One can usually run 15amp extension cords into their boat directly from the power post on the dock. Most have 15amp outlets (household looking) on them.

 

One can usually run commercial 50' 15amp extension cords into their boat directly from the power post on the dock. Most have 15amp outlets (household looking) on them, or as you said you can buy an adapter.

 

Most marinas have 30 or 50 amp twist lock receptacles. If so, you will need a 30 or 50 amp male to standard female adapter. I'm pretty sure you can buy them at either West Marine or Defender. Just plug an extension cord into the adapter and bring into the boat for service. Easy Peazy. Add even more convenience by adding a three way plug receptacle to the end of a 10 gauge extension cord.

 

If the pedestal doesn't have a 15A outlet, that's what I'll do.

 

It is not terribly hard to put a 120 shore power panel into a smaller boat or a larger boat they're already made just pick one up or order one blue seas is a top manufacturer of such items, if you do the extension cord routine you must be aware and careful about the 30 amp so you need some kind of safety GFI or inline breakers

 

The plan is to install a LiFePo4 house bank and an inverter, but that's for next year.

For this season I just need something to get me by. I already have a good 12V charger designed to plug into a 120V 15A household circuit. It's not going to overload a 30A shore power circuit.

 

The pedestals I've seen have both the twist lock connector for shore power as well as a regular 3 prong "convenience" outlet.

 

As a temporary measure, while you’re aboard, this sounds doable. You’re going to have sticker shock, when you see the price of the adapters, if you need them.

Presumably, you’ll be using an extension cord. Be sure it’s rating is sufficient for the length and load. Good heavy gauge cords are also expensive. Overloaded extension cords are fire hazards.

If you‘re tossing the batteries either way, it probably doesn’t much matter what kind of charger you’re using. If it’s just a low amp float charger, it won’t do much, unless the batteries start close full. If it’s a auto three stage, it’s probably generic, but just be sure either are the proper voltages for your battery chemistry, ie AGM v Flooded.

 

You're going to have sticker shock, when you see the price of the adapters, if you need them.

I was going to say that I would bet a dollar to a donut that they're not that expensive..... but then I realized that you can't buy a donut for a dollar anymore so I checked the price of the adapters.... $$$ 50 bucks...

 

You'll love the lithium, when you get there. If that's years off, you want to be sure you are properly charging your batteries, so they'll live that long.

 

I'll love having a boat that's in the water, instead of sitting in a boat yard.

Everything after that is just trivial details.