1987 Beneteau 305 First (dual spreaders) mast adjustment

[waterboyllp]

Hi,

I have recently purchased a 1987 Beneteau 305 First. The previous owner, during our pre-purchase discussions, mentioned, that there is very little adjust in the running backstay, due to (his belief), the vertical mast position is angled to far back/aft to stern, thus reduing the backstay adjustment travel.

There is a Tuff Luff foil on the forestay.

My questions,

1. Is there a methodology to determine the ideal mast angle?

2. Is there a documented, step-by-step process I could use to acheive this ideal.


Being a avid windsurfer, I know the difference a 3cm adjustment in the downhaul can make in the shape of the foil/characteristics of the sail. I do not have this same appreciation on a keel boat, thus the inquiry?

Thank you in advance for any suggestions.

[sailingfool]

What you are looking at is called "rake".

The ideal rake is that which produces an appropriate and pleasing weather helm.

The best thing for you is see if you can find a copy of the original boat manual, which provides rig setup instructions. i would expect the rake to be something like 5"-10", as measured at the gooseneck by a weight suspended on the main halyard. Whatever the initial setting, you then tailor it if needed to correct weather helm as experienced, or not.

[waterboyllp]

Thank you Sailingfool,


Follow on question

A. Fine tuning the mast to neutralize weather helm.

In windy conditions, flying the appropriate sail inventory, sails reefed and trimmed:

1. if the bow has a consistent tendency to round up into the wind, would one rake the mast slightly forward to compensate?


2. if the bow has a consitent tendency to come off the wind, would one rake the mast slightly aft to compensate?


Thanks

[mitiempo]

waterboy
The farther aft your sailplan the more the weather helm (rounding up into the wind). The farther forward the sailplan the less the weatherhelm until you pass neutral and get lee helm (tends to bear off away from the wind). More rake will give you more weatherhelm as it moves the centre of effort farther aft. You want a bit of weatherhelm but not too much. To answer your questions yes to both. But the best way is to tune the rig statically at the dock to what you think is right and go sailing. Best on a day when you don't have to reef and can sail with full main and jib. Hope this helps.

[waterboyllp]

thanks for the reply

[sailingfool]

Originally Posted by waterboyllp

Thank you Sailingfool,


Follow on question

A. Fine tuning the mast to neutralize weather helm.

In windy conditions, flying the appropriate sail inventory, sails reefed and trimmed:

1. if the bow has a consistent tendency to round up into the wind, would one rake the mast slightly forward to compensate?


2. if the bow has a consitent tendency to come off the wind, would one rake the mast slightly aft to compensate?


Thanks

The fine tuning is to minimize weather helm.

Minor weather helm is generally good, makes the boat a little easier to steer, and results in the boat luffing up if the helm is released...

RE 1: a consistent tendancy to round up is fine, but with normal heel, say 20 degrees, the weather helm should not be excessive, i.e. should not require high rudder angle (more than 5-10 degrees) to maintain course. If you can see a big wash off the rudder, you have too much weather helm.

At some point of excessive heel angle, most any boat will round up.

RE 2: Yes. You should generally only experience lee helm sailing with a headsail alone.

[blt2ski]

There is a pretty good how to HERE in the gear-maintenance area of this forum. Along with in sailing world, and sail iirc in the US, these rags have had some pretty good tuning articles in the last 12-18 months or so.

You have the same basic rig I have on my Jeanneau arcadia of the same IIRC vintage, mid 80's for you? Helps to have it correct. I pulled my forstay a bit more forward than it came, and helped a bit.

Sailingfool, where do you teach skiing at? I'm a lev 3 and lev 1 examiner at my school.

marty