Encapsulated keels

machurley22

machurley22

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With all the speculation recently about keels falling off I've been wondering why encapsulated ballast went out of fashion.

Is it that you can't make modern keel profiles in this way? Is it just cheaper to bolt on an iron keel or two? Encapsulated ballast can have it's own problems but such a design does seem a lot less likely to be the cause of catastrophic flooding or a sudden and permanent inversion.

In the case of the long fin Hurley 22 for example the construction gives the impression that the boat is attached to the keel rather than the other way round.
 
One problem with these keels was due to poor manufacture - it is very difficult to thoroughly wet the glass and remove all air pockets when ramming it down a deep narrow slot in a mould. Hence water getting into the lay-up, osmosis, delamination, punchings rusting etc.

On saying that I have encapsulated ballast in a long-keeler, which gives a great sense of security - there is no way it can fall off! Even if I crunch the bottom there is unlikely to be more than cosmetic damage.
 
Oh Aye
An encapsulated keel means ye can dink hielan' rocks at around 8 knots and just have a rendering job to do later instead of pushing the back keelbolts back down through the saloon floor.
Claymore_keel.JPG
 
You just love showing us that photo, don't you!

Remond me again, which bit of Scotland was it you hit?

Donald
 
Manufacturing demands

The whole idea is to keep as many subassemblies off the line for as long as possible. So, much better to start hull, interior, rig all separately and bring together at the latest possible moment. Same applies to keel, hence bolt-on, rather than extending the make time for the hull. imho.
 
Re: Manufacturing demands

The owner will naturally get a warm fuzzy feeling from the knowledge that the production engineer and accountant were thrilled with the design.
 
Re: Manufacturing demands

From a designers point of veiw the weight and shape of the keel can can be best produced in a casting.A lead stub keel should take some shock load as the lead will deform.Most serious boats now have bolted on keels as opposed to the early grp boats where the keel trough was filled will waste balls etc!
 
Was it a ledge? From the photo the collision point looks quite high up the keel

Donald
 
Re: What\'s all this?

Nah - in bed early after an exhausting day, slept like a little bobbin and up with the first crack of sparrowsfart to face the challenges of this new day. Actually its now about 13:30 and I'm wilting - probably go just a tickle after 3.
 
Re: Manufacturing demands

Does your observation mean I don't have a serious boat because it has an encapsulated keel? What do you mean by "serious boat"? /forums/images/graemlins/confused.gif
 
Re: Manufacturing demands

[ QUOTE ]
From a designers point of veiw the weight and shape of the keel can can be best produced in a casting.A lead stub keel should take some shock load as the lead will deform.Most serious boats now have bolted on keels as opposed to the early grp boats where the keel trough was filled will waste balls etc!

[/ QUOTE ]

Utter Borrox
 
Re: Manufacturing demands

I apologise for my comment ,what I was trying to say was that in the case where the designer wants to get maximum advantage from a given keel weight it would be best as a cast metal keel as apposed to inside ss amoulding.In the case of cruising boats which may have alower ballast ratio a cheaper ballast could be put in a moulded keel,yhis does dot I HOPE IMPLY that it would not be as "Serious",.
 
Re: Manufacturing demands

[ QUOTE ]
I apologise for my comment ,what I was trying to say was that in the case where the designer wants to get maximum advantage from a given keel weight it would be best as a cast metal keel as apposed to inside ss amoulding.In the case of cruising boats which may have alower ballast ratio a cheaper ballast could be put in a moulded keel,yhis does dot I HOPE IMPLY that it would not be as "Serious",.

[/ QUOTE ]

Yes but, an encapsulated keel is effectively one structure and therefore inherently stronger and resistant to impact.
The form of such a boat is more likely to be sea-kindly and less prone to pitching ergo, an encapsulated long or longish fin is most likely to be found on a "Serious Cruising Boat"
A Serious Racing Boat is a different kettle of fish entirely.

If you wish to place the weight in a lump further from the cofg or is it cofe to gain additional leverage then encapsulation is not practical and you potentially introduce huge stress loadings at the weakest point.

Sound engineering should dictate that the structure at the keel joint is sufficiently beefed up to absorb the predicted loads. I find it most interesting that fin keels bolted to a stub appear stronger maybe this is due to the strength of the stub in relation to spreading the load over a wider area of hull and a resistance to tearing. (If you know how to tear an old type London Telephone directory in half you will know what I mean).

Also if you view the underwater profile of three boats side by side as I did at the weekend, you can instantly see how the shock loading of an impact would be absorbed by the hull.

The 3 in Question are fairly representative, an HR with encapsulated long fin, a Moody with Iron Keel Bolted to a Stub and a Bav33 with Fin bolted directly to the Hull.

If you look at the form of these boats it is not difficult to imagine what damage would result from a grounding.
 
Re: Manufacturing demands

Well we more or less agree.In thecase of a cruising boat a cast metal keel bolted on to a stub keel would be the best as there would be room for a proper sump.In the past with say bilge keels they where very crude encapsulations but now in order to get th areodynamic sections they are cast solid and bolted on or bolted to stub mouldings as in the new Sadler29
 
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