Mast rake

[Darrel_Walters]

Looking for opinions if a modern mast with in mast furling really requires it to be raked back, if it does is there an average rule of thumb on how much rake may be required.

Also would rake change the center of effort on the foot of the mast

Any comments would be warmly welcome

Regards
Darrel

 

[Bobobolinsky]

Are we talking cats, cos there are specific circumstances related to them?

 

[Darrel_Walters]

In response ..... In particular 40ft single hull
Cheers

 

[Chrissie]

Seldon told me that their in mast furling masts should not be raked as it pushes the furled sail against the inside wall of the mast, it would be worth contacting the manufacturers of your mast to find out for certain

 

[Ex-SolentBoy]

Looking for opinions if a modern mast with in mast furling really requires it to be raked back, if it does is there an average rule of thumb on how much rake may be required.

Also would rake change the center of effort on the foot of the mast

Any comments would be warmly welcome

Regards
Darrel

We are 44 ft and Selden in-mast. The boat designer specified the amount of rake required and it was about 30cm on an 18m mast, including a slight pre-bend as specified by Selden.

 

[earlybird]

Seldon told me that their in mast furling masts should not be raked as it pushes the furled sail against the inside wall of the mast, it would be worth contacting the manufacturers of your mast to find out for certain

Can't follow that argument! Does boat heel matter as well ? I can understand mast bend being a problem, but not mast rake.
I've not got in-mast furling, but I would have guessed that rake might be called for, on the basis that the lack of roach, and generally poorer drive of such a mainsail might move the CoE forward, thus inducing lee helm compared with a "normal" sail plan.

 

[Ex-SolentBoy]

Can't follow that argument! Does boat heel matter as well ? I can understand mast bend being a problem, but not mast rake.
I've not got in-mast furling, but I would have guessed that rake might be called for, on the basis that the lack of roach, and generally poorer drive of such a mainsail might move the CoE forward, thus inducing lee helm compared with a "normal" sail plan.

Poorer drive? What poorer drive? With proper vertical battens you get just as much roach, and just as much drive.

The limiting factor is hitting the backstay - same for everyone.

 

[Darrel_Walters]

My mast is made by selden
With in mast furling
The foot of the mast on the deck has a curve on it and in the middle a pin to hold it to the deck plate, if you move the mast backwoods ie increase rake, the center of effort on the foot of the mast must move also backward.

So if there is no rake the center of effort would be in the center of the foot of the mast, my query is how much rake given a mean average be classed as normal

Cheers

 

[saltwater_gypsy]

Poorer drive? What poorer drive? With proper vertical battens you get just as much roach, and just as much drive. .

Roach is nothing unless the sail shape is good. Vertical battens are in the wrong place to shape the mainsail and generate drive. They just make a furling mainsail slightly better.
Ask any Americas Cup skipper!!!

 

[earlybird]

The foot of the mast on the deck has a curve on it and in the middle a pin to hold it to the deck plate, if you move the mast backwoods ie increase rake, the center of effort on the foot of the mast must move also backward.

Cheers

I don't think that the effect of that feature on CoE is of any consequence whatsoever.
The important fact is that raking the mast moves the CoE of the whole mainsail aft.

 

[lw395]

Seldon told me that their in mast furling masts should not be raked as it pushes the furled sail against the inside wall of the mast, it would be worth contacting the manufacturers of your mast to find out for certain

That's bend, not rake. In mast furlers need to be kept straight to within quite tight limits, but no reason not to rake it back if that gives better balance.
An in-mast rig might well need to be raked back if the mast step position etc was right for a normal main with a bit of roach.

 

[Bosun Higgs]

Looking for opinions if a modern mast with in mast furling really requires it to be raked back, if it does is there an average rule of thumb on how much rake may be required.

Also would rake change the center of effort on the foot of the mast

Any comments would be warmly welcome

Regards
Darrel

The centre of effort is a notional point on the main and the genoa ( and both combined so you have 3 of them) through which the thrust of the sail can be said to operate. In practise, the thrust of the sails is distributed to the boat through the sheets and standing rigging as well as the foot of the mast. How much goes where I wouldnt know but Selden will. Certainly the distruibution of the forces will change as the rake of the mast changes, and I would guess that more rake means less force on the foot of the mast and more on the sheets. But that is a guess

What is your concern when you say "Also would rake change the center of effort on the foot of the mast"?

 

[TRUNDLETRUC]

Mast rake depends on one thing - the balance of the boat going to windward with full rig in medium conditions.
If the rake is correct the rudder should be in the straight position ie. in line with the boat. (Mark this position on the wheel preferably before you launch with tape of something else).
In this position the rudder will have the least resistance to forward motion and will act as a keel at the back to reduce leeway.

My boat has in-mast reefing (Bavaria 36) and indeed it has got more mast rake than many boats I berth by.

 

[Darrel_Walters]

I dont know if this post has gone of topic a little, but with a modern Bermudian Sloop rig, sledon in mast furling etc, what in these days would a rigger rake a mast, and also is there need for rake. lets assume the rigger is not aware of the sail shape and is hoisting the mast for the first time

would he have no rake or 2 inches of rake or perhaps a foot of rake ?????

regards
Darrel

 

[Tranona]

You got me thinking. I have the same set up so I checked on the Selden booklet on setting up rigs. No mention of specific amount of rake. However my mast just like Trundletrucs has more rake than other boats. It has just been set up by an experienced rigger, so next time I see him i will ask him why he set the rake (although I suspect it has alweyas been like that).

 

[TRUNDLETRUC]

I thought riggers usually put the rig together approximately but that if an owner wanted the best performance from his/her yacht you either employed a sailmaker/boat tuner to go out in the boat or you did it yourself based on the way the boat performs.

Incidentally if you put more aft rake on the mast be careful the boom does not come into contact with bimini covers, heads! etc.