Mast Rake (with picture)

[jonathantwite]

Hi all,

When it was blowing old boots at hunts, I raked my mast back considerably. Having run out of adjustment on my shroud plates the strouds are now attached straight to the boat - essentially I have an adjustment of approx 1cm on them. When I returned to my club, I left the mast back as we had another weekend of pretty strong stuff. I went sailing today in light winds expecting the boat handling to be naff, however, I found that I had virtually no weather-helm (subject to keeping the boat upright), and I was outpointing our local Streaker. I was not able, though, to point as high as the Albacores.

My question is this - is weather-helm the only problem with too much rake or will boat speed drop. I.e. in practice, if I have no weather-helm the rake is ok and the boat speed will be ok?

I have attached 3 photos (2 upwind, 1 downwind). What do people think - is it too far back for ~5-6knts?

Thanks

Attachments:

[jonathantwite]

Pic 2

Attachments:

[jonathantwite]

Pic 3

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[polyfiller]

Jonathan....it is difficult to assess rake purely from pictures. I'll post a second reply with a guide to measuring rake (and doing it the way most do ... tape measure from main halliard to transom is pants).
First to comment on you question about too much rake. If your boat still handles well with a lot of rake, and doesn't have much weather helm, rmemebr this setting and use it when windy. Generally speaking rake de-powers a rig (actually it just makes the boat fee less powered by moving the moment of heal aftwards and upwards ....just think of a sailboard in a blow and you'll get the idea)....but most moths encounter a point at which too much rake makes the boat impossible to handle .. because the centre plate position and shape mean we end u with too much effort aft of the centre of resistance.

One effect of lots of rake is to de-power off wind.....the profile of the sale as presented to the wind is reduced .....put a sheet of cardboard in front of your face and then tilt the top towards you ....you will see that you are looking at a progressively smaller surface area. Mast rake is difficult to set without understanding all characteristics of rake, More rake encourages lift (like saiboard) footing speed, reaching speed. It also creates weather helm which is to be avoided (it is wasted energy). Standing a mast upright (less rake) actually improves pointing (but only to the point where you are not inducing lee helm).... but his is very dependent on sail shape and mast bend. If you go well downwind and not up wind add rake. If you go well up wind and not downwind, less rake. Tbh I always tune a moth to be manageable in a real blow and then sail around any limitations in lighter wind.

The key is to measure experiment, and interpret the results of experiments.