Ebb,
My mystery devices are home made. I designed them from reasonably-priced components available at my local sprinkler supply store. These parts are probably also available from most plumbing supply stores. We are talking four inch ABS pipe and fittings, and some neoprene.
Here is a shot of how they are put together from my new webpage. For more information on these devices, see my brand new (posted today) Pearson Ariel "Augustine" self-steering web page. I'll post more about that page on the self-steering thread soon.
Anyway, the URL for that webpage is: http://www.solopublications.com/sailariq.htm
A quote from that self-steering web page follows:
"The device in photo #103, is made from:
* Shown as "J": One four inch length of four (4) inch ABS pipe
* Also shown as "J": One ABS/SDR coupler for four (4) inch pipe with two hose clamps
* Also shown as "J": One end cap for four (4) inch ABS pipe with hole drilled in center to accommodate an oarlock. (the hole is not necessary unless oar locks are part of your plan.
* Shown as "I": One shim made of 1/8 inch neoprene cut to fit internal diameter of the 4 inch ABS pipe section.
* Shown as "M": Sleeve made of 5/8 inch clear tubing, with bevelled end to facilitate a tight fit into the winch handle slot on the jibsheet winch. (not necessary unless oarlocks are part of your plan)
* Shown in photo #102 as "N": one padeye and fasteners (bolt, two washers and lock nuts). The series 25 block will attach to the padeye. The padeye fasteners will hold the end cap onto the ABS pipe, and could also be used to secure the 1/8 inch thick neoprene shim "I".
* Shown as "K": One series 25 ball bearing block (also pictured elsewhere as block "G", however as "G" this block has an attached snap hook. As "K" it does not)
* Not shown here: A short Dacron line to tether the device to a pad eye or cleat. I used a piece of Dacron cord with a snap hook.This cord is attached to a pad eye used in my jackline system. The pad eye is located just forward of the jibsheet winch on the deck outboard of the coaming board"