DavidG

Members
  • Content Count

    63
  • Joined

  • Last visited

Community Reputation

2 Neutral

About DavidG

  • Rank
    Member

Recent Profile Visitors

The recent visitors block is disabled and is not being shown to other users.

  1. DavidG

    TIps for new sailors

    Get a copy of Eric Twiname "Start to Win" Keep a notebook
  2. Anyone know what CMS is? In the Ausi layup schedule (from what I can see) the stacking sequence is 2 off 200 gm CSM, 2 off 450 gm CMS, 2 off 450 CMS + the 300 gm CSM. whilst not legal, an extra 300 gm CSM on top of a 2200 gm does not seem particularly life changing, given that there must also be an overall weight increase, in the ends. I always understood that there was some Coremat in the Laser layup, but maybe this is in the deck?
  3. DavidG

    "fu ws" (from the front page)

    Cant help but think that a trick is being missed to come up with a family of designs, possibly using a common hull, that covers lightweights, medium weights and heavyweights to replace both Laser fleets and the Finn; this could be done presented in a way that the media and joe public could understand ...
  4. DavidG

    Lightning protection or no?

    I did a bit of research on this for a client who kept his boat on a dock in the Chesapeake. He put me in fouch with some people called Zapp Strap, who appear to have disappeared off the interweb. My conclusion was that no two experts agree; and that often there is little evidence remaining if the lightning protection system does not work! Few thoughts; Sintered grounding plates explode during lighning strikes as the water in the curfs vapourises Carbon masts will require detailed survey following lighning strike Any angles in the run of the bonding cable within the boat is a probable route for lightning to escape, and best for crew to stay well away Best not have the tallest mast in the vicinity during an electrical storm One question for the experts; Whilst I can see the merit of connecting the grounding/bonding cable to a keel bolt with an iron keel, is this a good idea with a lead keel?
  5. DavidG

    the greatest

    Imp
  6. DavidG

    The Yacht Club - Do you get value from your dues?

    This sounds like fake news. Whilst I have had the pleasure of attending a World Championship at St Francis Y C ... which in my 57 years still ranks as the most memorable of my sailing career, I would suggest that the ability to host World Championships or train race officials, Olympians is not the sole reserve of mega buck clubs ... on this side of the pond most of the talent that has found their way onto the rostrum has originated from the enthusiastic clubs, with member run bars and bacon sandwiches before racing. Some of the top Racing Officials in the World have also progressed from this background. And Youth sailing is generally promoted by keen sailing family members trying to impart worthwhile values onto the internet generation. Having had a scan through the membership charges of some of the UK's pre-eminent clubs GBP 500 should see you through a year of membership with clubs with dining and in prime locations, that run World Championships, train Youths, have Olympians amongst their members, have decent restaurants and bars ... mine costs GBP 250 for family membership and ticks most of these boxes. I would suggest that whilst clubs like St Francis or Annapolis YC are great, these are essentially country clubs for people interested in sailing, and whilst there is no denying that they do good things, this has more to do with a need to justify their existance.
  7. It's all about the people who do "stuff" to make sailing happen. If your club has plenty of them at different levels sailing will thrive. Sadly developments in society have seen the reduction in the numbers of "givers" and increases in "takers" ... I suspect that this applies on both sides of the pond.
  8. DavidG

    Cheeki Rafiki MAIB report published

    You may know different, and this may be the case in the aircraft industry. But I am less convinced that all laminators in a big production yard have much concept of the importance and need to recreate the same theoritical properties of the laminate in the keel area as the designer intended. Likewise ensuring that there is sufficiant adhesion with no voids between a structural liner and the hull skin. Nor am I convinced that all yards have top down quality control systems in place that ensure that this happens. I suspect that this is not the case with repair shops, where the diversity of work requires a higher level of skill ... assuming that the right people are delegated to jobs within their skill set.
  9. DavidG

    Cheeki Rafiki MAIB report published

    One consideration is that CE marking in Europe has resulted in declining standards; the goal posts have been set too low, and the engineering analysis is almost exclusiveky based on theory rather than inspection. Production boats are often type approved, often with the first in the line being the only boat that gets inspected. From the European purchasers perspective, if there is a CE Builder's plate with Category A on it, then it is OK for Ocean crossings, in the naive belief that the system is working. Back in the day, if you were trying to build a better blue water boat, there was an emphasis on building a reputation as a builder of quality products ...pushing you toward (in the UK) building to Lloyds scantlings, which were way more demanding than ISO 12215, and more importantly, regular "spot" inspections by the Lloyd's Surveyor, who was often waiting at the build shed at 7.30 in the morning! The RCD came about to protect markets, and I remember a salesman for a large production builder explaining that their boats had to be Category A, not because that is how they would be used, but because they were selling the dream of their boats being able to cross oceans. IMO this is in part contributary to the problems with the Bene 40.7 and the Match 42's that lost their keels. It might also be worth considering that many of the guys building these boats have no experience of sailing, and no understanding of the relevance of the significance of the structures that they are putting together, particularly in big production yards.
  10. DavidG

    Cheeki Rafiki MAIB report published

    I seem to remember my Southampton Institute structures lecturer expressing great scepticism of matrix/spider/tray mouldings. Out in the real world his views have been vindicated. As a surveyor it is reasonably easy to expose the outside of the keel connection, gel cracking can be indicative of a problem in the laminate at the fore and aft hull/keel connection, as can laying a straight edge at the aft keel connection. Tap soundings can work inside of the hull, but the reallity is that you cannot realistically confirm the quality of the bonding between the matrix and the hull surface, which have been bogged in place. Where ultrasonic and thermal imaging have been demonstrated to me I remain unconvinced of the reliability of the technology for this application ... I can for core debonding issues, but the grillage area is just too busy. There is too much risk of false negatives. To my eye, I yearn for Lloyds Green Book which detailed substancial laminate in the "fin and tuck" keel area, together with substancial keel bolt sizing; this promoted structures that were fit for purpose, accessible and repairable. This is why there are lots of serviceable 40 year old+ yachts around ... I am less convinced that many of the modern matrix boats will make it that long. On the positive side "Cheeki Rafiki" may help surveyors win the arguement with owner/operators for destructive testing where it is considered to be appropriate. As a surveyor it is usually easiest demonstrate a point if there has been a catastrophe that is the result of someone not heeding best practice. The problems imo have come about because ABS was vague on scantling specifications in the keel area, and the ISO standards were silent on the issue for too long. If you are going down the matrix route FEA is probably the only effective design tool, and this is only as good as the input loads and the build quality control. As has been pointed out by a previous poster, the costs of heavier scantlings and fastenings with some redundancy in the keel area is small relative to the overall cost, and the additional weight is going to lower the VCG. If builders must use a matrix, maybe they should consider using clear gelcoats below the sole, and include cutouts to allow inspection of the integrity of the bonded connection?
  11. DavidG

    Cheeki Rafiki MAIB report published

    Something to be said for Lloyd's Green book then
  12. DavidG

    Cheeki Rafiki MAIB report published

    On the whole I think that the MAIB report is a good. Ultimately survivability is what counts and the report points to various matters that might have served to have provided a better outcome for the crew. It seems to me that had the crew identified 24 hours earlier that the source of the water ingress was from the keel structure, then they would have identified their location and abandoned ship to the liferaft. I put my hand up to admit that I have not ever surveyed a First 40.7, so I don't know if it is necessary to dismantle the saloon table to open up the saloon sole boards in order to access the keel bolts and supporting structure. However it seems strange that the the source of a serious leak was not established, despite having a day or so to locate it, which by all accounts originated from the keel fastenings, A significant proportion of yachts that I survey, have fastened down sole boards in way of the keel fastenings and supporting structure, and whilst in most cases, it only requires a few screws to be removed, dismantling the saloon table is a bigger ask. Doing this in poor light in rough conditions would be a bigger ask. Maybe all manufacturers should provide ready access to all underwater through hull fittings and fastenings, including keel fastenings, shaft logs and rudder stock logs, without requiring the use of tools. I am unconvinced that an additional note in the Owner's Manual will do much more than cover the manufacturer's a**e. On another point, with a little experience in manufacturing, whilst Methylacrylates may be regarded as a wonder material, having observed a yard where I worked, racing against the clock to get the deck down inside the Plexus window, I can fully undersatnd why the theoretical properties of the bond might not be acheived. I also note that some factory operatives, who might be unaware of the structural significance of the "bog" might not take the care that may be warranted. I have seen failed Methylacrylate bonds that, if the manufacturer's data sheet is true, can only be attributed to the applicator using the material outside of the time and temperature window, I believe that this is more than possible, particularly if there is a problem getting the matrix or liner to mate in the correct position.