The Switch to Closed Molding

As we report in Professional BoatBuilder No. 126, Danish builder Luffe Yachts has made the change from open- to closed-molding—a changeover completed with help from its resin-and-reinforcements supplier, Bodotex Composites, based in Vejle, Denmark. Which is as it should be: good suppliers have the staff and expertise to train and instruct the builder’s crew in the proper use of their materials.

We won’t repeat the entire story here, but in the short version, Luffe Yachts owner Oluf Jorgensen decided two years ago to investigate infusing the hulls and decks of the performance sailboats in his product line. Axel Liebmann of Bodotex Composites was brought in to guide Luffe Yachts through the transition. The first boat to be infused was a Luffe 45 (13.7m), with Bodotex’s epoxy resin and a balsa structural core. The first infused Luffe was launched last year. Though Luffe Yachts continued to offer its models in standard polyester construction, the weight savings and stiffness were such that, according to Liebmann, all orders now are for epoxy boats.

Take a look at these instructive images of the build as one of those new infused Luffe sailing yachts takes shape.

All shop photos by Frantzen Fotografi, courtesy of Bodotex Composites 

—Dan Spurr, Editor-at-Large

Switch2Closed01A layer of peel-ply is installed, and the total surface is then covered with release film (type P1 perforation). Care is taken that no overlapping exceeds 1-1/8″/30mm. Distribution mesh is applied, cut, and sewn to the dry fiberglass as shown. It’s worth spending time to do the job properly, since the quality of workmanship at this stage determines the development of the resin flow-front later.

Switch2Closed02The tedious job of sewing the many corners of a deck structure, and later adding the profiles (infusion channels), pays off once the shoot begins.

Switch2Closed03Oluf Jorgensen, owner of Luffe Yachts, cuts inlet profiles to the desired lengths.

Switch2Closed04The profiles are versatile: they can be employed in so-called parallel infusion layouts, or the Dutch-inspired spiderweb configuration. Two of Bodotex’s customers, Luffe Yachts and Baltic Yachts, favor the parallel design because it’s deemed safer, even if slightly slower.

Switch2Closed05Inlet profiles have been placed. Since there is only one connection point fitted per line, the risk of leaks is reduced. The job is therefore also easy to oversee, with less confusion and less opportunity for careless mistakes.

Switch2Closed06After the profiles are placed, Jorgensen cuts consumables according to specs.

Switch2Closed07Next, he trims excess fiberglass.

Switch2Closed08The vacuum spiral is laid along the perimeter.

Switch2Closed09Fitting the vacuum bag.

Switch2Closed10Resin inlet hoses are connected to infusion boxes, which are designed to fit the profiles without leaving pressure marks in the laminate.

Switch2Closed11Empty 44-lb/20-kg gelcoat cans, connected between the mold and vacuum pump, serve to collect resin overflow.

Switch2Closed12The infusion shoot runs smoothly; only one operator is needed to oversee the process.

Switch2Closed13A deck section—demolded and trimmed—is ready for fitting frames, wiring, etc.

Switch2Closed14Hull structure being fitted.

Switch2Closed15aA finished Luffe 40.04 (12.2m) under sail.