Estimating Air Conditioning BTU Requirements

I made a rough estimate of ECHO's volume excluding the collision bulkhead spaces.

2000 cubic feet is perhaps a little on the high side, and I am OK with that given that my deck is flush and seems to absorb a lot of heat in direct sunlight. 

14 times is a multiplier for cubic volume to estimate the BTU cooling needs of a boat.  With this estimate ECHO needs 28,000 BTU's of cooling. 

So now the question is how do I accomplish this?

One 28,000 BTU or greater air conditioner with ducting could accomplish this economically but require a more complex control system.

Another option would be to use a number of air conditioners.  This would cost more but allow me to start with one small air conditioner suitable for one cabin and add more later.  It avoids running ductwork and a complicated control system.  I would occupy more space.

Space limitations may dictate the option I choose. 

I

Copper Bonding Sheet

These two photos show the 3" wide strips of copper sheeting used for RF ground and bonding. I will need to extend this into the back of the boat through the aft bulkhead. 

These particular pieces will be bonded to the fuel tank.  That is my left leg and paint spattered croc shoe on the left. 

Planning Shelves & Fuel Tank Mount Base

The first diagram is an accurate measurement of the plywood piece that the fuel tank will sit on.  Dashed lines show the location of the White Oak framing it will be screwed to. I used two 1.5" wide pieces of 3/4" plywood and four screws to establish the four corners.  I measured each edge and the diagonals.

This piece will also have the center cut out to allow access to the hoses when the tank is removed. 

The reason for this complicated frame is to provide a secure base for the tank.  Later ill be building a frame for the top of the tank such that it can be fastened with screws on all top edges.  Ill be able to remove one plywood panel, a couple dozen screws, the hoses, and lift out an empty tank to service the bulkhead hoses.

The following is a pattern to build two shelves under the forward area of the cockpit seats. The port side houses shore power connectors.  The starboard side houses the cockpit shower. My goal for these shelves is to provide extra storage accessible from the foot of each upper bunk in the aft staterooms.  

I plan to store motor oil on the starboard side, and filters and spare parts on the port side. I am debating installing dividers to keep these area organized so thing stay in position.  

Once these are cut, I have cleats in place to tab the starboard side in place.  After that sets up I can tab it from the bottom using plastic covered boards to pressure fit the underneath tabbing. 

Once these are done, I can cut pieces to raise the collision bulkhead higher.  Ill probably use two more pieces on each side to completely close off the back of the boat.  That will reduce the heating and cooling needs of the boat as well as prevent water from entering the middle of the boat from in a collision aft, or rudder failure. 

Bulkhead Tabbing--Aft Head and Galley

This photo show the final result of tabbing the two parts of this bulkhead together. The seam goes through the middle of the large hole, and the tabbing of the edge of bulkhead to the hull.

Here is the opposite side in the aft head. The seam got one layer of stitched mat tape. The hull joint got a foundation layer of mat, followed by a layer of roving, topped with a layer of stitched mat. The opposite bulkhead is blocked by the galley furniture, which will be ripped out later. The aft side of the bulkhead got the same three layer treatment.  I added a bit of extra mat and roving to use up my epoxy.

I had hoped to fillet and tab in the last of the settee tabbing.  While it is all cut and ready to go, with the exception of a few pieces to bond to one ring frame--which will need some filler, it was too later to finish that off. I'll do that on Thursday afternoon. 

There is a gap in the cabin sole in one settee locker that needs to be filled in also.  It should have some tabbing to bond the two sides together also.