1969 Chris Craft Roamer 46 Refit: DIY Marine AC Raw Water Pump Controller

I’ve got three Flagship Marine air conditioners on the boat–16k in the salon, 12k in the aft stateroom, and 9k in the V-berth–and one March mag-drive pump (model BC-4C-MD) that needs to push raw water to all of them should any one of them call for it. Marine AC pump control boxes start at $300, but I thought I might be able to DIY something as good or better for far less.

My Flagship AC units have 24VAC terminals that call for the raw water pump to turn on. So I just needed three 24v relays that can handle the load from the March pump.

I bought three Omron G7L-2A-TUB-J-CB-AC24 general purpose relays for $20 each on ebay

The relays take that 24v signal and will pass 120v to the pump. They’re rated for 25 amps, so they’re overkill for this application. That’s not a bad thing.

I’ll mount the relays in a generic water-resistant electronic project box ($12 on ebay)

A little tight, but this will work fine

I used a Sharpie to mark where the holes for mounting screws need to be

Back at the garage, I drilled the screw holes and holes for the cables to pass through

Stainless screws threaded into the holes from behind

Stainless nuts and washers attach the components to the project box

Next, I installed the cable connectors in the holes I drilled in the project box

I installed the pump control box up and out of the way near the pump

Line voltage for the pump courtesy of the big salon AC unit

Neutral and ground pass through the terminal strip to the pump. 120v line voltage is routed to the “IN” side of each of the relays.

“OUT” side of each relay is daisy-chained to the LINE terminal for the pump

If any relay energizes (or all of them) the pump will see the same 120v and start pumping.

Aft stateroom 24vac pump call line

Ditto for the salon…

…and the V-berth

Done

And that’s a wrap for the pump controller. Total cost was around $100, and there are no proprietary boards or components.

Next up in our 1969 Chris Craft Roamer 46 Refit: Major System Test — Air Conditioners

1969 Chris Craft Roamer 46 Refit: Installing the V-Berth AC Unit

With the salon settee mostly finished and the aft stateroom AC installed, next I tackled the V-berth AC installation. Since all three systems rely on the same raw water pump, I can’t use any of them until all three are ready to work.

All of the wiring, hoses, and main duct are routed and ready to connect

After installing the AC unit, I started cutting outlet holes

One AC outlet will be near the V-berth door to help chill the galley.

Sharpie marks the spot

Tape off the urethane clear coat and drill holes in the corners

I was very nervous about scratching the clear coat

Mission accomplished (with no clear coat damage)

I made a foam gasket for the duct transition box

Screwed in place from below

Ducting came next

I finished the other ducting for the V-berth back in 2018…mostly.

Mechanical, plumbing, and electrical connections are done in here

That is a fine looking air conditioner enclosure

The fiberglass filter material is ugly, but I need it until the refit is done

2″ PVC duct needs to be routed to the head

The plywood wall to the right is the forward wall in the head.

Next I cut a duct hole in the V-berth head

Next, I enlarged the hole to the size of the outlet frame

I sealed the exposed plywood all the way around with epoxy.

Duct outlet fits perfectly!

Duct connection to the transition box

The plywood with the first round hole and caulk seals the duct to the transition box

That’ll do

Buffalo Batt insulation wrapped in plastic finishes off the V-berth AC install

Next up in our 1969 Chris Craft Roamer 46 Refit: DIY Marine AC Raw Water Pump Controller