US navy finds wreck of missing yacht Cheeki Rafiki

[Island Time 1,235]

I have done a bit of research on the 40.7 over the last few days. As tuffy said, there are reports of two of them leaking from the rear keel bolts when max backstay is on, in one case from new. There are two cases of lost keels, one from a severe grounding, and this one, from as yet unknown causes.

 

There have been 550 first 40.7's made, and they have sailed several MILLION miles between them. Still, a failure rate approaching 1% is still too high when it is such a major component.

 

You have to consider operator error in these cases - the backstay, - what was the system in use, and was it overloading the design parameters? If it was my boat, and leaked from new with full backstay from standard gear, then the factory would have a warranty issue. One of these boats was sailed like that for 2 YEARS without sorting it out!! WTF? The grounding is obviously hardly the boats fault. This last one could have been a prior issue, possibly corrosion as a contributing factor, could be a maintenance issue.

 

Keel attachment systems;

This system could, of course be improved. Consider that there are literally thousands of vessels out there with this system, some approaching 30 years old, and with a lot of miles under them with no problems. Many vessels with this type of system have circumnavigated, some several times. Many are raced, and raced hard. I understand a number of the 40.7's cross the Atlantic every year for racing ( as this one did - a charter race boat).

IMO this system seems to be adequate, provided it is in good condition. Remember also that these boats are popular in the USA, and, if at all possible, the manufacturer would risk a major law suit if it were possible to prove it was their fault. Any item can be broken by abuse or neglect, intended or otherwise.

 

To improve the system, as mentioned above, a compression tube could be added to the frames, and the bolts could go through there, not the floors. This would add complexity and cost. These boats are built to a price. It is futile to argue that the "NZ Boats" bolt through the frames. There are no longer ANY NZ boats in production of this size. The scale, resources, and production facilites of the big brands has put paid to that, for better or worse.

 

Finally, to sum up, whatever happened to Cheeki Rafiki, everything at this stage other than "she lost her keel, and her crew" is pure speculation.

[waikiore 399]

JB and FNG are both right, with many of the production Euros now using flexible bonding for the keel -hull joint we are setting ourselves up for big issues in the future, the stainless bolts do work harden, and are less tolerant of long term flex loading than earlier aluminium bronze or Monel blends. It is simply not good practice, and shows a total lack of understanding of the loads imposed on these materials to bolt them just through the skin. As Bavaria found out over the last few years. But should we be surprised, when these builders are fitting Brass skin fittings underwater instead of Bronze. It appears unlike our local boats, that these yachts are designed with a particular lifespan in mind, witness Ally rudder stocks as well. Hey maybe im just turning into a grumpy old fart, but im happy on my multi skin timber glassed yacht with substantial laminated floors, and she doesn't smell down below!

[sow1ld 2]

It's hard to know from the safety of my chair but it looks like the problem is with the bolts rather than the grid system they have used.

I'm guessing here but the grid is probably a top hat type (hollow) that's glued in , which means there is no choice but to bolt the keel to hull rather than the floors. It's quicker to build this way in a mould and therefore cheaper.

 

I'm not a huge fan of inline bolts too much wiggle with probably s/s bolts too. I agree with leading edge about flexural fatigue. Dont some benes have galv keel bolts?

[John B 106]

I only even started wondering about the whole approach when I saw a bunch of euro imports on the dock in the viaduct , so it must have been in between or after the cups when it was that haulout area. But a few years ago now when imported boats was a new fashion. There were several keels waiting to go on whatever hulls they were, and they all had what looked to me to be short stubs of zinc coated metal of some sort sticking out. When you subtracted the nut and washer/ backing plate the bit that was left could only be described as SFA ,and it left you in no doubt that they did not pass through a floor, just a fat skin as we're seeing here. I couldn't tell what sort of metal it was but it was the exact same gold zinc plated finish that my bin of chipboard/ gibboard screws are.

I think the logic is that they don't get wet because they're all sealed. A bit like untreated laserline finger jointed 4x2 doesn't get wet because a house is watertight.

yeah right.

[Absolution 7]

How about this for a keel attachment:

 

 

Sure it's not gonna fit beneath the floor boards of an AWB but it ain't gonna fall off either!

[sow1ld 2]

Seems reasonable!

[John B 106]

I dunno , I think it could do with some more cowbell.

( but seriously , that is impressive)

[Island Time 1,235]

Actually, the use of stainless steel keelbolts presumes they won't get wet as well. Stainless is not really suitable for installations below the waterline, where it may come into contact with stagnant seawater. Monel would be heaps better... Galv is better in some situations, as is bronze.,

[sow1ld 2]

Totally agree about stainless and the issues that can arise from s/s in the absence of air. Monel is the best but it's too dear for production boats.

 

I have a leaking keel bolt and the keel is coming off in August to inspect. I'm hoping that because the bolts are Monel I'll be OK! !!

[benny14 6]

Anyone know what the approximate cost of a Monel keel bolt is compared to a SS one?

[too_tall 15]

Anyone know what the approximate cost of a Monel keel bolt is compared to a SS one?

 

Whilst I can't answer your question - I guess that the true question is "is it worth a life or several?"

[erice 732]

 

SS keel bolts from someone who says mild steel galvanised is the way to go

 

http://www.eventides.org.uk/tips4.htm

[Guest]

should only be 2205 if S/S

 

that's a pretty graphic picture there Erice, I wonder what the timeline was

 

ok read it ... three years

[John B 106]

Yes I agree about the exposure to water and stainless,crevice corrosion and all that, I tend to think in terms of the monel bolts I have through floors, monitor for movement and or leaks and believe in it.

My point really with the house analogy is the lack of redundancy you get with the sort of construction we're talking about here. Flex and movement on no significant structure , just a skin...leading to wet/ rust degradation and this sort of disaster.

Those boats I saw on the hard at the viaduct about 10 +- years ago definitely did not have galvanised bolts. Zinc plating is what it was. I have no idea what they were but it was all around that time Bavarias were shedding their keels, so I was interested to see what the new import boats were doing as a generality.

The fact is in boating , s*&^ does happen , you do hit things or go aground if you do it long enough ,and this construction does not cut you any slack, or give you any wiggle room. so to speak.

[tuffyluffy 76]

Is there an easy way to determine whether your keel bolts are stainless or monel?

 

I've just assumed mine were stainless but they could easily be monel and I'd be keen to find out especially after the doom and gloom pics here!

[sow1ld 2]

Use a magnet. Don't be afraid to tap the bolts with a hammer and listen for any difference in sound between all the bolts.

I can understand putting off keel bolt concerns. Drawing a keel bolt out can be a major expensive job especially if they are j bolts and getting a new keel is out of the reach of most of us.

My 3rd from aft keel bolt is weeping. It's a bit odd because I havnt hit anything and every year I've pulled her out there's no weeping in the join, no cracks, I torqued the bolts up so piece of mind I'll pull it off and have a look.

[Guest]

Meh...just put in a canter and you don't have to worry about the bolts.

[John B 106]

Use a magnet. Don't be afraid to tap the bolts with a hammer and listen for any difference in sound between all the bolts.

I can understand putting off keel bolt concerns. Drawing a keel bolt out can be a major expensive job especially if they are j bolts and getting a new keel is out of the reach of most of us.

My 3rd from aft keel bolt is weeping. It's a bit odd because I havnt hit anything and every year I've pulled her out there's no weeping in the join, no cracks, I torqued the bolts up so piece of mind I'll pull it off and have a look.

 

Whenever I've been shown monel metal, although it is in general silver in colour like stainless, because it has nickel and copper in its makeup it seems to me to have a flatter almost hint of brown/green in it.( which is logical) especially in a bilge , where there might even be more green / copper traces due to doing the log paddlewheel clean.

 

Would you agree with that sow1ld?

[Battleship 100]

I'd agree monel does tend to get a greenish tinge, whereas stainless steel rusts.

2205 stainless is also magnetic whereas 316 is not, I was told when replacing our rudder stock that 2205 can be more susceptible to wormhole type corrosion than 316, is a hell of a lot more resistant to flex though.

[Chewing Gum 17]

We confirmed our keel bolts were monel by cutting a piece off the top above the nut and getting it tested. As far as I am aware corrosion is not an issue with monel. Our bolts would be original ie 32 years old. I remember the Cav32 we had previously was fitted with monel bolts also. We did it ourselves by drilling the keel and then using a gas axe to cut slots in the side for the lower nuts and washers. That boat has been around the world and is now back in Asia somewhere.