September 2013

Vacuum infusion inside hull

August-September 2013:

Paul has a vivid memory of the build of his previous boat. The lamination of the hulls with the hand-lay-up method was a sticky mess. So far we are very satisfied with the choice of vacuum infusion method for the build of this boat.

After 10 or more vacuum projects on flat panels we really got the hang of it. However applying the vacuum infusion project on a 65m² surface that is 2 meters high is a sensation on a whole different level.

After deliberations with several specialist we have made the following plan of approach for the vacuum infusion on the inside of the hulls. These are the factors that we decided upon:

  • All fiberglass mats are being laminated in one turn. (above the waterline 900 grams per m², below the waterline 600+400 gram per m²)+ on the positions where the ribs (doorways) are located extra reinforcement by way of an extra 600 gram per m² fiberglass mat.
  • Double major supplylines on the keel with 2 extra inlet points.
  • From the keel every meter an Enka supply strip in vertical direction to enable the flow of epoxy in all directions to cover a distance of 50cm. The Enka strip does not leave any marks on the laminate.
  • A vacuum hose around the topedge with 2 extra adjustable extraction points.

In closing everyone unanimously agreed: The smart thing to do is to test the vacuum first. A suggestion we agreed upon wholeheartedly.

With 2 MDF plates placed in an upright position leaning against the wall we could mimic all the aspects and we saw that the chosen set up actually works.

Testing vacuum infusion in vertical way

The only uncertainty that remained was: did we succeed the packaging of the hull in the airtight vacuum bag? Did we close every seam with micro balloons?

Prevention is always better than healing so before we start first a test; the most critical point in our project is the part where the chamfer passes in to the bow. Our concerns where justified as this part had allot of leaks. With our ultrason leak detector we came to the conclusion that the attachment between the hull and the chamfer needed reinforcement.

This area is the hardest to get airtight. So first a test before apply all the glass fibers  You hear the smallest leaks with the air detector

We need to add multiple layers of fiberglass mats and infusion materials. In order to reduce the risk of the materials gliding out of place, we build a walking plank in the middle of the hull.

To avoid moving the glass fiber we make a gangway  The building frame is a good support for the gangway

The hull is made 15cm larger then needed because then we can fix the fiberglass and the infusion material on the top part of the hull. After the hull is also wrapped on the outside of the hull we can simply cut all the extra parts off. The edge is smoothend and airtight with microballoons and epoxy coating.

Now the wrapping can commence. First we lay the fiberglass mats at the reinforcements at the trusses, after that the mats below the waterline and we staple these with plastic staples in the topedge.

The fiberglass mats underneath the waterline have a 5cm overlap and we glue it with special squirtglue. The weight that ‘pulls’ the mats and it is really quite a hassle to form it properly.

On the keel an additional overlap of 5 cm. This way the fiberglass mats have some freedom of movement and space to expand for when the vacuum is initiated.

Note the 3 vertical fiber glass mats for reinforce the area of the bulkheads  Fixate the lower layer with special glue and plastic stamps

You need all your hands and feet to apply the fiber glass  Taylor made on the keel with an overlay of minimum 5 cm  And tailor made at the transition to the chamfer

The small part in the bow is adjusted in size in advance. The mats of the long sides also have a 5cm overlap to ensure that no loss in strength occurs.

The shape of the bow  The bow fits well also with overlay

While Paul placed the fiberglass mats, Jolanda prepped the vacuum infusion lines. For the main supplylines we used 2 thicker (14/17mm) spiral hoses. For the vacuum lines on the topedge we used a narrower 9/12mm hose.

By stretching the hoses first a couple of times the epoxy will flow more easily. Also now we wrap the supply lines in peelply. This ensure that the epoxy will flow easier and more evenly. In the supply line will have some residue epoxy that will now be trapped between the lines and the peelply instead of on the hull. This makes removing the supply lines and peelply much easier when the epoxy is hardend.

16 meters epoxy inlet hose ready to prepare  2,5 meter Peelply hoses are easier to handle. We connect them with a few stitches  The epoxy inlet hose is ready to install

First we stick the tacky tape to the edge. The vacuumbag will be attached to the tacky tape in the end. The tacky tapis a good reference for the rest of the vacuum materials. The wrapped vacuum hose is stapled as high on the edge as possible. On several points we connect a closed supply drain that we can manage with taps.

Tacky tape on the border. Later we connect the vacuum bag on it.  Vacuum afzuigslang vast nieten  On 3 places we make a connection to the vacuum pump

Similar to the flat panel infusion projects we use the all-in-one Compoflex fibers serving three main purposes. First, as a flow mat which equally distributes the epoxy. Second, a release film ensuring the vacuum bag does not stick. Finally, as peelply ensuring the Compoflex is much more easy to detach without damaging the laminated fibreglass.

By applying the compoflex a few centimeters below the vacuum line, the epoxy runs slowly at the end ensuring a more equal distribution in the extraction line. The small edge of peelply underneath prevents the vacuum bag from sticking to the fibreglass.

Stitching the compoflex (breather, release film and peelply in one) to the vacuum hose  a few centimeters space as a resin break

We use the Enka lines to create a sort of fishbone to spread the epoxy on the large surfaces. Spiral lines might leave a print on the laminate; therefore we used the Enka lines.

We spread the Enka lines with approximately one-meter interspace and approximately 50 centimeters below the vacuum hose.

We open the Enka hoses at the back to speed up the epoxy flow  Enka hoses ca 1 meter from each other and 50 cm from the vacuum hose  The base

The wrapped inlet hose is on top of the keel across the opened Enka line. We created 3 inlet points. To prevent the inlet hose from shifting, we used wooden blocks and CoreCell to place over the inlet hose. Additionally, we attached the inlet hose to the compoflex with a small wire on different places.

The main inlet over the keel to fill the enka hoses  3 supports over the main hose for epoxy inlet  Install the inlet supports and fixate the main hose

The first inlet point is at the back of the ship. The epoxy should flow through the spiral hose towards the Enka lines and through the compoflex until everything is filled with epoxy.

The main extraction point is on top of the highest edge. As soon as the entire hull is filled with epoxy, the extraction line will fill the bucket. By placing the line upwards (more than one meter) there is eventually less epoxy in these buckets.

First inlet at the stern  Vacuum line as high as possible

Applying tacky tape at the edge of the vacuum bag eases the application of the vacuum bag. We needed to wrap up the vacuum bag to place it inside the hull without damaging it or shifting the lines.

It was quite a struggle, but after taping the first bits it became more easy to tape the rest. We should really rethink our strategy for the second hull. Every 34-45 centimeters we create creases to ensure sufficient space for the bag to shape itself once the vacuum pumps are running.

Tacky tape on the border of a vacuum bag 6 mtr / 23 mtr  It takes 10 minutes to create an overview  After that is was easy to tape the bag on the border of the mold

Time to test our set-up.

Although we set up two pumps, only one is actually doing the job and the other serves as a back up. We use two sets of tanks to absorb the remaining epoxy. Per set we start with only one tank and change to the second once the absorbed epoxy begins to react. There is enough time to empty the first and use it as back up again.

1 pump with a main trap and spare trap. The other pump with traps are spare

The moment is there… will it be airtight?


As soon as all air is suctioned from the vacuum bag, we close the pump valves to check whether the vacuum % remains the same. Unfortunately, the percentage slowly drops meaning there is at least one leak.

After a few hours checking with the leak detector we found several seams in the edge of the bag and the bag itself. One small leakage was located in the excess edge of the hull and was easy to repair.

Searching for leeks  Most change to find leeks at the border  An unexpected leek in the seam is also reparable

Eventually we fired up the vacuum pumps and had a minor decrease of the vacuum percentage, but within our margins. So, the moment is there, start the infusion!

With a couple of extra hands of our good friends we started dividing tasks. Pepijn took care of the main inlet tank. John and Joris regularly mixed new batches of epoxy. In this way Paul and Jolanda had no specific task and were able to monitor everything and assist the others when necessary.

Eventually this “exciting” moment of our project turned out to be another relaxed day. Within just two hours the entire hull was filled with epoxy.

Epoxy flows from main inlet to enka hoses and compoflex  It flows steady  Also in the bow

At the stern it flows slower now  Looking from bow to stern

Even with a lower stern the epoxy flows steady  Also at this side

Just after, we especially had to check the outlet tanks and empty them on time. We used light bulbs to keep a steady temperature of 23-25 degrees Celsius to enhance to gelling process of the epoxy. After six hours de first signs of “gelling” appeared and we turned home after eight hours.

We filled the main inlet with smaller batches totally 120 kilo resin  Some extra heat from infrared light to speed up the gelling proces

Check the movie below, you’ll see how the epoxy steadily flows into the hull.

Vacuum infusion of the inside of a 51ft (15,5 mtr) hull

This Photo album shows more pictures about the vacuum infusion project of the hull. Open the first picture to read the text and scroll through all pictures.

After two days of hardening we were extremely curious for the final result. The vacuum bag was easy to remove and by bagging the entire bag we were again shocked by the size of it.

Unpack the vacuum bag  A lot of plastic

We started with disconnecting the inlet hose on the keel, after that the Compoflex with the attached Enka hose was easy to remove. They were easy to transport once folded.

Compoflex is really easy to remove

In 1,5 hour almost finished  The smaller parts are easier to handle  Fold up ready to throw away

In the end, we are exceedingly satisfied with the result. Although feeling the result is more fulfilling, we try to show it.

The left picture shows an untreated fragment of CoreCell, while the right picture shows a laminated (600 + 400 grams) fragment. By zooming, some small flakes of epoxy are visible.

Left plain foam, right with 1000 gr fiber glass

Ready for the next step

After the portside hull we soon started with the starboard side. We only changed one method, involving the vacuum bag.

We started with placing the bag over temporary beams (protected with Compoflex waste). As soon as the bag was evenly divided over the hull, we gently pulled the beams away while the vacuum bag placed itself in a good position.

Supports on the bulkheads make it easier to apply the vacuum bag in the hull  As soon as the bag is equally on his place, we remove the supports. note: compoflex on the supports to avoid leaks

After a vacuum test, it seemed that the project was airtight at once. Well done! Again, the entire hull was laminated within two hours.

During all of our major infusion projects we create a detailed planning involving calculations for the amount of epoxy we need to prepare and the amount of epoxy that flows into the hull. There is less than a kilo epoxy discrepancy between both hulls of 65m2. We conclude that the infusion method is clean, consistent in its bonding (glass/epoxy proportion of 60%/40%), and reproducible.


On to the next stage: Creating and placing the trusses.




Bulkheads installed

September 2013:  

Now that the inside of the hull is laminated we can place the previously made bulkheads. This provides extra security on the inside when rotating the hull. On the outside of the hull fiberglass mats need to be added aswel in order to reach full strength and structural integrity.

Some bulkheads became too big to saw out of one panel. The bulkheads made out of 2 panels are first being glued together. This is done by attaching the parts together and adding a mixture of epoxy and aerosil, place this mixture under pressure until it is fully hardened.

Glue the components together  The epoxy is almost cured.

To realize the full sturdiness the glue strip will hold another strip of fiberglass mats with the exact same weight as the fiberglass mat on the truss. On a piece of plastic we will roll the strips first through the epoxy mix so that the strip is fully drenched. We leave them to dry for a bit and then apply on the seam. On top of that we will place a strip of peelpy; also drenched in epoxy. The peelply is removed after hardening, this leaves us with a nice and even surface. The piece of baking paper underneath the truss ensures that the truss does not stick to anything.

Bandjes glas  Here also 2 components glued to gether. The peelply gives a smoother result.  This bulkhead is ready to cure

Aligning the bulkheads

The first truss is always the trickiest. In the beginning you lack a referencing framework. All resources are being tapped, Battens in the direction of the truss (we already marked the centreline and the waterline) and a long batten on top of the keel beam with a perpendicular line. After 15 minutes it is exactly the way we wanted.

Several supports are handy  Leveled at the centerline

Check level at each side  Check level at each side

Now that we know how the bulkhead has to be placed we will place temporary small brackets on the hull. Then we can remove them to add glue on sanded part. The epoxy with aerosol is being placed in a candy bag (like the chefs in a restaurant do with whip cream) to add a nice even and broad strip of glue on the hull. After that we pressed the bulkhead firmly in the glue and we secured it with the small brackets. Leftover epoxy is removed before it is fully hardend. Naturally we checked the alignment again before the placement of the bulkhead.

Temporary support to fixate the bulkhead  A think layer of epoxy on the grind-ed area  Remove the overload of epoxy before it gets hard

Bulkhead 5 was our benchmark. From there we measured the bulkhead from front to back. To measure the distance between bulkhead 6 and 4 we made 3 identical wooden beams. These wooden beams were secured in the doorway. This served an additional purpose as the alignment was made more easy.

Aligning bulkhead 4 on the reference of bulkhead 5  Only need some spare wood and glue clamp

Fillets in the seams

Now that the bulkheads are in place they will receive on both ends a fillet with a radius of 25 mm. Again we made an additional aid that ensured an easy applying process for the filet. An old piece of lexaan from the previous build was used here. Firm enough, easy to shape with the jig saw and the eccentric sander and after use, easily cleaned.

First we apply a layer of epoxy mixed with aerosol and cotton, with a formed spatula we made a nice smooth filet and the residue epoxy was immediately removed so we could keep a smooth surface. Later we will place additional strips of fiberglass mats for maximum strength.

A mold for the fillets  Apply a layer of epoxy and get in shape with the mold  Remove the overload of epoxy before it can cure

Underfloor web

After the bulkheads the web underneath the floor up for treatment. Working this way leaves us with even additional strength for the turning of the hull. Because they are allot smaller it is much easier to align and glue. Laying fillets is harder because you need to put your feet somewhere while working (preferably not in a fresh and nice epoxy seamJ )On these parts the floor will be placed, in the end you will stand around 20 centimetre underneath the waterline.

Aligning underfloor web   The underfloor web with fillets

It is starting to get its form. Left: one truss more. Here will be our shower/washing and toilet cabin. Right: (closed truss) here will be a cabin with a bunk bed.

The bulkheads in the star board hull. 1 extra bulkhead for the owners cabin with shower and toilet  The bulkheads in the port side hull

Above you see the view from the front till the back. The first truss wil become the entrance to the sleeping cabines. The hulls will be 2 meters apart. Above the chamfer (the sloping side in the middle path) there will be the bridge with salon and cockpit.

A preview of the layout. The space between the hulls will be ca 1,5 meter wider

Perhaps these images help shape your imagination:

Lay out plan