Bent lower section causing rocking

W

woakesie

New Member
I noticed prior to sailing this weekend that my Standard Rig lower section was bent (quite badly, looking up from the base the top was raked back about 2-3 inches). During racing the wind got strong (F6) and I found the boat very unstable despite having some kicker on and being sheeted in so the boom was not out much.

I've been sailing Lasers for 6 years now and have done a lot of heavy air downwind sailing and I was really suprised how badly the boat was behaving, I only just managed to keep it upright. Another sailor next to me sailed dow the entire run barely rocking at all. I was pretty sure his kicker wasn't much tighter than mine (judging by boom height).

I did manage to stabilise things for the next run by having a lot more kicker than I would normally have thought needed for a "safe" run.

Thinking about it since I wonder if the bend in the lower section was making the leech softer than usual for a given kicker setting and so it was able to flick open.

Anyone else have thoughts on this ?
 
Your thinking is right on. If you look at the rig 2 dimensionally (drawing it out on paper makes it easier for me to visualize) from the side view, with the boom in the same position to the deck, and then draw the mast in two positions, one straight and one with the tip back 4 or 5 inches (in scale of course, representing the bent mast).

The distance between the clew and the tip of the mast will be shorter on the "tip back" version. That represents the leech of the sail. We know the actual leech of the sail does not shrink/grow, so with the shorter distance between clew and top of mast, the leech is going to be looser.

So, in this case, judging by your normal boom ht or marks on the vang blocks or vang purchases is going to give you the much looser leech. It's a great reason to try and match up whatthe leech profile looks like at various settings so when something changes (bent mast, new control lines), at least you can always go back to what the leech looks like.
 
Sometimes...you can fill the tube with sand and carefully bend the mast back to straight. Be careful not to dent it.

Unfortunatly I can only offer very bad news.

It is almost certainly time to purchase a new bottom section.
 
My experience is mainly with Radial lowers. The key to not denting the tube is to spread the point loading that you will have to apply over a decent length of say at least 0.5 metre using say at least 38mm thick pine (or other soft wood). Slowly apply a force enough to apply a reverse bend of at least 150% of the permanent set bend. You will find that wont be enough so slowly apply more force (which is proportional to the applied deflection) in increasing increments measuring the reverse permanent set at each step. Apply this force in what ever manner you find practical. I have made a jig on a 200mm by 50mm piece of Oregon and used a 10:1 pulley system to apply the force. Using a car jack would be another suggestion. Dont think that you can simply wack it in a vice or in the fork of a tree and lean or jump on it cause odds are you will damage the section (I know from practical experience!!!!).

Cheers,
 
Thanks for the comments. I may think about trying to straighten it, but my insurers agreed to let me get a new one so I've done that.
 
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