Started by Itself

[endlesspursuit]

Here's one for the experts. I have a 1990 Cape Dory Flybridge Trawler with a TAMD 41B single screw. While I was out of town with the boat at the dock my neighbor calls and tells me my boat is running at the dock. After investigation he finds the saloon door still locked and the key sitting on the shifter, not in the ignition. Now I did forget and leave the battery switch on but what engaged the starter ??? No lightning in the area at the time. Private dock at my house. Thoughts ?????

[Rucksta]

Thoughts

Moisture in a starter relay, the solenoid or other short circuit in the start wiring.
Trace the wiring looking for insulation breakdown or poor terminations.

Lucky you left the seacock open and the fuel on.

[Sherpa17]

This situation once happened to a big sportfish tied up at Roscioli except the throttle and gear shift were advanced. Caused significant damage and the boat sank at the dock. Blamed on moisture

[Pete7]

Mouse

[rslifkin]

For those concerned about this, it's a big concern with mechanical diesels, less so with a gas engine or electronic diesel. The mech diesel only needs the starter to activate and then it'll start. An electronic diesel or a gas engine will crank, but unless the run circuit is also powered, it won't actually start. Of course, in any case there's a risk of the starter burning up after extended cranking.

[jimbunyard]

Common with Volvos of that era in general, and specifically 30 and 40 series engines.

Usually wiring harness connector related; check the ones where they connect to the engine and at the instrument panel. For long runs, cables are often joined together, those connectors can be hidden and hard to find.

The root problem seems to be a combination of undersized wiring, crimped connectors and corrosion in the connector itself, which leads to overheating and shorting between conductors within the connector.

There are various workarounds, generally involving finding the bad connector and either jumping the individual conducter(s) or eliminating it entirely by cutting it out and splicing all the wires.

[endlesspursuit]

Thanks for the input everyone. I 'll be at the boat tomorrow so I 'll be able to report back on the findings. FYI We run a dehumidifier in the boat and have seen no signs of mice / rats. Connector problem sounds possible. A good place to start. Report back. Thanks

[Bill O]

Do you have a battery switch directly to the starter?

Possibly turn it off when not at the boat.

[sailorboy1]

Switches go bad. My ignition switch decided last week to allow power across it when off, which powered the low oil pressure alarm . Had to take the wire off to stop it till I got a new switch.

[FPNC]

Install a battery switch between the cranking battery bank and the starter motor. Turn it off when you are not on board. This is boating 101 stuff.

[endlesspursuit]

Originally Posted by FPNC

Install a battery switch between the cranking battery bank and the starter motor. Turn it off when you are not on board. This is boating 101 stuff.

Yea Thanks. As I said in the beginning it has one and I left in on by mistake. In a hurry after the hurricane / storm went by.

[DougR]

As Jim stated there could be a problem in the wiring harness connections, and that needs to be checked out.

However there were also problems with ignition switches at that time which allowed rain water on fly bridge boats to enter the key switch and short the start circuit, starting the engine. This lead to a change in the switch. The early switches had no protection on the key slot, and water could enter, but the later design had a spring loaded metal cover on the key slot which kept water out.

[endlesspursuit]

Originally Posted by DougR

As Jim stated there could be a problem in the wiring harness connections, and that needs to be checked out.

However there were also problems with ignition switches at that time which allowed rain water on fly bridge boats to enter the key switch and short the start circuit, starting the engine. This lead to a change in the switch. The early switches had no protection on the key slot, and water could enter, but the later design had a spring loaded metal cover on the key slot which kept water out.

Thanks DougR. I do have a switch on the flybridge that is covered by a bridge cover but I'm sure it still gets wet when it rains or I wash the boat. I'll check that out.

[endlesspursuit]

Update: First I checked the solenoid activation wire for voltage at the starter. Found none. Then tried the saloon key and it worked like normal. I checked connectors and wiring and so far have found no problems. I'm starting to suspect the fly bridge key switch as we have a had a lot of rain. Pulled the starter and it is destroyed badly. The ring gear teeth fortunately look unharmed as far as I can see. I have a new starter ordered so I disassembled the old one. I've see race motors explode with less damage. I feel pretty lucky so far as it could have been way worse. Can't seem to attach any pics so that's all for now.