I have re-read the yachting news reports of the MAIB assessment of the causes of Chiki Rafiki incident. Here are some thoughts that I expect others can also add to in the search for understanding and to avoid similar outcomes in future:

The report at http://www.mysailing.com.au/news/cheeki-rafiki-disaster-report-highlights-safety-issues-with-grp-yachts seems to have specific information that the strengthening ribs fibre-glassed to the inside of the thin hull to give it structural integrity might have delaminated. "The investigation has identified that in GRP (glass re-enforced plastic) yachts that are constructed by bonding an internal matrix (or lining) of stiffeners into the hull, it is possible for the bonding to fail, thereby weakening the structure."

The YBM article quotes the MAIB report highlighting the importance of "the inspection and repair of yachts where a glass reinforced plastic matrix and hull have been bonded together." But it 's very difficult to inspect a matrix of stiffeners hidden between the outside hull and continuous inner accommodation liner.

I know of powerboats with a similar problem, when internal stiffening ribs lifted away from the inside of inaccessible areas of the hull. This problem seems to be created by water in the boat from previous causes. Some internal materials used as the core of stiffening ribs, covered with fibreglass and bonded to the inside surface of the hull, seem to deteriorate when exposed to salt water because they are no longer bonded to the hull. In the case of Chiki Rafiki, water might have been entering over some years due to successive groundings.

A significant focus of modern boat construction has been the pursuit of lighter - and presumably lower cost - hulls, which has been made possible by smart engineering; a thin hull skin, with a matrix of strengthening ribs on the inside, hidden by and bonded to a thin inner accommodation liner, which is what you walk around on, and sit against. From the text of the MAIB report, it seems these stiffeners could actually be fabricated on what is the outside of the internal accommodation shell and then bonded to the inside surface of the thin hull to reinforce it. Presumably by putting glue on the stiffeners and pushing them against the inside of the hull skin.

A consequence of creating a continuous internal accommodation liner is the difficulty of gaining access to the space between the inside of the hull and the accommodation liner, to inspect, evaluate or repair; either initially - to determine if the structural stiffeners have actually bonded to the hull and accommodation liner - and later, to check if they are still bonded after years of use. And when underway, to check for any internal signs of damage to the external skin (hull), or to locate where water is entering.

There is a Beneteau here owned by a local sailing club, and I run sailing courses on it for them. It is a modern dinghy style underwater shape, with retractable keel. Fast and convenient, but I cannot find the bilge, and I am routinely tasting the water slopping around on top of the inner accommodation liner to check if it is salt or fresh. There seems to be no way for this water to drain away into the bilge; or wherever the 2 x manual bilge pump intakes are located. Water on the accommodation liner floor must be scooped or sponged out from the inside.

If my interpretation of the MAIB report is correct, the Chiki Rafiki crew were faced with a very difficult problem created by this construction technique. They probably got water whenever they pumped the bilge. Perhaps it was sufficient water to somehow make its way from between the two skins - external hull and internal accommodation liner - and appear on the floor of the inner accommodation liner. They no-doubt checked and found it was salt, but if the boat is like the one here, the could not get access through the accommodation liner to examine the inside of the outer skin to locate the problem, to take action to stem the flow, or to see and understand the nature of the problem.

I expect the Chiki Rafiki crew would have taken very different actions if they could have seen the source of the incoming salt water, watched the thin hull flexing and perhaps observed elongated keel bolt holes. Instead of advising about an apparently manageable problem (water in the boat) and altering course to a closer port, they probably would have declared an emergency, deployed EPIRB and liferaft, and prepared to get off quickly; or perhaps have transferred to the liferaft and left the yacht.

The fact the liferaft was still in its stowage suggests they had no idea of the seriousness of their predicament.

"Where bonding is used to secure a matrix of stiffeners into a hull, it is possible for that bond to break down leading to weakening of the overall structure. Importantly, break down of the bond can be difficult to detect." (My Sailing article quoting the MAIB report.) Does that mean many of us could be sailing inside a thin-skinned yacht hull reinforced by a hidden structural integrity system that we cannot check is actually working as intended?

In light of this incident, I am thankful my yacht has no internal accommodation liner and sophisticated matrix of stiffeners to engineer a sufficiently strong structure from otherwise (inadequately?) thin and light materials; it 's just solid fibreglass with a moulded keel and external lead balast boolted on with the bolts visible in the bilge. What is see on the floor inside is not a thin liner hiding a network of ribs and a thin hull, but the inside of the actual hull material, up to 2 inches thick in places. If water is entering I can see exactly where - including in the proper bilge and at the keel bolts - and stick something in it to stem the flow. About 12 months after buying it, and despite a pre-purchase survey, I discovered soft areas in the laid teak deck. When I removed a section of the internal headliner I found massive fungi and extensive mould, all nicely hidden by the very attractive looking headliner. It was everywhere. When I replaced the entire deck I specified no internal head liner; if any water comes through again I want to know about it. The Chiki Rafiki incident could suggest a similar approach is also important for the hull. If you can 't see it you can 't know what is damaged and needs fixing when the boat is on shore. And when underway, you can 't know what might be about to cause a sudden and serious problem.

The MAIB report highlights how this modern construction technique can mask a serious problem which can very suddenly (now no longer unexpectedly) plunge the crew into a survival situation. Therefore, asking a nearby vessel to travel close by while a damaged - and perhaps fatally flawed - yacht limps to shore, now seems even more important and appropriate. In coastal waters or main shipping lanes with high traffic densities, nearby could mean in VHF range. In unpopulated coastal areas (like Australia), around SE Asia and other places without integrated coastal VHF networks (ie: most of the world), in the open ocean, and anywhere where a rescue helicopter, Coast Guard Cutter or RNLI lifeboat is not available for immediate deployment (ie: most of the world), nearby probably also means communication with any other vessels maintaining a 24/7 DSC watch on their HF/SSB radios.

If the Chiki Rafiki crew could have understood the gravity of their situation and made contact with an unknown but nearby yacht or ship to ask them to standby as they limped along, or to lift them from the fatally damaged hull or collect them from the life-raft, the outcome could have been very different.

As with numerous other incidents (at least over on this side of the world), using a satphone to contact a distant owner, relative or MRCC does not necessarily produce the required result, because they do not know what other yachts and small-craft are in the vicinity of the distressed yacht, and/or they have no means of making contact with them, either because these nearby vessels do not have an always-on satphone link, their satphone number is unknown, the MRCC does not have a HF/SSB radio with DSC (eg: MRCC Falmouth) or the yacht does not have a DSC capable HF/SSB radio switched on 24/7, scanning for calls - Individual, Group or Distress.

As recommended by numerous MRCCs on this side of the world, direct contact with nearby vessels via marine radio is more likely to get the required result in an emergency. Also, the "International Maritime Organization (IMO) has strongly recommended that non-SOLAS (Safety of Life at Sea - SOLAS) vessels (ie: under 300 tonnes) to be fitted with GMDSS-compatible equipment." (AMSA Australia website). Yachts and other small-craft with DSC capable VHF and HF/SSB radios can make direct contact with SOLAS vessels, MRCCs, and with each other.

The recent official ITU inquiry into scanning options to increase the effectiveness and range of boat to boat DSC calling via the General receiver in DSC capable HF/SSB radios (eg: the ICOM M802 and 801), also reflects the growing awareness of the importance of mariners contacting other nearby mariners for advise or assistance (which could prevent an emergency), and in an emergency.

I 'm sure in the Chiki Rafiki situation the US Coast Guard used its DSC capable HF/SSB equipment to transmit Distress DSC calls to initiate contact with any other vessels nearby, hoping to request they assist Chiki Rafiki. But while there might have been other small-craft nearby, including yachts, they probably could not be contacted because they did not maintain a 24/7 DSC watch on a DSC capable HF/SSB radio. The outcome for the Ckiki Rafiki crew - either when limping along towards their new destination, or after the inversion, when in the water with a PLB beacon - could have been very different if other nearby (but unknown) yachts could have been contacted by Chiki Rafiki directly prior to the inversion, or by the US Coast Guard directing other yachts to their PLB location.

A lot of very plausible reasons are regularly offered as to why yachts cannot maintain a 24/7 DSC watch on marine VHF and HF/SSB, but such excuses seem to lack foresight and a consideration for other mariners who could suddenly find themselves with a crippled vessel, in a life-raft or in the water. "On long offshore passages, search and rescue support cannot be relied upon in the same way as it is when operating closer to the coast, and yachts crews need a much higher degree of self-sufficiency in the event of an emergency." (MAIB report - YBM) My thought is this self-sufficiency should extend to enough diesel, solar panels and batteries to provide electricity to maintain a (silent) 24/7 DSC radio watch - in addition to running fridges, auto-pilot, GPS etc - to be able to help other mariners nearby, or the yacht 's own crew.

Read more at http://www.ybw.com/news-from-yachting-boating-world/maib-report-on-the-loss-of-cheeki-rafiki-identifies-multiple-factors-in-tragic-accident-10816#XRul3hcihCyvUT32.99

The fact that so many yachts (sail and engine powered) are now constructed in a similar manner to Chiki Rafiki seems to accentuate the importance of recreational vessels making the effort to work together to create a quick response mutual support network, simply by maintaining a 24/7 DSC watch on VHF in coastal/congested areas, plus HF/SSB in isolated or open ocean areas. A DSC watch is quiet, so it is not an intrusive burden. The radio silently does the work of listening for DSC calls, not the crew.

If all the world 's small-craft added their vast numbers to the existing mandatory DSC watch on VHF and HF/SSB by SOLAS vessels, a very substantial communications network would be created for everyone 's mutual support, convenience and emergency benefit.