Mast rake and pre bend

[Stovic]

Hi. Just bought a 20 year old Oceanus 411 and to me it looks to have too much mast rake but can't seem to find much info. Can anybody help me please?

[Cowpoos]

Can you post some pictures from a couple of angles, please? and you have adjustable backstays I gather?

[psk125]

What does Beneteau tell you? The drawings look like there should be some rake. How much depends upon how the helm balances. You will need to go sailing to determine how much windward helm you have going upwind. If it’s too much, with the rudder over all the time so that it’s slowing you down, reduce the rake. Prebend from the babystay should not be too much of a concern unless you’re buying new sails. Then your sailmaker will let you know.

[hlev00]

In addition to Beneteau, check into the 423 group over at groups.io. There are some 411 owners that follow that thread. Also you might find it helpful to get a sailmaker to take a look, probably while out sailing. Ultimately it does come down to how the boat sails.

[GordMay]

Greetings and welcome aboard the CF, Stovic.


The Owner’s Manual doesn’t seem to address rig tuning.
➥ http://dicksimonyachts.com/Brochures...ers-manual.pdf

From Neil Pryde’s Sail Trimming Guide for the Beneteau Oceanis41"
The ‘balance’ of helm is regulated through mast rake, fore and aft when the forestay is adjustable.
In the case of the 41, the forestay length is preset from the factory.
a.More mast rake aft will move the sailplan center-of-effort aft, in effect putting more loads on the sails aft of the keel. This will ‘pivot’ the boat around the keel, bringing the bow into the wind; which is weather helm.
b.Mast rake forward and the opposite is true, the balance moves forward and the boat will gain neutral or lee helm.
c.The OC 41forestay length is optimized by the factory.
➥ https://www.neilprydesails.com/image...ning_guide.pdf

See also:
➥ https://www.neilprydesails.com/image...ng%20Guide.pdf
➥ https://www.neilprydesails.com/image...im%20Guide.pdf

[Greg Mason]

On my Pedrick Cheoy Lee 41 offshore, I simply tied a crescent wrench to my main halyard and dropped it to just above the deck. The distance between the wrench and the mast told me how much rake I had. My sailmaker wanted 14", so I had to jack up the mast and cut off a wedge of mast base (deck stepped) to achieve the result. Never had weather helm.

[MJH]

Originally Posted by Stovic

Hi. Just bought a 20 year old Oceanus 411 and to me it looks to have too much mast rake but can't seem to find much info. Can anybody help me please?

The book Illustrated Sail & Rig Tuning by Ivar Dedekam has excellent instructions and illustrations on how to do this and more. Add it to your sailing library.

~ ~ _/) ~ ~ MJH

[iann]

Hi one of the problems with some production yachts is that they dont fit adjustable forestays , to save a few bucks , ok when new but over time the wire stretches quite a bit and the rigs end up with too much rake

[Oceansailor]

Originally Posted by iann

Hi one of the problems with some production yachts is that they dont fit adjustable forestays , to save a few bucks , ok when new but over time the wire stretches quite a bit and the rigs end up with too much rake

The stretch in rig wire is so little (0.021%) that you can totally ignore it for calculating the rake.

[Moontide]

How the boat sails is what counts, not how it looks. If the is a bit of weather helm it is probably fine. If a lot of helm then it may have too much rake.



Sails have to be trimmed correctly to know if the rake is too much, or too little.

[Stovic]

Hi cowpokes and you folks who have been generously replying. I will try to post a photo and yes it has adjustable twin backstays on turnbuckles

[iann]

Originally Posted by Oceansailor

The stretch in rig wire is so little (0.021%) that you can totally ignore it for calculating the rake.

are you suggesting that a new 16 M forstay will only streach 3.36 mm in 20 years

[Oceansailor]

Originally Posted by iann

are you suggesting that a new 16 M forstay will only streach 3.36 mm in 20 years

The years has nothing to do with this. Rigging wire does not get longer for every year you use it. The first time you tension the stay there is some compression if not pre stretched. But after that nothing happens if the stay is not overloaded.

A 1x19 strand wire will stretch 1 mm per 2 m @ 5% breaking load. This elongation is something the rigger will take in account when making your forestay.

I guess the stretch you are talking about is in addition to above?

[GordMay]

“What Mast Rake is All About” ~ by Dave Gerr [Updated 2017]
The practical aspects of raking masts and the effect of rake.
➥ https://www.sailmagazine.com/cruisin...e-is-all-about

[danstanford]

Too little rake can make the boat have problems pointing due to the center of effort being too far forward and pushing the bow down wind.
Our process is to go sail upwind and check for weather helm wanting enough to only have the rudder a few degrees down. The sweet spot is to have the angle of the rudder provide lift without being so angled that it creates drag.