The case for in-depth computer aided design

Apart from a brief few years running a mail-order company I have spent all my working life in or around manufacturing. In the late 1960s I still remember doing part of my apprenticeship in a traditional garment tailoring factory, lots of handwork with re-cutting and re-shaping parts as necessary. It was only through being sent to Germany to study production engineering that I realised how wasteful that method of manufacturing was and how the product could be somewhat further de-skilled by identifying and separating out the different tasks.

Upon my return to the UK, I became part of team that organised and ran clothing factories for a large group, creating some of the most efficient manufacturing facilities in the country, sadly later to be undermined by the lure of cheap labour in the Far East and the near total loss of that manufacturing sector. During that time I learnt (and it was easy to see) that it was not necessarily how fast the product could be built but about not wasting time between operations or having other forms of downtime. Time lost is money lost and you never get it back.

Because the clothing industry (and other FMCG – fast moving consumer goods) has always been under pressure it was forced to take up advanced technologies at a very early stage. We were experimenting with CAD/CAM in the early 1970s – computer size grading of the patterns, digitizing the patterns and waterjet cutting of the cloth. We undertook studies whereby we ‘commonized’ certain parts such as pockets across many styles so they could be made on pre-programmed machines.

So what has all this to do with boats? Everything. The boat manufacturing sector is under huge pressure, not necessarily to build more boats but to build them more efficiently, thereby offering better value or perhaps more importantly better margins so the industry can re-invest it its staff and equipment.

I now visit lots of boat builders and here we are in the 2020s with too many still being built by traditional ‘tailoring’ methods. There is still a huge amount of effort (quite rightly) put into creating a strong hull with a fair gelcoat but often with less regard to the inside of the hull and fixing such major items as the bulkheads in the right place – every time!

This means the bulkheads are too often cut with ‘green’ around the edges so they can be scribed in and everything else is then fitted to them. This means the boat can only built in a linear way; one section of the build after another – hull, bulkheads and bearers, engineering, floors furniture, deck, deckhead cladding etc. As these tasks mostly require different skills and lead times, the non-productive downtime is where all the costs mount up.

I’ve seen plenty of boat costings with every nut, bolt and piece of equipment on the Bill of Materials and even a fair stab at an accurate labour cost, but never a realistic quantification of the downtime.

Thankfully many have now seen the light and are committed to designing their craft on CAD as well as using advanced manufacturing methods such as vacuum infusion so there is some control on the inside dimensions of the hull. That having been said, it has been my experience that not enough time has then been allowed for the further design of the engineering and interior in that a lot of the finer details ‘will be all right on the night’! Unfortunately they so often aren’t and all these things impact upon one another.

The’ holy grail’ must be to have the design – all of it – right before commencing to manufacture; to have thought through all the little niggles like where the side cladding meets the deckhead or whether there is enough depth and width in the bow to create a proper bed etcetera.
If all these parameters can be fulfilled then the boat can be built ‘concurrently’ – ie: whilst the hull is being moulded, the engineering can be planned, ordered and such things as the electrical loom manufactured. At the same time the furniture can be committed to the woodshop or outsourced, any rigging made up and the soft furnishings planned and put into production.

That means all parts should be ready for assembly and no time wasted in constructing the boat – after all the automotive industry has been doing this for some considerable time now – parts are outsourced and only final assembly happens on the line.

The important point in all this is that there is no substitute for design time on the computer and building a complete virtual model of the boat. The time cost may look outrageous to some but there are no materials being wrongly or wastefully cut, no time spent chamfering or shimming pieces into place and no downtime waiting for parts to arrive or be manufactured. And of course the boat will finally be assembled in much less time.

Many companies in many countries have accepted this now, but it still worries me that many smaller companies in the UK, whilst using some form of CAD do not take it through to finish the job, usually because they are not sure exactly what they want and will decide when it’s in situ. Well, that’s no different to a potential owner asking for a change of specification during the boat build for which you would charge lots of money – only this time it’s costing lots of money in yet more downtime whilst decisions and lead times are considered.

It’s the smaller companies that in the main don’t have the resources to push through a difficult build and would therefore benefit most by working towards a complete design package before committing to fibreglass, resin and wood. “Measure twice, cut once”, I was always told. Take your time with the design and build the boat right first time- and on budget.

David Lewin

Global Marine Business Advisors


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