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-   -   Lead vs cast iron keels (http://www.sailnet.com/forums/general-discussion-sailing-related/97969-lead-vs-cast-iron-keels.html)

Gregrosine 03-29-2013 09:36 AM

Lead vs cast iron keels
 
Any opinions on the advantages of lead vs cast iron keels? With the additional mass of lead will a lead keel give a better ride than a cast iron keel?

jsaronson 03-29-2013 10:07 AM

Re: Lead vs cast iron keels
 
lead will give you a lower center of gravity than a cast keel of the same size. Alos, no corrosion issues. Lead is WAY more expensive!

msmith10 03-29-2013 10:16 AM

Re: Lead vs cast iron keels
 
Yard guys also claim lead absorbs a grounding without transmitting as much force to the hull. I think there's truth to that in small or moderate hits. Of course, hitting a rock a 6+ knots with either isn't going to have a good outcome.

night0wl 03-29-2013 10:24 AM

Re: Lead vs cast iron keels
 
From what i understand, the only advantage Iron has over Lead is that it tend to have better adhesion to epoxies and bottom paints. Get lead if you can.

PCP 03-29-2013 10:42 AM

Re: Lead vs cast iron keels
 
Quote:

Originally Posted by jsaronson (Post 1009404)
lead will give you a lower center of gravity than a cast keel of the same size. Alos, no corrosion issues. Lead is WAY more expensive!


On modern keels that is not very meaningful. They are made of steel for the foil and iron or lead for the bulb. The difference on the CG is not significant. What is significant is the size of the bulb and the associated drag.

Considering the same boat the one with a lead bulb will be slightly faster than the one with a iron bulb but the difference is much lesser regarding the time where the keels where all cast Iron or cast lead. There you would be right regarding the considerably lower CG on a lead keel. To compensate that the Iron keel would not only be bigger (more volume) but also heavier.

That would count negatively on the boat performance on two counts: Drag and weight.

Regards

Paulo

benesailor 03-29-2013 10:52 AM

Re: Lead vs cast iron keels
 
I have a iron keel and have had some very minor corrosion issues. I would agree that you can get a lower center of gravity with the lead but, i would think that is also factored in during design regardless its iron or lead. I will say; my neighbors 40" columbia hit something in the NYS Barge Canal (looks like it was steel) and just shredded his lead keel!! He has a 2" gash. I would have had a scratch.
I would say that the maintenance issues with a iron keel are way overrated.(mines 20 yrs old, in florida salt) If it did start to rust out it would take 20 years to corrode off its so thick. Now, the amount of give VS a iron keel? I don't know. I would assume they would be about the same if you hit a rock. I would hope a lead keel wouldn't fall off or "give". Not well versed in this department.
I would think that having a bolt on iron keel may actually present fewer maintenance problems. No "smile" or separation issues between GRP and lead to worry about. It is one solid component.
I used to think nothing but lead; i have changed my mind. I have actually read some modern designers prefer iron for it's durability. Please don't ask me to find that. It's in one of my books.
This is a long ongoing debate. Then again, what do they use in a Oyster, Morris, Passport, Discovery, Swan? Lead

benesailor 03-29-2013 10:54 AM

Re: Lead vs cast iron keels
 
I would definitely agree about iron be a drag issue vs a steel fin and lead bulb.
In a cruiser; does it matter that much?

msmith10 03-29-2013 11:04 AM

Re: Lead vs cast iron keels
 
Agree with Benesailor. Iron keel wouldn't be a deal breaker for me.

MarkofSeaLife 03-29-2013 11:36 AM

Re: Lead vs cast iron keels
 
The price difference is pretty large, something like $2,000 per unit.

Anyway, if Oyster uses them then they are good enough for my boat.

SloopJonB 03-29-2013 12:54 PM

Re: Lead vs cast iron keels
 
Quote:

Originally Posted by msmith10 (Post 1009408)
Yard guys also claim lead absorbs a grounding without transmitting as much force to the hull. I think there's truth to that in small or moderate hits. Of course, hitting a rock a 6+ knots with either isn't going to have a good outcome.

Bill Garden said the opposite - iron bounces off while lead "forms" around rocks & such. I've seen boats with iron bounce off and keep going but every lead keel I've seen hit came to a dead stop. Those observations would seem to back up Garden.

Iron keels also have the advantage of having removable and replaceable keel bolts whereas lead keels must have radical surgery or be re-cast to replace corroded bolts.

Properly coated iron keels do not present much, if any problem re: corrosion.

As far as performance, lead is unquestionably best, except for depleted uranium. ;)


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