Lat21

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many of these proas are incredibly beautiful works of art.  An amazing amount of intellectual energy has been spent by some very ingenious individuals trying to get them to work well.  Does anyone else get the feeling that the results may never justify the effort?  If the proa was the way to go wouldn't VPLP be designing and building them as a much cheaper alternative to the tri?  I am awed by the beauty of these proas but I find it hard to believe they will ever be more effective than a good cat or tri. 

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14 hours ago, ProaSailor said:

You're digging yourself a hole, DDW.  Multihulls have far more initial stability than monohulls so are "stiffer", putting greater loads on the rig in gusts because they don't respond as easily by rolling a little bit.  Have you done any big multihull sailing?

I have done some big multihull sailing as it happens. The stability of a monohull or multihull is what it is. The rig needs only to withstand that stability, then the boat will overturn. The shape of the curve makes no difference, nor does the roll energy. The graph you show must represent a monohull and multihull of the same displacement (and the monohull shape looks to be about 100 years old). Today's monohulls are beamy and pick up stability quickly with heel. Today's faster multihulls are light, and stability is directly proportional to displacement. Compare a 10,000 lb 45' catamaran to a 25,000 lb 45' monohull. The lateral bouyancy shift will be something like 8' for the cat, and 3.5' for the monohull. The monohull will have MORE ultimate stability, not less. On a 25,000 lb cat, the stability will be much higher - but that boat will not be fast, and the weight of the rig will not be a concern. 

6 hours ago, overlay said:

You are the one crusading for unstayed rigs. others are pointing out flaws in your arguments. 

The biggest of all  is probably the lack of control over mast bend once the epoxy and carbon  is put back in the cupboard,

With a stayed rig the all important mastbend / sail shape can be easily adjusted to suit the conditions. I though you of all people would have understood that.

You really need to research a little further before slagging off decksweepers.

See...

 

Used by Pete Burling, Scott Babbage and Harry Mighell at the 2017 Moth Worlds. Also used by Nathan Outteridge to win the 2018 Australian Nationals.

This sail provides great righting moment and adds the power down low in the sail where you need it best. It has proven to be quick and WIN races. 

 

 

I am an evangelist for the unstayed rig. But - one more time - READ CAREFULLY - I've NEVER said this was the universal solution. What I've said is that it is underutilized. The "flaws" people are pointing out are more often misunderstandings or pure ignorance. What I object to is your assertion that the stayed rig is the universal solution, or that unstayed rigs are necessarily slow, or necessarily heavy. Those are false. 

You are right about the unstayed rig being less tunable - as I have said in this thread already (look for example in post #480). In something like the Moth, where a single sail is used for every condition, this is an advantage for stays. In an oceangoing boat where the sail size can be varied from about 200% to 0%, this is less of an advantage. I've not missed it at all on my boat. The performance difference between a tunable section shape, and tunable area, favors tunable area every time. If you have the choice, you tune the area to the conditions. If you don't have that choice, the backup is changing the section.

I did not slag on deck sweepers - I happen to believe they are fast. Again read what I wrote, this time concentrating on comprehension:

On 4/7/2018 at 9:58 AM, DDW said:

Deck sweepers must be perceived to be slow (by your logic), as nearly all Moths don't have them.

Your logic is that if boats don't have something (like an unstayed rig) it must be slow. Most Moths don't have deck sweepers. QED.

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15 hours ago, DDW said:

You do not need to guess on section and wall thickness, this is well understood engineering. There is no difference between a monohull and multihull: in each case the mast section must be large enough to withstand the maximum overturning moment the hydrostatics can produce (plus a safety factor) and no more. For a light multihull this might be less than a heavy monohull.

Proa Sailor :  Stayed masts on monohulls or multihulls are primarily  seized for buckling under compressive loads (e.g. using Euler formula for Buckling). Maximum compressive loads are not determined by energy to capsize but by maximum righting moments (rolling and picthing restoring moments ! ) and rigging geometry. Under these aspect, as says DDW there is no difference between multihulls and monohulls. 

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I love this proa shitfights both for the entertainment and the information. Granted I don´t know much, but you learn a lot by reading the points and counterpoints

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17 hours ago, Russell Brown said:

I would be interested to know the length, weigh and cost figures for your mast. I like unstayed masts, even though I have little experience with them, I just can't picture adding those kind of loads on a multihull.

Hmm, my response to this got posted twice, I deleted one and it deleted the other as well....

My mainmast is 65' from heal bearing to truck. It supports a 960 sq ft mainsail and a 1050 sq ft asym downwind. Msurf says the hull has 105,000  ft lbs max righting moment at 30,000 lbs cruising displacement. The criteria for the mast was that it be bulletproof first, and it was designed with about 3.5x safety margin or just under 0.4M ft-lbs ultimate moment. The mainmast is 11" diameter at the partners, tapering to 4" at the truck. It  was braided in uni carbon then bagged, infused, and autoclaved by Composite Engineering. When completed with all fittings and reinforcements, it weighed 570 lbs. The mizzen mast is 40', only designed to support 260 sq ft but the criteria was it would stand in a hurricane. Finished, it weighed 120 lbs. The main boom is 24' long and has to withstand the semi-cantilever pusher vang load, 13,800 lbs down at the 'crosstrees' and 4000 lbs up at the clew. It was built on a 12m class boom mandrel (though significantly heavier wall) and weighed 121 lbs. In practice, we do not achieve those loads and it could have been lighter. The carbon vang struts and cylinders weigh about 60 lbs each. The mizzen boom was oversized for appearance, and weighed originally 41 lbs, but has been cut shorter, not sure now. The CG of the rig is low, because the masts are tapered in both diameter and wall. The CG of the mainmast is about a foot above the vang strut attachment.  

In 2008, the whole custom rig (two masts, two booms, and hydraulic vangs) cost about $90K. We never got it quoted as a marconi sloop, but I've seen the quotes and bills for similar sized sloops at the same boatbuilder. To compare you need to include all the standing rigging and fittings. 

Engineering the loads into the bridgedeck of a cat would be challenging, I'd be reluctant to do that experiment full scale on a big boat. In a proa or tri much easier. An unstayed rig isn't an isolated design choice, but part of the whole picture. It makes more sense on a una rig than a sloop, and on a monohull or proa than on a catamaran. I like the idea of a biplane cat, and am curious to see how the Chris White one works. 

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19 hours ago, DDW said:

Hmm, my response to this got posted twice, I deleted one and it deleted the other as well....

My mainmast is 65' from heal bearing to truck. It supports a 960 sq ft mainsail and a 1050 sq ft asym downwind. Msurf says the hull has 105,000  ft lbs max righting moment at 30,000 lbs cruising displacement. The criteria for the mast was that it be bulletproof first, and it was designed with about 3.5x safety margin or just under 0.4M ft-lbs ultimate moment. The mainmast is 11" diameter at the partners, tapering to 4" at the truck. It  was braided in uni carbon then bagged, infused, and autoclaved by Composite Engineering. When completed with all fittings and reinforcements, it weighed 570 lbs. The mizzen mast is 40', only designed to support 260 sq ft but the criteria was it would stand in a hurricane. Finished, it weighed 120 lbs. The main boom is 24' long and has to withstand the semi-cantilever pusher vang load, 13,800 lbs down at the 'crosstrees' and 4000 lbs up at the clew. It was built on a 12m class boom mandrel (though significantly heavier wall) and weighed 121 lbs. In practice, we do not achieve those loads and it could have been lighter. The carbon vang struts and cylinders weigh about 60 lbs each. The mizzen boom was oversized for appearance, and weighed originally 41 lbs, but has been cut shorter, not sure now. The CG of the rig is low, because the masts are tapered in both diameter and wall. The CG of the mainmast is about a foot above the vang strut attachment.  

In 2008, the whole custom rig (two masts, two booms, and hydraulic vangs) cost about $90K. We never got it quoted as a marconi sloop, but I've seen the quotes and bills for similar sized sloops at the same boatbuilder. To compare you need to include all the standing rigging and fittings. 

Engineering the loads into the bridgedeck of a cat would be challenging, I'd be reluctant to do that experiment full scale on a big boat. In a proa or tri much easier. An unstayed rig isn't an isolated design choice, but part of the whole picture. It makes more sense on a una rig than a sloop, and on a monohull or proa than on a catamaran. I like the idea of a biplane cat, and am curious to see how the Chris White one works. 

Nice post. I like to hear about actual solutions.

OTOH I think LAT21 has be driven away.  How have the repairs to Fujin been going. How bad was the damage?

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4 minutes ago, Mizzmo said:

Nice post. I like to hear about actual solutions.

OTOH I think LAT21 has be driven away.  How have the repairs to Fujin been going. How bad was the damage?

Sails destroyed, rig destroyed, interior pretty much trashed, electronics gone, etc.....

 

Work is in progress...

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26 minutes ago, ASP said:

Sails destroyed, rig destroyed, interior pretty much trashed, electronics gone, etc.....

 

Work is in progress...

That sucks, I was hoping it would be kind of a G-4 situation 

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9 minutes ago, Mizzmo said:

That sucks, I was hoping it would be kind of a G-4 situation 

Can you guys get back on topic?  This thread is about how cantilevered masts are better than masts supported by stays.

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45 minutes ago, ASP said:

Sails destroyed, rig destroyed, interior pretty much trashed, electronics gone, etc.....

 

Work is in progress...

Hoping they are working on boat repairs rather than court dates with insurance lawyers.  Too cool a boat to not see back on the water.

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1 minute ago, Wess said:

Hoping they are working on boat repairs rather than court dates with insurance lawyers.  Too cool a boat to not see back on the water.

To my limited knowledge, as of two weeks ago, things were going smoothly... Don't quote me though...

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2 hours ago, r.finn said:

Can you guys get back on topic?  This thread is about how cantilevered masts are better than masts supported by stays.

Original topic was big cats going upside down

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4 minutes ago, longy said:
2 hours ago, r.finn said:

Can you guys get back on topic?  This thread is about how cantilevered masts are better than masts supported by stays.

Original topic was big cats going upside down

@r.finn was joking.  You are right - after the C600 Race, of course.

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So, there were some hints that Fujin was maybe going to make the St Barts event. Did they put things back in order on time?

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On April 10, 2018 at 1:55 PM, DDW said:

Hmm, my response to this got posted twice, I deleted one and it deleted the other as well....

My mainmast is 65' from heal bearing to truck. It supports a 960 sq ft mainsail and a 1050 sq ft asym downwind. Msurf says the hull has 105,000  ft lbs max righting moment at 30,000 lbs cruising displacement. The criteria for the mast was that it be bulletproof first, and it was designed with about 3.5x safety margin or just under 0.4M ft-lbs ultimate moment. The mainmast is 11" diameter at the partners, tapering to 4" at the truck. It  was braided in uni carbon then bagged, infused, and autoclaved by Composite Engineering. When completed with all fittings and reinforcements, it weighed 570 lbs. The mizzen mast is 40', only designed to support 260 sq ft but the criteria was it would stand in a hurricane. Finished, it weighed 120 lbs. The main boom is 24' long and has to withstand the semi-cantilever pusher vang load, 13,800 lbs down at the 'crosstrees' and 4000 lbs up at the clew. It was built on a 12m class boom mandrel (though significantly heavier wall) and weighed 121 lbs. In practice, we do not achieve those loads and it could have been lighter. The carbon vang struts and cylinders weigh about 60 lbs each. The mizzen boom was oversized for appearance, and weighed originally 41 lbs, but has been cut shorter, not sure now. The CG of the rig is low, because the masts are tapered in both diameter and wall. The CG of the mainmast is about a foot above the vang strut attachment.  

In 2008, the whole custom rig (two masts, two booms, and hydraulic vangs) cost about $90K. We never got it quoted as a marconi sloop, but I've seen the quotes and bills for similar sized sloops at the same boatbuilder. To compare you need to include all the standing rigging and fittings. 

Engineering the loads into the bridgedeck of a cat would be challenging, I'd be reluctant to do that experiment full scale on a big boat. In a proa or tri much easier. An unstayed rig isn't an isolated design choice, but part of the whole picture. It makes more sense on a una rig than a sloop, and on a monohull or proa than on a catamaran. I like the idea of a biplane cat, and am curious to see how the Chris White one works. 

Sorry I didn't respond sooner to this post, DDW. A bit too much work happening at the moment and I didn't even see this until just now. Thanks for the info. I got to know Ted Van Dusen from Composite engineering by phone because I used their bolt rope track on my new rig. We have kept in touch over some other projects and I'm quite impressed by him and by what he has done with composites. Maybe you know this, but his spar division was basically shut down in the recession. It's recently back to full bore and they are looking for qualified help. There aren't many spar builders period, but even fewer that build unstayed masts, so it's good that it's going again. They have quite a mandrel list and seem to have a good understanding of the engineering of unstayed masts. I still don't see one in my future, but I do appreciate the advantages.

 

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1 hour ago, Russell Brown said:

Sorry I didn't respond sooner to this post, DDW. A bit too much work happening at the moment and I didn't even see this until just now. Thanks for the info. I got to know Ted Van Dusen from Composite engineering by phone because I used their bolt rope track on my new rig. We have kept in touch over some other projects and I'm quite impressed by him and by what he has done with composites. Maybe you know this, but his spar division was basically shut down in the recession. It's recently back to full bore and they are looking for qualified help. There aren't many spar builders period, but even fewer that build unstayed masts, so it's good that it's going again. They have quite a mandrel list and seem to have a good understanding of the engineering of unstayed masts. I still don't see one in my future, but I do appreciate the advantages.

 

Have used one of his spars (original mast kept as a spare) after breaking our aftermarket mast did not leave me as a fan.  Agricultural would be my most accurate description.

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His finish work does not match some of the other spar builders (which is why I did my own finish work on it) and his performance to schedule was certainly not on time . But he does know carbon fiber, and the equipment he has (the fantastic braiding machine and the 60' autoclave) is hard to match. Not going to do it in your back yard. At the time, no one else was braiding spars, I think there is some competition now. I believe he has only had one freestanding rig break (the ill fated Wylie Wildcat 44) and as I recall is was traced to incomplete infusion. The hull on that boat was also infused (by others) and incompletely, and was cut up for scrap. 

I had the mast quoted by another spar builder, they wanted to build it as two halves and glue it together, and clearly had a very poor understanding of free standing rigs. 

Ted's rowing shells are impressive - you can pick up a one man shell with one finger. 

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The most common unstayed mast is on every sailboard. That works very well because the rightng/control force/canting force is applied at the level of the boom. The tension/compression member is a human body.Cheers Bottman

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Bump.  How's the refit of Fujin coming along?  Such a cool boat should be sailing.

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2 hours ago, Rasputin22 said:

That ain't exactly the bunny slopes...

Hard to tell with all those bunnys'.:lol:

Is this race actually allocated a Category. ie CAT 1 or 2.

It seems from the notice of race that a lot of stuff is recommended but little actually required.

Is this a race that is still accesible to the wealthy weekend warrior unlike , say , the S2H?

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