What is it that makes a keel fall off. Does it get loose without the owners knowledge until something
gives way or is it to do with the SS keel bolts ?. I've heard that stainless steel can rust away if it is hidden
from the air, so is this the cause ?. For something that has such catastrophic results is there a way the
average boatie can check the bolts or is this a phenomena that only happens to vessels under extreme
stress like racing boats.

Think you find this was a lifting keel so hard to know.
Or maybe the bulb just fell off.

Some interesting reading here on the subject: www.yachtingworld.com/news/keel-failure-shocking-facts-60006

The ones I have seen have been poor design or poor repair. I am not aware of any falling off because of keel bolts failing on a well designed boat.
Where bolts failed it was a design failure, the bolts were in a straight line to allow a very thin keel and therefore the bolts flexed. Keel bolts should be offset each side of the centreline to take the load vertically.

That's not a keel falling off ---- this is a keel falling off.

wavetrain.net/2015/12/01/another-major-keel-failure-what-really-happened-to-polina-star-iii/

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samsturdy said..
What is it that makes a keel fall off. Does it get loose without the owners knowledge until something
gives way or is it to do with the SS keel bolts ?. I've heard that stainless steel can rust away if it is hidden
from the air, so is this the cause ?. For something that has such catastrophic results is there a way the
average boatie can check the bolts or is this a phenomena that only happens to vessels under extreme
stress like racing boats.

Gday Sam,
Mate, that's a question with a very long winded answer and probably lots of opinions. One issue: Some production boats were built really to suit a market and a price point, and this ain't blue water cruising! They were more suited to sheltered waters, and the actual engineering/build of the hull to keel mating frankly wasn't up to par for serious loads or groundings.
Another issue: lack of maintenance on keel stubs and bolt on keels on older boats. It is to me quite sensible and logical for basic maintenance to include checking of the keel bolts for the correct torque, which means of course an owner should know what that tension is. Say you get your boat anti fouled every 18 months, a simple check for any movement where the keel meets the stub , and a visual inspection of any cracks or joins to ensure they're not getting worse goes a long way.
Issue 3: groundings. We all run aground, and a hard grounding , or one at speed , should cause the skipper to evaluate the potential risk. Depending upon factors such a the keel construction, and particularly the way these keel loads are designed to be absorbed into the hull grid or matrix would determine the corrective action required. Also too, how easy is it to spot any potential failure of the hull structure itself all needs to be taken into account. If I was heading off on a transatlantic passage and did not have a long history with the boat, in a heartbeat I'd pay for an engineer to fully inspect the hull structure around the keel mating for any potential weakening or damage. Doddering around in Moreton Bay day sailing? Meh...not so much.

Others may have a difference of opinion mate, I'm no naval architect but like most things, I believe a common sense approach and that maintenance is fundamental to owning a boat is always a good point to start from!
SB

Thanks for the replies fellas. I might have to take a pic of my keel bolt set up so you can take a look. As MB pointed
out if the bolts are in a straight line I might be in trouble, I'll have to lift the sole and have a look. I remember the
Tony Bullimore incident and the TV pictures of his boat upside down with all his sails still up. His survival instincts
were spot on but I marvelled at how such a thing could have happened....but that was before I started sailing.
When Finistaire lost its keel I said to Missus 'I wonder if its a Bennetou ' Now why would I say that ??.

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samsturdy said..
'I wonder if its a Bennetou ' Now why would I say that ??.

I wonder too why you would say that Sam...
If you have a look at the article posted above you would see that it happen to other makes as well. 2x Bavaria, a few other makes I hadn't heard of and 1 (one) Benetaeu. The article also said there was 74 recorded incidents where a keel was lost so I tried to find a definitive list. Not too surprising I didn't find one but there were other makes including Oyster that had keel failures that came up in a search. Still, the only Benetaeu I found (and admittedly the search wasn't extensive) was one Benetaeu First, Cheeky Rafikki.
I am a Bendy boat owner and I may seem a little defensive, but I suspect the rather intensive investigation, probably sporn from the very intensive rescue/recovery of Cheeky Rafikki, has caused a somewhat unfair condemnation from the internet know it all key board warriors of ALL Benetaeu's.

That very true Toph. If you look at the sheer volume of Firsts (a lot that have successfully done Hobarts and nearly all major ocean races) out there sailing, let alone the staggering number of other types of Beneteau's, it's kinda nuts to single out Beneteau.
The Bavaria failures in comparison were far worse as the keel bolts and washers were plainly inferior from the factory,but as it was a longer time ago the unwashed won't mention these.
Im not a huge Beneteau fan, but thats a personal thing not a critique of their engineering, the overreaction to CR was in my view unfounded and over the top. People forget Bruce Farr designed the First's, last time I checked he knows a thing or two about naval engineering.

Sam I think even a brand new fin keel is a risk factor, although a calculated one to get performance. ie. A brand new boat with a brand new fin hitting a submerged object at speed could snap it off and they have. Inspecting them often can't fix that.

All my boating life I chose boats with solid keels. We have run aground from time to time and I was glad to have a solid keel. A few weeks ago I walked around the harbour near the CYCA and the fin keels under the boats on the hard with big lead bulbs looked scary to me. I must be a chicken!

Sorry Toph, no malice intended, but something was in my head so I must have read something that stuck. So I appologise
for the remark. I'm still going to lift the cabin sole and check how the keel is bolted on though. There's a lot more to boat
design than I thought. As a Pittwater sailor I don't experience the forces that blue water sailors do. I can only imagine
being flung about in high winds and huge seas. Boats are marvelous things....aren't they.

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Trek said..
Sam I think even a brand new fin keel is a risk factor, although a calculated one to get performance. ie. A brand new boat with a brand new fin hitting a submerged object at speed could snap it off and they have. Inspecting them often can't fix that.

All my boating life I chose boats with solid keels. We have run aground from time to time and I was glad to have a solid keel. A few weeks ago I walked around the harbour near the CYCA and the fin keels under the boats on the hard with big lead bulbs looked scary to me. I must be a chicken!

Trek,
Not chicken at all to me, sounds like a healthy dose of common sense unless you're into competitive racing!
The two things I am most focused on from a safety POV is the keel and rudders. Nobody wants to lose a rig, but unless it holes the boat you're not going to end up in the water. Finistere snapped the keel off at the hull exit, and it appears there wasnt even enough time to trigger the epirb, AMSA reported it was a crew PLB that triggered the alert.
On the subject of ruddersr, what worries me is a) the loss of control and b) if no watertight integrity the chance of flooding the boat.
I confess to a fascination on emergency steering setups. Most abandonments I've read about are from a loss of steering, or flooding from a rudder/tube being damaged.
Most good sailors will make do by sail trim steering, warps, drogues (insert favourite alternate method here) but if you read back over the majority of abandonments , a large percentage is through rudder failures, leading on to exhausted crew, fouled props and loss of power etc etc till the escalation of issues becomes overwhelming.
A good friend with a bazillion sea miles told me a tale of taking 6 hours in horrific conditions to rig an emergency steering setup as the boat had no tried and proven battle plan as to a workable solution.
Its worth noting too that most escalations happen in foul weather, adding more complexity to the problem.
It's an interesting topic.

When I had MB's engine out I had the chippies retorque the keel bolts. This meant slipping the boat therefore a cost. Th chippie asked why I wanted to waste my money. For peace of mind I said. Having them done I would know they are tensioned and if there was serious corrosion it is likely a bolt would have snapped of twisted.
Anyway, the bolts were all retorqued. Nothing untoward was found. I sleep soundly when heaved to in gales.

I had the 1970 vintage 28'ers keel bolts checked a few years ago. A couple had lost a couple of mm, which was a pretty good result IMHO for a boat in her 40s since there was still plenty of thickness and strength left in them. That would give me confidence about other boats.

Sam, the Santana was designed by Gary Mull who was, I think, a qualified naval architect and an alumni of the Sparkman and Stephens office if I recall correctly. Her builder Dave Hinton raced his own one inshore and on short offshores for eons; she'd be pretty tough I'd say.

Cheeky wasn't the only Benny 40.7 to suffer major keel issues, nor am I sure that the Farr office designed the structure. Several other 40.7s have required major keel structure work. That's not to say they aren't a good boat, since they are clearly an outstanding cruiser/racer for the price, but it's a recognised issue in some of the brand's output.

This is starting to sound like the front fell off

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Chris 249 said..
I had the 1970 vintage 28'ers keel bolts checked a few years ago. A couple had lost a couple of mm, which was a pretty good result IMHO for a boat in her 40s since there was still plenty of thickness and strength left in them. That would give me confidence about other boats.

Sam, the Santana was designed by Gary Mull who was, I think, a qualified naval architect and an alumni of the Sparkman and Stephens office if I recall correctly. Her builder Dave Hinton raced his own one inshore and on short offshores for eons; she'd be pretty tough I'd say.

Cheeky wasn't the only Benny 40.7 to suffer major keel issues, nor am I sure that the Farr office designed the structure. Several other 40.7s have required major keel structure work. That's not to say they aren't a good boat, since they are clearly an outstanding cruiser/racer for the price, but it's a recognised issue in some of the brand's output.

OK Chris. If Gary Mull has anything to do with Sparkman&Stephens then that makes me happy, for I know S&S's to
be well built very safe yachts, so thanks for that info.

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MorningBird said..
When I had MB's engine out I had the chippies retorque the keel bolts. This meant slipping the boat therefore a cost. Th chippie asked why I wanted to waste my money. For peace of mind I said. Having them done I would know they are tensioned and if there was serious corrosion it is likely a bolt would have snapped of twisted.
Anyway, the bolts were all retorqued. Nothing untoward was found. I sleep soundly when heaved to in gales.

Amen to that, Nothing better than battening down the hatches and having a nice sleep when the going gets rough. But to do that you have to trust your boat. The pic is the 500kg galvanised steel frame that steps the mast and attaches the keel in the X-yacht. You know for sure the keel wont be falling off that thing!!!

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samsturdy said..

Chris 249 said..
I had the 1970 vintage 28'ers keel bolts checked a few years ago. A couple had lost a couple of mm, which was a pretty good result IMHO for a boat in her 40s since there was still plenty of thickness and strength left in them. That would give me confidence about other boats.

Sam, the Santana was designed by Gary Mull who was, I think, a qualified naval architect and an alumni of the Sparkman and Stephens office if I recall correctly. Her builder Dave Hinton raced his own one inshore and on short offshores for eons; she'd be pretty tough I'd say.

Cheeky wasn't the only Benny 40.7 to suffer major keel issues, nor am I sure that the Farr office designed the structure. Several other 40.7s have required major keel structure work. That's not to say they aren't a good boat, since they are clearly an outstanding cruiser/racer for the price, but it's a recognised issue in some of the brand's output.

OK Chris. If Gary Mull has anything to do with Sparkman&Stephens then that makes me happy, for I know S&S's to
be well built very safe yachts, so thanks for that info.

Gary Mull was, for my money, superior to Sparkman and Stevens. He designed the Santana series, the Rangers and the Newports. Plus many other successful cruiser/racers that were not designed to any particular rule.
Ron Holland was his apprentice.
His designs sported a ring frame structure that tied the keel, mast and shrouds together in one strong unit. Of course in that era he didn't have to think about shipping his boats internationally so he didn't have to worry about keel bolts.

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PhoenixStar said..

samsturdy said..

Chris 249 said..
I had the 1970 vintage 28'ers keel bolts checked a few years ago. A couple had lost a couple of mm, which was a pretty good result IMHO for a boat in her 40s since there was still plenty of thickness and strength left in them. That would give me confidence about other boats.

Sam, the Santana was designed by Gary Mull who was, I think, a qualified naval architect and an alumni of the Sparkman and Stephens office if I recall correctly. Her builder Dave Hinton raced his own one inshore and on short offshores for eons; she'd be pretty tough I'd say.

Cheeky wasn't the only Benny 40.7 to suffer major keel issues, nor am I sure that the Farr office designed the structure. Several other 40.7s have required major keel structure work. That's not to say they aren't a good boat, since they are clearly an outstanding cruiser/racer for the price, but it's a recognised issue in some of the brand's output.

OK Chris. If Gary Mull has anything to do with Sparkman&Stephens then that makes me happy, for I know S&S's to
be well built very safe yachts, so thanks for that info.

Gary Mull was, for my money, superior to Sparkman and Stevens. He designed the Santana series, the Rangers and the Newports. Plus many other successful cruiser/racers that were not designed to any particular rule.
Ron Holland was his apprentice.
His designs sported a ring frame structure that tied the keel, mast and shrouds together in one strong unit. Of course in that era he didn't have to think about shipping his boats internationally so he didn't have to worry about keel bolts.

Question that has always confused me. Did Gary Mull also design the Sonata 8? I thought Jim Voysey designed the early Sonatas, but I remember all the Sonata 8 used to be attributed to Mr Mull?
It seems weird if so, as Gary hails from the US. Looking at his other designs, I can definitely see the similarities.
Does anybody know if this is true?

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shaggybaxter said..

PhoenixStar said..

samsturdy said..

Chris 249 said..
I had the 1970 vintage 28'ers keel bolts checked a few years ago. A couple had lost a couple of mm, which was a pretty good result IMHO for a boat in her 40s since there was still plenty of thickness and strength left in them. That would give me confidence about other boats.

Sam, the Santana was designed by Gary Mull who was, I think, a qualified naval architect and an alumni of the Sparkman and Stephens office if I recall correctly. Her builder Dave Hinton raced his own one inshore and on short offshores for eons; she'd be pretty tough I'd say.

Cheeky wasn't the only Benny 40.7 to suffer major keel issues, nor am I sure that the Farr office designed the structure. Several other 40.7s have required major keel structure work. That's not to say they aren't a good boat, since they are clearly an outstanding cruiser/racer for the price, but it's a recognised issue in some of the brand's output.

OK Chris. If Gary Mull has anything to do with Sparkman&Stephens then that makes me happy, for I know S&S's to
be well built very safe yachts, so thanks for that info.

Gary Mull was, for my money, superior to Sparkman and Stevens. He designed the Santana series, the Rangers and the Newports. Plus many other successful cruiser/racers that were not designed to any particular rule.
Ron Holland was his apprentice.
His designs sported a ring frame structure that tied the keel, mast and shrouds together in one strong unit. Of course in that era he didn't have to think about shipping his boats internationally so he didn't have to worry about keel bolts.

Question that has always confused me. Did Gary Mull also design the Sonata 8? I thought Jim Voysey designed the early Sonatas, but I remember all the Sonata 8 used to be attributed to Mr Mull?
It seems weird if so, as Gary hails from the US. Looking at his other designs, I can definitely see the similarities.
Does anybody know if this is true?

He did the 22 and up including the 27 (8). Also did some 6 meters for Ted Turner.
He was chairman of the technical committee of the Offshore Racing Congress for a while so I guess he was well regarded on the west coast of US. I think he died in the mid 90s. He must have been in his 50s.

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shaggybaxter said..


Question that has always confused me. Did Gary Mull also design the Sonata 8? I thought Jim Voysey designed the early Sonatas, but I remember all the Sonata 8 used to be attributed to Mr Mull?
It seems weird if so, as Gary hails from the US. Looking at his other designs, I can definitely see the similarities.
Does anybody know if this is true?

Mull designed the Sonata 26 (66) 6.7 (40)and 8.(?)
Voysey the 6 (166) 6.3 (20) and 7(210)
Hunter the Sonata (Thomas) 7 in the UK. (400)
All of Gary Mull Sonatas are fractional whereas the Voysey 6 and 7 are masthead with the 6.3 looking like a scaled down Mull.

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andy59 said..

MorningBird said..
When I had MB's engine out I had the chippies retorque the keel bolts. This meant slipping the boat therefore a cost. Th chippie asked why I wanted to waste my money. For peace of mind I said. Having them done I would know they are tensioned and if there was serious corrosion it is likely a bolt would have snapped of twisted.
Anyway, the bolts were all retorqued. Nothing untoward was found. I sleep soundly when heaved to in gales.

Amen to that, Nothing better than battening down the hatches and having a nice sleep when the going gets rough. But to do that you have to trust your boat. The pic is the 500kg galvanised steel frame that steps the mast and attaches the keel in the X-yacht. You know for sure the keel wont be falling off that thing!!!

Yeah, not sure I am too keen on any metal structure in a marine environment after looking at a 1970's Ericson 37. Had a large metal fabric that spanned the chainplates, engine bed and keel but was very rusty and suspect. Great idea in theory.

Mine's 16 years old, fully galvanised without a spot of rust, easy to inspect, hardly ever wet and will be good for the next 20 years at least and probably long after I'm dead.
Not only is it a great idea in theory it's also a great idea in practice.
I admit that if you're a total idiot and filled your bilges up with saltwater and performed no maintainence for a few years it could be a problem, but who is that stupid?
What your talking about is obviously a poorly designed/maintained system and has little relevance.
Seriously I doubt there is a stronger more robust system to attach a fin keel to a composite boat out there. Obviously it weighs a bit and that extra 500kgs affects the boat's light wind performance but it's still competitive with similar size cruiser racers with the added bonus of never having to worry about the keel/hull attachment.

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andy59 said..

I admit that if you're a total idiot and filled your bilges up with saltwater and performed no maintainence for a few years it could be a problem, but who is that stupid?

You see alot of boats with keel bolts always submerged in bilge water. Its sometimes the deal breaker for me when buying.
Even boats like ss34s aren't immune (and they haven't been immune) from keel problems that can occur from poor maintenance such as wet bilges. In fact, there is nothing really different from the way an ss 34 keel is fastened on compared to other boats with bolt on fins.

The biggest indicator that there may be a problem with the way your keel is held on is a distinctive crack along the joint to the hull. It's not until you investigate that joint and decide to remove the keel that you may find corrosion on studs or bolts.

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In fact, there is nothing really different from the way an ss 34 keel is fastened on compared to other boats with bolt on fins.

It depends which build of S&S 34.

I had an English built 34 which had two rows of keel bolts which were staggered and angled out from the top down.

I doubt that set up could ever fail unless you used your bilge for acid storage.

For those of us who have been forced to have our boats antifouled by a marina because of 'insurance'
problems, is there an obligation by those entrusted with the antifoul job to inspect the hull and report
to the owner any problems found, such as a crack at the join of the keel, so said owner can discuss
appropriate action.

Hi Sam,
No.
I think you'll find most professional guys will, and do, highlight any issues they see, my guy for example is a plastics/composite guru that loves this sort of stuff, but there is certainly no obligation.
A shipwright is far more credentialed to handle structural issues for me than a guy doing anti foul.
Cheers,
SB

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cisco said..

In fact, there is nothing really different from the way an ss 34 keel is fastened on compared to other boats with bolt on fins.

It depends which build of S&S 34.

I had an English built 34 which had two rows of keel bolts which were staggered and angled out from the top down.

I doubt that set up could ever fail unless you used your bilge for acid storage.

That sounds the same as the Swarbrick Mk 1, their keel studs arranged as a single one front, 3 pairs then 2 staggered singles. because of the stern tube,(central mounted motors) this leaves alot of lead unsupported aft of the last stud. There have been some modifications fitting an extra stud or 2 after an engine configuration change.
The studs enter the keel at an angle giving a wider footprint in the bilge than the keel (like a v). This means that the studs have to be removed to fit and remove the keel. The v also starts problems again in tightening the studs because the nuts will not pull flat onto the
parallel bolting surfaces of the hull and keel without trying to bend the studs, creating high torque and low clamping force. Wedge shaped plates or washers need to be made to offset this angle but I have never heard of them fitted, I have seen this problem exasperated even more from the fact that the nuts used where simply made from cutting slabs of 1 1/2" hex stainlles bar, drilling , tapping and fitting these crude things with no washer machined faces or corner relief,,, and none of the threads square with the faces.
Some of the ss34 have 3/4 bsf threads on the studs( 12 threads per inch) and some of the later ones might have 3/4 unf (16 threads per inch). The 3/4 unf thread has a smaller helix angle when compared to the bsf thread, so it provides a greater wedging force for a given torque,,, meaning that with the unf thread, there is less torque lost in the thread to provide a higher clamping force.

Another thing with ss34 keel stud tension is that It may be hard to get the keel clamped up hard at the correct torque/tension setting for a 3/4 s/steel stud by only tightening the nuts in the bilge. The studs can be as tight as hell in the fiberglass hull (more so if corroded) and loose in the lead. Tightening torque wont be uniform at both ends to the stud so a more thorough way of tightening the keel would be to tighten the nuts in the keel too. I have seen this where the nuts in the bilge are torqued right up yet the ones in the keel are only just over finger tight. This could be same for any bolt on keel arrangement.

The biggest danger to ss34 keel bolts is constantly having water in the bilge, if they are going to corrode they will corrode just under the load bearing washers or plates.

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Jolene said..

cisco said..

In fact, there is nothing really different from the way an ss 34 keel is fastened on compared to other boats with bolt on fins.

It depends which build of S&S 34.

I had an English built 34 which had two rows of keel bolts which were staggered and angled out from the top down.

I doubt that set up could ever fail unless you used your bilge for acid storage.

That sounds the same as the Swarbrick Mk 1, their keel studs arranged as a single one front, 3 pairs then 2 staggered singles. because of the stern tube,(central mounted motors) this leaves alot of lead unsupported aft of the last stud. There have been some modifications fitting an extra stud or 2 after an engine configuration change.
The studs enter the keel at an angle giving a wider footprint in the bilge than the keel (like a v). This means that the studs have to be removed to fit and remove the keel. The v also starts problems again in tightening the studs because the nuts will not pull flat onto the
parallel bolting surfaces of the hull and keel without trying to bend the studs, creating high torque and low clamping force. Wedge shaped plates or washers need to be made to offset this angle but I have never heard of them fitted, I have seen this problem exasperated even more from the fact that the nuts used where simply made from cutting slabs of 1 1/2" hex stainlles bar, drilling , tapping and fitting these crude things with no washer machined faces or corner relief,,, and none of the threads square with the faces.
Some of the ss34 have 3/4 bsf threads on the studs( 12 threads per inch) and some of the later ones might have 3/4 unf (16 threads per inch). The 3/4 unf thread has a smaller helix angle when compared to the bsf thread, so it provides a greater wedging force for a given torque,,, meaning that with the unf thread, there is less torque lost in the thread to provide a higher clamping force.

Another thing with ss34 keel stud tension is that It may be hard to get the keel clamped up hard at the correct torque/tension setting for a 3/4 s/steel stud by only tightening the nuts in the bilge. The studs can be as tight as hell in the fiberglass hull (more so if corroded) and loose in the lead. Tightening torque wont be uniform at both ends to the stud so a more thorough way of tightening the keel would be to tighten the nuts in the keel too. I have seen this where the nuts in the bilge are torqued right up yet the ones in the keel are only just over finger tight. This could be same for any bolt on keel arrangement.

The biggest danger to ss34 keel bolts is constantly having water in the bilge, if they are going to corrode they will corrode just under the load bearing washers or plates.

I am sure there are poorly maintained S&S34s out there with keel problems but that is normal, many of them don't get any attention nowadays. I tell people who contact me that this is a risk when looking at cheap S&S34s that have been sitting on a mooring unattended for a long time.
As the first Swarbrick built S&S4s are now nearly 50 years old and, to my knowledge, none have had a keel come loose or fail at sea I reckon Swarbricks probably got it right.
MB is the last Swarbrick built S&S34, hull number 119 launched in 1984, so I reckon I'll get plenty of warning of keel problems when the early ones start to have a problem.

Keels have been falling off because modern keel designs are more highly stressed due to:
* Being very long and thin (high aspect ratio), and deeper
* Narrow at the root (where it joins the hull.)
* Straight up and down leading edge

The last item on that list means there is no chance to dissipate energy in a collision by riding up the object.
Then add lightweight construction.
So you setting out to break all the rules of strong structural design.

Then add high speed planing hulls. Boats now going at more than double the previous speed. Lets say 2.5 times. That is more than 6 times the stored energy when it hits something.

All this in the quest for speed and light weight The downside is you are going to have failures. It is basic engineering. Take away the safety factors and you will have a greater probability of failure. But hey, it is what the customer wants?

Someone told me Finestere had a plywood fin keel. Does anyone know if this is true?