Additional  Information About Fitting RCB Shroud Tracks and Cars to an Existing Tasar

Note: Interpretation  37, which governs the retrofitting of RCB tracks and slides, was amended on August 17, 2008, to clarify the measurements that define the allowable movement of the slides. The information on this page was edited on February 8, 2009, to clarify   the references to these measurements.

ISAF has recently approved a request by the designer allowing 19mm RCB  shroud tracks and cars to be fitted to new Tasars. An Interpretation by the Chief Measurer will enable owners of existing Tasars to fit this same equipment to their boats. Note that use of 14mm RCB track is not permitted.

Following are notes and a guide on how to retro-fit the 19mm RCB system to an existing Tasar.

Mandy Stock, the UK Tasar Builder, has suggested that by using slightly shorter tracks - 235mm instead of 248mm, it may be possible to use the  same end cap holes as the old C track. With this method though there is about 5mm less car travel. Two additional holes will need to be drilled in the RCB track to accommodate the end caps, these will then match the  C track holes in the gunwhale.

Parts needed:

2 x Ronstan RC11902 Cars 4 x Ronstan RC11980 Track Ends 2 x 235mm lengths of Ronstan RC1190-1.0 track 2 x Clamcleat CL 268AN Cleats 4 x Ronstan RF 1850S Shackles (2 required, 2 optional) 8 x 2" x ¼" machine bolts (screw head) Approx 1 metre of 4mm laid (preferable) or braided line (to be trimmed            to length) 2 x 400mm lengths of 18mm alloy or stainless steel rod or stainless            steel bar to provide rigid under gunwhale support. These should extend            75mm past both ends of each track.

Note:

1. Buying a 2 metre length of Ronstan track, RC1190 is the most economical            purchase. It enables 3 boats to be fitted out. 2. Use of stainless steel rod for the under gunwhale support is preferred.            Whilst a little heavier than alloy it avoids any possibility of electrolytic            reaction between dissimilar metals. 3. The Clamcleat CL 268AN (anodised, hardened) is preferred. The RCB            Trial showed the material used in the Clamcleat CL268 (non anodised,            hardened) to be too soft and liable to be worn away by the friction            of the pull back line. 4. Exercise care when handling the RC11902 Cars, lest the ball bearings            escape.

Owners are reminded of the measurements which apply to RCB tracks,          namely:-

1. The track shall be fitted with bolts to the backing plate that            shall fit into the gunwhale groove. 2. The distance from the            bow U bolt, measured as shown at deck level, to the forward track end            bolt hole shall be a minimum of 2125mm and a maximum of 2135mm. Car            travel must not exceed 140mm. (see            Interpretation 37)

It is recommended that RCB          track is fitted using the existing forward bolt hole from the old C tracks.

Fitting the RCB tracks

Drill and tap the 18mm under gunwhale support rod to receive the ¼"          machine bolts. Alternatively, drill right through the rod and use nyloc          nuts to join the track to the support rod through the gunwhale, longer          bolts will be required.

Remove the existing C section stainless steel tracks and clean up the          upper and lower bearing surfaces of the gunwhale. Careful use of a small          angle grinder may help in removing frozen nuts and bolts.

Assemble the RCB car and track ends onto the track and place them on          the gunwhale in their approximate final position. Measure 2140mm from          the bow U bolt fitting at deck level (see photo 1) back to the bearing          point of the car shackle, when the car is in its most forward position,          ie, up against the forward track end.

Photo 1 - Measurements are taken from the bow U bolt at deck level

Through the holes in the new track, mark the location of the three locating          holes to be drilled in the gunwhale. It may be possible to use at least          one of the existing holes from the old C track.

Any unused holes remaining from the C tracks will need to be filled and          sealed.

Location of the RCB tracks athwartships is indicated by the holes that          were used to secure the C tracks and the need to properly locate and engage          the under gunwhale support rod. The final location of the RCB's          should see a little bit of overhang beyond the gunwhale - see photo          2.

Photo 2 - The RCB's will overhang the gunwhale a little bit

Care should be taken when drilling the new holes in the gunwhale. It          is important for the securing bolts to pass through the gunwhale at the          correct angle so they can easily pick up the under gunwhale support rod.          The use of a pilot hole in the first instance is suggested.

Liberal application of an appropriate sealant to all holes and fittings          is recommended.

With the new tracks in place, check to make sure the correct          measurements apply (Note: this wording was amended 2009-02-08).

Clamcleat Modifications

The Clamcleats (CL 268AN) will need to be drilled to accept the Ronstan          RF 1850S shackles. A 1/8" hole should be drilled through the cleat          5mm in from the leading edge and 5mm in from the base. An additional option          is to drill another 1/8" hole 15mm in from the back edge of the          cleat and 5mm in from the base to take another shackle, which acts as          a guide for the pull back line.

A 5mm hole drilled 3mm from the base and 17mm from the front of the          cleat will allow a 15mm clevis pin to be inserted just in front of the          teeth of the cleat, which will act as a bearing for the draw back line.

Finally, the forward screw hole in the base of the cleat should be milled          or filed out back towards the teeth of the cleat and rounded off in order          to accept the 4mm pull back line - see photo's 3 and 3a.

 

Photo's 3 and 3a - Detail showing modifications          to the Clamcleat

Rigging the RCB's

See photo 4. The Clamcleat is shackled to the traveller car. A hole          is drilled in the back of the aft track end cap to accept the knotted          end of the 4mm pull back line. This line is led directly from the track          end cap through the guide shackle to the Clamcleat then attached to the          pull back handle.

Remember that Class Rule 2.2k still applies, that is ......with the          slide fully forward and the line fully extended aft, the distance from          the aft end of the track to the bearing point of the pull back handle          shall not exceed 150 mm.

The shackle at the right hand end of the cleat (as pictured)              simply acts a guide for the pull back line, and is optional.

Photo 4 - Detail of the RCB traveller car showing how it is rigged