Free standing epoxy mast

[mrooven]

Hello

I'm thinking of buying a free standing epoxy mast (maybe that's why I've chosen such a title for this topic...:p). I'd be grateful for any useful information you may give me about it - is it a good idea for a boat with LWL about 30' designed for entertainment-sailing in the area of Europe (From Baltic to Mediterrenian). Would it be safe enough?

[Eric Sponberg]

mrooven,

You may have a hard time finding someone building production free-standing masts--in fact, I don't know of any. All the suppliers I deal with are custom builders. To learn more about the state of the art of free-standing masts, you can go to my website at: http://www.sponbergyachtdesign.com/StateoftheArt.htm. That should answer any questions about their design, strength, stiffness, and suitability on various designs. Free-standing masts are inherently safer than any other type of rig, assuming of course that they are designed and built properly to begin with.

Eric

[rob denney]

G'day,

We have just completed 12m, 14m and 18m freestanding rigs using a new low cost moulding technique, resulting in very low cost, high quality masts.

To quote for a mast I need to know it's length
diameter and the required laminate. If you don't have this, then the boats sail plan and righting moment will enable a rough quote to be made.

If this quote is satisfactory, we then get an engineer (yours, Eric or ours) to design the laminate, we fine tune the quote and proceed. The cost of engineering, if done by us is $500 Euros.

As to it's safety, I am in agreement with Eric. Far safer than a stayed rig, both short term and long term. Also far easier to sail with and cheaper to buy.

Regards,

Rob Denney
www.harryproa.com
Regards,

Rob

[grob]

The thing that is often forgotten is that you can't treat the mast as a seperate entity, Does the boat itself have to be re-engineered to take the cantilever loads that are now conentrated at the mast foot. My conclusion was that in a lightweight multihull like a beachcat, you end up with a heavier boat as well as a heavier mast.

Gareth

[rob denney]

G'day,

In a beach cat, a stayed rig is the only option, unless you put the mast in a hull or have a large structure mounted on the beams.

In monos, tris and bridgedeck cats, if you design the boat from scratch to have an unstayed mast, it will end up much lighter. Not only no chain plates, stays, turmbuckles, strikers and massive beams to take the rigging loads, but the entire boat can be built much lighter as the rigging is not trying to drive the mast through the boat by bending the ends up in the air.

Take this approach to one of it's logical conclusions and you may end up with a harryproa. We have just launched a 15m/50' cedar strip version with 2 huge double bunks, full headroom, covered cockpit with seating for 8, toilet and nav station. With an unstayed, balanced rig it weighs 2,000 kgs/4,480 lbs ready to sail. see http://www.harryproa.com/BlindDate/Jan_9.htm

A cat with similar layout and performance would weigh at least 3 times as much. A lot of the weight saving is due to the unstayed mast.

At beach cat level, next summer we will have a production 7.5m/25' beach proa available, weighing under 100 kgs. This is 40% lighter than the 6m/20' Tornado cat, but with the same sail area and righting moment. Again, mostly because of the unstayed rig.

regards,

rob

[stewi]

You could go to Istanbul:

“As for Perkins, he needed three carbon fiber free-standing masts as tall as 192 feet. Since nobody makes anything like that, he had to do it himself. He started by buying 25 tons of carbon fiber thread in the Far East, which rated a 'thank you' note from the manufacturer. Then he had to overcome the problem of exporting material used in B-1 bombers to an Islamic country, because he was creating a mast-building facility, and training the workers, for the Perini Navi yard in Istanbul. It's been risk after risk, and challenge after challenge - which is what these guys love. By the way, Mirabella took seven years from concept to completion, and Maltese Falcon will have required about 4,000,000 man-hours before she's done later this year.”

Otherwise:
http://www.cstcomposites.com/marine.htm
http://www.marten-spars.co.nz/
http://www.superspars.com/
http://www.accmarine.com/
http://www.southernspars.com/

Ultimately, consider doing it yourself:
Some companies to be contacted in Germany/Switzerland:
http://www.paucoplast.ch/de/faserverbundtechnik_kohlefasern_s01.htm
http://www.geisendorf.de/techtex.htm

[rob denney]

Stewi,

Any more details on the 3 x 192' high freestanding masts?

regards,

Rob

[yokebutt]

I was very surprised at the lack of reinforcements the first time I looked inside a Wyliecat 30. After a bit of pondering I realized that the loads imparted by the mast is largely parallel instead of transverse to the areas it's pushing on, (deck and hull) and as such, is a much better structural situation to start with.

Yoke.

[rob denney]

G'day,

Not only is all the reinforcement at the top and bottom bearings and in a transverse plane, but it is loaded in either tension or compression. Therefore, given that the deck and hull are thick enough not to buckle, only half as much material is actually required. If you use tow (the individual bundles of fibre used to weave carbon cloth) as that material, it can be spread out into the hull and deck with very little weight added.

Regards,

Rob

[stewi]

Rob,
I was searching in Google for "free standing mast" and got to this link:
http://www.latitude38.com/LectronicLat/2005/0505/May13/May13.html
Regards,
Stefan