There are many reasons why you may want to mould your own fins - you may want to save money, to make a shorter copy of a favourite fin or improve the performance of a fin in certain conditions. In my case I want to experiment with Twist, Flex & Fin Rake. By making a durable mould many fins (10+) can be made with little or no damage to the mould itself. If you are wanting to make 1-3 fins, there is a quicker and cheaper method I will cover in DIY – Fins – Making a fin Mould – Quick Mould.
If you have a range of fins from the same family use the longest to make the mould from. I am making the mould using a Select 39cm SL7. These are great fins and 39 is the biggest you can buy.
If you have a range of fins from the same family use the longest to make the mould from. I am making the mould using a Select 39cm SL7. These are great fins and 39 is the biggest you can buy.
Materials and Equipment
You will need and Epoxy System(resin & hardener) for making fins and this same system can be used to make a durable mould. By adding fillers such as Talc, Carbon Black and Aluminium powder you can make a variety of gelcoats, putties and fillers that can do just about anything related to fins and moulds. I buy 500ml PP(polypropylene) cups from a health food shop to use for mixing the resin and fillers together. They are cheap and can be re-used if not damaged and are the perfect size for the resin quantities required.
To mix the resin and work with the filler you will need to make some spatulas. Power hack saw (& plain hack saw) blades work well as they are thin and stiff and can be ground easily with a variety of fillets on the tip for mixing and filleting. You will need to grind the teeth off of the cutting edge to make cleaning easier.
The powersaw blades are also great for making a blending stick, stick sand paper of different grades to each side using double sided tape and you have a flexible sanding or blending stick. These are handy for doing board repairs when you have to sand down filler flush with the surface of the board.
For making the mould you will need some scraps of MDF of melamine coated chipboard. I prefer the melamine as you dont need to seal the surface and therefore save time when building the mould. MDF will allow a finer edge when cut with a jigsaw.
Plastic putty or Car Bog is required when setting up the fin on parting plane. To clean-up the putty put some metho in a detergent squeeze bottle and label it!. Another useful tool is a scraper or chiseled end on the filleting tool or spatula to use for shaping and cleaning of partially cured(green) bog.
Here is the first stage of making the fin mould...
