Are You Using a GNAV and Where are Your Lowers

[Warren Nethercote]

I have a GNAV and my lowers go (went) to just above the GNAV Gooseneck. The mast first broke right at the attachment point for the lowers ....

Who else has a GNAV, where do your lowers attach and what has been your experience? The 49er has a similar rig and the lowers are 'low' but terminate perhaps 6 inches above the GNAV gooseneck. An engineer friend has suggested that the lowers should terminate half way up the lower mast panel. Vipers have a GNAV but attach the lowers to the mast conventionally, just under the spreaders. The Viper tuning guide also sees the GNAV as contributing to mast bend management, which is contrary to the usual argument for the 'low' lowers, but the Viper mast is keel stepped.

The mast is going back to the builder for a new lower section, so we have an opportunity to do things differently if warranted. Opinions?

[Chad]

Did you omit the lowers? A gnav stay should be in addition to the lowers, not instead of...

Ooof, I just saw the "bottom is wet" pic on FB from June 30, with no lowers. I wish i would have looked more carefully when I first saw it. That's a reallllly long panel to go unsupported, from gnav-stay to I-point. Did you notice the forestay getting soft uphill in breeze?

[Warren Nethercote]

Thanks Chad. Ooooh. And yes, keeping headstay tension was often a challenge. We could always get it because the headstay has a 24 to 1 purchase, but it comes at the expense of more and more pre-bend, and then ..... (poof?)

[Warren Nethercote]

The FB group is showing a preference for conventional lowers and the gnav-equipped PDX boats did that. One contributor noted that he'd never seen gnav lowers alone on a boat of this size ....

When I had the mast built we included t-hook plates for both conventional and gnav lowers, and I only used one set ...

[Tim Ford]

Just read Chad's comment, above and I agree, that's a long section of unsupported mast, having gone back too to re-examine the "bottom is wet" photo. I didn't notice the lack of "conventional" lowers the first time around.

The photo from August 9th sort of gave me the willies with all that forward mast rake, but I'm not an engineer and maybe that is unrelated. In any case, I hope you get the rig back soon and the mast folks can fix it. Are they doing an internal sleeve?

Best of luck, Warren!

[Warren Nethercote]

Some of the forward rake may have been related but it was largely a result of not having enough (aft) rake in the first place and soft uppers. We are likely to reuse the top and bottom bits, with a new middle bit, all sleeved together. The bits are en route via freight and we will make final decisions when they get to CCI.