The Epoxy resin that I chose to use was 105 West System manufactured by Gougeon Brothers, Inc.
I really like using West system as I learnt to use it for many different jobs on my Trimaran.
Not only was it used on the obvious fibre glassing work, but thickened up with additive powders it was used to bond in the bulkheads and furniture, as well as the final water barrier protection before applying the 2 pot undercoat and top coat paints.
I also fitted all my hardware fittings without having to use nuts and washers, as all that was required was too drill an oversized blind hole, fill it with a thickened epoxy resin mixture, place the fitting such as a winch over the filled holes, and drop the stainless bolts through the mounting holes into the epoxy filled holes. It is a superior methodof attachment to the conventional nut and bolt technology.This proved to be a fantantastic solution to preventing water leaking down through bolts into the hull or inside the hull etc. If used on wooden boats it would also prevent ingression of water rotting timbers etc.
The resin is a clear, light-amber, low viscosity epoxy that can be cured in a wide temperature range to yield high strength, rigid solid bond which has excellent cohesive properties and also is an outstanding moisture barrier.
There are two types of hardeners formulated for use with 105 resin.
205 and 206 hardeners require 5 part resin to 1 part hardener mixing ratio. 207 and 209 hardeners require a 3 to 1 ratio, and solid state 6 to 8 hours.
205 hardener is mostly used for general bonding, barrier coating and fabric application. It was also formulated to cure at lower temperatures and to produce a rapid cure that develops its physical properties at room temperatures. Its pot life is 9 to 12 minutes at 22 degrees C, and cures to solid state 9 to 12 hours.
The 206 hardener is a slower hardener and provides a longer working time especially when working in climates of higher temperatures. I tended to use mostly this hardener as its pot life is 20 to 25 minutes at 22 degrees C.
Special pumps can be purchased to dispense the correct amount of resin per 1 full stroke of the resin pump, and the correct amount of hardener per 1 full stroke of the hardener pump.Mixing containers can be bought, however being a scrooge I preferred to put my money into the boat and not the rubbish bin. I had my wife and our neighbours saving plastic milk bottles and other suitable containers for me. My supply of milk bottles was insane at times. I cut the tops off those to make suitable containers.
Showing posts with label boat hull. Show all posts
Showing posts with label boat hull. Show all posts
Saturday, 23 May 2009
4. Hull mould and datum waterline set up
After couple of days later all 14 temporary hull mould frames were cut out, and were ready to be installed onto the strong back.
The photo to the right shows the temporary frames set up on the strong back inside the shed.
The strong back had to be marked out for the position of each of those mould frame stations.
Then to help accurately align each mould frame, a piano wire was set up set up on the centre line of the strong back, and about 25mm clear of and above the strong back.
I used a piece of angle iron bolted to each end of the strong back so that the piano wire could be pulled very tight and tied off once it was level. The point to note here is that you do not want any sag in the piano wire, or your boat hull will have sag in the middle built into it.
I bought a line level that just hooks over the piano wire. It is a simple tool, and does not cost much.
Then all the datum waterline heights marked on the mould frames were then set up the same distance above the piano wire.
A long accurate builder’s level was also used to check that each mould frame was standing up perpendicularly to the piano wire at 90 degrees, using the vertical centre line marked on each station for the level.
A Builders Square (used horizontally against the hull mould frame) was used to check that each mould frame was horizontally 90 degrees to the piano wire.
All this care in setting up is extremely important if the hull is to be perfectly fair (smooth without humps and hollows). It will certainly pay off with a hull fairness that you can really be proud of.
Then after all those set up operations were completed a laser level was hired to do the final check, and then the temporary frames were finally screwed securely in place so that they would not move under the weight of the hull as it was built over this male mould.
The photo to the right shows the temporary frames set up on the strong back inside the shed.
The strong back had to be marked out for the position of each of those mould frame stations.
Then to help accurately align each mould frame, a piano wire was set up set up on the centre line of the strong back, and about 25mm clear of and above the strong back.
I used a piece of angle iron bolted to each end of the strong back so that the piano wire could be pulled very tight and tied off once it was level. The point to note here is that you do not want any sag in the piano wire, or your boat hull will have sag in the middle built into it.
I bought a line level that just hooks over the piano wire. It is a simple tool, and does not cost much.
Then all the datum waterline heights marked on the mould frames were then set up the same distance above the piano wire.
A long accurate builder’s level was also used to check that each mould frame was standing up perpendicularly to the piano wire at 90 degrees, using the vertical centre line marked on each station for the level.
A Builders Square (used horizontally against the hull mould frame) was used to check that each mould frame was horizontally 90 degrees to the piano wire.
All this care in setting up is extremely important if the hull is to be perfectly fair (smooth without humps and hollows). It will certainly pay off with a hull fairness that you can really be proud of.
Then after all those set up operations were completed a laser level was hired to do the final check, and then the temporary frames were finally screwed securely in place so that they would not move under the weight of the hull as it was built over this male mould.
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