Mats Enblom from Uppsala in Sweden was the first to use the hull mould for the Stradivari owned by Swedish 2,4 NA to build a boat for himself. He is a former OK-dinghy sailor and has built an OK-dinghy before.
During the winter/spring 2004/2005 he built his own Stradivari 2,4, first sail was in august 2005. Judging from the pictures Mats has done a nice job.
Below is his report from the project.
I have probably used close to 300 hours. Itâ€™s hard to make an accurate estimate, if you include the transport of the mould, time for planning and purchasing materials itâ€™s probably more than 300. As a hobby project it hasn't been that effective all the time.
The laminateschedule for the hull was as follows,
450gr/m2 biaxial 45/45
3mm Lantor Sorec
In the keel I used epoxy gelcote, one layer of 160gr/m2 + 6X450gr/m2 biaxial 45/45
The Lantor Sorec material is like a dish-clout that absorbs the epoxy and becomes a rigid core material when hardened. As it is soft and comes on a roll it is easier to use than a foam core and the complete laminate schedule can be laid down in one hit.
Doing all the laminating alone wasn't optimal; it would have been more efficient with an extra hand. It's also important to make sure your garage is warm and cosy for the wetting out with the epoxy. 20C is minimum and having a heat gun in one hand and the roller in the other is a good trick to help the wet out of the glass fibre. This is very important in order to achieve a glass/resin ratio of 60/40.
When doing the second half I kept the epoxy under a halogen lamp which made a great difference.
The internal structure is made up from 4 12mm plywood frames that were laminated onto the hull.
The back support is made of thin plywood 4 mm thick. The floor is made of 6 mm plywood and keel support is of 6 mm plywood laminated with 2 layers 450/epoxi, in these the centerlift is fastened.
The deck was glued to the shear strake. The deck was held down with screws that were plugged. I had too muck deck camber in the front which gave me some trouble so I would either build that part separately or use less camber next time.
If you are interested in building a 2,4 this way you are welcome to get in touch with me. I would appreciate to give a hand. I enjoyed my project though it is always more work than you can imagine and without the advice from Hasse Malmsten I might not have been sailing yet.
I bought the materials from Epotex in Stockholm who are agent for NM epoxy, a high quality epoxy and also compatible fibres and fillers.
The worst part was laminating the radius at the sheer. As mentioned its better to halt the Sorec an inch under and add some extra layers of glass fibre.
Using 12mm plywood in the frames was probably overkill. 6mm frames laminated to the hull would have done the job as well. But you must glue deck beams on to the plywood frames to glue the deck.
It's probably better to cut the parts for the keel support construction out of a flat laminate panel instead of plywood.
The sheer strake had better be built from 4-5 strips instead of one piece.