50A shore power with 30A boat?

[Rockinar]

Moved to a new Marina. They only have 50A shore power, my boat is 30A.

The harbor master said "Just get a pigtail". Is this a simple matter of using an adapter or do I need more than that? I just spent a fortune repowering the boat and just got it back. Im just double checking so I dont zap all my electrical.

[smac999]

Yes you can buy adapters. Marinco makes lots.

Make sure to check if it’s 50a 120/240. A 50a 120v plug is different (and rare). Adapters are made for both.

[Kettlewell]

The proper "pigtail" adaptor will be safe, but that is rather odd for a marina to only have 50A outlets. I've never seen that. They must mainly cater to big boats. But, you have to get the right adaptor based on what the marina is providing. Some 50A outlets are strictly 125V, while most are 125/250V. My understanding is that most marinas that have 50A are 125/250V. https://www.marinco.com/en/products/...apters/Pigtail

[Hartleyg]

And after you shell out for the adapter "pig-tail", be sure to mark it conspicuously with your boat name. I also took some brightly colored paracord and covered ours with a "Cobra stitch" (same thing you make zipper pulls with) so folks are less inclined to "borrow" it because they don't have one (and yes, they WILL try to do that!).
Some marinas will loan you one, but we've found owning one is more reliable



Hartley
S/V Atsa

[Cheyne]

Our home marina only has 50amp on their new docks. If you go to old fix docks (the place boats go to die) it is only 30 amp.

Cheyne

[Dr. D]

Herrington Harbour North, our marina, is converting all the ashore power posts to 50 Amp (the marina has some 500 spots on land for boats). I borrowed a pigtail from the office, but I bought one afterwards. A guy with a boat nearby had to borrow a pigtail and as we were talking he said this season he docked at a marina on the Chesapeake Bay that only had 50 Amp outlets on the docks.

Might be the future.

[SailingHarmonie]

In a very technical reading, plugging a 30 Amp cord into a 50 amp supply leaves the cord, and everything inside the boat up to the first main breaker, unprotected from certain over current situations.

Assuming the boat has a proper main breaker that prevents drawing more than 30 amps (and not all do!) the real risk is probably very small. You’d have to come up with a short circuit that would draw more than 30 Amps, and less than 50 (which would trip the shore side breaker).

Lacking a proper main breaker, the risk is much larger, and very real. If you pull 40 amps through a 30 Amp cord set, bad things will happen. Up to, and including, fires.

Generally, this risk is small enough that it is tolerated, and the simple adapter pigtail is used. I have seen boats that use a weatherproof box with a 30 Amp breaker as part of their 50 to 30 adapter, but this is unusual.

[Tin Tin]

Push your test button on your boats 120v 30amp breaker when turning on the 50Amp shore power.

[GordMay]

Originally Posted by SailingHarmonie

In a very technical reading, plugging a 30 Amp cord into a 50 amp supply leaves the cord, and everything inside the boat up to the first main breaker, unprotected from certain over current situations.

Assuming the boat has a proper main breaker that prevents drawing more than 30 amps (and not all do!) the real risk is probably very small. You’d have to come up with a short circuit that would draw more than 30 Amps, and less than 50 (which would trip the shore side breaker).

Lacking a proper main breaker, the risk is much larger, and very real. If you pull 40 amps through a 30 Amp cord set, bad things will happen. Up to, and including, fires.

Generally, this risk is small enough that it is tolerated, and the simple adapter pigtail is used. I have seen boats that use a weatherproof box with a 30 Amp breaker as part of their 50 to 30 adapter, but this is unusual.

Indeed, the 30A cord is only protected by the 50A shoreside breaker. Not ideal.

[Kettlewell]

Indeed, the 30A cord is only protected by the 50A shoreside breaker. Not ideal.

Hard to imagine the scenario that would cause between a 30A and 50A draw on just the cord, and it would have to be outside your boat somewhere along the cord to the power box so I imagine the risk would be pretty small.

[GordMay]

Originally Posted by Kettlewell

... I imagine the risk would be pretty small.

Indeed.
It's an unlikely event, with [possibly] catastrophic consequences.
Chaos theory, which is the study of complex and nonlinear systems, has shown that small changes, in initial conditions, can lead to vastly different outcomes.
See:“Predictability: Does the Flap of a Butterfly’s Wings in Brazil Set Off a Tornado in Texas?” ~ by Edward Lorenz

[Dr. D]

My boat has two 30 Amp circuits. The wiring for both goes from the outlet to the breaker box. That should (yeah, I know, "should") provide sufficient protection.

[Kettlewell]

I am reminded of a dock in the Bahamas where the shorepower hookup was a couple of bare wires protruding from the bottom of a lamp post.

[Tinker Bill]

Originally Posted by Kettlewell

I am reminded of a dock in the Bahamas where the shorepower hookup was a couple of bare wires protruding from the bottom of a lamp post.

😅

I lived in Honduras for a year(San Pedro Sula). Unfortunately we found housing in one of the ‘newly upgraded’ homes with hot water systems. Couldn’t find the water heater until we tried to shower the next day…two pigtails poking out of the shower head with wire nuts spliced to wires hanging from a hole in the ceiling.

[Dr. D]

Originally Posted by Hartleyg

And after you shell out for the adapter "pig-tail", be sure to mark it conspicuously with your boat name. I also took some brightly colored paracord and covered ours with a "Cobra stitch" (same thing you make zipper pulls with) so folks are less inclined to "borrow" it because they don't have one (and yes, they WILL try to do that!).

My pig tail should not be "borrowed," but we will see.