refit-repair

Grand mistral 80 mast refit

Eight Grand Mistral 80 racing yachts were built between 1995 and 1998. Bruce Farr, who designed the yachts, had already developed a conversion concept for a performance cruiser for their use after the racing period. So far none of those yachts have been converted in a proper way.

When the customer contacted me in 2013 and introduced the project, I was immediately enthusiastic about it. I love to participate in a project were something “old” gets a new life with the serious investment of a passionate sailor.

Our part was to change the carbon mast and boom to make it easier to handle: eliminate the runners and checkstays, build a new masthead for a hydraulic backstay, move the gooseneck up about one metre to allow the mainsheet traveller to be mounted on an arch. This improves the aesthetics and keeps the cockpit clean. The boom has received new Park Avenue wings by Carbon S Concept to fold the mainsail easier on top of it by the help of lazy jacks.

In most cases the mast tube has to be reinforced to keep the mast stiff enough for sailing without runners and checkstays. The original mast, that was built by us, was so strong that I had no doubts about the feasibility without adding new reinforcing. The distance between the headstay and the masthead was over 5 metres. Taking the headstay tension by using the new backstay only was not recommendable with this large distance. There would be more mastbend induced than necessary, so we decided to cut 2 metres off the mast top and build the new masthead in that position. Carbon plates were watercut, glued into the mast tube, and the UD prepreg laminates applied. The masthead crane was engineered to resist a 20 ton breaking load.  The max working load is about 8 tons. The masthead weighs an amazingly low 12.4kg.

The cherry on the cake is Kevin’s finishing work: the majority of the mast tube has been painted in black, but the masthead and the bottom of the mast, visible inside the boat, is in clear coat with a beautiful blue tint

Mast head Conversion

Gooseneck Conversion

Mast Reinforcing

Working in Izola on the GM 80 project we got a call from an old acquaintance in Trieste.

He found some strange deformation near the mast foot of his Frers 60 foot racer.

After inspection we found that the mast builder, who built a nice tube in prepreg, reinforced the mast foot area using wet lay-up. This can’t work unless the prepreg part of the tube is by itself strong enough to withstand the compression load. Wet lay-up laminates are generally weaker than prepreg laminates. A prepreg structure built following the book, has no fatigue life. It is either 100% or it is broken. Aluminium or steel structures can be permanently bent when overloaded. This is also the case when using wet lay-up, because the epoxy resins don’t have the same quality as prepreg resins.

In this case we removed the layers done in wet lay-up and laminated in pepreg new reinforcing. The whole foot was cured at 85°C and the mastjack holes redrilled.

A few days later the yacht participated in the Barcelona and was 4th overall leaving some much bigger yachts behind.