Aft cabin HVAC project

[km1125]

My boat (83 3607) did not come with any HVAC. I've used a portable for a couple years in the salon and it does pretty good, but a friend of mine gave me a nice unit when the controls failed and he had to replace it. I bypassed the circuit board and turned it into a older manual style without the fancy controls. It'll do heat or cool and I have a thermostat for both. Right now the fan is either 100% on or it's off... someday I'll put a variable control on it.

First part was to drill some holes to run some of the hose ducting. I wanted to run everything as out-of-the-way as possible and not use up any storage space. Had to drill a few 4" holes though the cabinetry to run it from the port side cabinet, under the berth, through the starboard cabinetry and over to where I wanted to mount the register in the closet. These will run at the very back of the cabinets up just under the drawer units.

Started with a DULL bit and nearly burned my way through the first two holes!! Went and bought a new bit to do the rest... and found out I need to do three more holes than I thought!! (good thing I got that new bit!)

First, I had to move the accumulator that I had installed. Here is is unmounted, but I wanted to put the hose just to the upper-left of it and it was too close. So I had to unmount and move the supports about 3" farther forward for clearance. I had to also move the trim tab pump on the other side for the same reason.

accumulator.jpg

Here is the last hole I drilled into the closet. The ducting is going into the closet then up to the register:

last_hole.jpg

Here is the register. Still have to finish the ducting inside the closet;

register.jpg

[RGrew176]

Drilling holes in something. Always a bit of a pucker factor until the holes are in place. Really nice looking job. A previous owner added A/C to my Carver. They too, did a pretty nice looking job with the installation. Good luck with your project.

[AaHubb]

Yeah I know what you mean, I had a whole stack of boat holes when I installed my A/Cs.
..Aaron

[Viper]

I want to draw everyone's attention to the 4" round hole in the above pic. Unless the photo is deceiving, that's what REAL Marine Ply looks like
KM can probably confirm that there's likely 5 layers or more and that there are no voids.

[Midnightsun]

Speaking of plywood, every project I tackle on the boat I use Baltic Birch Plywood or Russian Birch as it is commonly called. This stuff has an amazing finish on it and definitely no voids. You know you bought the really good stuff when you get it in 5' x 5' sheets. I like working with the 12mm 9 ply format.

https://www.woodworkerssource.com/blog/ ... to-use-it/

[km1125]

Source of the post I want to draw everyone's attention to the 4" round hole in the above pic. Unless the photo is deceiving, that's what REAL Marine Ply looks like
KM can probably confirm that there's likely 5 layers or more and that there are no voids.

Yes, it's 5 actual layers, then a thin laminate on each side. Depending on the placement, some of the laminates are either woodgrain, an off-white solid or a light brown solid.

[km1125]

So, I renamed the thread to cover the whole project and not just the holes I had to cut for the ducting.

Here's the whole layout for the project:

hvac_layout.jpg

Inside the closet, I was going to have to transition from the 4" ducting under the cabinets to the 4x6 register that is located over the cabinets. Because it was going to take two sharp 90 degree turns, I was going to have to use something like this:

hvac_hose.jpg

Instead, I opted to make a custom duct. This way it's only impinging on the closet space by about 2 3/4". I insulated the outside with some foil bubblepak product and lined the inside with a space-blanket material (foil on both sides of a poly liner). Not sure I really had to do any of that, but I felt better there wouldn't be condensation and also it would protect the wood better. I made it out of some very old marine ply that I had left over from my first boat (>25 years ago!)
Here's how it came out:

hvac_duct_outside.jpg

This is what the inside looked like before I put the liner in there. I sealed it all with polyurethane too before I covered it all up:

hvac_duct_inside.jpg

[Viper]

Great job KM, did you put any gasket material around the edge of the plywood box to make it air tight against the wall? If not, are you confident that you won't get much air loss there?

[bud37]

Looks good , nice job....

[Midnightsun]

What viper said or a small bead of sealant will work well. Maybe overkill but I would spray the inside of the box with a rubber coating like this. https://www.amazon.com/Flex-Seal-Rubber-Sealant-Coating/dp/B00CD9FGNW?ref_=fsclp_pl_dp_3 Looking Great!