: Is this skeg controlled by a sheathed push/pull cable?

Yes. This can be accomplished using a thick (1/8") braided cable or a thin (1/16") solid wire. For the outer sheath, you can use poly tubing and compression fittings that are available at most home centers.

: Have you thought about any way to downspring it so you could control it with
: tension line, secured with a simple cam cleat? What are your thoughts?

This is common on older commercially made boats (Brit' boats, in particular), though most have switched to push pull systems in recent years. The problems with tensioned systems are:

- Designing a reliable tensioning mechanism that's not visible from the outside.

- The tension system makes retracting the skeg harder. Stretch in the acutating cord, friction where the cord goes over edges and play in the cleat can make it difficult to fully retract the skeg.

- If the control line fails, the skeg is stuck in the down position, where it is subject to damage during launching and landing.

- In a tensioned system, the skeg does not stay retracted if bumped during a landing, exposing it to damage. In a push pull system, any upward pressure on the skeg typically causes it to retract partially or fully and stay in the retracted position.

Push-pull systems eliminate all of these problems and are very reliable. They also allow a finer degree of skeg control.

There's a reason why most boat companies have gone with push-pull systems, they're simply better.