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  #1  
Old 02-16-2012, 10:20 PM
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rubyjeaan rubyjeaan is offline
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Another stupid question - rerighting a folding tri

Was reading a blog on tri's flipping over, but that they don't sink. My quesstion is: if you had a folding tri, could you possibly fold the ama's and re-right. Courious....Michael..
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  #2  
Old 02-16-2012, 10:50 PM
cavalier mk2 cavalier mk2 is offline
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The only thing stupid is having a question and not asking it. You should get on amazon or your favorite old book finder and look for a copy of "The Capsize Bugaboo" put out years ago by Charles Chiodi the old Multihulls Magazine publisher. It covers ideas along those lines and many others. Most people don't take the time to work it out but re righting without assistance is possible. Sailing without capsizing though, takes less work!
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Old 02-16-2012, 10:53 PM
cavalier mk2 cavalier mk2 is offline
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The head over heels approach is probably easier to rig than a fold and roll. Ian Farrier had some ideas on the method you mentioned for some of the F boats but I'm not sure if any were tried.
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Old 02-16-2012, 11:43 PM
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Scharnhorst a sprint 750 recently capsized at Airlie Beach they pulled in the floats and righted the boat with a little external help. Most tris are righted bow over stern with a tow from the rear seems to work best that way with less risk of damage to the mast. As Cav says its better not to go upside down in the first place but accidents can happen particularly when your racing and really pushing the boat.
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  #5  
Old 02-17-2012, 05:56 AM
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oldsailor7 oldsailor7 is offline
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Yes. When Logan Apperleys Kraken 40, "Mana Moana" was tipped over in Manly harbour, by a bullet gust from East Head, the water police were right on the job pulling her bow over stern and on her feet again in about 20 min.
Might have been a different story in the open ocean though.
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Old 02-17-2012, 11:26 AM
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spidennis spidennis is offline
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Michael,
Which blog was that? And to what size boat are you asking about?
I'm designing a folding beach cat for adventure racing
and gave this same idea some thought.
I'm interested in unassisted recovery,
and with gear stashed in the hulls a traditional righting may not be possible?
Anyway, it's in the back of my mind to try this at some point.
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Old 02-17-2012, 12:20 PM
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I've had a few ideas. I like idea used on the MacGregor 33' catamaran. Basically a whisker pole mounted to the bottom of a cross beam in the center, then using a line over the top to a winch and a water bag for ballast. I believe the same could work even easier, better for a trimaran. The only key to doing so is to make sure that you aren't completely turtled. You'd need to get the mast up to water level somehow. The Macgregor catamaran uses a masthead float.

If it were me, this would be my desing, and I may well use this on the 18' trimaran I'm planning to build soon.

I would do one of two things:

1 run a small air line up the mast internally to a balloon on top; or

2 rig my baloon on a small cable internally in the mast, such that when I pull the cord it discharges the Co2 cartridge into the baloon.

Either way, a durable balloon on the tip of the mast could be implemented for around 3lbs of additional weight (Google avalanche airbag for an example).

Once your turtled you pull the rip cord - how to rig so that you can access when the boat is turtles is something that will depend on the boat.

The airbag will raise the mast to water level. Once in this position you affix a whisker pole to the bottom of the center hull and run a line over it to a fabric water bag that can hold enough water to right the boat.

I believe all of the tools to do this could be added at less than 200lbs weight penalty. For a small 18' trimaran like I intend to build, I'd guess 15lbs max - although I believe I could flip it over easy enough with just the weight of two crew members.


I also do think that it would be do-able to fold in the ama on one side on a farrier type design, and roll to that side, It would make righting much easier, the big problem is that you have to disconnect the shroud that goes to that ama, meaning you might be dis masted in the process. I'm not sure how you get around that issue.
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Old 02-17-2012, 12:30 PM
Jetboy Jetboy is offline
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Thinking a bit more about this in my head, you could also build the mast tip air bag into a small assembly that would just hook on to the head of of the main sail when you raise it if you think conditions warrant.

A 12gram CO2 cartridge will provide roughly 7 liters of volume. So, that means that there will be about 7kg of lift provided. You'd have to calculate whether that is enough bring the mast tip to the surface. It may take a larger cartridge or multiple small ones. I like the idea of disposable cartridges because they are cheap and easily available as well as easy to adapt existing hardware to work with them.
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  #9  
Old 02-17-2012, 12:49 PM
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spidennis spidennis is offline
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I like the CO2 charged mast float, hadn't seen or heard of it mentioned but figured someone else would have thought of this at some point. I think it's a great idea!

there is a type5 CO2 pfd that fires off when it gets to a certain depth. This technology could be used for the mast head float?

somewhere on this site it that product:
http://www.mustangsurvival.com/
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Old 02-17-2012, 01:05 PM
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rubyjeaan rubyjeaan is offline
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Quote:
Originally Posted by spidennis View Post
I like the CO2 charged mast float, hadn't seen or heard of it mentioned but figured someone else would have thought of this at some point. I think it's a great idea!

there is a type5 CO2 pfd that fires off when it gets to a certain depth. This technology could be used for the mast head float?

somewhere on this site it that product:
http://www.mustangsurvival.com/
Intresting idea, this could be a inflatable bag, attached to a gear bag on one of the ama's & raised to the mast head w/ a spinaker halyard. This way it could be deployed when your ready for the righting moment. I don't think it would take that much bouyancy to start the mast to float. et's keep up the thoughts...Michael..
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Old 02-17-2012, 01:14 PM
Jetboy Jetboy is offline
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I think a depth release cartridge would be ideal. You could even just buy one of those PFDs and just build a nice sleek fixture to house it in at the tip of the mast. Ideally it would just slip down inside the tube, but that would depend on your mast set up.

I think the ideal location would actually be where the highest stays meet the mast. I could imagine a situation where the mast wouldn't be strong enough in heavy waves etc. and buckle above the highest stay shroud attachment points.


If you wanted to get really slick, you could actually use the mast step structure to house a pole internally that would have a screw type fitting on the underside of the hull. once upside down, you'd just unscrew or somehow telescope the pole right out of the bottom of the main hull. And it would be at the strongest point on the structure to have it attach. You could even use a second hatch of some sort that would be exposed in a capsize to hold the water ballast bag and line to right. Then everything needed would be available quickly in a capsize to get the boat righted quickly.

One thing I'm not sure about though is how you would go about removing or retracting a fixed pole on the bottom of the hull once you're back upright. It may be best to have it just slip into a some type of fixture so that once upright gravity causes it to fall out and then you can pull it back up attached to the line with the water ballast.
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Old 02-17-2012, 01:23 PM
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The whole capsize thing has been done to death most tri's that capsize do so when racing and even then it doesn't happen very often. It's been examined and righting systems have been designed but most people decide that the space they occupy and the weight they add isnt worth the penalty. A workable system for trimarans was designed by Len Surtees years ago and I think Derek Kelsall and others also tested their own designs with good results. If it's safety from capsize on a small trimaran you want then lower volume floats are the way to go, if you look at the Farrier website the small trimarans with the best safety record are the boats with low float volume but performance is reduced because you start to bury the float sooner. Ian Farrier did some tests with righting a folding trimaran and managed to do it unassisted I'm not sure I'd want to try better to have a safe platform upside down and call for help.

There is some dramatic footage of ORMA racing trimaran's capsizing keep in mind they had a 100' wing mast on an extremely light 60' trimaran and massive sail area. Gary might be able to confirm this but I believe the later boats were so powered up that they reefed in anything over 6 knots. They were also square length to beam so pitchpoles were sudden and violent and their skippers always pushed the boat to the max often singlehanded. When really big tri's like these capsized they normally towed them in and righted them at the dockside with a crane.
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Old 02-17-2012, 01:25 PM
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spidennis spidennis is offline
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ok here's the link to the Mustang

The award-winning MD3184 Inflatable PFD with HIT (Hydrostatic Inflator Technology) and Sailing Harness is Mustang Survival's top-of-the-line inflatable PFD with an integrated harness that exceeds ORC standards. Designed for serious sailors with exclusive technology that enhances safety and minimizes maintenance, this is our most popular inflatable PFD in the sailing community.

The Hydrostatic Inflator Technology offers reliable inflation in a low maintenance design that will only automatically inflate when submerged in 4 or more inches of water and not inadvertently due to rain, spray or humidity. Exclusive to Mustang Survival in North America and maintenance-free for 5 years or until inflated. Made for the most severe marine environments the Deluxe Inflatable PFD with HIT will meet the challenges of the most demanding users. It also features the patented SecureZipô closure system to ensure the PFD will stay closed during even the most rigorous activity and still opens effortlessly upon inflation.

This lightweight and comfortable PFD can be worn over a T-shirt on warm days or over thicker garments in colder conditions. It is low profile and allows for maximum mobility. The neoprene Comfort Collarô is soft on your neck and is part of a sleek design that is so comfortable you'll forget you're wearing a PFD.
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Old 02-17-2012, 01:27 PM
Jetboy Jetboy is offline
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Here's a poor quality scan of a Macgregor 36 brochure. Look at page 14 for how he provides to right it.

I like the idea for a trimaran. I've never owned one though. I'm concerned about how stable they are when on their side. Would it tend to roll toward the bow or stern? It could make a dangerous situation if they are inherently unstable like that.
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Old 02-17-2012, 01:35 PM
Jetboy Jetboy is offline
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Quote:
Originally Posted by Corley View Post
The whole capsize thing has been done to death most tri's that capsize do so when racing and even then it doesn't happen very often. It's been examined and righting systems have been designed but most people decide that the space they occupy and the weight they add isnt worth the penalty. A workable system for trimarans was designed by Len Surtees years ago and I think Derek Kelsall and others also tested their own designs with good results. If it's safety from capsize on a small trimaran you want then lower volume floats are the way to go, if you look at the Farrier website the small trimarans with the best safety record are the boats with low float volume but performance is reduced because you start to bury the float sooner. Ian Farrier did some tests with righting a folding trimaran and managed to do it unassisted I'm not sure I'd want to try better to have a safe platform upside down and call for help.

There is some dramatic footage of ORMA racing trimaran's capsizing keep in mind they had a 100' wing mast on an extremely light 60' trimaran and massive sail area. Gary might be able to confirm this but I believe the later boats were so powered up that they reefed in anything over 6 knots. They were also square length to beam so pitchpoles were sudden and violent and their skippers always pushed the boat to the max often singlehanded. When really big tri's like these capsized they normally towed them in and righted them at the dockside with a crane.

With an inflatable mast float, a pole, some rope, and a water bag, your weight penalty is almost nothing. Getting the mast up to water level is the hardest part. Flipping it back over form there should be a piece of cake. The avalanche airbags only weight around 3lbs.

I see no reason why a trimaran can't have the provisions for self righting. If it can be done easily with a small weight penalty on a 36' catamaran, there's no reason it can't be done on small trimaran.
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