SO32 Rigid Vang I am not a great fan of topping lifts on booms when modern rigid boom vangs are relatively cheap and work extremely well.
I recently converted my SO32 from the original 4:1 rope vang to a 8:1 Selden rigid vang, the process is quite simple and allows you to completely remove the topping lift.
The Selden rigid vang was chosen because its the most cost effective quality vang on the market, it comes in three sizes and for the SO32 the Rodkick 10 (the smallest in the range) is the correct unit. When purchasing the Selden vang you can choose to have the straight vang which will limited the boom from falling onto your spray hood, cabin top etc and tension to eliminate kick or you can also purchase a gas that easily inserts inside the vang.
The gas strut provides a lifting force that holds the boom up when running downwind opening the leech and improving sail shape. The boom and mainsail on the SO32 are by no means large and as a result I elected to pit the vang without the gas strut however this is very easy to retrofit at a latter date.
Fitting the vang is very simple, the only real trick is that the overall length of the Rodkick 10 is greater than the distance between the original mast and boom fittings. This is easily overcome by drilling out the rivets that fix the boom fitting in its track and sliding the boom fitting backwards towards the cockpit. To set the correct length for the vang follow these instructions:
1. Remove the original vang rope and blocks.
2. Drilling out the rivets that fix the boom fitting in its track and slide it backwards towards the cockpit.
3. Fit the mast fitting end of the vang first, measure the distance between the lower (mast attachment end) fittings on the Selden vang and deduct the thickness of the stainless mast fitting to establish the "gap" you need make or purchase stainless packers for. Remove split pin and stainless dowel from the vang and fit to the original Sparcraft mast fitting.
4. Measure the distance between the upper (boom attachment end) fittings on the Selden vang and deduct the thickness of the stainless boom fitting to establish the "gap" you need make or purchase stainless packers for. Remove split pin and stainless dowel from the vang and fit to the original Sparcraft boom fitting. Remember your boom fitting is sliding in the boom track at is not secured along the boom length at this point.
5. Release the topping lift and drop the boom to the lowest position you want it to sit eg: 100mm above the spray hood etc) now slide the boom fitting forward to take the weight off the topping lift rope. Mark the boom through the holes on the boom fitting and drill and re-rivet the fitting in place.
6. Remove the original topping lift rope.
The Selden vang uses standard external blocks for the rope purchase system and I used Rutgerson 35mm blocks which match perfectly in colour to the original Sparcraft blocks. Use 35mm doubles, the one with the becket at the top or boom end the plain at the lower or mast end. Fit a single 35mm block to the aft centre mast set fitting and you are done.
Stephen Stones - "H2Eau" - Auckland, New Zealand