PART 1. ABOUT BUILDING WITH COMPOSITES

1.1 Why Build?

There's a wealth of production boats out there to choose from and some of them are very good. Most of them can be test sailed. The price and delivery date is known in advance. You can normally speak to existing owners and read reviews to asses the product.

So why build a one off custom or stock design, rather than simply purchase a production boat?

 

• Firstly production boats are usually fairly generic in nature. This is simply to maximize the potential customer base and keep the cost competitive. The performance might be lackluster due to a relatively heavy build and a conservative rig. The styling might be uninspired. And the overall accent might be on the accommodation layout and creature customs which is fine if that's what you want. But if you're keen to see the occasional firehose of spray off the bow  and have tropical islands slipping by quicker than you can finish your drink then you might feel a bit disappointed with your purchase.

 

• Secondly a production boat is a significant one off expense. You get to go sailing as soon as you've paid the money, but if you're not in a big hurry and your pockets are not overflowing with cash then the one off build project gives you the option of building over time as the resources become available.

 

•Thirdly, for some the boat building project holds value as an expression of creativity. The building of the boat can be very rewarding simply as a statement of self achievement. If you are having the boat custom designed and built you can make a unique and definitive statement about your taste and style of sailing.

Cut Loose; a custom design built by Jamie Morris of Australian Custom Multihull Yachts
Cut Loose; a custom design built by Jamie Morris of Australian Custom Multihull Yachts


1.2 What is Composite Construction?

Any structure or component that incorporates the bonding or mixing of dissimilar materials to form a unified element in a structure can be said to be of composite construction. So technically speaking a mud brick reinforced with straw or a laminated bench top is a composite.

 

However in modern boat building the term composite construction is generally used to describe sandwich construction; a laminate commonly made of PVC foam core, glass or carbon reinforcements, and a matrix of polyester, vinylester or epoxy resin.

 

The principle is simple. If we just use multiple layers of fibreglass we have good strength - but we need many layers to achieve adequate panel stiffness and that makes the panel too heavy . So we put PVC foam, aluminium honeycomb or other light material between the inner and outer layers of fibreglass to provide panel stiffness. Now we have a sandwich which is still strong enough for the job, but is also very light and stiff.

 

In creating the composite structure there are some critical engineering properties we have to be mindful of. The materials we put between the inside and outside layers of glass have to be able to carry the shearing loads. So the material properties of the core and the way it is bonded to the skins is critical to the structure. It's in dealing with these issues of optimizing skin thickness, core thickness and shear strength properties that the composites engineers earn their keep.


1.3 The ever increasing presence Composites

Photo of a large composite wind blade.
Above: 78M Long blade at NASA's Michoud Assembly Facility

Composites are taking over in many fields . Many structures that were once built in aluminum, steel and concrete are gradually being replaced by composites. These include aircraft, cars, wind turbine blades, bridges and building facias.

In the early 1980's it was very difficult to find someone who would willingly put the title "Composites Engineer" to their name. It was even more unlikely that you could find such a person who would confidently and competently engineer a boat structure in composite.

A lot was leaned by trial and error.

It's very different today, with large auto and aero manufacturers, as well as specialised engineering companies employing  large numbers of very skilled composites engineers.



1.4 Amateur or Pro. Who can build?

We've seen magnificent examples of yachts finished to a very high standard and built entirely by an owner without any formal boat building training or previous experience. Quite often such examples rival the quality you might expect from a professional yard.

 

Most of the top professional boat builders in the world have been through a course at a technical institute or university, and then served an apprenticeship with an established boat builder, often over an extended period of time before establishing their own boat yard.

 

But many boats are built to a very high standard by owners without this background. So how can this level of quality be achieved if you haven't studied boat building or served an apprenticeship?

 

• Hire the expertise and the skills you need. Make an acquaintances with others on a similar journey and compare notes. This is increasingly easy to do with social media and other online services.

 

• Do your research. It's not easy to come across good information for composite yacht construction and many of the boat building courses at technical institutions are woefully inadequate in providing good information and training for building lightweight composite structures. Seek out those who are building and sailing lightweight composite boats - that is; living their life in the real world of modern composite yachts.

 

• Outsource. When in doubt call in the experts - those who do what you need to get done for a living.

 

• If you have the time find a company that will employ you and train you in the use of composites and the associate technologies. Learn the skills and build your bank account at the same time.

 

. Hook up with a specialist supplier of composite materials. If you are purchasing materials and equipment from these companies most of them will provide you with training and technical information to assist you with your project including vacuum bagging and resin infusion. Dont quibble about the price of their resin system being a little more expensive if they are providing a quality product and good technical support.

 

Quality composite boat building is as much a mindset as it is a learned and practiced skill. It's  about paying attention to details, it's about sourcing the information your need and practicing at small scale before you tackle the big project. It's recognizing when you are out of your depth and need some professional assistance. It's also about planning and thinking through the problems and challenges that will inevitably arise. As much as anything its about your own resourcefulness.

Photo of hand laminating
Hand laminating a carbon reinforcement prior to vacuum laminating
Photo of vacuum laminate operation
Applying the vacuum to the wet laminate


1.5 Plans

The plans are the language designers use to transfer the intent of the designer and the engineer to the workshop floor. They comprise text, drawings, diagrams specifications and rendered images. The details on the plans are important and your designer would prefer that you ask questions rather than proceed without being certain you have interpreted the drawing correctly.

 

One good practice is to using a marking pen to mark off details on the drawing after they have been attended to, that way once the drawing is all coloured in you can be sure you haven't missed an important detail.

 

See an example of plans for a sailing catamaran in this link