Centerboards are perfectly safe and perfectly good sea boats for offshore
and the shoals. Of course, much depends on the design and construction. Check out the CB trunk on a well made boat and you will see a large, thick metal plate with bolts on 1-2 in centers all the way around.
One of the best naval architechs of all time, Ted Hood
, made a career of Keel/CB boats. His designs have been built by Bristol, Hinckley, Wauquiez and Little Harbor. The Keel/CB design (perhaps a more specialized notion than just a centerboard) is used widely on Alden's, Hinckley's and Bristol's. As far as I know, none of these boats and no Wauquiez's have ever had a problem with water integrity in a grounding.
K/CB's, like anything on a boat (including bolt on keels) have their considerations. Cables
need to be inspected every two yrs and probably cut and reattached every 4. Many owners now use high modulous line, such as spectra, instead of cables
and thus can forgo that maintenance
If a CB in a K/cb boat fails or even falls off, no matter, all these designs are design to sail without a need for the board. It simply enhances pointing and reduces leeward slippage.
Lest you think bolt on keels are immune to failure, I would point out the bolt on keel
of a Bene Oceanus 39 that was ripped off in a blow, the boat rolled and crew were killed. More recently a new Bavaria
, boat rolled and crew were killed. Go to a boat yard and look at some boats with iron keels, you may find one that has actually fractured, as I have and you may find a few whose bolts are being replaced (due to corrosion). Plenty of bolt on keels have come off in groundings.
Obviously, the above is rare...but simply exemplars to say that unless you are going to pour a very large amount of money
into a boat, cruising means living with a certain amount of work, maintenance and risk.
Some people have reported that their CB has bumped from side to side. That is generally either due to poor design, poor construction or a lack of maintenance. Most people I know that have sisterships to mine have no problem with this and I never have either.
If you plan to sail to shoal areas, such as the Ches, much of the SE coast of the US, Fl and the Bahama's, being able to get into skinny water is a significant advantage. Look at the charts
for areas you plan to go, then decide what draft
boat you should look for.
Hope this helps