Building new masts - need advice for Bluewater crusing rigging

[Jannik.Dk]

Hi,

Not long ago, I bought some used masts. The masts were produced by John masts, a danish company producing decent quality aluminum masts.
It got the masts cheap, with all hardware included. The previous owner did brake the spreader fitting for the mizzan mast, when taking down the masts. But for 800 euro i found it a good purchase.

The masts does not fit my boat in height! My reason for buying the masts, is to use the fittings to build new masts. The masts have the correct diameter / profile.

I know the construction of masts is a difficult task, the only reason I dare and feel comfortable to take on this job. Is that my father, has been building masts for 30 years. Both aluminum and carbon. We have access to all the necessary machinery to fabricate what we would need in aluminum and ss.

We have startet working toward starting the project. The masts have been stripped down to bare aluminum poles and all fittings has been inspected and sent to re coating.

The boat is a 48 footer, trintella v. It is ketch rigged masthead and from 1980, it's a heavy displacement boat. The masts is the original, both has single spreader. The main has one headstay and straight spreaders and the mizzan has swept back spreaders. Very common design in the seventies, for these type of yachts.

There is a few things I would like to upgrade, change and add, when constructing these new masts. But it is mainly the changes, I need some insight and ideas for.

The the main mast is going to get double spreaders. There is one main reason for this, the mast profile I'm going to use is thinner then old profile. (the original is very thick and heavy - there has been some development since the seventies) I have the fittings needed to do it, and I don't think double spreaders add too much complication on the rigging. The mizzan will continue to have single spreader.

I want to add an extra furling stay on the main mast. So we can have a big 140 genny on the forestay and a jib on the solent stay. (Genakker will added for light wind aswell, but needs no special features).
Additionally I would like to add a removeable babystay, for hank on storm sail.

Neither my father or my self is engineers, and I don't access to a mast designer/calculator. And due to, I'm not getting the masts build at a mast fabricator I'm not getting much advice/help anywhere I ask. So everything will have to be done with enough safety margins.

My main concern is about the "I" and "J" measurements with the extra stays and the aft support of these.

I found in selden mast guide, that they recommend that the solent stay is within 6% of the total "I". Then the back stay will take the load, and mast buckling should be avoided.
With the measurements of my masts, that means I would get 1 meter to work with.

As I see it, there is two(three) main ways to approach to adding extra stay.

1. Add the extra two stays within 1 meter of the headstay(from the top). The baby stay can be mounted just below the solent stay, but with enough room so you can use the solent stay. (on tack you would need to furl/unfurl, as with the genny)

This should give a distance(on the mast) of 75 cm from headstay, till the solent stay. And 25 cm from the solent stay, till the baby stay.

The "J" measurements is not that important, and could be made to fit the desired sail size. I would prefer the solent stay to be fairly parallel to the headstay for the looks. But the baby stay could be mounted further in on deck.

Pro = backstay takes all the load, no extra fittings required. (maybe add some reinforcement to mast tube in that 1 meter section. But fairly easy job)

Con = it could be difficult to keep enough tension on head- and solent stay at the same time.


2. Add the solent- and babystay in the area of top spreader. Same as if you would do a cutter rig. (this would be about 4-5 meters down the mast from the headstay).

Here I would need to support the mast aft, and add runners.

(I know you can also choose to add forward facing spreaders, but this is for me a very complex solution. And would rather not go down this route).

Pro = adding separate aft tension for solent- and babystay. Better fore and aft support of the mast overall.

Con = adding more work on tack. (I allready have runners on my mizzen mast) and it's a bit more work on the boat, adding chain plates for runners etc.

2.1 as 2, but instead of runners. Adding fixed immediate back stay.

Pro = as 2

Con =
- main boom will get restricted in the most forward position.
- high compression load on mast, due to sharp angle of immediate stay.
- high loads on deck fittings for the immediate stay.


Equipment on stays =

- Headstay is going to be electric furler (genny 140)
- Solentstay is going to be manual furler (I have both a drum and flat double line furler to choose from) (jib 110-120?)
- Babystay is going to be removable (storage at mast) made from dyneema with a Highfield leveler for tensioning. (storm sail)


The reason for wanting to add the extra furling headsail and babystay, is to be able to adapt to different wind strengths fairly easy.
And I would like to be able to fit my Headstay with double sails on down wind passage, where I would be able to roll up and still have the jib for off wind sailing.

I don't mind going to the deck, most of my lines will be at the mast anyway. But I would rather not take down sails from my furler in heavy weather. The idea of having a hank on, manageable size storm sail (about 18m2) that I prepare in advance, seems like a good choise.

Just to give a price frame, I'm expecting everything to cost me under 10.000 euro. I have most of the fittings and pieces. But still need to buy mast tubes, and alot of small things. (bare in mind, this is for 2 masts).

But this is for me a bargain, I can't imagine what a new set of masts would cost.


So basically, if it was you. what would you choose and why? Any other ideas?

If you have contact information to a mast designer, or you are one your self. Don't hesitate to send me private message, I might be interested in professional consulting at some point.

If I missed anything, let know.

Looking forward to get some input on this project, been struggling with it in my head for a while. Not quite sure what way to go.

Best regards,
Jannik

[psk125]

Sounds like you need an engineer. Who engineers the masts your father builds? He’s not just throwing carbon fiber at a mandrel and waiting to see what sticks. Someone worked out a layup schedule.

[Fore and Aft]

My first thought was can you find a sister ship with the rig you want? Or even a similar vessel in your local marina that has the rig you want. I always think its easier to copy something rather than try and reinvent the wheel.
Cheers