GC Marine
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GCRC developed this design to work with various transom types where normal gudgeons or brackets would not work. Provided we have the transom characteristics, we build a very strong lower bracket that is customized for a particular boat. Compression tube lengths and brackets placement can be finalized on location once the lower bracket is bolted onto the transom.
The lower bracket has a 1/2" bolt that locks the vertical tube in place. The vertical tube has a carbon doubler on the inside for added strength where the bolt goes through. On the outside we glue some spacers to make a perfect fit with the bracket. Once tightened, the lower bracket attachment has zero play. We use a hollow stainless steel pin to lock the cassette to the vertical tube. Cotter pins can be replaced with quick-pins for easier deployment.
Opposing the upper cassette attachment, we have two carbon compression tubes that run forward and outboard and pin into two carbon brackets. In this case the carbon brackets are bolted to the cockpit floor. On transoms like the J120, they could be mounted on a vertical surface directly forward of the transom edge. The compresion tubes end in delrin cones that are bonded and bolted in place, and have threaded ball joints to adapt to a very wide range of angles and greatly simplify the installation process.
The system as seen from above. Final tube lengths can be determined quite easily either prior to or during the installation and must be within a certain angle range for maximum side-to-side and fore-and-aft support.
Once the vertical tube and the cassette are firmly in place, the blade drops into the cassette. A pair of composite padeyes are used to attach the steering lines that run to either side of the aft pulpit. Alternatively, we can incorporate an "S" tiller that avoids the backstay.
To demonstrate the length of blade below the waterline, in this pic the tip of the blade is just touching the water surface. With a line steering system, the amount of blade in the water can easily be varied. With tiller steering, the range is greatly reduced.