pre-bent top mast

L

lasereng

Member
Hi,

A master at my club reckons having a slightly bent top mast is faster in light winds but i can't figure why. I've recently bought a new one because the offending top mast seems to no longer want to bend back anymore.

Whilst I know it's illegal - just wondering if anyone has any theories on bent / straight top masts and their speed across the different conditions?

cheers
 
As far as I know, you always want a straight section.

I remember once, I was sailing with an Aussie top section. It was super, super stiff. The difference in sheeting difficulty was immediately apparent. While practicing races before an event, I found I was able to sail very, very high, while maintaining exceptional speed. I was pinching off and going faster than guys much, much better than myself. (Unfortunately, this did not carry over to the event.)

Maybe it had nothing to do with the top section, but I don't think I can give myself all the credit haha.

Basically, I would not sail with a bent top section. I think I've heard about possibly benefiting from a bent bottom section in the light stuff, but I don't remember exactly, it's been too long.

Something to do with mast rake, maybe? No idea.
 
We fooled with a bent top section that had been end for ended and put back in service.

This means, the top foot of the mast had a slight bend.



With the tip bent toward the front>>>
In medium winds when power was being sought out, the sailor who had the bent top section could point higher and get there faster.

As soon as the sailor ran out of cunningham and had to spill any wind at all, the sailor with the normal top section had way more foreward speed and blew by.

I must include, we did those trials before the gazillion to one cunningham was available.

Perhaps today it is possible to get sufficient purchase on the cuningham to open the leech with a tweaked mast tip and be faster in all conditions.

But. Remember...a bent section is not legal in races and if you use one you may as well just use an outboard motor.

The object is not to build yourself a boat that is faster than a Laser .

The object is to make your Laser go faster than anybody else's Laser.
 
You put the sail out flat on the ground, it isn't straight. Whilst it's not advisable to bend it yourself, just put enough kicker + cunningham on to make it bend (very useful in high winds. My class captain at my club makes sure the younger people's boats are rigged like this before racing in stormy conditions). The same is said in light winds, having it dead straight isn't ideal but it doesn't need to be too bent. Please amend me if I am wrong.
 
For nearly all dinghy's, mast straightness across the wind range is as follows:-

Light winds - bent mast to give flat entry and open leach
Medium winds - straight mast to give tight leach and fuller entry
Strong winds - bent mast open leach flat entry.

From the replies above, you can see what an advantage it is to have a straight or even bent forward mast in medium winds, lots of power and high pointing from the firm leach.

Strong winds in a Laser is all about kicker and cunningham to get the sail as flat as possible with an open leach.(The wind actually blows the leach open anyway)

Light winds is the problem in Lasers. The wind is "lazy", so keep the flow across the sail, it wants to have minimum "obstructions". Therefore a flat sail with an open leach is what the wind wants. However, in a Laser we have no direct mast controls (rig tension/mast strut etc) so the only way to get the mast to bend to match the luff curve in the sail, is to use the kicker. However, this then tensions the leach which is not desirable, so there is always a comprimise to be reached.

Having a bent top mast means you get a flat sail and an open leach, so you should be faster in light winds.

I'm sure Bruce Kirby/Laser knew this in 1971, hence the straight mast requirement in the rules.
 
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