lead keel modification

[mayrel]

We've been continuing our research for that "perfect boat" and came across a CP-19 which the owner had replaced the concrete in the keel with lead.  The boat was sold and I couldn't contact the owner to find out how he did this modification.  We still haven't located a CP-19 to inspect, but my curiosity is killing me....how is this modification possible and does anyone have the details?  Obviously lead is better for ballast than concrete, but this seems like a difficult/expensive modification.  Early thanks for any input...John

[Craig Weis]

So why would cement turned into concrete as it dried be not as good as lead? And in addition to cement, pig iron is added during this 'fill'. 

I suppose a vibrator is used to shake out the air bubbles and firm-up the mix. Thus avoiding air pockets. About 40% of the boat's 2000 lb weight in fact for this mix in the keel.

My first thought was, "I hope he did not fill that void in the 'tail' of the keel with lead. This would move too much weight astern, squatting the stern further down into the water and slowing the boat down as she sails."

Second thought was, "Was the lead poured at a liquid temperature? Certainly not! As this would set the resign afire and...well there is just no way to do this as a hot pour. But a mold and bolting can be done. But why? You don't want to change the hull shape that NASA developed for the 19."

Third thought is, "He just chipped the glass away on some rocks or some darn fool thing like that and for 'fun' banged out the concrete from the sole of the cabin and used the VC to suck out all the pieces. Then fixed the outside of the keel's glass and dumped in what he hoped was enough lead chunks to equal the weight of the concrete he pulled out of the keel.

Fourth thought, "If he filled the keel's whole hole up with lead he may have added too much weight and now the Com-Pac 19 is over ballasted and under 'masted' with a sail too small. Thus suffering in performance. May as well keep her a 'dock queen'. skip.

[mayrel]

I agree with your assessment/thoughts on this idea.  I'm a firm believer in leaving things stock unless there is an obvious design flaw, and then I would contact the builders/designers before making any modifications.  Thanks for the response Skip....John

[Craig Weis]

I was wondering why lead is better then cement?
Can't pour hot lead into a fiberglass mold like the shape of the keel without a bit of trouble.
Kind of burns through the bottom and any water in the hole that hot lead is poured into will explode as it touches the water, you don't want to be around there. skip.

[mrb]

For a boat designed for concrete ballast lead would not be better per say, and would probable have all the neg. effects you mention.  Thats why they have naval architects.

cubic foot for cubic foot lead much heavier than concrete so you more ballast effect from the lead for a given volume.

[Craig Weis]

Yes and so the lead would say stop a few feet from the bottom of the cabin sole? One could use that void, again not filling the last 'astern part of the keel' for icy cold adult beverages. Or some N.Y. Strips. Yummmmy. skip.

[mrb]

Now we just have to chip that pesky concrete out of there make a mold cast one out of lead drop her in add the beer and ice and let the good times row.  Ooh with all that lead would we have to post a warning and keep all the children off the boat.

[CaptK]

The only CP I know of that this was done to, and it was a 19 also, was down in the Tampa region, IIRC. When I had the CP23, I seriously considered replacing the concrete with lead. It is a better material for the application.

If you weighed all the concrete and steel/iron ballast you removed, and replaced it with an equal weight of lead, I don't think that would harm the boats performance at all.

The reasons for replacing concrete with lead would be numerous:

1) Lead is denser, so with the same amount of weight as original, it would be taking up a smaller space, which would free up some bilge room.

2) This same lead would also be sitting in a lower space. That would allow you to lower the Center of Gravity of the boat, which would make her stand up better (and we all know that CP's point better when they're sailed flat!). This was my main reason for wanting lead ballast.

3) Lead is impervious to soaking in water, and most concrete - even fully cured - isn't. I don't think that Hutchins used any special concrete in the ballast mix. So if you have long-term standing water in the bilge (likely in a boat in a slip), your concrete will eventually soak up the water, and expand or get crumbly.

4) In addition, Hutchins 'embedded' all sorts of metal scrap into the concrete. If water gets to *that*, you will have rust, which will expand and further damage the concrete ballast. And possibly the hull.

5) The lead could be cast into pigs or ingots, then lowered easily into the bilge, and have resin poured around it to fix it into place - no 'hot pour' necessary.

The only consideration I can think of is that you might want/need to beef up the hull at the turn of the bilge down to the ballast, since conceivably the lead might sit so much lower that there would be support missing at the top of it that had otherwise been there. You could probably make some transverse ribs of heavy plywood and glass them in to provide the support. This would also section the bilge for better/more organized stowage.

[Shawn]

Not on a Compac but here is the site of a guy that did this replacement on a Montgomery.

http://havasumontgomerys.piczo.com/?g=23004804&cr=1

Reading his page on the swing keel repair makes me glad to just have a keel on the Compac.

Shawn