One piece mast & Out of Autoclave manufacturing

One piece mast & Out of Autoclave manufacturing

Rondal is the only company in the world capable of building a 60+mtr superyacht sailing mast in one piece. How do they do that: Rondal was an early adopter of the innovative OOA (Out of Autoclave) method and has since, for decades now, mastered the art. This allows Rondal to produce without the limitations and expenses of an autoclave.

Many mast builders still stick (or shall we say ‘are stuck’?) to conventional and inept autoclave manufacturing at high costs, forcing themselves to build masts in multiple sections which subsequently have to be bolted together. This method doesn’t keep things ‘simple’, lean or elegant.While others still measure their competitiveness by the size of their autoclave, Rondal has moved on and perfected the OOA method. Besides eliminating expensive tooling costs for autoclave moulds, OOA allows for a very lean and flexible production process and building virtually any diameter and length.

AC versus OOA, Whats''s best?

There used to be a strong push for the autoclave method – not surprisingly, as many specialists came from the autoclave school and autoclave manufacturers. In the meantime (and for obvious reasons such as high costs, inflexible production, etc.), there was a clear need for OOA methods, and so this technology was keenly developed and matured. Now, the differences in end quality of composite products are evident to all, which is further proven by numerous tests, studies and reports. Naturally, composite industry leaders are increasingly moving away from autoclave manufacturing and instead, embrace OOA manufacturing through the use of advanced pre-preg laminate products.

OOA pre-preg yields faster production and has greater manufacturability while easily achieving aerospace-grade results without having to resort to autoclave cure. It is widely being applied in a range of demanding leading industries such as aerospace, military and maritime.

VOID Content

Void content – to composite engineers, this term is equally nightmarish as ‘beetlejuice’ is to little children. Equally scary, but also equally untrue. The misguiding void content argument has been used tirelessly with the aim to disqualify OOA, but has already been debunked by authoritative studies and tests. Void content between AC (Autoclave) vs. OOA marginally differs by less than one percent. Moreover, void content is only one of many factors determining composite strength, and to a far lesser degree than is made to believe. More important factors (primary parameters for mast strength) are laminate properties such as section shape and size, fibre type and direction, mast tune, etc.

In fact, autoclave manufacturing, in this context, has no significant benefits over OOA, so you might wonder why not every composite company adopts OOA? After all, guess who’s paying for this expensive production method at the end of the line? But, of course, applying OOA successfully does require expertise and experience gained over the years.

One Piece Mast

Without showing all our cards, Rondal is proud to provide a little insight into how one piece masts of any length over 60 meters are achieved. First, several thin carbon composite moulds are made to

create the shape of the mast. Not just ‘your average moulds’ as, apart from shaping the mast, these will also add its structural integrity (an additional step in efficiency, cost and waste saving). The ‘structural moulds’ make up about 20% of the total laminate thickness. Internal patching, compression tubes and conduits are inserted after which the remaining 80% of the laminate is added over the full length of the mast, with a combination of UD carbon composite pre-preg. All Out of Autoclave, of course!

Before painting the mast, which we do in-house, the pre-assembly and minor fairing is done. Once the mast is painted, we carefully mount tracks, locks, instrument and other equipment.

Is it that simple? Guess again: Rondal didn’t become the only company in the world capable of building the largest masts, overnight, nor by luck.