What To Do When The Engine Does Not Crank

You’ve been in a beautiful bay for a few days, and it’s time to move on. You push the starter button, and the engine does not crank. Now, what? It might very well be on the top of the list of fears of boaters. Mind you, this is probably not on the level of sinking or losing steering. But, many of us always have that little voice in the back of our mind saying, “what if she won’t start?” What do you do when the engine won’t crank?

Making sure you have a good electrical system before you leave the dock is the first step. You should have it inspected and tested by a licensed professional. Each spring you should do an “at-the-dock” shake-down test without the shore power cord, to ensure your system is performing as it should. Keep in mind this must be multiple days because the first day for an unplugged vessel is easy on the batteries and doesn’t provide reliable data. Most marine mechanics have a capacitance tester that will be able to test the start batteries cranking abilities, but they really cannot determine the condition of large house banks.

All boat electrical systems should have two power sources, a ‘start’ and ‘house’ bank (or, at least, two batteries and a 1-all-2 switch). We highly recommend that every electrical system includes a way to start the engine from this second source.  You need to make sure you verify how it works and that it functions as designed.

Battery Life – Monitor, Test, and Recharge

Batteries don’t last forever and live a very hard life. Usually, with good quality batteries and charging sources, they will last 5 to 7 years, but we can kill them much sooner! Always keep records, inspect the batteries for corrosion, leaks, and for lead-acid batteries check that they are full of good distilled water. Have your batteries tested–starting from year one so that you have a base reference point. Also, while you can purchase batteries in many locations, you shouldn’t  plan to do this while on vacation. Although batteries are expensive, it is not recommended to replace just one battery or bank of batteries if they are not up to acceptable levels. When one battery is weak, it is time to replace them all.

One of the most important things to consider with battery banks is that you have to be able to easily monitor the state of charge for each battery. What if a bad thruster battery leads to a docking error (and a possible accident)? A replacement battery is a much cheaper way to go but only if you know it is time!  Look online and you can find many digital 12 volt meters for testing for less than ten dollars, a worthwhile investment. Battery installation is pretty simple for many boat owners though the weight of house batteries and their placement can be a challenge. As with any equipment installation on a boat, it should meet the American Boat and Yacht Council (ABYC) standards for safety. A shoddy installation, not to standards, will show up on the survey when you go to sell the boat and will have to be repaired to standards anyway. Pay for it now when you can benefit from the repair, or pay for it later for the next owner.

Knowing when a battery is fully charged and when a battery needs to be charged is also a key to keeping your batteries able to perform.  A fully charged battery reads 12.8 volts when tested or if you have a battery gauge on your boat.  When your battery reaches 12 volts at rest, it’s time to recharge.

Battery Tips and Devices

What happens when the start battery does not power and spin the starter?  Be sure you know how to engage the starter manually – unless you have modern electronically controlled engines. Diesel engines are very reliable and will run for thousands of hours, once we get them started (and the usually won’t quit unless the fuel filter gets plugged (another topic). Being able to manually engage the starter in the engine room has been the get-home for many boaters allowing them to make it back to port to find assistance. All this method requires is a push button with short leads and a 5-10 minute demonstration.

Some boaters carry other devices such as starter-jumpers or even jumper cables.  Genius has small lithium-ion starter battery jump packs that are small in size but large enough in power to crank medium-sized diesel engines.  You may also consider keeping a set of long jumper cables.  You can keep these items onboard in the spares area.  Many great checklists are readily available to help you become self-reliant and maximize your enjoyment while on the water.


About Mike

Mike Beemer is a partner and instructor for Fine Edge Nautical Seminars and the Seattle Boat Show University. He is also a faculty member for Skagit Valley College’s Marine Maintenance Technology program. He holds numerous ABYC certifications and has been a master mechanic repairing and modifying boats for years.
Mike holds a Bachelor of Arts in Math from the University of Washington and a Masters in Career and Technical Education from Ball State University. Mike and his family are avid sailors, and it’s not unusual to find them cruising the waters and bays of Washington and Alaska during the summer and weekends throughout the year in their heavily modified Skookum 50 – Black Pearl.