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Mini boat - Maxi challange

 

 

MINI BOAT
MAXI CHALLENGE

WB-News will follow in a series of articles the building of a 6,5 m long Mini-Transat boat. This article is the introduction to the series.


Reima Alander, sailmaker at WB-Sails, has launched his Mini-Transat project. With a little help from his friends, Reima plans to finish his boat by the end of summer, to sail the first trials at the beginning of September. WB-News will follow closely the building of the boat. in a series of articles on these pages.


Carving the mold with a robot

The manufacturing process, which uses the latest CAD-CAM technology throughout, is rather unusual and novel. The mold was carved by TwinCam Ltd, in Styrofoam with the help of a computer controlled milling machine. The entire process took some 40 hours, for the deck and the hull mold together.

A rough contour of the boat is first built from 15 cm thick blocks of Styrox. The crafting robot, which can handle pieces of 3x5x10 m at one time, then accurately sculpts the lines of the 6,5 m long and 3 m wide little boat, first at speed with a coarse blade and then with a finer blade to produce a perfectly smooth surface. Once the robot has done its job and the milling is completed, the boat builder, RTM- Composites, finishes off with a plastic covering (exactly how this is done is RTM's big secret) and voilà, the mold is ready for lamination. A substancial saving in labour & construction materials, Stryrofoam is cheap. Of course, at over $100 an hour, the milling is not inexpensive, but the accuracy is unmatched.

Designer Karl-Johan (Kamu) Stråhlman drew the lines with the help of MultiSurf, a relatively new and particularly user-friendly program by Dr. John Letcher. TwinCam's Silicon Graphics workstation had no problem in digesting Kamu's DXF-file. The production method cuts down manufacturing time dramatically: the molds were done in two weeks time after Kamu had completed the design.

We will look closer at the design in a future article.

Frames cut with the laser

Another area of time, labor & materials savings: the frames and girders were cut directly from Divinycell foam with the sailloft's laser cutter. The PC- produced frames were transferred into Plotmaker, a Macintosh- based sail cutting program by Sails Science. In Plotmaker, the 30 or so pieces of Divinycell were nested to minimize material wastage, much the same way as is done with panels & corner patches that form a sail.The cut-out foam cores are then covered with epoxy draped E-glass and vacuum bagged, to form the frames, bulkheads & stiffenings.

With the help of the sailmaking software, the pieces of the frames and bulkheads can be nested into the smallest amount of Divinycell, resulting in material savings. Even more important is the time savings: the cutting process took some 20 minutes, as opposed to several days of hand plotting & cutting from offset tables provided by the designer. Neat!



What is the Mini-Transat

The Mini-Transat race goes over the Atlantic in two legs: first from Brest, France to Funchal, in Madeira, and then after a stop at Madeira across the Atlantic to St. Martin in the Caribbean. Single-handed, in a 6,5 m (21 ft) long boat!

The rule for the boat is most simple: Length not more than 6,50 m, max. beam 3,0 m, and maximum height from the bottom of the keel the the top of the mast less than 14 m. There are other rules regarding stability, structures & safety equipment, but it could not be more simple.

The boats have water ballast tanks of 200 liters on each side, and some even use canting keels. The size of the asymmetrical masthead spinnaker is some 80 sqm, and the fully battened mainsail sports a huge roach. The boat is completely over- canvassed, to make the best of the calm moments on the Atlantic crossing, and needs to be reefed almost immediately as the wind starts to build up.

The winner of the -93 edition of the race, Frenchman Thierry Dubois in his boat Amnesty International, reached an incredible average of 8,2 knots across the Atlantic, with a best 24 hours run of 254 miles - alone, in a 6,5 m long boat. On the first leg of the race the fleet was hit by a deep depression 12 hours after the start from Brest. The race committee decided to cancel the race, but not all of the competitors received the canceling notice through their radios. Most turned back at their own will, but three boats sank and their skippers were lost, and masts broke in numbers.

Amnesty International never knew about the canceling but continued beating upwind towards Madeira. The astonishment of the skipper was great when arriving to Funchal, he saw the rest of the fleet awaiting him, transported there by a cargo vessel. ²It was tough all-right, but why should I have given up - this is no picnic anyway², commented the exhausted skipper.

Reiska, the wannabee Minitransit

The journey from behind the sewing machine to the South Atlantic is long and winding, and Reima is in need of many more sponsors before he can fullfill his dream. He hopes to complete the boat by the end of the summer, to do some practicing before setting sail south - away from the cold winds of Autumn that will by December cover our little Gulf of Finland with ice.

The Mini-Transat race itself starts in September -97, so Reiska

TwinCam Ltd Lohja-Lojo, Finland


RTM-composites Ltd Valimotie 11, 00380 Helsinki, Finland
Karl-Johan Stråhlman Björnviksvägen 7 A 11, 02110 Esbo, Finland

Copyright © WB-Sails -96
All rights reserved.

 

 

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