Feature 4 | MEGA YACHTS • Gel coat defects


• Film thickness In doing so it references other


appropriate ISO standards and sets out some useful terms and definitions to ensure that everyone involved speaks the same language. Immediately it can be seen that the list of


factors that have an impact on appearance has increased and it is interesting that an item of technical quality has emerged on the list, namely in the form of film thickness. Tis would appear to confuse cosmetic quality issues with technical quality issues. In reviewing the draft, then, the following observations can be made:


• Gloss to be measured using a gloss meter


• Colour difference to be measured using a spectrometer


subjective requirements in terms of cosmetic quality. Once that is done, then a profile of the


acceptable values of TQI and CQI could be developed for any yacht project. To date discussion has focused on


one standard and that is the super-yacht standard. Te implication to yards and owners is that, as long as the subjective element of this remains, there is no really clear point at which a decision could be made to say that the finish that is presented meets the standard or, if it fails, by how much it fails and for what reasons. The danger is that “beauty is left to the


eye of the beholder” and no two people may agree as to what the standard is. It is clear that the important factors


• Appearance (orange peel) DOI, to be assessed using a wave scan.


Work is still ongoing to cover the other


aspects of: • Fairness


• Superficial defects • Gel coat defects


• Gloss


in assessing the cosmetic quality of a Super yacht finish include, but are not limited to:


• Colour measurement (initial and over time)


• Definition of Image • Dust inclusions • Fairness


• Gel coat defects


• Film thickness With the advent of laser scanning (4),


the issue of fairness control could be developed in an objective format without the reliance of a subjective judgement based on observations on a show coat, or possibly the use of a metal baton. Improved fairing should help improve


the TQI and the CQI to enhance overall appearance and reduce filler consumption and make the process easier. Thus, there are strides being made


across many aspects of the cosmetic quality issues to remove the subjective element, with a view of making the processes more objective. The reality, however, is that even if


the Technical Quality Index is correct and the measurable elements of the Cosmetic Quality Index are correct and in accordance with measurements, the results may not look pleasing to the eye. Tis would imply that more work needs


to be done to better define the standards so that the objective values agreed at the start of a contract do align with the


68 factors such as:


• Other surface defects In addition these can be enhanced by


• Tension (ratio of short to long wave light reflected)


• Hardness of surface (propensity to mark and scuff)


• Haze (cloudiness) Of course the TQI requirements must


also be met. Finally, not withstanding how all


the other factors are determined and measured, the visual appearance cannot be ignored, as it is the most critical, and it is ultimately subjective. In theory, it is possible (but unlikely)


that all other elements of TQI and CQI are not achieved but the vessel finish may be accepted based on the visual appearance. The simplest method of establishing


the standard required for a particular super-yacht, would be to take a prospective owner and show him a selection of yachts (this is how the car industry sets about establishing its acceptable cosmetic quality). The owner, having selected a suitable reference vessel, can then have the


vessel analysed and a profile of the vessel can be built up and that would create a standard for that particular owner and that particular yacht, which may be different to another owner and another yacht. If this assessment could be undertaken,


then the various measurements could be combined on a scale that could represent a CQI profile: The final visual assessment can still


• High visibility


exert great influence, but there are opportunities to mitigate some of this influence, certainly one route would be to divide the visual impact into four broad categories:


• Medium visibility • Low visibility


• No visibility Te high visibility areas are those where


there can be no compromise on the finish and are visible to guests and passers by. Medium visibility would take into


account those areas that have limited visibility to passengers e.g. lockers. Low visibility areas are those that are


not on display at all (perhaps inside a motor housing). Finally no visibility areas are those that


will be covered by linings or decking or other materials. Tus for the no visibility areas the TQI


is paramount, while for the high visibility areas the CQI is the critical element. In summary, a working standard for


yacht finishes remains elusive, although previous proposals and the ISO draſt text go a long way toward quantifying some key elements, there has not been a method proposed onto which the technical and cosmetic aspects of a finish for a super yacht can judged against in a consistent manner. Te proposal set out here, may offer


a route for consideration and is under continuous development. It is slowly being applied to appropriate projects with an initial focus on the TQI elements and the use of increasingly complex instrumentation for the CQI elements. Perhaps beauty will always remain


in the eye of the beholder, but it may be possible to define that beauty on a project- by-project basis and give all parties an opportunity to work to an agreed standard. NA


The Naval Architect July/August 2009


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88