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Old 15-03-2007, 23:18   #1
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Any Benifit To Iron Keel?

Hi all. I did a quick search but didn't turn up anything. I'm pretty new to this but I've noticed that while the inexpensive American brands (hun and cat) choose heavy lead keels all of the euro brands that I've seen use iron keels. Obviously lead has the clear advantage of being far more dense, and this is reflected in the fact that the American keels tend to be heavier. My question is what are the disadvantages of lead? Why don't expensive euro boats splurge on lead keels? Do they know something American makers don't or are they just cheap?


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Old 16-03-2007, 00:16   #2
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Iron is less expensive but the only advantage's that I can think of is the iron keel bolt fastenal would hold up better in a hard grounding and the keel would plow thru a coral reef with the greatest of ease.

Another problem with iron, if it's not sealed it will bleed rust if sitting in one spot. It creates an acid that blackens the outer surface and also builds iron oxide then flakes off. It will also get potholes creating a rough surface.

As for lead it is softer and takes some of the shock out of a hard grounding but probably not really enough to measure. Lead is heavier by almost twice so it makes better ballast without taking so much displacement space. If not sealed it will turn chocky but only corrodes on the surface unlike iron.

Cast iron = 7300 Kg/cu.m

Lead = 11340 Kg/cu.m.

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Old 16-03-2007, 02:05   #3
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Think you may be mis-intepreting yacht specifications.

Most EU quality build medium to large cruisers DO have lead keels.

That said, iron is usually used on swing keeled or bilge keeled yachts - the latter simply because its anticipated those two bilge keels will more often take the full weight of the yacht. The former to minimise any change in keel shape which needs to fairly fit up and down in a casing.

Most other production mid sized yachts would have a steel web first casted which they insert into a sand mould, and in turn have a lead / antimony mix cast over that web. It most often results in a keel which has more steel at the top and more lead at the bottom.

FYI they rarely use 100% lead but rather a lead / antimony mix to stiffen the lead section. Were it 100% lead you'd find lumps scuffed off too easy when grounding. They also cant have just lead at the top of a keel - or the keel bolts would pull out of the material.

If any production yard does skimp and go for just steel on a mid sized yacht - then IMHO they are doing so just to save money - and that might also be reflected in other things they save on which you can't see or recognise.

Hope this helps

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Old 16-03-2007, 02:18   #4
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Cost is the only advantage of Iron Keels, over Lead. The disadvantages are legion.
As noted, the Lead is alloyed with Antimony at about 2 - 4 %, for hardness.
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Old 16-03-2007, 07:17   #5
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Might have something to do with their very rigid regulations concerning lead. As far as the keel goes, lead is best. As far as the enviro goes lead is bad.

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Old 16-03-2007, 08:30   #6
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Thanks a lot guys, you're pretty much confirming what I though. Guess that's one strike against Jeanneau / Beneteau and Bavaria. Not that it rules them out but it might make me look at the Americans a little harder...
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Old 16-03-2007, 20:13   #7
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Yup, iron keels are cheaper and enviromental rules in Europe make lead more expensive still. If you hit a reef, a lead keels deformation means reduced hull damage. An iron keel transfers more of the impact into the hull.

Even the bigger Beneteaus use iron in many cases.
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Old 17-03-2007, 23:40   #8
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Originally Posted by GordMay
Cost is the only advantage of Iron Keels, over Lead. The disadvantages are legion.
So far in this discussion, I see the advantages of lead over iron being:

- Iron can rust, lead does not. (You still paint them both.)

- You can use a smaller volume of lead for the same shape, resulting in some minor reduction of wetted surface. (I get 55% greater volume of iron from delmarrey's numbers.)

You say the disadvantages are legion -- are there others that have not been mentioned yet?
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Old 04-04-2007, 15:59   #9
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My comments pertain only to the twin keel boats such as those built by the former Westerly company of England.

Having owned two with iron keels I admit at first I was suspicious. I've found that iron keels, all four of them on two boats, to have only one 'temporary' disadvantage. Certainly no 'legion' of disadvantages.

The one case was a pair of iron keels that has been sheathed with fiberglass. Exactly the wrong thing to try as a fix.

Once stripped and the keels properly cleaned to grey metal, treated primed and painted mine have shown no problem with rust etc. The trick is to clean to grey metal and then use Pettit Trailer Coat also called Rust Lok and in Europe it's called Screw Fix. That bonds with the metal and expands/contracts with temperature changes. It doesn't flake or chip off. Once the Rust Lok is applied then normal priming and antifouling follows. In short proper maintenance just like anything else.

In the case of twin keels the use in supporting the boats when the tides are out is correct. Lead probably can't do that day in day out for decades. Hitting a bottom though is not nearly as likely as with single keeled boats. Twin keel boats sail faster when more upright and are usually shoal keeled. We heel them as little as possible to gain the most speed not the other way round. They also produce a longer 'wave' and not being displacement boats the formula multiplier is more accurate at 1.4 than 1.34. Besides no one plows through reefs isn't eco-friendly.

I would far rather have a well built, properly maintained seaworthy iron keeled boat than for example some of the single lead keeled boats whose list of problems are in fact legion.

Problem you will encounter are osmosis, difficulty tacking in very light airs, and not pointing quite as high but better than full keel boats.

Hardly what I'ld call 'legion.'

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Old 04-04-2007, 16:17   #10
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Iron keels can be formed finer to produce a more hydrodynamic shape than lead keels which must be thicker for structural support.

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Old 04-04-2007, 16:33   #11
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Lead is a better material.

Lead is a better material.

Iron / steel rust. If it were just the corrosion, it might not be as much of an issue, however it is not. The iron expands as it rusts, cracking off the paint that seals it. If encapsulated in fiberglass, it is free to corode until it eventually splits it's covering.

Since it is less dense, it has to be bigger, and since it is bigger there is more surface area that will eventually work to destroy whatever is temporarly protecting it.

Lead is a better material.
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Old 04-04-2007, 19:05   #12
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SV Faith and Begorrah you must not have read my post

Your comments are incorrect except as they pertain to all the improper maintenance procedures such as flaky paint and encapsulation. They do not apply to proper prparation and maintenance as I described in detail two or three posts further back.

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