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.

Risk mitigation philosophies from the radiation world

Submitted by Matthew on

Quite a few issues of safety, in the yachting world, come down to the preferences of the skipper and crew. There will never be universal agreement on how (or if) to use tethers, or on where a life raft should be kept, or on whether an extra EPIRB is a better investment than an AIS-B transponder upgrade.

We can, however, apply some general principles of risk analysis and risk mitigation at the design stage. The maritime world already has some ways of figuring this out, but for today, I think I'll shake things up a bit with some principles from a different field: ionizing radiation.

Starwind 860 design logic

Submitted by Matthew on

"Why that?"

It has to be among the most common questions I get about the Starwind 860 trimaran. Why a tri-hull? Why that size? Why is it a powerboat?

Here's the short version of the design logic.

Dynamic Stability of a Monohull in a Beam Sea

Submitted by Matthew on

The last post in our series on yacht stability looked at the static case. We saw that a yacht's response to heeling forces can be described by a stability curve, the shape of which tells us a lot about the boat's purpose, sailing characteristics and seaworthiness.

A real yacht in a real situation is of course far from being a static case. The static stability curve is one of our best tools for quantitatively comparing different designs, and I don't mean to denigrate its importance. In practice, though, dynamic factors can often have a bigger effect on the actual stability of the boat as it relates to safety, seaworthiness and comfort.

Engine technology to watch for

Submitted by Matthew on

With the recent release of the final report of Nigel Calder's HyMAR project, marine internal combustion / electric hybrid powertrains are making waves once again- and not necessarily in a good way, as Calder's team found that the benefits of the expensive hybrids were limited to a relatively narrow, low-speed operating regime. We've known for quite a while that the major advantages of gas/electric and diesel/electric hybrid cars- namely, instant start/stop and regenerative braking- don't apply to boats. We've also known for quite a while that hybrid systems only make economic sense aboard ship if the house loads are comparable to, or larger than, the power required for main propulsion.

Tech addicts need not fear, though: There are many other fuel-saving and pollution-reducing technologies waiting in the wings, and hybrids aren't quite out of the running yet.

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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.

Back On Track

Submitted by Matthew on

Our little hiatus is over. We're settled in, the essential work is done, and it's time to get back to the boat.

The next thing on the Starwind 860 build schedule is to finish up the crossbeams. Today, with perfect weather and (for the first time ever) plenty of space to work, we laminated the lower flanges of both forward beams.

Crossbeams Closed In

Submitted by Matthew on

With the temperature now dropping below zero on a regular basis, temporary permission has been obtained to bring boat parts indoors for short periods so that the epoxy can fully cure. (In this weather, the resin will kick off and gel just fine, but the reaction slows down dramatically once it starts to solidify.

Crossbeam details

Submitted by Matthew on

The crossbeams of the Starwind 860 are its most complicated parts, from a construction standpoint. Today I'll show you a few internal details from the aft pair.

Crossbeams, little by little

Submitted by Matthew on

Trimarans are finicky to build. There really aren't too many ways to simplify the highly loaded crossbeam structure, particularly when (as in our case) it has to be able to fold for trailering.

Our Starwind 860's aft crossbeams are now sitting partially assembled in the garage. The webs, the strut blocks and the centre blocks are in place, and it is now time to start closing them up.

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