Dunno much yet but a mate sent me these photos

Just google oyster yachts keel

I think thats a race course marker. The story of keel bolts yet again.

I've seen some comments on social media stating its not a construction or design issue, the boat hit a rock!

Are people serious, the keel shouldn't fall off because you hit something, every boat suffers a grounding at some time.

The question is, "Who moved a rock into a race route?"

It isn't okay for a keel to fall off because owners shouldn't hit a rock, because eventually we all do stuff up. That is why we wear seat belts in cars, have crumple zones and other safety features and why we wear harnesses and inflatable vests on boats. Because things can and eventually do go wrong, including hitting rocks at speed with our boats. I have hit three in about 35 years in my boats and I reckon I am pretty good on the water, twice going at more than 7 knots - all the times the boats were fine (but my heart rate and daggerboards were not). In all cases I was an idiot, but for 99.99 percent of the time I care properly for the boat, just sometimes it has to cater for me neglecting my duty or for a multitude of bad choices to line up the Swiss cheese.

So it should not matter what the boat hit, ANY boat should be able to hit the ground at a good clip and not fail. So it doesn't matter if the Oyster hit a whale or rock, there is no way that the keel should fall off - it was poorly designed or built. There is no getting around the fact it was found to be unfit for purpose. Oysters don't do 20 knots so you don't have to design for hitting a rock/whale/container/sunfish/log at those speeds, but you do have to engineer and build the keel to hit something up to 10 knots or so.

F**k me lads, a 50+ tonne boat hits an immovable object at probably well over 10 knots (kite up).

Something needs to break yeah?

Easy to say "keel shouldn't break" but it's not grazing the sandy bottom or bumping a rock whilst parking.

He was in a 10 ton boat under motor at night, doing one assumes under 5 knots in that location.

The Oyster was a 50 tonne boat - if they were at hull speed about 11.5 knots.

My rough calculation says that's 25 times more energy that had to go somewhere during the impact.

Genuinely I ask - where would you like that energy to get dissipated?

Shaggy's example is a particulary nice one - I assume that was a steel fin Shaggy? The kind that everyone thinks is terribly dangerous? Absorbing the energy by bending the fin whilst keeping the lead attached to the boat seems like a pretty good way to fail.

JonE said..
He was in a 10 ton boat under motor at night, doing one assumes under 5 knots in that location.

The Oyster was a 50 tonne boat - if they were at hull speed about 11.5 knots.

My rough calculation says that's 25 times more energy that had to go somewhere during the impact.

Genuinely I ask - where would you like that energy to get dissipated?

Shaggy's example is a particulary nice one - I assume that was a steel fin Shaggy? The kind that everyone thinks is terribly dangerous? Absorbing the energy by bending the fin whilst keeping the lead attached to the boat seems like a pretty good way to fail.

Hi JohnE,
Not a steely, composite upper, lead lower swing keel. Had a hydraulic ram with a bypass system to let the keel fold back if you hit anything nasty.
She needed some fairing on the leading edge aftwards, but that was the extent of the damage.
It was built by the same mob that do the IMoca canting keels, much smaller but still a nice piece of kit to have.

JonE said..
That's cool. Always interesting to get a look at that high-end kit.

By they way, your "Queensland" post over on SA nicely illustrates what I was thinking about "something has to give way".....😀

😀😀😀😀
I hope that bloke gave himself an uppercut. I love those cars.
Found a picture of the aftermath of the rock incident. Still hurts me to see this pic, but as this thread highlights, it could be so much worse.

I really do think a keel should never go. There will be ways to reduce load on the root - one - increase root area and length as it attaches to the hull or stub, two put a reasonable rake on the front of the keel, third, increase keel bolt size at the front to cater for tension loads when hitting, fourth , round off the bottom of the keel so that it rises up as it hits the bottom. Easy to do and it will make the boat better for cruising.

I think the idea that an IMOCA should not be expected to hit a rock makes sense, but an Oyster is a cruiser. It is not impossible to build a keel so that it can't fall off at normal speeds - it is just engineering. Who cares if you get a little heavier in a keel, or you have a 25% longer root. The fact that any builder could produce a boat that couldn't is worrying. I mean people have died because of short root keels. It aint hard to build them so they never fall off, has anyone seen a shoddy Tophat lose a keel after 60 years?

I don't get many modern boats, dagger keels on some cruisers (although I usually like Sayer boats) . I once recommended Percy Island Lagoon to a Leopard catamaran owner. It is great I said, you dry out every low tide but you are secure and able to walk all over the island. He told me the cat was not designed to sit on its keels - I was flabbergasted. What is the point of having a cat if you can't sit on the keels. Who designs these stupid boats? Why would anyone buy one?

Oh and don't get me started about Schionnings, sure sloped windows look racy but in reality probably provide about 0.1 kn speed and move the center of mass back 300mm in a 36ft boat but now you'd struggle to fit a table and chairs in the cockpit? On a cat in my opinion that's where you want to spend time, who'd buy one of those :p
(I'm being hyperbolic here but I'm making a point : ) )