It's a sad fact: Every spring, shortly after being launched and commissioned for the season, boats sink while safely tied up at the dock, turning what should be a good time of the year into a real mess. BoatUS' Seaworthy magazine, which combs through the BoatUS marine insurance claims files for important accident trends or lessons to learn, has identified the top five reasons for springtime sinkings, and created a free spring commissioning checklist to help boaters start the season right.

Main Causes Of Spring Sinkings

1. Missing or damaged hose clamps: These clamps are often removed in the fall to winterize the engine, and then forgotten about in the spring when the boat is launched. Tight spaces in engine compartments make it difficult to see some unsecured or deteriorated clamps.

2. Unsecured engine hoses: Over the winter, freezing water can lift hoses off seacocks (valves).

3. Spring rains: Combine heavy rains with leaking ports, deck hatches, cracked or improperly caulked fittings, chain plates and even scuppers clogged by leaves and your boat could be on the bottom soon.

4. Broken sea strainer: Glass, plastic and even bronze strainer bowls can be cracked or bent over the winter if not properly winterized, allowing water trickle in when the seawater intake seacock is in the open position.

5. Leaking stuffing box: If equipped, a steady drip from an improperly adjusted stuffing box (the "packing" around the prop shaft) has been known to swamp a boat.

Spring Commissioning Checklist:

Before you launch —

1. Inspect and lubricate seacocks.

2. Hose clamps should be inspected and replaced as necessary. Double clamping hose connections with marine-rated stainless hose clamps, or keeping seacocks closed when you are away, are wise moves.

3. Inspect cooling hoses for stiffness, rot, leaks and cracking. Make sure they fit snugly.

4. Replace deteriorated sacrificial anodes.

5. Inspect prop(s) for dings, pitting and distortion. Make sure cotter pins are secure. Grip the prop and try moving the shaft - if it's loose, the cutlass bearing (on inboard drive systems) may need to be replaced.

6. Check to make sure the rudderstock hasn't been bent.

7. Inspect the hull for blisters, distortions and stress cracks.

8. Make sure your engine intake sea strainer is not cracked or bent from ice, is free of corrosion, clean and properly secured.

9. With inboards, check the engine shaft and rudder stuffing boxes for looseness. A stuffing box should only leak when the prop shaft is turning, and needs to be inspected routinely.

10. Use a garden hose to check for deck leaks at ports and hatches. Renew caulk or gaskets as necessary.

11. If equipped, ensure that the stern drain plug is installed.

12. After the boat is launched, be sure to check all through-hulls for leaks.

Editor’s Note: See continuation of this story on www.azbw.com. There is further information there on engine outdrives and outboards, engines and fuel systems, sailboat rigging, trailers, and more.

Engine Outdrives and Outboards:

1. Inspect rubber outdrive bellows for cracked, dried and/or deteriorated spots (look especially in the folds), and replace if suspect.

2. Check power steering and power trim oil levels.

3. Replace anodes that are more than half worn away.

4. Inspect outer jacket of control cables. Cracks or swelling indicate corrosion and mean that the cable must be replaced.

Engines and Fuel Systems:

1. Inspect fuel lines, including fill and vent hoses, for softness, brittleness or cracking. Check all joints for leaks and make sure all lines are well supported with non-combustible clips or straps with smooth edges.

2. Inspect fuel tanks, fuel pumps and filters for leaks. Clamps should be snug and free of rust. Clean or replace fuel filters. Owners of gasoline-powered boats with fiberglass fuel tanks should consult a marine professional to inspect for any ethanol-related issues.

3. Every few years, remove and inspect exhaust manifold for corrosion.

4. Clean and tighten electrical connections, especially both ends of battery cables. Wire-brush battery terminals and fill cells with distilled water (if applicable).

5. Inspect bilge blower hose for leaks.

Sailboat Rigging:

1. Inspect swage fittings for cracks and heavy rust (some discoloration is acceptable). Inspect wire halyards and running backstays for "fishhooks" and rust.

2. Remove tape on turnbuckles and lubricate threads, preferably with Teflon. Replace old tape with fresh tape.

3. If you suspect the core around the chainplate is damp, remove the chainplate to inspect and make repairs.

Trailers:

1. Inspect tire treads and sidewalls for cracks or lack of tread and replace as necessary. Check air pressure - don't forget the spare.

2. Inspect wheel bearings and repack as necessary.

3. Test tail lights, back-up lights and winch to make sure they're working properly. Inspect hitch chains.

4. Inspect trailer frame for rust. Sand and paint to prevent further deterioration.

5. Inspect brakes and brake fluid reservoir.

Miscellaneous:

1. Check expiration dates on flares and fire extinguishers.

2. Check stove and remote tanks for loose fittings and leaking hoses.

3. Inspect bilge pump and float switch to make sure they're working properly.

4. Inspect dock and anchor lines for chafing.

5. Check shore power cable connections for burns, which indicates the cable and/or the shore power inlet must be replaced.

6. Make sure your boating license and/or registration is up to date. Don't forget your trailer tags.

7. Review your boat insurance policy and update coverage if needed.

8. Make sure you have properly sized and wearable life jackets in good condition for each passenger, including kids. Check inflatable life jacket cylinders.

9. Test smoke, carbon monoxide, fume and bilge alarms.

10. Be sure to get a free vessel safety check from the U.S. Coast Guard Auxiliary or U.S. Power Squadrons. Find out more at www.Safetyseal.net.