It is important that a foot block be very strong. Since the genoa
sheet typically enters a genoa car at about 45 degrees, the load applied to a genoa car is only about 30% of the load on the
sheet. But a foot block, because it is mounted aft of the winch and turns the
sheet 180 degrees, must withstand 200% of the load on the
sheet.
Assume the load on the
sheet is 650 pounds (easily that much on a Catalina 30 with a 110% jib in 25
knots of wind). A genoa car will be loaded to 650 * .3 = approximately 195 pounds. A foot block will be loaded to 650 * 2 = 1300 pounds, over 6-1/2 times the load on the genoa car! The old Lewmar block with its plastic sheave rolling on a stainless pin was simply not up to the task.
The Lewmar block was used on the Catalina 30 beginning with the introduction of the MkII boat with hull #4726 in 1986. When the MkIII was introduced, a different block was used. Use of the Lewmar block may have ceased before the introduction of the MKIII, but there is no record of that.
Use on the Catalina 320 was likely throughout the same period but we have been unable to locate any definitive record.
