Thursday, September 9, 2010

Building Foam Composite Panels for the Hulls

Having gained some experience in the making of the flat panels under the hulls, I come to the most exciting part of the work so far...building COMPOSITE panels for the hulls. Normally when a boat maker wants to build a composite panel vacuum bags will be used. The air is sucked out at a few atmospheric pressure so that the FOAM bonds with the skin. Now, if I am mass producing boats that is the option to use but then I am only going to build one boat so a LOW Tech solution has to be made. Luckily I have bought Richard Woods' plans and he has given instructions for a low tech way of making hull laminates. Reasons why a Foam laminated hull is more superior is that it is light, Very strong, heat insulator and the foam does not burn. Of course it cost much more than solid fibreglass and wood but in the end it is worth the extra cost and work.This year's weather has not been normal....a lot of rain even during this "dry" period so I had to extend my tent workshop and buy extra canvas so that if it rains after I had laid a glass panel it will not be affected.These 16 mm thick melamine boards are the mould for the production of the composite panels. It had to be on a level floor and are joined together with cellotape. The dimensions as per the plans are drawn onto the hulls. Flanges, which are strips of 4 mm melamine wood are placed at the edges of the drawn hull shape. these flanges makes the joining of one panel to the next easier later on.After the shapes and flanges are ready, a layer of gelcoat is applied. It is laid to set for several hours.When the layer of gelcoat has almost cured, a layer of 600/225 biaxial matt is applied. I had requested my friend Robin Tan to come over and give me some hands on training on the making of these panels. Robin has magical hands and he has built several boats including a catamaran (24 ft) . He explained the correct technique of rolling the matts and how to minimise and get rid of air bubbles which are the natural enemies to the panels.These are the PVC Foams that I bought from DIAB Australia. DIAB has a branch in Thailand and I had to deal with the Thailand branch . Now listen very carefully.....if you have to deal with them, be very very careful. My plan calls for Grid Scored foams and my request from DIAB Thailand was Grid Scored Foam.Yes we have problem we can sell..etc and they invoiced and delivered me the Plain Foam. The foam comes in sheets of 7 ft by 4 ft . Quick correspondence with Richard Woods the boat designer suggested the only way that I could use the plain foam is to cut it into 6 inch squares with a hole in the centre and paste the pieces together again so that a good laminate could be achieved. It is a real pain in the **se! What you see here is the amount of foam for one panel.The foams had to be bonded onto the layer of glass using a special paste Divilette 600. The paste is VERY expensive, had to be imported from DIAB Australia and is classified as a dangerous good so the handling charges are a lot! And even though DIAB has a regional office in Thailand, no stocks are kept in Thailand so each user had to individually import the stuff from Australia. It looks like poor business sense but the real reason is that these paste has a life of 90 days if stored at a room temp of less than 25 C. Of the 90 days, 30 days are spent at sea and wharehouse so that leaves me with only a month to work.I did a trial with a few pieces of foam on a small part of the panel and waited for it to cure to see if the method works. Once I established that it works, then the work work of tiling and gluing the foams began. It is a back breaking task and I had to work fast so that the bonding paste do not cure in the pot. Each foam had to be inspected for proper bonding.

After the layer of foam is ready, another layer of 600/225 matt is laid on top the foam. the foam is now "sandwiched" in the middle of the two glass skin. 600 mm strips are placed all around the panel for extra protection.There is only so much of mixing and working that one person can do so in the later panels i had engaged the services of my friend Yee who is a fisherman to help. I imparted whatever knowledge I had on the subject to him and he was of a great help.
The cured panels are then trimmed and stored. a total of 35 man hours is required to produce on of these panels so it took me about 5 weeks of free time to produce the 4 panels for then hulls.


  1. It looks like this is one of the toughest portion of the building process so far you had gone through!

  2. I am looking for good Composite panels, thanks for finding this post