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.

Starwind 860 design logic

"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

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

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.

Boat manuals need to include electrical schematics and software details

Good drawings take time to make. Time costs money. Therefore, good drawings are not cheap.

Some boat builders seem to think that this logic leads to a fourth point: "Therefore, we will not include drawings."

Er, guys? Not cool. Seriously, not cool. Just see what happens the very first time the owner has to have something fixed, and the technician spends most of a day rooting around in the bilges trying to figure out where the hell all the wires are going.

Pages

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.

Crossbeams, little by little

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.

More S860 crossbeams: Centre bearing blocks

The Starwind 860 trimaran's crossbeams are joined on the boat's centreline by a massive hinge pin. This mechanism ensures that the two outriggers fold in sync. The peak load on the centre bearing could be up to 41 kN (about four tons) port-starboard or 11 kN up-down, and the structures around it need to reflect that.

Coloured epoxy?

What does it mean when your epoxy hardener comes out coloured? Will it put your project in jeopardy?

Nope. It turns out that this is not really a problem for strength or curing characteristics, only for appearance.

Crossbeam construction

It's been a while since we kept you folks posted on the Starwind 860 project. Don't worry, it hasn't died – we've just been busy!

Pages