Curved Panels for Pod and Cockpit

I have been bad about posting.  I started working on curved foam panels back before the holidays.

The pod and cockpit are assembled out of curved foam sandwich panels.  Most all parts that are above and outbound of the deck are divinycell cores with two layers of carbon on each side.  The external side gets an additional e-glass layer for durability.

Paul designed these appendages so that all of the sides use the same curve.  This greatly simplifies the building.  All seven or eight panels can be layed up on the same mold.

The mold was build out of three CNCed pieces of MDF that define the curve.  These were joined to a base plate and some lightweight supports were added.

The tool face is two sheets of 1/4 inch melamine glued down to the structure.  I added screws along the edges to strengthen things a bit.  There is a seam between two sheets of melamine that needed to be fairly smooth and airtight.  After pondering how to seal this, I settled on about five layers of overlapping packing tape.   The whole surface is waxed and has some mold release as the outer coat.

Panels are vacuum bagged to the surface.  The layup is either a two or three step process.  The best inside finish is obtained when the inner skin is cured separately from the core.  The core can be laid over the the inner skin in one step, but thickened epoxy used to fill the foam surface can be forced through the carbon clouding the finish.

In either case, excess cloth needs to be trimmed from the inner surface using the core as a guide for a router before adding the outer surface.

Here, the inner skin is laid over some peel ply.

The core is being bagged to the inner skin.  This panel is the leeward side of the pod.

I'll show more pictures in future posts.

Mainsheet Beam Carbon Layups

Each side of the mainsheet beam gets about 12 layers of carbon.  These include uni, bi-directional and plain weave cloth.  It seems quite easy to wrinkle the cloth as it goes around the compound curves in the vacuum bag. As I learn, I tend to get less of this.  It is definitely not good since to get a smooth layer a wrinkle must be sanded a little bit, causing a small area of reduced strength.

A pattern for cutting cloth.

A typical layup applied to the beam before going into the vacuum bag.

I had to cleanup the nubbins with a router after a few layers that did not lay well into the groove.

Above, I am putting a few layers of scrap carbon back into the groove.  The dowel matches the size of the router and is used a clamp to compress the carbon.  I lashed the ends of the dowel around the beam to pull it tightly into the groove.

The dowel was removed after cure. I used packing tape to keep most of the new material off the surrounding beam. 

The  excess cloth has been trimmed and sanded.  This beam needs three more layers all the way around.

Each layup has quite a few steps including cutting the cloth, peel ply and breather, setting up a vacuum bag, wetting out and applying the cloth, peel ply and breather and getting it into the bag.

I have been wetting out the cloth on a piece of plastic.  I spread the epoxy over a layer and squeegee it back and forth.  Another layer of cloth goes on top and more epoxy.  At about three layers maximum, I  stop.  The plastic gets folded over the cloth.  I then squeegee the whole stack very firmly on both sides of the plastic envelope.  This forces air out and epoxy in.   The stack is then peeled off the plastic and laid on the beam where it is smoothed down tightly before the peel ply is smoothed over the top.  I tend to error on the side of too much epoxy.  The bag squeezes out the excess and you really want the carbon well wet out.

I am getting to the last layer which will be a bidirectional woven sleeve.  The sleeve should conform well and leave no seams.

Task time: 20 hours

Total project time: 331 hours

The Slows

I have been busy with some other projects and have only spent about 20 hours on the boat the last couple of weeks.  Tasks include more layers of uni carbon protrulsion and fairing corners of the pultrusion layers into the beam corners. The stacks of pultrusion create gaps that have to be faired before layers of bi-directional cloth can be laid over the top and bottom of the aka beams. You get glue squeeze out under the clamps and it makes for inconsistent edges.  I'm doing some test layups to see if I can find a more uniform way of doing these.  Pictures later...

I have calculated there are about 20 more carbon layups for the beams.  About 16 of these require hand clamping every six inches.

There is more information on the Cheers posters at PT Watercraft.

Task time: 20 hours

Total project time: 232 hours

Like Coffee...

Strong and Black.  Did some shopping for carbon fiber yesterday.  The cloth came from Fiberglass Supply. The pultrusion came from Goodwinds LLC.  These are both local Washington companies that supply projects world wide.  The cloth will support high load areas such as the akas, mast step, mainsheet beams, etc.  The pultrusion will replace unidirectional carbon in many places such as the akas, rudders and dagger foil.

400 gsm (12 osy) bi-directional knit.

200 gsm (6 osy) woven coth.

Pultruded flat rod.

The picture of the pultrusion shows 2000 feet in four 500 foot rolls. I have not weighed it, but is probably is about 45 pounds. Paul tells me that this is 1.5 times stronger than the same thickness of wet laminated unidirectional.  Quality is higher and more consistent.