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Go Back   SailNet Community > On Board > Boat Review and Purchase Forum > why keel bolts?
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Thread: why keel bolts? Reply to Thread
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Topic Review (Newest First)
05-07-2003 07:02 AM
JohnDrake
why keel bolts?

05-07-2003 07:02 AM
JohnDrake
why keel bolts?

05-07-2003 07:02 AM
JohnDrake
why keel bolts?

05-07-2003 07:02 AM
JohnDrake
why keel bolts?

05-07-2003 07:02 AM
JohnDrake
why keel bolts?

As one poster wrote, there is no one right answer. I did want to add the other point of view since this thread seems to go against encapsulated ballast and seems to indicate that cruising sailors would tend to avoid them. In my reading, research and experience, quite the oposite is true.

There is no doubt that if you buy a poorly built boat, bang it up on rocks or coral bad things will happen to the keel. There are encapsulated ballast boats built where the glass layout is done poorly, the ballast is low grade iron or even cement and it is not properly encased in the keel. However, there are many very well known well designed and well built boats, that use lead as the ballast, where this is not the case at all.

One quick note about bolt on keel boats. No matter what the built quality, keel bolts will stretch over time and need to be adjusted. Obviously, this cannot go on forever and at some point they will fail. In addition. Any water in the bilge will, over time, will facilitate any rusting.

But to the point about grounding: bolt on keel boats have been known to have the keel break through the underbody of the boat and cause catastrophic sinkings. This is documented in the case of a Beneteau and I personally was at the scene of a near sinking when this very thing occured in a Catalina 27 that hit the soft mud bottom of the Chesapeake Bay. Had it not been less than 1 mile from a harbor, this boat would be on the bottom (it was apparently picked up by a swell and planted squarely on the bottom, causing a break at the keel stub).

Many cruising sailors seek encapsulated ballast boats specifically because they feel they are safer in a grounding, less risk and less maintenance. By and large these boats are either full keel or modified full keel and thus have a more shallow draft. That in and of itself lowers the probability of hitting something. Most well built encapsulated ballast boats, when grounded, need no work (because of the heavy glass layup). If they do need work...it is generally only some epoxy, which is available worldwide. If an encapsulated ballast boat goes hard aground and does punch a hole in the keel, she will still be able to sail, as there is a fully closed off canoe body above the keel. Later she can be lifted, dried completely and epoxy slathered in there. Not much of a problem.

As noted above, there are many poorly designed and poorly built encapsulated keel boats. There are also many very good ones: Hinckley, Cabo Rico, Gozzard, Alden, Bristol, Little Harbor, Wauquiez Hood 38 (my boat), Hans Christian to name a few.

The question is really not encapsulated ballast or bolt on keel. If you want a performance boat or a race boat, you will buy a bolt on keel boat. If you want to cruise, or want a shallow draft boat an encapsulated ballast boat will be a consideration...and at that point the question will be built quality and condition.

Just another point of view.

My best to all

John
S/V Invictus
Hood 38


05-04-2003 03:27 PM
Jeff_H
why keel bolts?

I think Paul has covered most of the big points. This is another one of those there are ''no one universally right answer'' type questions. In other words an argument can be made for either type of keel.

(For the record, I personally strongly prefer a bolt on keel rather than an encapsulated keel and for myself would not consider buying a boat with an encapsolated keel.) Here''s the way I see it.

Bolt-on keels tend to offer more performance since the ballast must be cast (rather than made up loose ballast and mastic) and without the keel stub skin thickness tend to be lower relative to the center of bouyancy. They also tend have significantly less wetted surface and frontal area making them theoretically faster on all points of sail. Bolt on keels are simpler to repair and generally can be repaired satisfactorily no matter how bad the damage. The keel structure of bolt on keels are generally a better engineering design because they require internal transverse framing in order to spread the loads out to the hull and so tend to have more sophisticated framing schemes. Proper transverse framing is often omitted even on expensive internal ballast boats. All other things being equal, the denser nature of a bolt on keel often means a larger sump volume than would have resulted from a similar displacement encapsulated keel.

On the down side they are more expensive to build; requiring precision casting, careful bolt hole drilling and a lot more hand fairing. They are higher maintenance requiring fairing every 10 years or so and depending in the materials used, new keel bolts at some point in the boat''s life.

Encapsulated keels are less expensive to build. There''s less labor and less precision required. Boat builders will often use less expensive forms of ballasting with encapsulated keels, such as iron or lead scrap cast in concrete, resin or other binder to further reduce costs. If they are not damaged in a grounding, encapsulated keels are less expensive to maintain.

On the down side, beyond being less efficient from a sailing standpoint, the real disadvantage of a bolt on keel is the difficulty in doing a proper repair when damage. Typically, in a hard grounding a number of things happen on an encapsulated keel. Typically the skin of the keel encapsulation gets ruptured and separates from the ballast at the point of impact. This allows water into the small cavities between the keel and the ballast and once wet it can mean the ''beginning of the end'' for the boat as this permanently wet fiberglass blisters itself from the interior and the wet areas spread out around the ballast. This is especially a problem on a boat that is hauled out during the winter in the climate permits freeze/ thaw cycles which can really pry the skin loose from the ballast. The problem gets worse when the ballast contains ferrous materials. Here the ballast begins to rust and can reduce the ballast into a loose mass of matrix and rusting iron.

Beyond that, in a hard grounding the ballast is often forced aft and upward as well. In an encapsulated keel the membrane of the hull is at the outside of the keel and the membrane above the ballast is often quite thin. In a bad grounding the ballast keel is often pushed through this membrane causing a serious and difficult to repair damage and what can be a major inaccessible leak.

In my family we grounded a boat with an encapsulated keel that we never could permanently fix for as long as we owned the boat. The problem would get worse with every year, spreading from a small dimple on the leading edge of the keel to an area that was much of the bottom and sides of the keel.

Lastly, further compounding this issue, it is very hard to lay-up the glass in the keel cavity. As a result the glass work in this vulnerable area of the boat is often inferior to the glass work else where on the boat with large lenses of unreinforced resin or improperly wet out cloth. So instead of being the strongest part of the boat, this vulnerable area becomes the weakest.

In the end this is a classic question of low maintenance vs long life. In theory, a well made boat with a bolt on keel can be maintained forever but over its life it will need a fair amount of maintenance. In theory an encapsulated keel has low maintenance but at some point it will delaminate from its shell which will pretty mean the end of the boat as a structurally sound entity.

Jeff
05-04-2003 05:22 AM
paulk
why keel bolts?

Encapsulated keels have their own problems. There are stories about people who have gone agrround, knocked a hole in their encapsulated keel, gotten off, and then lost their ballast piece by piece, out the hole. Worse is when the ballast is iron and hitting something causes a leak in the encapsulation. The iron then swells as it rusts, increasing the leak, and the rusting, all while the bilge stays nice and dry until the whole hull is split open and the boat sinks whereever it happens to be at the time. Some people in rock or coral-prone areas avoid encapsulated keels because of this. Even if you want to fix a crack, how do you dry out the insides first??? Fiberglass cracks (and leaks) relatively easily when it hits a rock. Lead absorbs more of the shock and deforms. You can bang the lead back into shape with a hammer. If the keelbolts leak, or there are cracks in the floors, (unless the hit was bad enough to actually sink you) they can be fixed. There are lots of ways of doing things, and each has plusses and minuses.
05-02-2003 10:55 AM
jbarros
why keel bolts?

Hi,

I have a small sloop, with a fully encapsulated lead balast in the leading edge of my keel. The keel is an integral part of the hull. This seems to make sense to me.

I''ve noticed that almost every larger boat has a keel bolted on, and that eventualy, the keel bolts become an item of concern. Why dont they simply use encapsulated lead and build the keel as part of the hull?

At first I thought that the strain on the hull may be too great when the weight is 8,000 lbs rather than 800, but if it''s getting bolted on anyway, I think it would have to bear the load regardless (and spread out over a much smaller area with only the 2 bolts.)

Then I considered that Perhaps the bolts didnt connect to the hull, but to framing within. But then the question remains, why couldnt this have been done inside the hull, where it was easily acessable for inspection, and kept away from the ravages of sea water?

So I''m stumped. What am I missing?

Thanks.

-- James

 
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