I tested dozens of gross trim/fine tune setups including the Harken Magic block system before settling on a two-line 4:1/4:1 (see page 24 system G of the 2000 Layline Catalog). It uses the existing hexaratchet base, but the double with becket on top is replaced with a low profile triple with becket, ratchet and cam. On the boom I used two of the existing three sheeves for the gross trim, added a small floating double for the fine tune. Use different colored sheets and keep both aft of the traveler during the tacks so they won't get tangled. While the fine tune is very nice, the real advantage is being able to quickly ease or trim downwind with the gross trim. That's the reason I chose 4:1/4:1 over 6:1/2:1 which could be done with the same setup and a single floating block. Be sure to ease the fine tune before dumping the main to duck or round the weather mark or you won't be able to release the gross...email if you want details.
