Sunday, June 19, 2011

Post curing the mast

The weather forecast predict good weather the next 24 hours, the last of that for a while.  So I had to exploit the situation.  The mast is hanging under the rams.  I put a ladder and other long things I found on top to provide for a longitudinal support, then a layer of building foam on top all the way.  After this I covered it all down to the floor with several layers of tarpaulin.  A 3.3 kW blower is located each end.  I'm not sure this will generate enough heat, but I will see what the meters read tomorrow.  I managed 25 deg C above ambient temperature quite fast.

Saturday, June 18, 2011

More mast

I had the day off, that's always good for building progress.  Removed the bag this morning, and the bleeder was evenly saturated as a sign of adequate wet out, and also that the epoxy hadn't cured before I got the bag on.  It takes a lot of time singlehanded to apply 7 11m long pieces of carbon, all the consumables and getting the bag tight, so it was a bit exciting to see how well it had worked.

After making the necessary measures I started to cut the top of the mast clean.  I cut the top at 6 deg relative to the axix of the mast in order to compensate for the log and get a horizontal top.  I used a regular carpenter's saw ant that worked well.

A closer look at the mast section.  Note this is the top and the UD fibre area is half the thickness of below the hounds.

I started fitting the top U-shaped insert that carries the main halyard sheeve and the termination of the 2:1 halyard.

Then I sat nup the mast with the trailing edge up to make the slot for the sail bolt rope.  This is the jig for cutting slot with circular saw. I finally got my 12mm drill back as well, as it has been sitting in the bolt rope tube at the join since building the mast.  I put it in to align the two pieces but couldn't get it out afterwards.

From the other side of the cutting jig.

After cutting I had to sand the track well.  I used a 10mm round steel inside the tube, with sanding paper going in one side and out the other, turning around the steel.  Then, when  pulling the paper back and forth the slot is being rounded well on the inside, in the transition between tube and slot.  I think this is important in order to get the sail run smoothly in the track.
I also glued in reinforcements on the inside of the track at the top before glueing in the U-shape. I would not like to pull the boltrope out of it's track.

Then I made the top cap on a piece of foam as mold.  This will serve as attachment for the wind transmitter.  I will have to make it removable some how.

I did some fine cutting at the lower end, dug out the foam and filled with fibre reinforced and thickened epoxy.

At last, a kind of an overview shot, showing the mast from hounds down, leading edge up.

Friday, June 17, 2011


First, it would not be wrong to state that I was a bit disappointed that, after two days at the glazier, after I had been in contact with them several times in advance to make sure everything was planned for and OK, the boat was still untouched. As there are more to be done than the windows, I had to take her back to my garden and I am currently mounting stuff between other tasks.

The weather turned summerish again today, and I did the other side of the mast. The recesses each side of the section is supposed to be filled with UD carbon in order to provide sideways stiffness. Calculations showed that 210 mm^2 of T700 fibres would give slightly less bending when loaded to balance the righting moment of the boat than the specified carbon section with spreaders and diamonds. The section itself was not part of the calculations.

The bottom of the recess was previously covered with a hand lay up of 200 gsm Formax 45/45 fibres. I sanded this down, and a section outside the recess. Then, after preparing all the 11m pieces of fabric and consumables needed (carbon was cut on the firewood saw when still on the roll, NB don't do this at home and make sure to cover EVERY piece of skin when doing it, don't ask me how I know), I did a wet lay up of 6 layers 430gsm Devold T700 UD fibres. Three layers were staggered and tapered above the hounds, hoping for a bit of flex here.

This is 6 layers of 70mm wide UD and then a piece of 150mm wide 45/45 overlapping the section wall.  Covered with peel ply, about to do the final wet out.  Next was release film, bleeder fabric and the vacuum bag, before the big find-the-leaks-game started.  Seems to have lost a picture here, I recall an error message on the phone.  After a couple of rounds around the bag I was able to pull about 0.85 atm, a bit less than the other side, but sufficient to avoid any air or lift off in the laminate.

Then the mast was covered and heat (around 6kW) put on to let it cure over night.  Summerish here means somewhere between 10 and 20 deg Celcius, close to 10 during night.

Earlier today I recieved this picture from Eivind, he had noticed a familiar shape in the hall at NTNU where my daggerboard molds are currently being milled.  Time to start building soon, as it looks.

Tuesday, June 14, 2011


I picked up the main hull today after work. It looks really good IMO. The painters were very satisfied as well. Rest of the parts will be done tomorrow. As my camera is still missing and my phone serves as camera, the pictures are of the usual reduced quality.

The two last pictures is taken in front of our local glazier business who's going to put in the windows tomorrow.

I'm waiting for the aluminium to come back from anodizing.  One side of the unidirectional reinforcement on the mast is now done with good result.

Monday, June 13, 2011

June this far

Most of June this far has been more fairing.  One thing I did much too late was buying a cheap paint gun.  This was a very much better way to get the high build primer on in even and thick layers.  I have sprayed several layers of different makes, and also modified some primer with a small percentage of microballoon, in the area of 2% by weight, with much better build as a result.  This way I was able to get most of the uneven transitions between different fairing compound mixes faired.

I made a set of new supports for the boat.  Wheels underneath.  Makes handling the boat very easy.

I finally reached the point where I decided to stop fairing (you will never finish, as someone wisely stated in the F-boat forum some time) and I had a lot of friend over helping me to carry/roll the boat out of the workshop and on to the trailer.  Guesstimated weight when lifted by two persons 160 kg.

With the boat safely on the trailer it was time for refreshments according to local tradition and recipe, served from the swim step

I have also been working on the mast, preparing for the final structural laminations.  A layer of 200 gsm 45/45 was added in the groove to bond the halves and make sure it was air tight for vacuum bagging the UD that will fit on top of this layer.  Obviously, I did not take a picture after the lamination.

Also, I was foreseeing enough to make an extra piece of mast so I could practice making the sail groove and the feeding opening.

The boat is currently at the paint shop and will be picked up tomorrow.  I was able to sneak in and take this picture late Friday evening: