What length of Mast?

[robertfairclough6]

I have recently purchased a 25ft yacht that’s never, ever been on the water. Odd but true, 42 years old and never completed. He has done a great job on the interior, but died before he completed the build. It had no keel or method to put one in, got round that! There is a mast, it was brand new in the late 90’s. But for a 25 ft boat, it’s massive and very heavy. Roughly 13/14 metres. It’s brand new, if old. It’s never been used. There are lines of fine rope for rigging, each with a tag for its design use.. its alloy is thick, it’s 150x 90mm. I’ve been sailing 50+ years, while others in the same class, can mast up and rigg, single handed. You’d need a crane for this. Heaven knows, a good wind in full rigg, you’d be over!
Qtn. What’s the formula for rigging a boat? What’s the method for judging what’s right or too much?

 

[Praxinoscope]

Mast length will obviously vary according the boat design, but I would have thought 9 or 10 metres would be far more in line with a 25’ yacht, 13/14m would seem more appropriate for a 30/35’.

 

[Bodach na mara]

You'll need to contribute a few more posts before the system will let you add pictures or send and receive Private Messages. Until then we will be only guessing what type of boat we are discussing and how it should be rigged.

A few basic rules apply to standing rigging (the stuff that holds the mast up.) The shrouds on each side should each be of a strength capable of lifting the weight of the boat. For a 25 ft boat that will be a 6mm diameter 1 X 19 wire. Probably!! The main shrouds will pass over the ends of spreaders each half the beam. Lower shrouds are attached at the spreader roots, which are about 55% of the mast height from the deck. The forestay will be of wire a size larger. There are various points on the mast where it can be attached. Usually at the mast head these days.

To start making sense of this I suggest looking at lots of different boats and talking to a rigger. The mast sounds a bit long. On a 25 ft Folkboat the mast was about 30 feet long and on my 28 ft Commando it was 31 feet. I could just about lift either of them but putting them up was best done using a crane, although I once stepped the Folkboat mast on my six-mtere hull ( long story) using a convenient, disused, railway bridge over the canal where it was laid up.

 

[LittleSister]

I worry (perhaps unnecessarily) about both the boat you have bought, and how you are approaching it.

Was the builder working to a recognised design - if so follow that - or was he just making it up as he went along?

That it had no keel or provision to attach one makes me suspect that other critical aspects of the boat will be at least questionable.

How did you get around the keel problem? I wonder how you knew the appropriate weight, dimensions and positioning of the keel if you don't know what the rig should be.

Likely the mast was a chance purchase of one that was available cheap. You could cut it down to length, if it wasn't still too heavy for the keel etc. Does the boat have provision for fitting a mast (e.g. step and support)?

 

[Neeves]

Make the appropriate number of posts, adding as much detail as possible and then when you are permitted to post images - do so.

Your yacht might be a version of Kon Tiki (in which case it would not be designed for ballast). We simply don't know and nothing we say will help you - unless its a very lucky guess.

Once you can post pictures you will enjoy the full depth of knowledge available here - and much more than you need.

Just post and be patient.

Jonathan

 

[Tranona]

there is no constraint on posting pictures for new members.

You will get sensible advice if you provide details of the design of boat with photos. Just length is meaningless as a racy fractional rig could be as tall as 11m on a 25' boat, but a conservative family sailer around 9m. My 26' heavy displacement cruiser had a mast just under 10m from the deck.

 

[LittleSister]

Qtn. What’s the formula for rigging a boat? What’s the method for judging what’s right or too much?

It's more than just the total amount - though that will give you a starting point. Decisions have to be made about the fore and aft point(s) of balance, aspect ratio, etc. All of those need to take into account hull and keel (and rudder) shapes, sizes and positions, etc., together with the type of sailing it's aimed at.

There are a few books on basic yacht design, but it's a complex subject people spend lifetimes studying (and even then, most production boats undergo some revisions once the prototype has been tried out). (There are a lot of books on those complexities in their various aspects, but you wouldn't understand them until you've mastered the basics.)

You might consider commissioning advice from a qualified yacht designer. It might be cheaper in the long run than getting it wrong, and having to put it right. You could probably work out a reasonable approximation with a bit of study if your boat is middle of the road, and you are willing to experiment and put up with whatever you end up with.

 

[William_H]

It seems to me that the mast he has is not suitable. However the dimensions of a mast is a compromise much dependent on your sailing use.
A tall mast will give you good light wind performance, but then will be a liability in strong winds and especially if you want to lower or remove the mast yourself. So will you have an engine and will it be in effect a motor sailor or a true sailing yacht. One 20ft keel boat here was available new in 3 different mast heights.
First thing to decide is if you want a fractional rig or mast head rig. A typical fractional rig will be lighter tapered mast with swept back spreaders which are robust so there is no inner forestay which makes tacking easier.
A mast head rig is perhaps simpler. Provides for a larger jib, but needs either one central inner forestay (an impediment to tacking the jib) or twin intermediate forestays which may get in the way of tacking. A fractional rig mast will typically be based further forward than a mast head rig based further aft. So things like mast support location under the mast base might dictate rig type.
So perhaps OP needs to scout around to see what is available in the way of lighter masts. Then rig it. I don't believe that slavish following of boat design is critical. I built a cat of similar size many years ago with virtually no experience. 30ft mast mast head rig. Found cheap sails all successful.
Of course OP should not spend huge amounts of money on the fit out simply because a second hand in service boat might be cheaper than all new fit out.
Just keep asking on this forum. ol'will Too late now but this boat might have made a lovely displacement type motor boat.

 

[Neeves]

Accepting there appears to be no keel, which with a rather tall mast seems unlikely (unless its a raft ) than a 13m mast, keel stepped is slightly different to a 13m mast deck stepped. We simply cannot make any comment in the absence of more information - and photos are the best place to start.

We need photos of the yacht and of the existing mast.

In the absence of photos we are wasting our time and you, yours.

I confess I'm not going to be able to comment, well outside my knowledge base - but I do know photos are worth 1,000 words and I also recognise people who post think the members here are magicians who can conjure a recommendation based on a couple of sentences.

Dream on (they are free)

Everyone has a camera on their phone - use it (that's what you ;aid for when you bought it).

Jonathan

 

[Black Sheep]

a 13m mast, keel stepped is slightly different to a 13m mast deck stepped.

This.
The dimensions of the mast suggest a keel-stepped unstayed mast.

Is there a hole in the deck for the mast to go through? In which case it is intended to be keel-stepped. The mast may be 13m total length, but this means probably only 11m above deck.

I'd be very interested in what the tags say about the purpose of the lines, as that will give a clue to the rig.
It's possible that the boat is not designed for a Bermudian rig, but for a freestanding rig such as a Junk rig.

If the boat is designed for a junk rig, it may be easier to stick with that than to try to convert to a Bermudian.

 

[DownWest]

OP mentions others in the 'same class'. Is this general length or more specific, like the actual design? Average 25ft boat would do fine with 5mm SS rigging, some do with 4mm.
It does sound like the mast might be a bit long...

If the OP (& welcome BTW) looks at SailboatData.com at similar boats (if the actual design is not listed) then some idea might guide things.

 

[Wansworth]

Why to OP sort of disappear…..more info is just a question of typing

 

[jamie N]

My new Folkboat mast is precisely 9.68 metres long, but you should be aware that it's deck mounted, keel mounted would be a metre or two longer.

 

[Wansworth]

Bought a secondhand mast and added on another three feet,it was of heavier section and wall size but didn’t make a difference to the boatsstability but it didn’t bend out of shape….fitted to a Commando class motor sailer designed by Primrose

 

[coopec]

How do the dimensions compare to the Bruce Roberts 25ft Trailer sailer?

Roberts Adventurer 25 Trailer Sailer Boat Plan | Designs

I have a heavy mast but the riggers told me to use lead ballast instead of iron ballast. I'll be interested to see how good their advice was!

 

[Bodach na mara]

Bought a secondhand mast and added on another three feet,it was of heavier section and wall size but didn’t make a difference to the boatsstability but it didn’t bend out of shape….fitted to a Commando class motor sailer designed by Primrose

I also had to remast a Commando. But as it was an insurance job I got a kit from Z-Spars and got the wiring done by a local rigging company. To get the mast section right I made an accurate drawing of the cross-section and worked out the second moments of area fore and aft and lateral by finite element analysis then chose a suitable section.

A very different process was used when my old 1912 Anker and Jensen 6-metre mast got broken during a gale by another boat breaking loose. No insurance involved as I didn't have any and I don't think that the owner of the other boat had either. A friend told me of a damaged mast from a Folkboat which I purchased. The only damage was at the heel where it had been rubbing against rocks after falling overboard. I cut about a foot off and spliced it about 3 feet of Oregon pine supplied by my friend. The standing rigging is a long story but the executive summary is that it was made from 7X7 galvanized wire and I learned how to splice it.

 

[Wansworth]

I also had to remast a Commando. But as it was an insurance job I got a kit from Z-Spars and got the wiring done by a local rigging company. To get the mast section right I made an accurate drawing of the cross-section and worked out the second moments of area fore and aft and lateral by finite element analysis then chose a suitable section.

A very different process was used when my old 1912 Anker and Jensen 6-metre mast got broken during a gale by another boat breaking loose. No insurance involved as I didn't have any and I don't think that the owner of the other boat had either. A friend told me of a damaged mast from a Folkboat which I purchased. The only damage was at the heel where it had been rubbing against rocks after falling overboard. I cut about a foot off and spliced it about 3 feet of Oregon pine supplied by my friend. The standing rigging is a long story but the executive summary is that it was made from 7X7 galvanized wire and I learned how to splice it.

The extension was solid wood set into the alloy mast about 15inches.Wooden extension was perfect for fastening cleats

 

[Wansworth]

Also removed the rudder and mounted further aft on a s keg which worked well,a lot of the interior had dry rot but was easily replaced

 

[Bodach na mara]

Also removed the rudder and mounted further aft on a s keg which worked well,a lot of the interior had dry rot but was easily replaced

I thought of doing that with the rudder. Where it was as designed and built made the boat a real mare to manoeuvre at low speeds. The next owner did what you did but after a few years more or less abandoned the boat on the hard at a local marina and she is now a sorry sight with lots of rot in the hull.

 

[Neeves]

The other factor omitted - does the yacht have a bow sprit.?


However the big question now is - will the OP return?

Jonathan