by Matthew on

Longer boats are faster. We tend to take that for granted, because it tends to be true. Put two boats of similar type in a race, and the longer one is almost certain to beat the shorter one to the finish line. The difference that length makes is quite remarkable, but we rarely get to look at it on its own- and that is the subject of today's post.

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In The Shop

Dispatches from the shop: Progress reports on our boat building projects, plus some useful information for those of you who are building, restoring or repairing your own boats.

Making the best of mediocre wood

Submitted by Matthew on

Boatbuilders like to have really good wood. The best stuff is quarter sawn, vertical grain, air dried two years, felled by ceremonial beaver at midnight under a full moon.

What you actually get, especially when buying in small quantities from lumberyards that are unfamiliar with boatbuilding, is plain sawn, a bit warped, and often a bit wet, like the batch of western red cedar I'm using for various small parts of the Starwind 860 power trimaran.

Outrigger struts for the Starwind 860

Submitted by Matthew on

It's time for another boat parts update! The only way this project is going to make it to completion is if a little bit of work gets done at every possible opportunity. So, slipping in a task or two a day, we are making slow but steady progress on the Starwind 860 trimaran.

The struts that link the 860's crossbeams to her main hull have aluminum end sleeves and a red oak core.

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