A Unique Perspective
Here again we have the unique perspective of having used many different ballast systems over the years. The early Bayfields all used fully encapsulated lead ballast similar to what is offered by some current manufacturers (although I can say we never did use cement to bed the lead ingots in place before we glassed over the sub floor!). From 1980 on, we designed all our boats with externally mounted lead keels. Today you will find a few manufacturers claiming internal (encapsulated) ballast is better than an external mounted lead keel. They say it is stronger and safer. From our point of view, these statements are more marketing than actual fact.
Honestly, we believe the real advantage of an internal ballast system is that it is far more cost efficient and production friendly than a correctly engineered and manufactured external lead keel. And we know this well... recently the cost of casting a modern external lead keel has increased to the point where it is at a cost disadvantage, where it might not make economic sense for some customers. The need to stay competitive has meant we are now offering our boats with either the encapsulated ballast or the optional upgraded fully external lead shoe. But there are differences in the two systems and as opposed to using marketing to sell one system over the other, here are some of the facts...
- Lead is considerable heavier than glass. It is then, without question, that if you are using lead for stability it is best placed as low as possible for the maximum effect. Encapsulating the ballast inside a fiberglass structure reduces the lead mass. Because it has to fit inside the glass structure, it is obviously smaller by the thickness of the structure. Clearly if the lead were as big as possible, it would have a more positive effect on stability.
- Using individual lead ingots to make up your ballast also compromises the mass. The space between the ingots is generally filled up with a resin slurry (or in some cases even cement) which is obviously much lighter than lead, again reducing the overall effective mass of the keel. Our encapsulated ballast designs use a number of smaller castings designed to mate together with the shape of the enclosure... of course, unlike the external casting, these do not have to be cast in a continuous pour, do not contain Antimony, and are therefore considerably less expensive to manufacture. We use only lead - we do not use cast iron.
- What about the claim that encapsulating ballast gives you get a double hull effect and therefore safer? While we do use the same argument regarding the safety of our cored hull construction (see structure), in this case we do not think it applies quite so well. For one thing, if you conside a chunk of coral wearing away the bottom of a fiberglass laminate, would it not be a lot better if the bottom of the keel were metal. Wearing a hole in a lead keel pretty much negates the need for a double hull.
- Encapsulated ballast systems do not use bolts - so they can't break or corrode. Of course they don't have the expense of having to buy them either but if they are correctly engineered with appropriate safety factors and installed in designed dry sections of the structure, the negatives only remain with the additional costs. Design - Here is something you never hear mentioned... from a design aspect it is far easier to design a new boat while holding back 5 to 10% of the total ballast in reserve for placement after the boat is launched. This way you can add the remaining ballast to adjust the trim to account for any errors in your weight and ballast calculations or construction. With a full keel you can simply add it back in after the boat is launched to adjust the trim. In the case of an external keel, you have to get it right the first time without being able to adjust.
No, from our point of view an internal ballast system is far easier to design and build and hence is less expensive. External ballast has the advantage of being more durable and is a better lightning ground plain, creating a better righting arm, but is substantially more expensive. We will leave that decision to you.