What is new and different with the Boomtrims?
Line purchased rigid boom vangs are steel or gas spring preloaded. The extension is altered by a system of blocks and pulleys. The Boomtrim™ BTE does not need blocks and pulleys; pressure and extension are achieved by an electrically powered linear drive.

This sounds technical complex ...
No, principally an electric motor with a planetary gear in a telescopic tube is turning a threaded rod in a drive nut which is fixed to another telescopic tube. Turning the rod will produce a linear movement to the telescopic extension arm. The rods are self locking and there are no lines under constant tension, no friction in blocks, pulleys or stoppers and no counter spring forces to overcome.

Why do you believe in any demand for threaded rod boom vangs?
Except for expensive hydraulic systems, there is simply no other way to build very compact rigid boom vangs for such high working loads. And even moderate cruising sailors will need this power because the way we sail and trim is changing. It is somehow like a paradigm change in trimming nowadays.

So, what is changing?
Well, modern synthetic sailcloth with little stretch and precise computer aided cuts had brought some disadvantages also. These sails need much higher trim forces for their optimal balance and with a bad trim they are not as forgiving as the more stretchable former ones.

Do you have an example to explain this?
Yes, when you have to spill wind in gusty conditions because excessive heel and rudderpressure are critical you slack the main sheet or release the heavily loaded boom vang (with a kick!). Slacking the main is not efficient and kicking the boom is not controlled. Every sailor knows this, the main flaps until you tighten the sheet or vang again or bear away to regain speed.

So what's wrong with throwing off the vang or mainsheet?
Nothing, because, except on racing dinghies, you didn't have had real strong and easy to use boom vangs. There was no other way to diminish excessive wind pressure. Inevitably you had to accept a loss of speed by altering the angle of attack to the main also. Older sails and heavier boats are more tolerant to these manouvers. But modern light weight constructions and sails let you often stall in the next wave. Beside, why do want to give away all the power of this gust?

And that is where you need the Boomtrim?
Yes, years ago the dinghy racers had brought up the expression "Vang Sheeting", the control of heel by using the vang to play the leech. When the main is the power plant the vang is the throttle to control it. Usually, in light conditions you apply little tension. If the wind gets stronger you tighten the leech to keep the sail flat. In heavy gusts on contrary you open the leech to depower the upper third of the main where the angular momentum and the wind are strongest. The wind angle and pressure point of the lower part of the main will remain unchanged, thus preserving the speed.

But racers say they need to throw off the vang in critical conditiones?
And I have never met any racer who told me that he could have done it precisely and controlled. In situations like this, there is no time to pull the vang sheet around a winch first, then unlock it from the stopper and release it just a bit.

Doesn't take it too much time with the Boomtrim also?
No, in practise you have to release the boom just a marginal way. Imagine you pull a long rope with an attached small weight in the middle. Your will not be able to lift this weight much. Analog, to overcome the wind forces on the sail and leech it needs very high forces to control the twist.

You say this is only possible with thread driven boom vangs?
Certainly there are more solutions, but the enormous power you need to handle the leech and control it precisely in gusts can't be done by line purchased systems anymore. Slip, friction and stretch of long lines plus additionally counter spring forces of line purchased systems prevent this. Hydraulic systems do handle these forces, but unless you have an installed system they are too complex and costly. They are also not as responsive as an electric linear drive. So, Vang Sheeting is a dynamic trim, therefore we call our product Boomtrim.

more information (links & citations) on Vang Sheeting