Crab Claw from the jungle|
or the cheapest solution to make a Wharram HITIA 17 sailing
(short english version)
In february 2001 I communicated with Dieter Hinrichsen who was building a HITIA 17 (Wharram design) to test this catamarans for coastal trekking. He was looking for a more effective rig as the original spritsail and asked me for a hint. Short time before I saw a very special rig at the site of HSS (Horizontal Sailing Systems) which I recommended Dieter for use and sent him a sketch of what I imagine. After some further emails he invited us to visit him - and on the spot we spent our holidays in Panama.
In Panama we lived for a week in a 15 m Clipper in the Pedro Miguel Boat Club near the sluice from where we made some trips into the jungle and and a ride with the new Panama Channel Railway to Colon at the Atlantic. In the meantime the HITIA was finished and we could start to develop the rig.
View from our 'houseboat'
The existing free of charge building material was bamboo in several length and thickness from the near forest. The first 'design' of the rig has the motto 'simple is the best'. Two bamboo pipes would lashed along the beams with a little carve against sliding. The mast was placed between the pipes and fixed by a broomstick which was sticked through the pipes and the mast (see sketch). So the mast could turned over for trimming too.
The length of the spars should be max. 17 feet like the length of boat. A rough looking at Marchaj's formula says : '100 % Crab Claw match over 175 % Bermuda rig'. Therefore a sail area of 9 sqm was planned to reach adequate 15 of the original spritsail. The small sail area caused a the small angel between the spars. The mast height was only 1,50 m!
First rigging without sail
First tests with the rig work great, now the sail must be made. The first idea to make it from Polytarp was not possible, because we could not get it. But Dieter had a lot of the strong tarpaulin from which the trampoline was made. Because no camber is need in a Crab Claw, we placed the tarpaulin from the roll at the bottom of the shed and put the empty triangle of the spars on it. After that we marked with chalk the contour plus some extra for sewing and cut it. Up and away to the sail maker - Dieters girlfriend Marlene.
Sail maker in Panama manner
The standard sewing machine needs a handful of needles, but Marlene made the sail in one afternoon! And it fits exactly. Afterwards we made even some tests and then disassembled the boat for the transport to the Pacific coast.
In Flamenco Bay, a bay in front of Panama-City Dieters home 16m Formosa Ketch was anchoring. At ebb we assembled the HITIA at the beach and launch it. The first ride with three men at lightly winds shows the efficiency of the Crab Claw.
In following I did a series of tests to learn the tricky maneuvers. The down sheet you need to keep the sail close and the above sheet you use to put the sail slantwise in courses of beam reach. Tacking is a pain. Like many catamarans the HITIA with his long lateral plan turns only with high speed through the wind. At light wind you have no chance to tack - but therefor you can always make perfect gybes instead. To optimize the speed beam reach we installed a rope traveller between the bows. So we can move the tack of the Crab Claw to luff to enlarge the projection of the used sail area. Resume: The 'Tacking Crab Claw' is a very efficient rig - especially if you compare the performance with the very low costs!
Later in the Archipielago de Las Perlas the bamboo bearing breaks in a heavy rain gust - not the bamboo spars! The bearing was not bamboo specific designed by me. You may not carve bamboo if he should loaded strongly. The repair at the Island Espiritu Santu was like customary with a jungle rig - you take your machete and saw and go into the forest ;-) A strong driftwood plank and a thin stem of hardwood - ready!