Laminating Technique

This is a quick section of laminating. There are some excellent resources available on the SP systems and National 12 website that discus laminating and vacuum bagging in detail. Below are some of my experience that hopefully you’ll find useful.

First precut and layout all the cloth and vacuum consumables before you mix any resin in the order that you will use them - i.e. vacuum bag on the bottom and fabric on the top. This allows you too work quickly later on when your working against the pot life of your epoxy.

First the inside layer of carbon is applied at +/-45 degrees. On sharp chines the cloth will go round better diagonally across the chine. Also straight joins are easier to fair in on the outer layer rather than diagonal joins.

Wet the mould out with slow curing resin and apply peel ply over the mould. Having peel ply on the inside performs two functions, first it provides a good surface to bond the bulkheads to. Furthermore I think that it helps distribute the resin through the cloth more evenly. This is my personal opinion, other builders only apply peel ply where bulkheads are present.

Try using a credit rather that a brush. I find it doesn’t disturb the cloth as much and large areas are easier to wet out quickly. The quantity of resin applied to the cloth is also more even. Aim to have the cloth damp rather that soaking wet. You should use the same weight of resin per unit area of cloth as the cloth weighs. So maybe 0.5 Kg for the inner skin. Buy a cheap set of scales from Lidl to measure the resin out.

Overlap the cloth by about an inch. Once the carbon cloth is on apply the peal ply. This needs to be saturated in epoxy to provide a good finish to bond the foam to. You may need to add more epoxy here but try not to over do it!

The whole boat needs to be vacuum bagged to consolidate the laminate and remove excess resin.

For the vacuum bagging a release fabric is first applied to the mould. This is a thin film with small holes spaced 1 cm over the entire surface. The purpose of this film is to stop the peel ply sticking the breather fabric, but sill allow the excess resin and air to pass from the peel ply. On top of this is the breather fabric that soaks up the excess resin and allows the vacuum to spread around the mould.

To seal the stack, a vacuum bag is placed over the top. The photo below is taken from an SP systems publication and shows the total vacuum bag stack.

Once the stack is assembled, a vacuum is applied to compress the laminate together and remove excess resin. A special fitting is available for connecting the vacuum hose to the bag, however I insert the tube under the edge of the bag and seal with vacuum tape. The end of the vacuum hose needs to be wrapped in breather so that the bag cant seal the tube. The suction need to be appled while the resin cures. I like to leave a blob of resin on the top of the bag so I can judge the cure state.