Hi JM,
Unfortunately your comment on this thread made no sense because apparently it was plucked from a long thread on SA which I couldn't find
Tongue in cheek reference to a car event on the Gold Coast, some muppet wrapped a pristine HT Monaro around a tree (immovable object)

I'm still not sure whether this was the pivoting keel which seems to have been mentioned or a regular fixed bolted keel although it certainly looks to be the later. With that cord length depth and hull shape however I doubt that the impact was with an immovable object at high speed.
It's a swing keel. The hydraulics has a pressure bypass valve that lets the keel fold backwards to absorb the force of a big impact, ie: shipping containers and such like.
We also hit a whale at 11 odd knots on a delivery to Hammo one year. Same result except that one also caused a slow leak. The repair bill was an o-ring and a few sweaty weekends.

Kraken Yachts is the competitor to Oyster Yachts

Oh Gary, your post deserves more upvotes for the first line. That guy has serious chutzpah doesn't he!

cammd said..
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.

Designed to class, in this case it's said to be DNV.
Whether plans were approved by DNV and the keel was supposed to have been engineered by a professional, or even whether they supervised construction is what the insurance companies investigator will be looking at if they are compenetent. Often there is minimal investigation, or forensic failure analysis unless the coroner is involved. But the payout amount might result in a proper investigation.

The design phase of the Oyster 825 (2011–2012) and its subsequent production run (2014–2017) directly overlapped with the introduction and enforcement of the ISO standards that started to mandate keel strength.
Under ISO 12215-9[/b], <!--qkimaf Bs0fKe_58/HugV6--><!--cqw1tb Bs0fKe_58/HugV6-->a sailboat's keel, its internal supporting structures, and the hull must be specifically engineered to withstand a longitudinal grounding at it's maximum operational speed <!--TgQPHd|||[[]]-->. ISO provide a formula derived from experimentation that is used to calculate this , with a factor of safety.

The ISO standard mandates that the keel attachment and hull laminate must be robust enough to survive the dynamic forces of hitting an underwater obstacle without catastrophic failure. That includes hitting anything, rocks reefs or even hard sand, the deceleration and energy dissipated has a similar energy profile.

The bulk of the collision energy is absorbed through hydrodynamics provided that the boat is free to rotate longitudinally. When it's free to trip on it's keel the loads are a lot lower than the worst case design loads.

A lot of earlier keels were attached bolted through laminate that was woefully deficient, designed to the earlier very popular ABS OSRY standards , the standard was amended before it was abandoned in favour of ISO, but there are still designers who mistakenly use it. There are also a lot of sailboats designed to dodgy standards. That makes grounding a bit of a lottery and means keel loss from grounding is an accepted phenomena, even by insurance companies.

Everytime a keel is engineered nowadays there is a requirement to show structurally that the keel can handle just such a collision without sinking or making the boat innoperable. That doesnt mean no damage, and any hard grounding on a modern design warrants a full inspection of the laminate and keel bolts.

I have lost my prior login on this forum, so now I cant post attachments.

MikeJohns said..

cammd said..
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.

Designed to class, in this case it's said to be DNV.
Whether plans were approved by DNV and the keel was supposed to have been engineered by a professional, or even whether they supervised construction is what the insurance companies investigator will be looking at if they are compenetent. Often there is minimal investigation, or forensic failure analysis unless the coroner is involved. But the payout amount might result in a proper investigation.

The design phase of the Oyster 825 (2011–2012) and its subsequent production run (2014–2017) directly overlapped with the introduction and enforcement of the ISO standards that started to mandate keel strength.
Under ISO 12215-9[/b], <!--qkimaf Bs0fKe_58/HugV6--><!--cqw1tb Bs0fKe_58/HugV6-->a sailboat's keel, its internal supporting structures, and the hull must be specifically engineered to withstand a longitudinal grounding at it's maximum operational speed <!--TgQPHd|||[[]]-->. ISO provide a formula derived from experimentation that is used to calculate this , with a factor of safety.

The ISO standard mandates that the keel attachment and hull laminate must be robust enough to survive the dynamic forces of hitting an underwater obstacle without catastrophic failure. That includes hitting anything, rocks reefs or even hard sand, the deceleration and energy dissipated has a similar energy profile.

The bulk of the collision energy is absorbed through hydrodynamics provided that the boat is free to rotate longitudinally. When it's free to trip on it's keel the loads are a lot lower than the worst case design loads.

A lot of earlier keels were attached bolted through laminate that was woefully deficient, designed to the earlier very popular ABS OSRY standards , the standard was amended before it was abandoned in favour of ISO, but there are still designers who mistakenly use it. There are also a lot of sailboats designed to dodgy standards. That makes grounding a bit of a lottery and means keel loss from grounding is an accepted phenomena, even by insurance companies.

Everytime a keel is engineered nowadays there is a requirement to show structurally that the keel can handle just such a collision without sinking or making the boat innoperable. That doesnt mean no damage, and any hard grounding on a modern design warrants a full inspection of the laminate and keel bolts.

I have lost my prior login on this forum, so now I cant post attachments.

Agree with Jon great post, but IS0 standards do not seem to working, otherwise keels wouldn't fall off. I dont agree with kraken that all bolted keels are not suitable for offshore, that is a sales pitch, however

I have heard of new production boats suffering seperation of the grid from the hull from wave action alone. That doesnt leave them operable.

We have all seen examples of damage incurred during haulouts when a boats weight is rested on the keel. An offshore cruiser should be able sit on her keel at haulout.

So whats going wrong with the standards to produce fragile boats, I have theory, it will upset chris249 again but the problem is the standards are written by manufacturers to suit their interests first and foremost, that is cheaper production whilst maintaining the marketing message.