Tuning Single Spreader Masts


The Olson 30 was factory equipped with a single spreader mast, at least for most of the production run about 250 boats. The single spreader rigs were built by both Sparcraft and Ballenger, however the Ballenger masts are more prevalent. Many boats came from the factory with a Ballenger single spreader rig with Navtec -4 rod shrouds and a 5/32″ wire intermediate shroud, this article relates to this rig configuration. We’re not quite sure if or how many boats were factory equipped with double spreader masts, however Buzz Ballenger has been quoted to say he no longer supplies a single spreader rig. But this article relates to the single spreader w/intermediate setup found on many boats that still retain their original factory rig.


From the Sailpix message archives:

Hello Everyone,

Can someone provide me with base settings for a double spreader rig?

I reviewed the Ullman tuning guide and it calls for:
35 – uppers
26 – intermediates
32 – lowers

I spoke to Buzz about this and he said 35 on the rod tension gauge is about 1600-1800 lbs – about half the breaking strength of the rod rigging and way too much tension. I read on the ULDB site that most people are running 20 on the rod tension gauge. Is this correct?

The issue I have right now is my mast is inverted forward above the top spreader.

Greg F


I think that 20 on the rod gage is common for the uppers. What did Buzz say about the inversion? If I understand you correctly (forward bend above the upper spreaders), I’d suggest that your headstay length is too short or/and the lowers/intermediates are too tight.


Perfect Balance runs with 25 on Caps, 10 on lowers, this is on a Loos ROD gauge. The intermediates on a wire gauge are 16. Of course we normally are sailing in under 20 knots down here. I would probably put a little more in the rig if it was real windy.

Paula Sharpe

Using my rod tension gauge (NOT the wire tension gauge) …uppers are usually 20-21.

35 on the Ullman guide must be referring to a measurements with a Loos wire gauge. 35 would be WAYYY too high if measure on Loos rod gauge.

If someone has a contact at Ullman they should let them know to clarify their numbers in the tuning guide before someone does serious damage to their rig or rod rigging. (this has been done – webmaster)


Your most accurate guide for tuning the shroud tension will be to go out on the water with 6 people in 14 knots, throw up the #1, and hike the boat flat upwind. Tune the mast so that it is centered, there is no deflection, and the leeward shrouds are not loose or flopping about, but not tight. Too much tension will deform the boat. If you are sailing in lighter breeze usually, then carry a little less.

A good baseline is 1100 pounds to start, and just go from there.


This quote seems to point to a reason why the Ullman Guide has tension numbers that are so high:

I’ve been using an old cable-type Loos gauge for years. Since it’s not (and never has been) calibrated for rod, I don’t know what my actual rig tensions are – I only know that if I repeat a reading of 31 lowers/29 intermediates/ 30 uppers I get the rig about where I want it for 15-20 knots of breeze. The bottom line is that you want the rig to stay in column with minimum sag (with a good amount of backstay tension on) until you hit about 16-18 knots of breeze; then you want the rig to start “falling off” a bit above the intermediates, which self de-powers the rig progressively by spilling off mainsail.  With a #3 up in 15-18 knots of breeze or so, take a look at your leeward shrouds. If they’re extremely slack, tighten everything up. If they’re slack but not “floppy” – you’re OK. Then take a look up the rig and see if it’s staying in column. If not, adjust accordingly. BTW – this is all assuming that you start with the rig in the middle of the boat, and in column in static condition.

Loos RT-10


Additional Tuning information from the Sailpix message archive available here, you must sort through messages:

Search Sailpix for “Rig Tuning”

Search Sailpix for “Single Spreader Rig Tuning”

Conversion chart at left for the Loos RT-10 gauge.