More of the Same

There has been slow steady progress.  Most of the work has been on the akas and mainsheet beams and I have posted about those before.

This is the 16th and final pultrusion glue up on the beams.  Nice to have that done.



Here is a quick vid of the outer sleeve going on the second mainsheet beam.

The wet-out went on for a while to force epoxy through the sleeve.

Task time: 40 hours

Total project time: 402 hours 

Mainsheet Beam Ready for Bonding

After fill coats and sanding I have a mainsheet beam ready for topcoats.  First, it must be bonded into the hull.

Task time: 12 hours

Total project time: 358 hours

Last Carbon on Mainsheet Beam

After a bit of fairing to level any previous layup seams, I have applied the final layer of carbon.

This is a 300gm/sqm bidirectional sleeve. The sleeve went on before wet out.  It looked pretty hard to wet it out and then slide the slimy, slick tube over the beam.  I rolled and squeegeed multiple coats on the beam, as I was a bit worried about full saturation of cloth this heavy. 

There was some creative clamping going on.  I skipped vacuum bagging to avoid wrinkling.  The sleeve can be stretched pretty tight by hand.

Finishing will require fill coats of epoxy and sanding smooth.  The worst of the process will be sanding the gathered ends to blend them into the end shapes.  

Task time: 12 hours

Total project time: 346 hours

Mainsheet Beam in Vacuum Bag

This is just an extra shot I had of one of the many vacuum baggings of the beams. The envelope is made of plastic packing tubing.  Only the ends need to be sealed on the tube, simplifying matters and reducing the potential for leaks.  I have been sealing the ends of the tubes with these plastic snap-together flanges from ACP Composites.  They are cheaper and more consistent than bagging tape.

The packing tubing can be found at ULINE and other places.

Thanks to Dan Newland at Pegasus Aeromarine for turning me on to packing tubing.

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

Mainsheet Beam Cores Finished

 I spent several hours working to shape the laminated fir blanks.  The first order of business was to create an MDF template of the shape off of the drawings.   This required lofting a few points onto the MDF.  I then pulled a batten in line with the points against small nails. Next I hot glued the batten with support blocks to the MDF.  I could remove the nails and trim away excess material from the MDF sheet.  I then took the batten and MDF to the router table where I used a flush trim bit to cut fair curves.  This seemed more accurate than trying to sand fair curves to a line, especially on the concave side.

The batten flexed across nails.

Once the template was finished, I attached it to a laminated blank.  Using a saw and a belt sander (I still don't have a jigsaw), I removed excess material.  I then trimmed the blank to match the template using a 2 inch flush trim bit.  Almost all the excess has to be gone before using the large flush trim bit given the large load on the router when trimming over an inch and a half height (40mm) at once.

The finished template attached to the blank.

The blank cut and sanded close to the template.

With the blanks the correct shape, I moved on to rounding over the edges.  This is for aesthetics as well as getting carbon fiber to bond over the edges.  I also cut "nubbin" slots at each end.  These will keep the lashings that hold the blocks to the beams from slipping.

Finished cores after trimming, rounding over the edges and adding nubbins.

These are now ready for the first layers of carbon uni.

Task time: 6 hours

Total project time: 294 hours

Mainsheet Beam Progress

Both of the mainsheet beam laminations are done.

Here are the beams after coming off the mold.

Here they are after sanding and planing them flat to a 40mm thickness.

Next step is modifying the upper (concave) curve and shaping them.

Task time: 3 hours

Total project time: 288 hours

First Mainsheet Beam Layup

I ripped some Doug Fir for the mainsheet beams.

I went with wider 7mm boards to try and reduce spring back after unclamping.  The thicker laminates put up a fight when tightening them down.

The layup is molded to the lower more gentle curve.  The top asymmetric curves will need to be cut with a bandsaw later.

The beams run athwart the main hull as shown in the picture.  There will be a block lashed to each end.

Task time: 7 hours

Total project time: 260 hours

Slow Progress

Life got in the way and between a trip to get materials and other responsibilities not much got done for four days.

I did do some prep for the next steps on the akas.  Surface sanding and rounding over the edges.  I have also been pondering the best methods to apply layers of strips of pultrusion and 400 gsm carbon double bias.  These have to be clamped and/or vacuum bagged over the eighteen foot span.

A layer of five strips of pultrusion will look something like this only longer.

Current state of the beams.

Also got a stack of douglas fir ripped for the mainsheet beam laminations.  These were a bit wet and will need to dry with the heaters and a fan for a while.  Think I need a moisture gauge.

Task time: 8 hours

Total project time: 194 hours