Can all yachts sit on their keels?

[Kelpie]

A friend's boat purchase recently fell through because it turned out that the yard had soft ground, causing the props to sink, and the keel subsequently punched up in to the hull causing structural damage.

I'm a bit surprised about this. It's an early 2000s AWB. Are they really not able to sit on their keels?

I didn't think twice about drying out my 39ft MAB on its keel, in the exact same spot I've used for my previous boats.

 

[Dipper]

We had a fin keel boat in our club yard one year that got damaged because it was stored in a cradle on its keel. I believe it was one of the French models. Some apparently can't rest on their keels without damage..

 

[scottie]

NO

 

[srm]

No,
I had a bit of a discussion with the yard where I bought my current boat. I wanted her moved into a cradle with all side supports above the waterline to give a clear run for Coppercoat application. The yard guidelines were for no more than 70% of the weight to be taken by the keel.
All resolved when I got the manager to come and look at the boat; a 60's design with "wineglass" sections and longish keel. These traditional hull shapes will take their weight on the keel no problem, as long as the base of the keel is long enough and parallel to the waterline. Modern sailing dinghy hull forms with bolt on keels will not, as your friend discovered.

 

[Refueler]

Its a question of sharing the load .... the keel unless of a particularly thin design etc. - should be capable of carrying most load. Yards generally do not lower a boat into cradle side supports or props ... they lower to stand keel on the base / ground - then add the side supports / props.

I have only observed older boats that have suffered from weight on keels ... and that is usually due to aged GRP hull or if wood - the keelson - going soft.. Good example recently viewed - Carter 30 .... needed to have slings made to support hull in the cradle because keel flexed the soft hull ...

My race boat (Saaremaa Cup boat) had to have her keel dropped, main keelson completely replaced .....

This is before the work and keel is OK ... 2 years later - not so good !

 

[MikeBz]

People use our scrubbing posts for a wide variety of AWBs, so either it’s not generally a feature/restriction or it’s generally OK to sit them on their keel for the duration of a tide?

 

[ProDave]

We have a bilge keel boat because it lives in a drying harbour, but I kind of assumed that all such boats could sit on their keels. Some Westerly's had problems with not enough strength and the keels would spread but most have been reinforced I believe.

But there are some designs of boat that simply cannot sit on their keels, not because they are too weak, but the bottom of the keel is nowhere near the centre of gravity. The two I have seen one was a swept back long keel, and the other was a rounded off at the front long keel. Both would need a lot of weight at the front taken on props and neither would be any good at drying out against a wall.

I guess this is a question to ask before buying a boat?

 

[Refueler]

We have a bilge keel boat because it lives in a drying harbour, but I kind of assumed that all such boats could sit on their keels. Some Westerly's had problems with not enough strength and the keels would spread but most have been reinforced I believe.

But there are some designs of boat that simply cannot sit on their keels, not because they are too weak, but the bottom of the keel is nowhere near the centre of gravity. The two I have seen one was a swept back long keel, and the other was a rounded off at the front long keel. Both would need a lot of weight at the front taken on props and neither would be any good at drying out against a wall.

I guess this is a question to ask before buying a boat?

My BK boat (Sunrider 25) is presently propped on blocks sharing load between keels and centre hull.

Having stbd keel repaired after hitting submerged concrete block. The hull did deform slightly - you could just detect it with the eye - when she was all weight on blocks and keels free of weight.

She was moved after the major work of keel fastening was completed internally .... to stand with divided weight keels + blocks ... so that external work could be completed later when winter is over. It also allows hull to return that tiny bit back to normal ...

 

[Poignard]

Not something I have ever worried about

 

[Concerto]

I am surprised that a yard would try and support a boat on soft ground, that is asking for lots of trouble especially if it is on one side of the boat and causes it to list or fall over. The internal damage mentioned in the OP's post could have most likely been caused by hitting something solid like a rock. This is a common fault of many modern boats due to the egg box matrix hull reinforcing either becoming unbonded or cracked or both, which can also dislodge any furniture. The OP's friend made a wise move to back out of the purchase as it would be a very expensive repair. Either way the boat needs repairing, possibly under an insurance claim by the current owner before it is offered for sale. Otherwise it will only sell for a song to someone prepared to take the time and expense to fix it, most likely to make a profit from their labours.

A couple of years ago I was chatting with the crane operator from Hythe Marina. He said many modern boats were difficult to lift as the straps must be on a bulkhead, otherwise the hull flexed badly. The same applied to any supports once sitting on the keel. I have heard many owners comment that some doors or lockers either will not latch or jamb whilst chocked out of the water.

When I bought my Fulmar, the surveyor commented that the aft end of the keel rib was not strong enough on early models and had not been strengthened. He showed me using a straight edge how the keel was pressing the hull in by 10mm just aft of the keel whilst out of the water. It was a job he advised needed doing, but was not urgent as she was 33 years old at the time. This year, 9 years on, I finally reinforced the keel rib whilst in the water and am awaiting getting lifted in a couple of weeks time to check if the 3 layers of 300gsm mat and epoxy have strengthen the area affected sufficiently.


This was how the keel rib, looking aft, was like when I purchased Concerto. Notice the poor corner laminations that the previous owner added that did not add any real support.


This is the completed job after being Danboline painted, looking forward. Where the step box is resting you can just see some of the reinforcing that had not been painted. None of the reinforcing was taken over the top of the ribs as this would have raised the floor. The reinforcing stopped in the section by the bilge pump strum box and went back to just behind the start of the engine bearers. If you look closely you can see the forwaed ribs over plywood are thinner than the aft ribs, but I also covered all the flat areas within the ribs.

 

[srm]

Not something I have ever worried about

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Likewise, but then we obviously prefer "sea kindly" hull forms.
My current boat stayed in the water for ten years before I lifted her out. All she needed was pressure washing while safely leaning against a wall between tides.
My first monohull (other than an MFV work boat) spent at least one winter, mast down, on a pair of beaching legs. That was a Trintella 29. Again the same hull type.

 

[srm]

He said many modern boats were difficult to lift as the straps must be on a bulkhead, otherwise the hull flexed badly.

Are crane spreaders no longer used? They were normal practice when we used to hire construction cranes to lift boats out in Shetland.

 

[MoodySabre]

In my marina they insist that fin keels are in cradles with keel rests. I have a Jacobs cradle. Part of the weight must be taken by the keel to stabilise the boat in strong winds. Their insurance inspector said they will not insure boats where the weight is solely on the pads as it is top heavy. I know this because, after many years with the keel just sitting on a large block of wood, I had to buy some keel rests Or they would charge me for the use of their cradle.

 

[Grith]

Not a problem I have to worry about thankfully. Just pull mine back up into the hull and go really shallow.

 

[pandos]

Ina Swiss boatyard I saw a number of boats all of which were seriously deformed by being left on their keels. I discovered that the reason was that all of the hulls were full of water....

An example of when being watertight was not an advantage.

I thing the summer heat was also a factor.

 

[Tranona]

A friend's boat purchase recently fell through because it turned out that the yard had soft ground, causing the props to sink, and the keel subsequently punched up in to the hull causing structural damage.

I'm a bit surprised about this. It's an early 2000s AWB. Are they really not able to sit on their keels?

I didn't think twice about drying out my 39ft MAB on its keel, in the exact same spot I've used for my previous boats.

As ever the devil is in the detail. It does not take long looking at the underneath of boats to see that even for "2000s AWBs" there is an enormous range of keel designs. Add to that, "props" sinking does not provide anywhere near enough detail to get any real idea of what actually happened - hence the speculation here.

Resting solely on the keel is not a key factor in keel design - a ballasted keel's job is primarily to provide a means of keeping the boat upright and to provide a foil for lift as an aid to performing under sail. Support for the boat when not in the water is a secondary benefit and some designs of keel are better than others. Those responsible for supporting boats when out of the water should at least understand what is needed for each type of keel and provide the necessary support. Post#13 describes a typical regime for fin keel boats and is basically the same as used in our club, and in many other boatyards. Propping, even on solid ground is not considered acceptable, particularly if the mast is up - and was discontinued in our club 20 or more years ago following an incident with a fin keel boat falling over.

Likewise with lifting and positioning of slings. It really is not difficult to position slings at the 2 main bulkheads or thereabouts as not only are these points obvious but usually result in good fore and aft balance. For both my fin keeled Bavarias the factory provided a diagram of lift points and also had available on request a schematic for making a cradle showing the trough for the keel and the recommended position of the supports.

 

[William_H]

It seems to me that here fin keel boats are simply sat on keel with props to keep it vertical. However as said not all fin keel boats have the bottom of the keel above the cofG. hence a lot of fin keel boats have a fine swept aft to get bottom of keel at cofg but bulk of keel centre of lateral resistance forward.
Anyway 45 years ago in Port Moresby I saw a lovely GRP 18fter (Fox moth I think) where keel attach had failed and fin keel ended up in cabin. It was repaired witha lot of epoxy. I don't know if boat was lowered slowly on to keel or dropped. But we usually expect small GRP boats to be very strong. ol'will

 

[Neeves]

A friend's boat purchase recently fell through because it turned out that the yard had soft ground, causing the props to sink, and the keel subsequently punched up in to the hull causing structural damage.

I'm a bit surprised about this. It's an early 2000s AWB. Are they really not able to sit on their keels?

I didn't think twice about drying out my 39ft MAB on its keel, in the exact same spot I've used for my previous boats.

I think we are missing some information.

I've watched, or monitored, yachts being commissioned and after attaching the keels, to say a 40' Bavaria, then the yacht is left sitting on its keel as the sealant sets off, simply balanced in the cradle. When the yacht is lifted all the weight of the keel is supported by the yacht's structure. That same structure is what stops the keel punching up into the hull (the props have no relevance) if beached (held vertical using legs or a scrubbing grid).

Multihulls are slightly different.

They are known to dry out on their keels - but the seabed can be so soft that the sail drives and the rudders can sink into the soft seabed, as well as the keel.



Kelpie talks of an early 2000 AWB, which I take as being a monohull.

Analysing the information, the keel(s) sank into the mud, allowing the sail drives to also sink into the mud (not actually sure why this is relevant), then the keels stopped sinking but the yacht carried on 'downwards', the keels reached a harder layer and stopped sinking - punching into the hull.

When a yacht, any yacht, is lifted in slings the slings are not usually located exactly at the fore and aft section of the keel (were the keel to have a big flange). The slings are located slighter and slightly after of the keel - the hull structure supports, or hold the keel.

It all sound very unlikely - either the hull integrity was already compromised or the mass of the hull was increased to a point where the structure of the hull was inadequate. Both of these concepts have already been aired, see earlier posts.

Now ...if the sail drive(s) punched up into the hull, possible.

Jonathan

 

[Bobc]

My boat will not sit well on its keel. The CoG put all the weight on the front of the keel and so the boat needs support under the bow to take some of the load. The underside either side of the keel is also quite flat, and needs some support, otherwise the boat "sags" and the floorboards lift a bit.

Each boat is different, but the bigger and heavier the boat, the more likely this becomes.

 

[XDC]

Not something I have ever worried about

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Nor me.

Ryde



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