Main sheet lower block upgrade

Maintaining, repairing, upgrading, commissioning, decommissioning topics.

Moderators: forumadmin, j30_rhapsody

Post Reply
Posts: 22
Joined: Thu Mar 05, 2015 12:16 pm

Main sheet lower block upgrade

Post by bmastror » Fri Oct 13, 2017 8:54 am

Harken has upgraded the lower block and the traveler swivel (you have to buy the entire assembly)
Item Number: HSB456, Description: #14CAM BASE-LG SWV J109 UPGRADE

The replacement U adapter info:
Item number H-29180A, Description: U-ADPT FOR 1/4in PINS J109
I attached a picture with the old U adapter next to the new one. As you can see, the new one is much larger. Hopefully this will prevent the U adapters from breaking in the future.
IMG_0147 (1).JPG
IMG_0147 (1).JPG (684.2 KiB) Viewed 743 times
IMG_0146 (1).JPG
IMG_0146 (1).JPG (558.46 KiB) Viewed 743 times
IMG_0463.JPG (949.14 KiB) Viewed 743 times

Bengt J
Posts: 28
Joined: Tue Oct 25, 2016 2:36 pm

Re: Main sheet lower block upgrade

Post by Bengt J » Thu Oct 19, 2017 9:08 am

Brooke, Thanks for posting this info!
The upgrade is a safety issue and absolutely Class Legal. Other custom solutions for heavy duty versions of this connecting piece are also Class Legal as long as the function of the Block/Swivel assembly is not changed.

Bengt Johansson

User avatar
Posts: 200
Joined: Wed Dec 31, 1969 8:00 pm
Location: Newport, RI

Re: Main sheet lower block upgrade

Post by j30_rhapsody » Tue Oct 16, 2018 10:40 am

This past week with big wind at the NAs three boats blew up the plastic swivel plate that holds the upright clevis pin attached to the lower block. Additionally many boats deformed the stronger Harken model H-29180A, U-Adapter with 1/4in pins made for the J/109.

This winter I will look at the possibility of fabricating a small stainless disk that fits over the plastic swivel and is bolted using the existing 4 screws. Something like this should take the load off the plastic piece. If successful, I'll suggest that Harken may want to incorporate the upgrade.

category 2
Posts: 1
Joined: Tue Nov 06, 2018 11:05 am

Re: Main sheet lower block upgrade

Post by category 2 » Tue Nov 06, 2018 11:38 am

The Harken midrange swivel, 1574, fits the existing platform, sports a 280 offshore cam cleat and should be much stronger. It utilizes 1/4" fasteners and 5/16" pins which accept the 1550 midrange ratchet block. This is a readily available stock piece of hardware.

Post Reply