What Lies Beneath
So what can you expect when you run aground? It's quite likely that sooner or later you will. Boat design and build have everything to do with damage when it comes to groundings. Let's start with sailboats. As new sailboat designs evolve, they are made from lighter materials, which results in a higher proportion of damage. Simply stated, the more we're making keels thinner to go faster, the higher the rate for damage there is. It's a matter of the geometry involved. Thinner, deeper keels that strike objects tend to have the aft end of the keel pushed up into the hull, while the leading edge is pulled down in somewhat of an equal but opposite reaction. Both actions can and often do result in hull damage.
When it comes to what lies beneath the water's surface, there are regional differences, of course. In New England, the Great Lakes, and on the West Coast, there are granite ledges and rocks — completely unforgiving of a skipper who neglects to pay attention to his or her depth sounder. New Jersey's waterways, along with most of the southeastern states, ICW, and Florida (some Gulf Coast, too) have more of a sandy, silty bottom. This is much more forgiving when it comes to running aground. But hit a coral reef, for example, and not only will your pride and your boat be hurt, your wallet may be hurt as well from fines associated with the reef damage.
Sailing Toward Damage
Let break down some typical grounding scenarios, starting with a hard grounding on a solid reef or ledge. With the rugged bottom of a full keel with heavy laminate, you may get lucky and bounce off. In many cases like that, a haulout and external repair of the damaged area is all that is needed. On occasion, there may be damage to ballast or laminate, but rarely does the damage become a structural game-ender.
This is not the case for the lighter, faster, and deeper keelboats discussed earlier. For boats with deep-fin keels, spades, or skeg-hung rudders, with a keel step mast, the keel (typically a nice big piece of shaped lead) is attached to your hull with a series of keel bolts. Usually there is one bolt in the front, a series of pairs following that, and then one in the aft end above the trailing edge (back) of the keel.
If the impact is significant enough, your mast and rigging may be damaged from movement of the mast step and possible compression and tension damage to the rigging. For this reason, a sailboat that's taken anything more than a bump needs to be inspected by a professional.
For our powerboat brethren, grounding damage is typically simpler to inspect, diagnose, and repair than on sailboats. Let's take a look at a few issues facing powerboat owners and repairers with today's powerboat offerings.
As with full-keel sailboats, the powerboats out there with a full keel (displacement trawlers, single, or double screw) usually avoid too much trouble at 8 knots since they're protected by a massive chunk of fiberglass (although old fashioned, heavy solid-laminate construction has pretty much gone the way of the landline telephone). Aside from hull gouges, straightforward damage includes shaft, strut, propeller, and cutless bearing damage. There is the potential for transmission damage from a hard hit. I've inspected many boats that hit so hard that the engine-transmission case or bell housing broke, and a few that even pulled the engine right off its mounts.