I have the drain hoses but there's no way to get them out through the drain plug. I made an adapter that fits my oil extraction canister tubing and suck it out that way after they're warmed up.

I had the drain hose attached to the drain plug. Unscrew the drain plug and the hose came out with it. Took about 15 minutes to drain warm oil. Worked great.

Use the kit 302Sport posted. It passes right through the drain plug opening and it has the bonus of a bilge plug you will never lose since it is on a tether/swivel. Be warned....while convenient the drain is apocalyptically slow to drain. Warm engines, start oil drain, leave, come back next day.

Prev owner of my boat had installed what looks like 3/8" ID hyd hose from the oil pan's drain fitting to a 1/4 turn brass valve and from the valve out thru another hose and a thru-transom fitting located close to the plug. It was really slow to drain and I didn't like the thru-hull fittings going thru the transom so I removed them.

Now I suck out the oil from the same hyd hose and valve with a home-made vacuum system made up of an old 20-lb propane cyl and use an air-powered chemical-sprayer (venturi-pump) to create the vac. With engs warmed-up, I can remove the oil from the bottom of the pan in abt 60 secs and not spill a drop,.. The valve is normally secured in the closed position with stainless steel safety wire.

3/8 hose right out the drain plug in a 5 gallon bucket punch a hole in filter and let it drain in a garbage bag & spin the filter off drop it in the bag and no mess right in the oil heater ...

This is what came with my oil pan. https://www.hardin-marine.com/p-1333...20-thread.aspx

I added the oil drain tubes to each of my big boats. My jet boats didn't have enough clearance to do so.

I preferred to not have my oil drain tubes down in the bilge where I could not keep an eye on them (having an issue, loose, split, crack, leak)...
...so I had them pinned up with a carabiner on the end of the cable up near the oil filter so I always had my eye on the plug, and it was higher than the oil pan for obvious reasons.

After a day on the water, when it was time to drain the oil, I would flush the motors pull the drain tubes through the bilge drain plugs with a coat hanger when I parked it in the barn...
...and dropped the two drain hoses in a 5 gallon diesel jug; and walked away. Any floaters were suspended, and the oil was warm enough that the majority drained in a few minutes and leave it for a few days so the pans literally went completely dry.

Then the night before going back out, button everything back up, change oil filters, add oil and head out.

Great ideas!!!

The cat has the engines up high and there`s room underneath so I rerouted the line , put a shut off on it and utilized a refrigerant tank.. let`s see how this works out.

Do it. Makes oil changes a breeze and 98% of old oil drains out