Mast bend, is this weird?

[reidmefirst]

I've been sailing my boat a few years now. Last year I had the standing rigging replaced, including adding a furler (gasp, heresy, I know, I'm sorry).

One thing I've noticed is that my mast shape seems a bit...odd. When I bought my boat it came rigged with the original mast, but came with one of the 'new' style masts (stiffer, etc), so I immediately rigged up the new mast.



I've tuned the rig according to the Doyle tuning guide from the class for the 'new' style masts: the uppers are around 27, the lowers are around 15, and the mast is straight left-to-right. The oddness (to me) is seen in the image above: the mast seems to curve forward at the top (forestay/furler is on the left, the spinnaker halyard and topping can be seen going straight down and they are not under a lot of tension, while the mast itself has a slightly bowed shape). I should note that I am using a Loos gauge 'Model B', while the Doyle Boston tuning guide only mentions 'Model C' and 'Professional/Model A'.

I will also note that my forestay/furler sags a bit in high wind, for example if I sail on just the jib in ~10kts I usually have to add a bit of backstay to keep the furler track from bowing. I have not actually measured the length of the whole furler unit, which I suppose I should do the next time I drop the mast...but I would think if it was too short (which could cause the odd bowing), that it wouldn't sag without backstay? I do note that the Doyle guide says to keep the backstay on for a while at the dock, which I've never done and guess I will start doing to see if it helps...

Anyway, curious if this is normal for 7.9 masts, or if something has gone sideways with my rigging?

[TBoston]

That is weird. Have you checked the forestay length to make sure that you are close to max rake? That would help I would think.

[reidmefirst]

Not yet, but I will when I take the mast down next time. Had a competent rigger make up the furler system and forestay but I guess 'you never know' when somebody else does it.

Anyway I did put on a lot of backstay and tightened the uppers quite a bit, and the shape looks a lot more normal now (top of the mast bent back a bit). If I ease on the backstay though the mast takes the shape in the photo, though it isn't quite as pronounced. May have to tighten the uppers even more. Makes me nervous though, as they're quite tight now and turning them requires a wrench. Will check 'em with the loos gauge once the temperature is not deathly hot out...

[hwpratt]

I have a similar "reverse mast bend" on #352 (with max rake).
I attribute some of it to the way the mast was stored on the boat and the middle pulled down too hard for trailering and storage.
When I set up the boat in the spring I pull as much backstay tension as I can get, then set up the tension on the uppers, and lastly tension the lowers.

It seems strange to have to do that but I can manage it.

[reidmefirst]

After mast-down I measured the forestay and it's perfect length.

For the last couple of months I kept the uppers a bit tighter and kept the backstay hard on while sitting in the slip. The mast shape looks proper now, even when I ease the backstay and loosened the uppers. Thanks all, for the tips!