Should a mast be perfectly vertical?

carl170 · 22 Jun 2014

Hi all!

I have just raised the mast on my new (to me) boat.

The mast seems to tilt back toward the stern.

It is perfectly straight though, so it is not curved like a rake in the mast.

Is this normal? I suppose I could put a smaller turnbuckle on at the front and pull it forward?

Any thoughts or opinions much appreciated.

Regards

Carl

sarabande · 22 Jun 2014

some masts are raked for'd or aft, as the sails will induce or reduce a curve, which may be designed to be there to make the flappy things work effectively, or to make the centre of effort move for'd or aft of the CLR. Some masts have pre-bend as well, for the same reasons.

What is the boat please, and what kind of sailing are you doing ? Cruising, racing, pottering ?

Rigger Mortice · 22 Jun 2014

It's perfectly normal for a mast to lean back a little.
To be pedantic any leaning is "the rake". Any curve is "pre-bend"

oldharry · 22 Jun 2014

carl170 said:
Hi all!

I have just raised the mast on my new (to me) boat.

The mast seems to tilt back toward the stern.

It is perfectly straight though, so it is not curved like a rake in the mast.

Is this normal? I suppose I could put a smaller turnbuckle on at the front and pull it forward?

Any thoughts or opinions much appreciated.

Regards

Carl

Perfectly normal to be raked back a little, many are designed that way. Some early racing ychts had msts raked back as much as 15 degrees. Some modrn rigs the mast is designed to have a slight curve aft, often adjustable in a racing rig to allow for a fuller or flatter main for changin ' g conditions. Some trad; working boats like the Brixham Trawler had forward raked masts, but this is very rare now.

What is vital is that he mast isvertical across the boat, or she will perform differently on opposite tacks. Check the builders specs for the exact degree of rake the designer allowed.

oldbilbo · 22 Jun 2014

G'd morning.

It is a normal setup to have one's mast(s) raked aft. The extent depends on the needs of the boat and the intentions of the designer.

Raking the mast aft moves the effective 'centre of effort' of the sailplan - especially the mainsail - further aft and should influence the balance of the boat between the tendency of the sails to turn the boat up into the wind, and the tendency of the hull/keel/rudder to turn the boat downwind.

The 'ideal' balance is, for many, where the boat tends to turn slowly up to windward, and where this tendency is counteracted by a very light/fingertip pressure of the tiller 'up to windward'.... i.e. slight 'weather helm'.

Most would adjust their mast rake, little bit by little bit, to achieve this optimum, in normal sailing conditions. Have a look at what owners of similar boats do.... and ask them.

Other factors besides mast rake affect the 'balance' of the boat, including changing the position of the 'centre of effort' by reefing the sails, changing fore and aft trim by having half-a-dozen heavyweights and their crates of beer back in the cockpit, raising/lowering any centreboard.

There are several pages on this on the web, and in books on sailign techniques. Here's one of them : http://johnellsworth.com/writing/nautical/balance_helm/balance.html

Seajet · 22 Jun 2014

carl170,

remember the designer will have hopefully allowed for the weight of a typical crew in the cockpit, which will effectively rake what appears a vertical mast when viewed from afar with nobody onboard.

It is however normal to rake the mast a little relative to the waterline, in the case of my Anderson 22 the 25' 6" high masthead is 4" aft of the foot, using the main halliard as a plumb-line, without any pre-bend.

Lakesailor · 22 Jun 2014

The OP doesn't say what boat it is.
After a bit of digging about it seems he has a Halcyon 23
Perhaps that will help with replies.

KellysEye · 22 Jun 2014

As a rule of thumb mast are designed to be straight and placed at at the centre of effort, rake it and you you move the CofE and affect the balance of the boat. There are exceptions such as racing boats some schooners etc.

Seajet · 22 Jun 2014

More traditional boat masts with masthead rig especially will expect a straight mast without bend but even their designers may expect a little rake as this aids performance, though too much will give unwanted extra weather helm.

With a Halcyon 23 I'd expect very little rake but if she were mine I'd try 2" aft at the top.

carl170 · 22 Jun 2014

Sorry for the delay, I wasn't expecting replies so quickly!

It is indeed a halcyon 23!

Thanks for your replies!

Regards

Carl

VicS · 22 Jun 2014

Digram here shows the mast vertical

http://sailboatdata.com/viewrecord.asp?class_id=3651

akyaka · 22 Jun 2014

You might find the Offshore Yacht Class Owners Association site helpful

http://markjohnson.websitetoolbox.com/?forum=291468

Birdseye · 22 Jun 2014

Depends entirely on the boat design whether or not the mast slopes back towards the stern. No slope side to side.

Rum_Pirate · 22 Jun 2014

You decide

The type derives from pilot boats as did the Baltimore Clipper. The raked masts and fine lines show an effort at attaining speed. At various times pungy schooners served as cargo carriers and oyster dredges. They were replaced in the oyster trade by the skipjacks which survive to this day

Lakesailor · 23 Jun 2014

There was a similar thread to this a couple of years ago. It may help. http://www.ybw.com/forums/showthread.php?335099-Mast-rake-tricky-geometry

Davegriff · 23 Jun 2014

Just read Carl's blog. Looking good; nice to see 'older' boats being restored.

William_H · 23 Jun 2014

All that has been said about mast rake is correct. However beware this concept of weather helm where the boat naturally turns into the wind. The concept of ballancing this by adjusting the mast rake or amouint of sail fore and aft is OK for conditions where the boat is flat in light winds. As soon as most keel sail boats get any real heel on them then the inballance of drive from the sails not over the drag of the hull will cause weather helm (boat tries to turn into the wind) this is normal and an not be adjusted out by mast rake etc.
Only reduction of sail area usually jib will reduce heel and so reduce weather helm.
Regarding mast rake you must ensure that the boom remains high enough above the cockpit. Also as sid a mast will take on rake ina small boat when crew pile into the cockpit.
My little boat used to have mooring chain hauled onto foredeck so pulled bow down and she had a distinct mast leaning forward look. However when sailing with crew the stern sank about 10cms and mast raked aft. (As related to the horizon.) So basically don't worry about mast rake. If it looks OK it probably is olewill

Birdseye · 23 Jun 2014

Your problem will be finding the correct designer information on an older boat but it will be there somewhere. For example my boat with a masthead rig has a sternwards slope of 15 inches measured by dropping a halyard from the mast head and checking where it hangs against the gooseneck. It also has pre bend ie curve of half the chord width of the spar again measured using a halyard.

Try talking to a big sailmaker . Their designs have to take into account both mast lean and bend

carl170 · 23 Jun 2014

Davegriff said:
Just read Carl's blog. Looking good; nice to see 'older' boats being restored.

Thanks for that!

It is slow going though, as I only have some evenings and weekends to work on her.

The hull is finished, only the cockpit, cabin and interior to do!

If anyone is interested, the link is:

http://halcyon23.blogspot.co.uk/

Regards

Carl

PS - I have tried to add in my autosignature, but it just doesn't seem to save! Any ideas?

carl170 · 23 Jun 2014

Thanks for all your replies.

I will stop worrying and start sailing!

Regards

Carl

Should a mast be perfectly vertical?

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