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Many moons ago, before I became a racer, a friend came over and wanted me to build a Karelson hydro from plans he had purchased. So you set up the cockpit walls and then glue all those itty-bitty hull bulkheads on in free air? This was an alignment nightmare to us, so we redesigned the assembly procedure. One long piece of 5 mil wood cut to the shape of the hull at the inner sponson wall. In future boats I built this included the deck fin and air traps. Stringers that conformed to the inner hul shape, bottom and deck, were glued to this airfoil shaped wood. The "sponson girders" were then mounted on L jigs and the hull was built upright - an easy job to keep all the frames aligned.
I built a sponson girder jig shown in the attached (hopefullY) pictures. Cross slots allowed the clamp blocks to be set in any position. 5/8" square stringers were clamped in place and set to conform to the bottom and top hull shape. After slobbering WEST resin on the stringers the precut long plywood piece was lined up on the stringers and *papa-pap-pap* (sound of me trusty air stapler). Once stapled the assembled sponson girder could be lifted off the jig and set in a flast spot to cure. During me'n Big Dave's C hydro buildfest we assembled four port and four starboard sponson girders in one short evening.
Pic #1 - an overall view of the 10/ long jig. Pic #2 - close up of the clamp blocks which are wood chunks with a T-nut below and flat head screw above. Pic #3 - a 6' X 1" X 5/8" piece of mahogony clamped in place in a rough curve of a hedlund hook setup. I put tape on top to increase contrast.
The jig is coated with mold release wax to prevent gluing the part to the jig, that would bite. My last use of this jig is over. I built a 17' framed plywood faux beam cover for my rec room and the jig kept the assembly straight. The jig is not going with me when I move in a couple months so if anyone wants it, come and get it.
I built a sponson girder jig shown in the attached (hopefullY) pictures. Cross slots allowed the clamp blocks to be set in any position. 5/8" square stringers were clamped in place and set to conform to the bottom and top hull shape. After slobbering WEST resin on the stringers the precut long plywood piece was lined up on the stringers and *papa-pap-pap* (sound of me trusty air stapler). Once stapled the assembled sponson girder could be lifted off the jig and set in a flast spot to cure. During me'n Big Dave's C hydro buildfest we assembled four port and four starboard sponson girders in one short evening.
Pic #1 - an overall view of the 10/ long jig. Pic #2 - close up of the clamp blocks which are wood chunks with a T-nut below and flat head screw above. Pic #3 - a 6' X 1" X 5/8" piece of mahogony clamped in place in a rough curve of a hedlund hook setup. I put tape on top to increase contrast.
The jig is coated with mold release wax to prevent gluing the part to the jig, that would bite. My last use of this jig is over. I built a 17' framed plywood faux beam cover for my rec room and the jig kept the assembly straight. The jig is not going with me when I move in a couple months so if anyone wants it, come and get it.
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