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Viper 640: JCD Mast Chocks**ND**

Viper 640: JCD Mast Chocks**ND** JCD Viper 640 Mast Block Set
This HDPE mast block set consists of five (5) 1/8" blocks, two (2) 1/2" blocks and one (1) 3/4" block. The 3/4" block has a milled 7-degree mast rake curve. The width of these blocks is 3-1/8" and the total thickness is 2-3/8".

JCD Viper 640 Forward Mast Block
This is a 3/4" think HDPE forward mast block. It has a milled 7-degree mast rake curve. Having the curve follow the mast rake, along with the perpendicular face will help to keep the thinner blocks in front from pushing up. The width of this block is 3-1/8" and the total depth is 2-3/4".

Viper 640: GNAV Vang Upgrade

Viper 640: GNAV Vang Upgrade

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The Viper 640 comes stock with a GNAV vang that runs along the built in groove of the boom -- it tends to bind up a little and is plain bearing. To get a more responsive vang, we recommend the following:

We've put together all of the parts that you'll need to upgrade your GNAV vang on the Viper 640. If you're doing full-on upgrade, you'll need all of the parts listed below:
  • Harken Micro CB (Captive Ball) Track (1)
  • Harken Micro End Stops (2)
  • Slug Slides (10) -- These go in the boom groove, helping to anchor the track to the boom.
Available as a full kit, that includes the track cut to length, car, end caps and all necessary mounting hardware. Reuse your existing blocks and line or replace.

The Harken GNAV kit requires you to reuse your boom-end strut bracket to mount the strut to the new Harken car and you most likely (read: almost certainly) need to drill out the strut bracket to fasten it to the Harken car. The kit requires a bit of installation, but this is the best/only solution to work on all vipers.

H2706 Micro Track End Stop, Low-Profile (pair) Price: $7.22 H2707600 Micro CB Track, LB, 0.6m (1.97') Price: $30.05
HV640GNAV Harken Viper 640 GNAV Kit Price: $166.32 SOM230 3/8 Slug Slide, 7/8 long(PR) Price: $8.93

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