Straighten your Spars

I think this mast is longer than it should be.

ILCA Rule 5 states: "No mast which has a permanent bend shall be used at any time."

New top-sections are springy, and resist taking on a permanent bend, but with use they take on a permanent bend more easily. Of course, sticking your Laser upside-down in a shallow mudbank is a sure-fire route to a bent top-section, new or old.

So what constitutes a bent mast? If measurers had to attend meetings with a jig to measure absolute straightness they would have to cart the whole lot around in a van. The human eye, and other senses, can detect really small amounts of bend. Any amount too small to be readily detected won't make a difference on the water, and mast bend is judged by eye.

Note: the author and publisher of this site takes no responsibility for any consequential damage from any advice given on this site. Even a new spar can snap on first use; it can also snap the first time you try to straighten it.

Bottom Sections

Standard-rig bottom-sections rarely bend (though Jon Emmett reckons they do quite often), but they do break. The good news? They break only rarely, with old age and usually under the considerable stress of a strong wind: Force 5 or above. They usually snap at the rivet-holes for the Y-section tang mounting for the vang. When one does let go on you it's an odd experience: one second you're fully hiked-out, going hell-for-leather on a screaming reach, the next you're sitting in a soap dish wondering where the hell the wind went. Persuade a light-wind sailor into lending you their bottom-section for the afternoon race and go buy a new one on Monday.

Radial bottom-sections do bend. (Sometimes they break, but they generally bend before they break. Can you straighten it? The simple answer is - don't bother trying if it's racing you're after, for there's damn-all you can do about it. Just go out and buy another one for racing, and use the bent one for practice or messing around in a Force 7. I haven't heard of anyone successfully unbending a Radial bottom-section enough for it to be raced, though Steve Cockerill probably has. One problem lies in finding the centre-point of the bend, and in gaining sufficient leverage and strength to be able to un-bend not one but two concentric tubes of aluminium.

Radial bottom-sections are quite likely to be tested for a permanent bend at a regatta. Check yours out before setting out. A bent one is slow downwind anyway, as you lose out on leach-tension.

I have seen Jon Emmett sailing with a Radial bottom section with a fractured outer, and probably reliant on the inner sleeve to keep it in one piece. Rather him than me, even in the Force 1 at Farmoor where he used it!

4.7 rig bottom-sections are pre-bent at the factory, and these are strong enough not to bend (either further or less) under normal use. ('Normal use' should include use by an 80kg sailor having a blast in a Force 7.)

Top Sections

A new top-section is relatively springy and soft. It is therefore likely to be quite resistant to bending in 'normal' conditions, but it will get a permanent bend easily if you capsize your Laser in shallows, or sail in really strong winds. It is easy to straighten at this stage.

With use it will become progressively more brittle, making it more 'powerful'. It will not absorb gusts as well as a new one, but will be more powerful offwind. Age increases the probability that the mast top-section will snap when you try to straighten it, but it is more resistant to bending than a new top-section. It is probably gives its best performeance just before it snaps. Always take a spare top-section with you; you can never tell when one is going to go. I had one snap on me in the dinghy park after a light-wind Torbay Nationals race, when I put pressure on the boom to take the vang off!

How to straighten a bent top-section

First, find out which way it's bent, or even if it's bent at all:

  1. Stand at the front of the boat, facing it, just like I'm doing in the picture at the top of the page, holding the top-section at the top end. Place the bottom-end on the rear deck. Roll it from side to side, looking along the spar. If there's a bend you'll be able to spot it easily, by seeing if the collar rises and falls in relation to the base as you rotate it.
  2. Note which way the bend is by looking at the rivet and the Laser badge: it is more likely that it will be bent backwards; the mast will have a convex bend uppermost when the Laser badge is uppermost. (I am assuming you have been sensible enough to sail with the rivet hole towards the rear.) It is not good practice to sail with the top-section rivet at or near the front; though you might straighten the top-section, it's likely to snap long before its time.
  3. Mark exactly where the top of the convex bend is on your top-section. It may be off to one side of the badge, especially if the bend was cause by you dumping the boat in offwind.

Prepare to un-bend your top-section:

  1. Put your top-section in the bottom-section, but with the max-convexity mark at 90 degrees to the gooseneck. This prevents your gooseneck hitting the ground when you put the pressure on.
  2. Place the top-section on the gunwhale of your Laser, and at a right-angle to it. The mast should touch the gunwhale about two-thirds of the way up the top-section, so that the distance between the collar and the gunwhale is about the same distance as the length of the bottom-section, with the convex side of the mast uppermost. Place the mast-base on soft ground, an old jacket or a buoyancy aid to protect it.
  3. Now comes the crunch. Stand facing the joined-together mast. Place one hand gripping the spar about a foot above the collar, and the other gripping just below the top of the bottom-section. Then, with straight arms press gently but firmly downwards, using your body-weight not your arm-strength. If you're light you can place one knee on the top of the bottom-section (or where you have seen the bend to be greatest) and press down, but the force will have more of your weight on it, and should be performed with considerable caution.
  4. You can always use more strength if the first attempt isn't enough, but don't overdo it. It is quite possible to snap a mast that is either old (and therefore stiff and brittle) or one that has already been straighted a few times.
  5. If the top-section snaps, be philosophical. Better it goes onshore and not during a race when you would otherwise have to count a DNF or your worst result. And you can use the snapped part to make a boom using the parts from an old bent boom: time-consuming but worth it.


Booms acquire a permanent bend over time with the amount of vang tension necessary to sail upwind in strong winds. It is legal to race with a bent boom. There's only one minor drawback: if the middle is lower it will be more difficult to get underneath when you're tacking, especially if you're a Master and don't bend too well yourself.

It's useful to know this if you are in the habit of chartering a Laser and want to keep your deposit.

Checking for bend

  1. As with the top-section, with the gooseneck-end on the boat. (The bend is most likely to be around the vang-key fitting.) li>Check the boom itself for signs of corrosion around the rivet-holes. Booms tend to get a lot of corrosion on the vang-fitting, the mainsheet blocks, and the becket-block. If you see corrosion, best for you to hope to snap a top-section soon, or go out and buy a new boom. Re-riveting might save a temporary emergency, but re-riveting can cause the crack to widen fast. A broken boom on the water tends to ruin your day and your results.

Unbending a boom

  1. This is more difficult than unbending a top-section. For one thing you've got a reinforcing tube inside the boom tubing, unless your boom is really, really old.
  2. Place the gooseneck end of the boom on a padded gunwhale of your Laser, the other end on the ground. The boom should be inverted, with the vang-key hole uppermost.
  3. As with the top-section, place your knee this time on the underside of the boom, just behind the vang-kjey fitting, and press down using your body-weight. You can afford to be a lot less subtle than you had to be with the top-section.