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In short: If your boat won’t start and the battery seems dead, check four things in this order: the engine cut-off switch, the battery connections and ground wire, the battery voltage, and your battery switch for your backup battery. If all are in order and nothing gets the engine running, or the wires are hot, call Sea Tow at 800-4-SEATOW.
Many boaters know that dreaded sound of an engine trying to turn over with a dead battery. In fact, low voltage, or a dead battery, is a call that Sea Tow Captains frequently receive. So, what should you do if your battery won’t start your engine? According to Captain Christian Orfanello of Sea Tow New Orleans, there are a few thoughts every boater should keep in mind when stranded with a dead battery.
“We typically jumpstart over 50 boats during the summer months alone,” Captain Christian said. “But we’re also able to talk boaters through a few simple troubleshooting steps that helped to get their boat up and running again without us leaving the dock.”
1. Check the Engine Cutoff Switch
The engine cut-off switch (ECOS) is the lanyard or wireless fob that automatically shuts the engine off if the boat operator falls or is thrown from the helm. If your boat won’t start, Captain Christian recommends that you first check the engine cut-off switch. “It’s common for the ECOS to become disconnected when there is a lot of activity on a boat that is anchored, especially if young kids are onboard,” he said. “It’s just a fact that kids like to sit in the captain’s seat and play with things. We always ask the boater to first ensure that it’s properly connected before doing anything else.”
2. Check the Battery Connections
Next, check the connections. Ensure that all connections and the ground wire have a proper and tight connection and that there is no corrosion buildup on the battery. Captain Christian also says to touch the wires to make sure they aren’t hot. “If the wires are hot there’s likely a bigger problem somewhere and that could lead to other issues or even a fire. If this is the case, do not jump it, we will tow it.”
3. Check the Battery Voltage
If possible, keep a small meter/battery tester with you on the boat. This can help you determine if your battery is actually dead, has low voltage, or if something else is wrong. A battery is fully charged at a minimum of 12.8 volts with no load. However, due to on board computers and other technology, it is completely normal for the full-charge voltage to be a bit lower. When a battery reaches no higher than 12.4 volts at full charge, it’s ready to be replaced.
| Voltage with no load | What it means |
| 12.8 volts or higher | Fully charged |
| A little under 12.8 volts at full charge | Normal on boats with onboard computers and electronics |
| 12.4 volts or lower at full charge | Ready to be replaced |
4. Switch to a Backup Battery
Some boats are also equipped with more than one battery and a battery switch. If one battery does not start, try switching to the backup battery, or the “BOTH, ALL, or 1&2” position to get the motor running again so you can make it back to shore.
If the battery checks out and the engine still won’t turn over, go through what to check when a boat engine won’t start despite a good battery.
5. If All Else Fails, Call Sea Tow
Sea Tow members receive jump starts as part of membership. If you’re ever in need of assistance, call our 24/7 Customer Care Team at 800-4-SEATOW.
How to Keep Your Boat Battery From Dying
- Check the battery voltage before you leave the dock.
- Clean any corrosion off the terminals and make sure every connection and the ground wire are tight.
- If your boat has two batteries, run electronics off one and save the other for starting the engine.
- When the boat is stored, disconnect the batteries and keep them on a smart charger.
- Replace a battery that reads 12.4 volts or lower at full charge.
Member Benefits Beyond 24/7 Towing
Jump starts are one of the on-water services covered by Sea Tow membership, along with towing, fuel delivery, oil and parts delivery, prop disentanglements, and covered ungroundings. Membership covers every boat you own, rent, or bareboat charter, and Sea Tow Captains routinely arrive in under an hour from more than 500 ports. Compare membership options, find the Sea Tow closest to you with the service locator, or call the 24/7 Customer Care Team at 800-4-SEATOW for more information.
Frequently Asked Questions
Why won’t my boat start if the battery is not dead?
Check the engine cutoff switch first. If the lanyard or fob is disconnected, the engine will not start even with a good battery. Then check that every battery connection and the ground wire are tight and free of corrosion.
What voltage should a fully charged boat battery have?
A fully charged boat battery reads at least 12.8 volts with no load. Onboard computers and electronics can make the full-charge reading a little lower, which is normal. A battery that reads 12.4 volts or lower at full charge is ready to be replaced.
Should I jump start a boat battery if the wires are hot?
No. Hot wires usually point to a bigger electrical problem that could lead to a fire. Do not jump the battery. Call for assistance instead.
Does Sea Tow jump start boats?
Yes. Jump starts are covered by Sea Tow membership. If you’re not a member, Sea Tow can still assist at a fee-for-service cost. To request assistance, call your local Sea Tow franchise location, use the Sea Tow App, or call our 24/7 Customer Care Team at 800-4-SEATOW.
Sea Tow Team
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