Just about the only good thing that happens after you run your underwater gear into a rock is that the locals may name the rock after you assuming no one has run afoul of it before. (I've got an underwater gravel pile bearing my name.)

On the other hand, there's no end of bad stuff that can come from a grounding including bent props, broken skegs, bent shafts, blown transmissions and even sunk boats. At the very least, a grounding will be scary, embarrassing and potentially expensive.

This month we're going to talk about what to do immediately after the grounding- staying afloat, assessing damage, getting home, cutting costs. So let's start with the most basic of the basics-if you hit something, STOP! A loud bang or hull rattling thump usually means you've struck something underwater. If your boat is a stern drive or an outboard, the engine (outboard) or outdrive (sterndrive) may swing up on its hinges. The engine may stop and, if you hit hard enough, passengers and other loose items may be thrown around the boat or even over the side.

Human life and safety should always be your first concern. Count noses. Is everybody still on board? If anyone is missing, visually scan around the boat and push the MOB button on your GPS in case an extended search becomes necessary. If you spot the person in the water, throw them anything that floats and, if your boat is operable, maneuver toward the victim. (Be sure to shut down the engine when you approach the victim to keep them out of the prop(s).) A swimmer should enter the water to aid the ejected passenger only if the swimmer is wearing a PFD and has a line so he/she can be recovered.

Under almost all circumstances, it's best to call for help immediately if you have one or more persons in the water and possibly injured. Call for help on channel 16 or an appropriate local hailing frequency. Report your location, the number of people in the water and on board, and a way to identify your vessel. You want help moving toward you as soon as possible. You can always tell them to go away if you manage to recover your victims yourself.

Once you've got everyone accounted for, do a quick check for serious injuries and make everyone don a personal floatation device (life jacket). Finally, check to see if your boat is taking on water. Inboard boats will take on water if the grounding pushed (or pulled) a strut through the hull or pulled a shaft out of the log. Of course you can always experience flooding if the hull was holed by a rock before the underwater gear impacted. Activate the bilge pumps, radio for help (MAYDAY) and, while you're waiting, try to stem the rate of flooding by stuffing pillows and cushions into holes, wrapping towels around shafts. Inboard engines can be used to help bail. Close the seawater intake valves, disconnect the intake hose and stick it into the bilge water. The engine cooling system will suck water from the hull and discharge it overboard.

If your outboard lower unit hits hard enough it can break off altogether or overstress the transom. You need to check for water and cracks. If you've got an I/O and hit hard enough you may find the entire sterndrive unit missing and water pouring in through the 2-inch diameter transom shaft hole. Plug it and call for help.

Assessing the Damage

Happily, most groundings are not catastrophic. Passengers remain on board and uninjured and the hull remains watertight. The engine may still be running and there may be few overt signs of damage. Here's what to do.

Stop!

We're assuming that if you knew the underwater obstruction was present, you would have navigated to avoid it. Look at a chart or chart plotter. Where are you? What's the depth of the water? What did you hit? Are there other obstructions around? In tidal waters is the depth increasing or decreasing? When you get these questions answered, you'll be able to get back into safe waters once you've assessed the mechanical situation. If you don't have a chart or other resource at hand, get on the radio or cell phone and call for help. Local marina operators or fishermen are the best reference for getting out of tight spaces.

Assess the damage.

Can you see the propeller(s)? Are they there? Are all the blades in place? Are they chewed up or curled or both? Is there oil in the water near your lower unit or gear case? (If oil is in the water, call for a tow.) If the propeller is in place and has all its blades, you may be able to get into a marina for repairs under your own power. If blades are missing, don't try to move on your own. Vibration will cause too much damage.

If your only propeller is damaged but still more or less propeller shaped, attempt to start the engine. Does it sound normal? Try the steering. Will the wheel turn throughout its entire range? If the engine vibrates without a load or the steering seems inoperative, turn everything off and call for help.

If the engine idles okay and the steering linkage seems to be working, try shifting into forward idle. Does the boat move forward? Is the vibration relatively low? Shift back to neutral and then to reverse idle. Does the boat make way? How about the vibration? Remember, even if if you get your boat running, you'll have to control it underway and back at the dock.

A damaged propeller, at best, will be inefficient. The distorted blades will create turbulence and will cavitate more at lower RPM than an undamaged prop. At worst, an out-of-true propeller will send damaging vibrations back through the power train.

Vibrations can also come from a bent propeller shaft. Powering your way home with a chewed up prop and a bent shaft can damage seals and gearing up stream in the powertrain. Consider a tow.

When assessing the probability of damage with an outboard or I/O, keep in mind that aluminum propellers absorb a lot of energy and deform easily when they strike an underwater object. Stainless steel props are stiff and hard and tend to transmit a great deal of impact energy to the drive train. If your aluminum prop looks distorted, you may have shaft damage. If your stainless steel prop looks damaged, you probably will have shaft damage.

My recommendation is to call for a tow (if you've got insurance) unless the engine turns in gear with minimal vibration and maximum controllability. If you do decide to run on your own, select the lowest controllable forward speed, check the bilges periodically, head for the nearest repair facility, keep the lower unit tilted down. (Don't run if the lower unit or drive has been knocked into the up position and will not come down. Doing so puts too much strain on the internal gearing.)

If you have a twin engine boat, try the engines and transmissions separately. One may run better than the other. The length of the shaft on an inboard can provide mechanical amplification of propeller damage. A bent shaft (or strut) can put unusual loads on the transmission and cause seal and plate damage. So do not treat the go/no go decision lightly after a grounding.

Back at the Marina

Whether you return to the marina under your own power or get towed back, you?Ĵll want to haul your boat to inspect the hull bottom and underwater gear. Send the propeller( s) to a propeller shop for inspection and repair. It's amazing what these folks can do with a mangled prop. The cost to refurbish a propeller is usually about one half the cost of a new unit. Sometimes, the propeller is simply too badly damaged for repair. Obviously, the only thing to do in this case is to purchase replacements.

Marina technicians will inspect the rest of the underwater gear. In the case of inboards, they'll measure the strut angles and inspect the hull structure where the struts are mounted. They'll also look at the cutlass bearings, the shaft, the shaft log, and even the transmission and engine mounts if the impact was extreme. Bent shafts can be sent out for straightening so long as the damage is not on the keyway taper. Struts can be repaired, but may have to be sent out if they are cracked.

For outboard engines and I/Os, the technicians will inspect the gearbox for fractures, broken skegs and alignment. Broken skegs can be repaired. (Usually the old skeg stub is cut off and a new one is welded on.) Cracked cases are rarely repaired, but rather replaced in their entirety.

The technicians will dial indicate the prop shaft to see that it is in spec-typically five to seven thousandths. If the shaft dials out okay and the case is not cracked, the inspection will stop at this point. If the shaft is out of spec or there is ?ĺcrunching?Ĺ in the drive train, the entire unit will have to be torn down and inspected.

You may elect to pay for prop repairs or a broken skeg out of your own pocket. But cracked gear cases, broken gear teeth, bent and distorted shafts and struts can be very expensive. Consider getting your insurance company into the project. (On outboard engines and outdrives, the insurance company will typically authorize a tear down to inspect other powertrain components if the prop shaft appears bent.)

Prop Nicks and Scuffs

During the course of a typical boating season, your propeller may become scuffed and nicked-especially if you fish shallow water or gunk hole along rocky shores. Any distortion of the propeller blade or face reduces the efficiency. Bends in blades produce vibrations and nicks in the leading edges produce stress risers that can lead to fatigue failure. If you fall into this category, buy a spare prop and use it as backup when you periodically send your nicked and scuffed screw in for reconditioning.

And one last suggestion. Buy a chart or ask someone with local knowledge to sketch out the hazards in your boating area. Prevention is always better than expensive repairs. .