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.

Why I over-design electrical systems

Submitted by Matthew on

"Why", I'm sometimes asked, "do you specify electrical stuff that's bigger and more powerful than I had expected?"

It's a justifiable question. Batteries are expensive, heavy and bulky; why would you want any more of them than necessary? And what's with the multiple shutoff switches, subpanels, and other non-typical features of my electrical designs?

Criticality One

Submitted by Matthew on

Anything that people make is going to break. This is inevitable. It's a direct consequence of unavoidable, fundamental laws of the universe.

Part of the art of engineering is to control where, and after how long, things will break. We can't prevent failure entirely, but we can focus our efforts on the most critical items and we can ensure that the complete system – an engine, boat, spacecraft, whatever – is unlikely to fail at all within a certain service life.

The Factor Of Ignorance

Submitted by Matthew on

"Safety factor." It's probably one of the most common, and most misused, terms in engineering.

The "factor of safety" might be better described as a "factor of ignorance". It's a multiplier, applied to loads and/or structural components in a design, to account for things that weren't explicitly taken into account in the design calculations. Those things could include variations in material quality or workmanship, uncertain overload conditions, accidents, and other hard-to-predict conditions that could cause a failure.

Weak Links

Submitted by Matthew on

Is there an advantage to designed-in weak links, where a cheap and easily replaced part fails so that a more expensive one can be saved?
In many cases, there is; nevertheless, we shouldn't apply this design philosophy to everything we design.

Pages

more

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.

Epoxy & Fibreglass in Winter

Submitted by Matthew on

It's still winter up here in the great frozen wilds of Ontario. That doesn't mean that boatbuilding has to come to a complete stop. We can, with a few tricks, turn ice-cold epoxy into something usable.

And Then There Were Two (Hulls)

Submitted by Matthew on

141214-200007-8151s.jpgThere's still a long way to go, but now it *looks* like two-thirds of a trimaran!

Compound curvature in plywood

Submitted by Matthew on

Conventional wisdom says that plywood can't take compound curvature. That it can only be bent into conically developable sections.

That's not entirely true. The Starwind 860's amas have a bit of compound curvature, particularly in the forefoot. Here's how we create it.

Planking the Port Ama

Submitted by Matthew on

This past weekend, we started planking the Starwind 860's port ama. With her first section of hull skin in place, the Starwind is looking more and more like a boat!

Pages

more