Finished Panel

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Now that we have a finished panel, we have to get it off the table and store it somewhere for use later. Steve has prepared an area to stand the panels up to store them out of the way.

This framework will support the panel and keep it upright. View from the front of the first panel in the frame. Doesn't look very big, does it?

How about this view?

So there you have it. From starting with a waxed table to a completed panel ready to join up with it's mate to give us a hull. Not bad for a few hours work. Here are the times for the first and second panel as provided by the builders, Steve and Larisa.

Go to http://www.ksstennesseeworkshop2010.com/photos to see the photos of the workshop. Click on user galleries to see all the albums.

Well, we did it. We built half a 42 foot catamaran hull in 15 hours. It took another 8 hours the next day to shape the bottom of the hull so all up 25 hours. Of course Steve and Larisa had done a lot of prep work so that when we arrived, it was full steam ahead on the building of the hull. Nevertheless, if the other half took another 25 hours and maybe another 10 hours to join the two halves together, 60 hours to build one hull is unbelievable.

OK, back to reality. The 15 hours to build the half hull is really 15 X 7 people = 105 hours if you are doing this yourself and the 8 hours of shaping is 8 X 7 people = 56 hours. Still, 161 hours of effort to produce one half of a 42 foot hull is amazing. So, let's see 161 hours for one half, plus 161 for the second half and say 80 hours to join the two halves together is 402 hours. 

Now a lot of the people there were not always busy and there was a lot of gabbing going on, about how this works and how that works so I would estimate one person working along could build one hull in 200 hours.

Of course the hulls are not the whole boat and there is a lot of structure to be built after the hulls are complete but in my boat, the hulls are the major component of the boat as there is no center accommodations to consider. This could save me a couple of years of build time.

My calculations were way out to lunch. Steve and Larisa have completed a second half hull and here are the times in Steve's own words.

Let's see. Two people 

   Two easy days to cut and prepare

      Cut and prepare foam

      Rough cut glass

       Prepare tubing

       Gel coat the night before infusion

       14 hrs

   One day to infuse

       7 hrs

   Remove bag, peel ply, etc

       2 hrs

   One day to groove and put on frames -3 hrs

   One day to bend and glass -5 hrs

   Remove from forms and take outside about 3 hrs

    Extra help 5 hrs ;-)))

    Computer planning 2 hrs - used the Turbo-cad program to calculate the fiberglass cuts and resin line lengths.

14+7+2+3+3+5+5+2= 41 = 40-50 hrs

When working we do not waste much time. 

The bending is real fast and easy. 

Larisa and I raised the panel onto the forms by ourselves. A couple 2x4s and concrete blocks helped.

Larisa and I removed all but the last 4 forms but had help for 30 minutes to lower to table and haul to back yard. 6 people can easily carry a half hull. With a good two wheeled wheel barrel I think two people could move it, definitely 4.

2nd panel easier than first.

So.....we are looking at 40 - 50 hours for two dedicated people to build half a hull or 100 hours for two people or 200 hours for one person to build two half hulls. Of course even two people need a bit of extra help once in a while and the two have to be joined together. But really........the small amount of time spent to this stage is ridiculous to anyone who has built a hull the conventional way.

And this is our happy builders.

Glassing the inside of the panel

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Once we are satisfied with the shape of the panel, we need to make sure that shape stays in when we release the panel from the forming templates. To insure this, we have to glass the inside of the panel at the curve of the bottom of the hull. 

The first thing to do is fill all the cuts we made previously. While the forming straps remain in place, we fill with a mixture of micro balloons and resin to provide a smooth surface for the inside layers of glass.

Run your hands over the whole surface to make sure there are no large bumps of fill that would give the glass a problem and make it stand proud of the surface. It is a lot easier to sand the fill material at this point then it will be once the glass and resin is applied.

We apply two layers of 10 oz. glass cloth with resin. Stagger the layers so there are no abrupt changes in height. Make sure you get the cloth close to the inside layers of glass that cover the inside of the panel. Do not go all the way to the edge of the panel as there will be more glass added here when you put the two panel halves together. You will have to work the cloth with serrated rollers to get all the air out and to insure good bonding.

The glass is applied as close to the forming templates as possible without glassing them into the panel. The straps remain on while the glass and resin cures.

The panel is now formed, glassed and cured, ready to be taken out of the forming frames and templates.

Shaping the panel

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The next big step is to pull the shape into the panel. It is hard to believe we are starting with a flat panel and will end up with a "half hull" shape in just a few steps. We have our flat panel on the table, deck edge radius molded in, glass and gel coat on the outside of the panel and glass and foam on the inside of the panel. Ready for the next step.

Here are the forms we will be using. They are made out of 3/4 inch material, lumber or cut pieces of chip board cut to 4 inch wide strips, some eye bolts and wing nuts and our patterns. The pattern shape is provided by Derek and you just have to cut them out. There is a diagonal support in the framing that will be used to hold the panel at the right angle.

You will probably need some help here. We have to raise the panel up and install it in the frames. The panel is not heavy but it is wiggly and you do not want to bend it or break the deck edge radius or the dart cuts.

All the frames are numbered to correspond to the positions marked on the panel. Once you get a couple of frames up to hold the panel, you can take some time to align everything.

It helps to have feet on the frames so they stand up by themselves.

This is the time to do all the little adjustments. 

We now have all the frames in place and all the adjustments for shape are complete.

Here is a view of the frames from the bow. You may notice that the diagonal support is not at the same height in all frames. It is lowest in the middle of the panel and highest at the bow of the panel. This gives us the fore and aft shape of the hull.

Derek is now attaching the straps to the frames. Notice the strap starts at the bottom of the frame at the shear line of the hull and goes around the panel and back to the top of the frame. We want the pulling force to be applied to the top of the panel as it sits in the frames. The ratchet is at the top of the frame where it will be easy to operate and provide this top bending force. Notice the full length batten is in use again. The batten in this position distributes the bending force on all sections  of the lower hull and contributes to a fair curve.

The straps hook through the eye bolts in the upper and lower corner of the frame.

As you can imagine, there is a considerable amount of force applied to accomplish the forming of the panel. The deck edge radius is next to the frame edge and all this force is applied to it. It is not strong enough to withstand this pressure so to help it survive the strain, we screw it to the frame work close to the foam. Two screws applied here on each frame will prevent the deck edge radius from being broken or deformed.

All the straps are in place, all the adjustments made, so let's get on with it.

Start at station 0. Take up the slack in the straps and then take a couple of clicks. Go to station 1 and do the same. Do this all the way to the stern. Go back to the front and take a couple more clicks in the strap. Work you way down to the stern, taking the same number of clicks at each station. By doing this in a regulated manner, no sudden pressures are applied on any part of the panel and you develop a fair curve as the hull bends into position.

You will notice that you are bending the hull to come up snug to the pattern that is attached to the frame. The bottom end of the pattern starts the bend in the panel and you pull the panel all the way to the top of the pattern.

You can see the outside of the panel taking shape. Notice the gel coat, nice and smooth. No long drawn out fairing needed here. How many hours will this save you?

But wait! Something is not right. Things are creaking and making noise. It sounds like two things are trying to fit in the same space. Derek says to look at the darts. As the panel takes shape, the full length batten allows the pieces between the dart cuts to move as they slide into shape. As two of them come together, there is not enough room for them to move so we must open up the darts a bit more. You do not want to open them too much as this is an area that will have to be filled later. A little jig saw work is all that is required.

The panel is now pulled into position. You can see that the pattern has shaped the bend into a fair curve all along the hull bottom. The hull is touching the pattern at the top and bottom and alone the sides nice and snug.

But what is this? the foam is not even on the inside. There are dart cuts between the frames and patterns and the pressure is not applied exactly even all along the panel. To eliminate this unevenness, we will have to shim up the outside of the panel. This is easily done with bits of wood placed between the straps on the outside of the curve until all the foam is even on the inside.

Well, that just about does it. We have one more step to do and that is glass the inside of the hull.

Prepare for forming the panel

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We have to clean up the panel in preperation of forming the bottom of the panel. There are lots of little bits of resin left on the panel from the bag removal.

It was decided to remove the small bit of resin that had been deposited on the lower section of the panel. This is the area that will be formed to make the bottom of the hull. A random orbital sander makes short work of this and does not damage the foam.

This closeup shows how the resin penetrates between two sheets of foam. You can see the resin goes right to the bottom of the foam and meets up with the resin that fills the glass on the outside of the panel.

The panel is now clean and all the excess resin on the lower part of the panel has been removed.

We have to cut the foam to allow the required shape to take place. A series of cuts are done from stem to stern with a skill saw. We are removing a kerf the thickness of the saw blade. Derek would like to see a "V" shaped kerf as it makes it easier to fill later and allows more space for the panel to bend. If you know you are going to do this, you might be able to purchase a "V" shaped blade or possibly make one. As we did not have one or have the time to make one, a standard blade was used.


The cut lines were drawn between the upper and lower tangent lines previously marked on the panel. They are approximately 1 inch apart and run the complete length of the panel. They penetrate about half way through the foam.

We are again using the full length batten to cut the kerfs. Lots of weights and help needed here.

We had an interesting thing happen right at the start of this operation. You will notice the wavy line in the first kerf made, on the right side of the picture. Steve had a normal wood cutting blade in the saw and when he started to cut the kerf, the blade heated up and distorted and caused the saw to wonder all over the place. This would not do so what was wrong? Interestingly, I had the same experience cutting scarfs in a long piece of plywood. One of the guys suggested getting a carbide blade with sufficient cooling holes in the blade to prevent this happening again. A good quality saw blade was purchased, with the cooling holes spaced around the blade and it cut nice straight lines.

The kerfs are cut about half way through the foam. This is the stern view.

Here they run off the panel at the stem.

Now we come to the second set of cuts to be made. These cuts are called "darts" and are cut right through the panel, including the glass on the outside of the panel. When you pull the form into the panel, there is rocker formed in the bottom. This means the panel shape must rise to the bow and well as the stern. Cutting the darts removes enough material for the rocker to be placed in the panel.  The darts are marked on the panel from the template information. Careful not to cut the table underneath the panel!

We were going to cut the darts with the skill saw but the kerf was way too large. The rest of this dart and the others were cut with the jig saw.

OK, the panel has all the cuts necessary to pull the shape into it. It looks like it is already trying to take the shape we want as the edge is lifting off the table.

Even with the straight sided kerfs in the foam, the panel bends with a nice fair curve.

Start the Resin

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The resin is starting to flow over the panel. We have only one hose open at this time. You can see the resin flowing out from both sides of the number one hose. We opened this hose first as the resin has the longest distance to travel from this hose to the deck edge radius. 

Steve mixed small batches of resin and brought them to the reservoir as the previous batch was used up. If you mix large batches of resin, they have a tendency to kick faster if there is a large volume in the reservoir. We want as much time as we can get with a panel this size. 

Do not allow the reservoir to be empty as this will allow air into your system and will effect the resin flow. We are infusing this panel in the evening and the temperature was cool so we thought we would have ample working time before the resin gelled. You can see by the watch in the corner, we are into the infusion just over 9 minutes.

You can see the resin working its way along the scoring on top of the foam. 

There were a few times during this process that we had to help the resin flow. We found that if you pulled up on the bag a bit, it would create a channel and that would help the resin flow to areas that we felt were not getting enough resin, fast enough.

Here is the panel, over 30 minutes into the infusion process. Looking good. With close inspection, there does not seem to be any area of the panel that is not covered with resin. 

If you look carefully, you can see the resin has already passed the deck edge radius and on its way to the vacuum lines that circle the panel.

View from the stern of the panel.

We are at 30 minutes, 58 seconds and it looks like the whole panel is finished. You can see the resin has gone past the edge of the foam and is making its way to the vacuum lines. We did not have any resin get into the lines and they could be used again. Any hose or material that the resin comes into contact with will be unusable as the resin cures and can not be removed. 

We left the panel over night. We wrapped it in tarps and blankets. The next morning we removed the bag and all the hoses, etc. This is one reason for the peel ply. It allows easy removal of the bag, shade cloth and hoses. 

A Look At Some of the Equipment

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First item we see here is the vacuum pump set up. We have the pump with a vacuum gauge on top, connected to a paint pot used as a resin catcher to protect the pump. You have to make sure the resin never reaches the pump. If it does, you will have to buy a new pump. Any resin that gets though the panel and comes towards the pump, will be caught in the paint pot. The preventative measures placed on the panel worked very well and we never had any resin even get into the vacuum hose running from the table to the paint pot. The whole affair is mounted on a little trolley on wheels so it can be moved around with ease. The black plastic hose is the hose coming from the table.

Next we have the resin reservoir. You can see the resin input lines that go right to the bottom of the bucket. Make sure you do not allow air into these lines once you start your infusion process. The hoses are attached to the sides of the bucket with wire to make sure they do not move off the bottom once the process starts. You will want to cut the hoses at an angle to allow resin to enter the hoses from the bottom of the bucket. We are using "Vice Grips" as valves for the the resin. This will allow us to open or close any hose as the infusion goes on.

We now have the full vacuum applied and the bag is down tight. We do have leaks and are trying to find them now. If the leaks are too severe, you will jeopardize the infusion and you might end up with a dry spot on the panel. We see our resin reservoir and feed lines going to our three distribution hoses.

We are ready to roll. Larisa is holding the reservoir up off the floor. You need the reservoir to be as close to the level of the table as possible to assist in the drawing out of the resin. You can see two areas where we were trying to solve leak problems. The areas are enclosed with the yellow sticky tape. We figured the leaks could have been caused by a problem joint in the table and that would let air into the bag from the bottom. Even with the leaks, we managed to pull 17 on the gauge. Steve had managed 25 previously on some other items they made on this table but Derek felt we could go with 17. So, off we went.