Foam Install

120 Cubic Feet of Insurance...

Foam, pillowed up out of the hull and cured.

Another hot topic out in the boatbuilding community is whether or not to use 2 part expanding polyurethane flotation foam. This is really only an issue among the amateur boatbuilding folks because USCG rules require professional boat builders to provide positive flotation or the ability for the vessel to float if swamped.  The counter-argument to this practice is that some installation practices provided water intrusion into the foam that is naturally water resistant and with continual immersion can begin to hold water. 
Now, basically, water weighs between 62 to 64 lbs. per cubic foot dependent on salinity (additional weight of dissolved salts and mineral). So every cu ft. of foam we add will give us that much flotation less the actual weight of the foam itself.  Typically 2lb. flotation foam is used in these applications.  It is not considered structural but can serve to stiffen floors and insulate as well.  We calculated that to fill the floor and space between the frames we would need 80 cu ft.  That's around 500lbs of flotation. The plywood itself is around 36 lbs. per cu ft. so there is a difference of 26 pounds so the hull itself is providing some buoyancy. She would still sink if holed and its a risk I will not take with love ones aboard.  Heck, I don't have a death wish if it were just me.  So, an 80 cu. ft. foam kit was ordered shipped in 10, 1 gallon part B cans and 2, 5 gallon part A drums.

Bow chamber with bag liner - View from up top

Interior view

We started at the bow.  There were three chambers starting at Station 2 through 6.  On the rest of the boat, the chambers were lined with plywood, the hull serving as one side and the pilot house's interior and coaming as the other side with the frames themselves boxing the chamber in. The bow was different because the chambers were open to the under berth area around the tanks.  In order to provide some containment, we used large plastic bag drum liners that were stapled in at the deck and foam poured in around the water tanks and water heater set in place.  Once done, relief will be cut away and sealed with epoxy resin.  All of these pours were mixed in 24 oz. batches. Leave plenty of time between pours so that the subsequent pour doesn't melt the last pour.  Also, mix with precision and the hotter the better.  Those two factors are the most important to get the maximum amount of expansion, approximately 25 to 30 times the volume.  The interior  view shows how this bag worked as it molded around the tanks.  The plastic bag peels easily from the foam.
With this part completed we moved on to the floor and worked our way back toward the stern.





Foaming Sequence in pictures...



Port side pours.  cups can be reused

The following sequence shows how we get the foam in the floor and walls.  The floor was hole sawed in various places and pours were made as we watched for foam-out to know that it was completely filled.  Once the foam had progressed up the wall cavity we continued to make pours until we reached the bottom edge of the pilot house wall where we then stapled heavy plastic sheeting with battens to bring the foam to the top of the deck.  One thing to remember is that all of the foamed out cups can be removed and thrown back in the "to be foamed" chambers.  Once there, we used a combination of saws and sanding boards to flush the foam with the deck. 
Around the fuel tank, we bagged the tank and plugged any of the conduit turning up for control, steering cable, and wiring.  We also built dams where space needed to be left for the fuel fill, tank sending unit and vent out of scrap pink board.
The following sequence of pictures should be self explanatory.  Note that the fuel tank requires room to expand.  I cut about and inch of relief where foam touched the rear quarters of the tank.


Holes cut in floor and foam poured.  Note the foam out in the bilge sump.

Trimmed and flush sanded foam deck.

Foam scrap everywhere.

 Fuel Tank and Blocking for Cleats...

Carved with 4" grinder and sanding disk.

One last piece to handle before the decks are added is to block under the cleats for additional reinforcement and to provide access to those cleats.  The front cleats will have 6" inspection ports in the cabin wall to access the cleat studs.  The amidships cleats will be accessed through the cabinets to be installed via a notch between the pilothouse wall and hull liner in the PH.  The stern cleats will have wells carved out, epoxy coated and painted with 6" deck mounted inspection ports.  The following pictures show this...

Cleat installed and ring in basic position.  Location is noted on hull exterior.

Amidships Cleat before 1" pine blocking is added and sealed with thickened epoxy resin.

The fuel tank was mentioned previously.  The back wall of the coaming is installed and will be opened up with two long hatches after the deck is installed. There will be an emergency 500GPH Bilge pump installed in the fuel tank compartment along with a blower to vent.

Tank installed.  Foam was sealed with epoxy and painted with 100% acrylic as further protection.
Neoprene pads under tank hold down straps (Moeller).

Coaming installed.  Glued and screwed.

 At this point we are ready for the deck.  Cleats are in, foam is removed from the wood surfaces for proper bonding of the deck.


By the way... It took another 40 cu ft to fill it all. That's 7400 lbs. of flotation in a fully loaded #5000 lb boat. Over 150 24 ounce batches mixed and poured.

Cabin Roof and Bathroom

Composite Roof Experiment...

1/2" Ply edge buildup

 No guts no glory right? The original plan called for a tripled 1/4" plywood buildup for the roof.  Problem for us is that we want some insulation in that roof and we have some swanky little recessed LED lights that we want to install in the roof of both cabin and pilothouse.
So to accomplish this we need to build it up like a sandwich with edges that can be shaped.
We ripped 2" strips out of 1/2" marine ply and simple epoxied and screwed them along the edges with plenty of overhang so that they could later be "flushed" with the cabin sides.

First layer glued and stapled down with 5/8" narrow crown staples.
Note the epoxy poured out ready for the second layer.  Stagger the seams.

The next decision was what kind of insulation? I knew that one source of information may be the surfboard community and I spent a little time on a few forums where builders expounded on the virtues and pitfalls of the two main types of ridged board insulation, Polyisocyanate and Polystyrene.  Polyiso for starters can be though of as what is commonly used in spray foam for home walls or the canned foam used to fill cracks and voids around doors and windows.  This isn't entirely accurate but they are all pretty similar.  Polystyrene, and specifically extruded polystyrene, is the product used in building construction usually referred to as "pink" or "blue" board.  I opted for polystyrene as I am gluing all of this together with epoxy and it is locally available.  Polyiso carves better but is harder to find un-faced (typically comes with foil face locally) and I am not carving this.  It will live between two plywood skins and only serves as an insulating core.
The Owens Corning product came with a plastic skin that had to be peeled off before gluing.
Two layers of sheet insulation went down easy.  I used a narrow crown stapler to secure each layer starting with 5/8" for layer one and 1" for layer two that I bounced hard off of the foam so that it recessed enough to grab the ply below.

2-1/8" recessed light holes bored from the inside

Now, all was allowed to setup good and hard.  The lights needed a 2-1/8" hole to mount and we crawled into the berth and measured from the walls to layout a pattern of lights that would avoid the future hatch and Dorade vents.  Once bored with a hole saw it was back to the outer foam surface to route channels to fish wire, daisy chain fashion, from light to light.

Port side

 The grooves were just simple routed with a 1/2" straight bit about 1/2" deep.  Nothing special in guiding it or jigs.  It routes without any resistance except for the occasional staple that get struck and mangled.  Startling but uneventful.  We just picked them out.  We used 3/8" pex pipe for the conduit.  Channels alone would get filled with epoxy as the outer skin was laminated.



Starboard. Note the Pex sticking up around the pilothouse.
Had to be heated and bent to the groove.  The opposite end
is drilled through the pilothouse behind the future location of the
instrument panel (and DC supply panel) at the helm.

Scribed to the windshield and clamped to be marked along the cabin sides.

Now comes the outer skin and it was a learning experience. First it is a curved surface laying against an angled windshield panel.  I have seen other builds that basically started the windshield panel above the cabin roof but I thought it left hard angles that looked strange. Definitely gave the impression to the viewer that intersecting curves were scary to the builder. The answer is simple, use a compass.  Mine is one of those Lee Valley multi jointed affairs but just about any kind will do.  Run your plywood hard against the windshield, set your compass to the widest gap and run it from one side to the other. Cut this and take it back.  Clamp back down and mark along the outside edges.  Now piece number one is ready, number two is easy. But it to the first and mark.

Every ratchet strap I own... Need more for the pilothouse...

The assembly was the sort of frantic, "Oh hell!" part of the build that my wife walked in on. I ran spastically around the boat, cutting clamping cauls to spread the pressure and constantly readjusting.  I thought that I would simply pull it down and screw the edges, nope... It left the center of the 1/4" marine ply panel with little to no contact with the adhesive.  So, I energetically sprinted around the boat as clamps slipped their hold and visions of solidifying epoxy raised blood pressure.  The wife walked in with a question and I immediately responded with a God d*** that let her know I was struggling.  She immediately grabbed the strap ends and held them as I built pressure on the panel and adjusted pressure.  Advise to all, if you do this sort of thing, line up some help.  Everything is slick and at some sort of angle that ratchet strap hooks don't like.

The end result seems solid.  It allows for the lights to be installed that seem unobtrusive and should add a real custom touch.  I intend to install a dimmer for both the pilothouse and cabin so that light can be adjusted to provide just enough for getting around without making us night blind.  The pilothouse roof will be an even larger challenge due to size and height.  We went ahead and installed the first layer to get it along as far as possible before moving this outside to be finished.  Not permanently, so we will devise a method of rolling or skidding it in and out.

The only noteworthy mention regarding the first layer of beadboard on the PH roof is the mahogany beam cut and installed.  Not structurally necessary, it nonetheless serves as a way to hold the proper shape for future layers to come.
Of course, some of this build is out of sequence as I post it and I am trying to lump similar portions together.  In reality we have moved around and prior to attaching the roof panel we had to install the bathroom walls as the roof panel joins to the wall.

 

Ship's Head and Shower

Hot glue and cardboard pattern

One layer installed.

You'll remember our plumbing the shower sump a few posts back.  Now we frame that in and make ready for the foam fill that will follow in a subsequent post.  We start with a paper pattern of the two additional layers of ply laid on the floor.  This is to gives us enough thickness to install a proper drain grating 1-1/2" thick.  Once the pattern is cut we epoxy and screw these down and begin layout of the long wall.

Doubled Beadboard glued and cut.

The long wall incorporates a door and will have a "show" face on both sides so will need to be laminated from two
beadboard panels.  The door is cut and this wall panel was taken to the pilothouse to be scribed to match the subtle differences in angles inherent in boat construction.  We shoot for a tight fit.

Toilet will fit into recess.

The remainders of the walls were a "try and fit" situation (better known as boat building) as subtle differences in floor to wall angles caused us to adjust and scribe.  They weren't enough to worry about and aren't noticeable until you mate two right angles together.
I did opt to create a shelf in the bath that is basically the largest dimension I could hold on the width below the hull's sheer line. 
The entire room will be coated in multiple layers of resin before painting with marine poly tinted white.  All corners and joints will be filleted and smoothed to completely seal.  Now that this is done, its time to foam the hull or as I think of it... 30 gallons of life insurance.

View looking into the bath and shower.