View Full Version : self righting motor trimaran
Catamarans and trimarans have some advantages, but I wouldn't want to roll over in one - very likely that it would remain upside down.
What if the center hull were free to rotate in the roll direction? Ie, it would be weighted such that it would always orient itself to be right side up, even if the outer hulls were upside down (assume they are sealed and symmetrical so it doesn't matter). There would be a swivel at the bow and stern of the center hull that would allow it to roll 360 degrees wrt the outer hulls.
Could it work? Has anything similar been done?
Luckless
01-01-2010, 02:29 PM
Isn't one of the points of a wide body multi hull like a Cat or Trimaran that it is harder to flip in the first place?
It sounds complex and is a major system that could be prone to failure.
I think a safer design would be one that is intended to stay afloat when flipped. If you want a manually controlled self-righting function built in for half way clam weather (as in you can survive in the upturned craft till the storm passes) then a water ballasting system may be your best bet. Basically a series of controllable ballast tanks that you start flooding at one end or the other of the boat till it stands up right in the water, then over balance it and start empty the tanks.
You have to remember to consider the structure of the craft when it comes to righting. Most multihulls, from what I have read, are best flipped end over end because it reduces the chance of structural damage. However there is one unmanned Trimaran I came across a few months ago that is designed to flood one ama till it sits on its side, then flood a tank in the bottom of the other ama while emptying the top ballast tanks on the flooded side.
I personally vote for the "Just don't get yourself in position to flip it in the first place" option. It isn't the safest option, but I like it better than wondering if the rotation rig is going to fail and I find my boat doing funky things.
apex1
01-01-2010, 03:09 PM
The headline is a contradiction in itself already!
Multies do´nt self right, they are cuffins!
Stefan H
01-01-2010, 04:01 PM
Good idea! I think it could work if the center hull had round sections fore and aft with grooves. The crossbeams would have rings similar as giant ballbearings around the central hull. It would not work for a sailing trimaran though since the mast would get stuck...but for a motor trimaran, why not?
However, a motor trimaran with ballasted center hull dont need the floats in the first place...or maybe as a sundeck?
apex1
01-01-2010, 04:06 PM
A mono would need less thoughts and provide more safety................
Stefan H
01-01-2010, 04:29 PM
Apex, what a creative idea...a mono. It is a design forum, new ideas should be encouraged.
apex1
01-01-2010, 05:09 PM
Apex, what a creative idea...a mono. It is a design forum, new ideas should be encouraged.
After some three cicumnav.s and about half a dozen of newbuilts (for my personal use) I would claim to have at least a idea how a boat could look like.
another idea how a good boat could look like.
But no idea how it could look like a multihull! Not when given for free and all expenses paid for 50 years, I would sail a multi for more than a afternoon trip in sheltered waters,
They are coffins! Fast moving coffins! No experienced sailor ever sails a coffin.
Luckless
01-01-2010, 05:15 PM
They are coffins! Fast moving coffins! No experienced sailor ever sails a coffin.
So, if they are so dangerous, and all experienced sailors would never sail on one,... Then why are they still being made and experimented with? And used by experienced sailors?
Do you have any data to back up the idea that they are 'coffins'? Statistics to show that they are actually more dangerous, and analysis on why they are more dangerous? After all multihulls have been used in the pacific regions for how many hundreds of years?
Are modern super fast sailing races really any more dangerous in Mono vs Multi configurations?
Doug Lord
01-01-2010, 05:23 PM
After some three cicumnav.s and about half a dozen of newbuilts I would claim to have at least a idea how a boat could look like.
another idea how a good boat could look like.
But no idea how it could look like a multihull! Not when given for free and all expenses paid fot 50 years, I would sail a multi for more than a afternoon trip at sheltered waters,
They are coffins! Fast moving coffins! No experienced sailor ever sails a coffin.
=======================
Thats among the most ridiculous comments I've yet seen on this forum.
apex1
01-01-2010, 05:33 PM
=======================
Thats among the most ridiculous comments I've yet seen on this forum.
You see, one can learn every day................
apex1
01-01-2010, 05:41 PM
After all multihulls have been used in the pacific regions for how many hundreds of years?
That is a wide spread lie! The native outriggers have NOTHING in common with a contemporary multihull!
Sail them, and you know what I mean.
A multi is a fast sailing coffin period!
And every racing event involving these coffins prooves how much I am right, and you are wrong!
Typhoon
01-01-2010, 06:01 PM
WHy not have one outrigger you can fill with water, then blow down with air?
Theory goes, when capsized, fill one hull then when vessel is at around 90 degrees, blow water out and it rights.
Of course, you'd need a small lever or something to start the airborne hull in the right direction, but the forces wouldn't be great.
Tri's are particularly hard to capsize when you don't have sail loads acting on them......
Regards, Andrew.
Doug Lord
01-01-2010, 06:04 PM
From: http://docs.hydrofoils.org/vallejo.pdf
Conclusions
Inherent advantages of multi-hull ships in the deck area, speed/power performance,
seaworthiness, and safety can provide reliable fast passenger transportation in regions characterized
by high sea states and austere harbors. New concepts, such as small water-plane area ships with
outriggers and wave-piercing trimarans with aerodynamic unloading, can offer a step change in the
capabilities of marine vehicles and are economically more efficient than contemporary ships.
========
apex1
01-01-2010, 06:26 PM
Yes I agree CAN.
Fanie
01-01-2010, 06:27 PM
Andrew, some flotation in the mast could assist. There is a trimaran that does right itself, a link to a video was posted a while ago. It looked like it worked pretty well.
Come now Richard, we're not opening the mono vs multi thread again and not here. Next you'll want to ban all sailboats and only talk steamers.
Besides, mono's spill more beer than any other boat and my wife won't get on half a boat :D
My opinion is capsizing on a multi is not even an issue if you sail it within safe limits. Only in racing where the limits are pushed then may be. Other than that they seem to be some of the safest boats around.
No, you won't convince me otherwise.
Stefan H
01-01-2010, 07:31 PM
Actually a mono is safer, although I have a fast trimaran myself I would not cross an ocean with it because once upside down there is not much to do unless you can right it by yourself. However, If there was a way to do this...
Here is one example:http://3.bp.blogspot.com/_kiLtqc-FT2Q/SmL2jy5zk-I/AAAAAAAABw8/nqqYvNole6E/s1600-h/Exploder+25+trailer.jpg
Doug Lord
01-01-2010, 07:41 PM
Powerboat record around the world: http://www.earthrace.net/index.php?section=1 Now out to stop Japanese whaling...
Fanie
01-01-2010, 07:41 PM
Shouldn't the question be how to prevent capsizing.
The tri you show in the picture has an enormously long mast...
I would guess that in the right conditions, Earthrace could find itself upside down.
An example of where you want a stable boat that can flip over and then keep going is a surf rescue boat.
Luckless
01-01-2010, 08:09 PM
That is a wide spread lie! The native outriggers have NOTHING in common with a contemporary multihull!
Sail them, and you know what I mean.
A multi is a fast sailing coffin period!
And every racing event involving these coffins prooves how much I am right, and you are wrong!
I'm personally trying to learn and gather knowledge. You say "multihulls are death traps!" and then say a type of multi hull that has been used for centuries (and I would assume thus is safe.) has nothing to do with another type.
Do you have any suggestions on where to find studies that actually back up your claims on them being more dangerous than a similar sized mono sailing at similar speeds in similar conditions?
And still if they are so dangerous, why are there so many of them still sailing?
oldsailor7
01-01-2010, 11:55 PM
Pay no attention to Apex 1, he is talking out of the top of his head, :eek:
I have been sailing multihulls, both Cats and Tris for 48 years, with never a problem.
Once we were sailing a cruising trimaran at speed and hit a deadhead floating in the water.
It punched a hole as big as a fist in the forward underbody, and in a few minutes the floorboards were floating.
The outrigger floats took up the support and we simply sailed on to our destination in safety.
If that had been a leadmine we would have been left swimming as it went to the bottom. :eek:
Multihulls float---even if upside down.
Monohulls SINK. :eek:
Take your choice. :D
Doug Lord
01-02-2010, 07:32 AM
Catamarans and trimarans have some advantages, but I wouldn't want to roll over in one - very likely that it would remain upside down.
What if the center hull were free to rotate in the roll direction? Ie, it would be weighted such that it would always orient itself to be right side up, even if the outer hulls were upside down (assume they are sealed and symmetrical so it doesn't matter). There would be a swivel at the bow and stern of the center hull that would allow it to roll 360 degrees wrt the outer hulls.
Could it work? Has anything similar been done?
-------------------------------------------
In the wild side of sailing design both Sean Langman and Julian Bethwaite have conceived of "hybrid" boats that would have multihull speed coupled with
the ability to self-right. A sailing tri righting system(from 180 degrees) has been devised and tried. Perhaps some combination of these ideas could be used to allow a power multi to be automatically self-righting-I'd bet on it.
Here are Langman and Bethwaites concepts-I posted this in another thread and then realized it could be appropo here as well:
Hey Doug , what's up with the helpful and reasonable posts?
oldsailor7
01-02-2010, 03:14 PM
Catamarans and trimarans have some advantages, but I wouldn't want to roll over in one - very likely that it would remain upside down.
What if the center hull were free to rotate in the roll direction? Ie, it would be weighted such that it would always orient itself to be right side up, even if the outer hulls were upside down (assume they are sealed and symmetrical so it doesn't matter). There would be a swivel at the bow and stern of the center hull that would allow it to roll 360 degrees wrt the outer hulls.
Could it work? Has anything similar been done?
That idea was presented at the World Multihull Symposium in 1976.
It was rejected on the grounds of technical feasability. :o
Anything specific? - no offence, but I think "not feasible" has been said about every new thing that has ever been made.
gonzo
01-03-2010, 08:18 AM
Make a symetrical boat that can sail in either position.
FAST FRED
01-03-2010, 08:18 AM
Shouldn't the question be how to prevent capsizing.
On sailing craft the "old" answer was a self releasing sheet lock.
Most were simple cam cleats mounted on a ski binding.
With a fully battened main , no damage occurs with an early release.
KISS, and keep the Blue side up!
FF
gonzo
01-03-2010, 08:20 AM
Isn't there any Batman fan here? A batrimaran.
Fanie
01-03-2010, 08:44 AM
Once we were sailing a cruising trimaran at speed and hit a deadhead floating in the water.
It punched a hole as big as a fist in the forward underbody, and in a few minutes the floorboards were floating.
The outrigger floats took up the support and we simply sailed on to our destination in safety.
Get yourself a few pieces of PE foam blocks. You can cut and push this into the hole. Since it's flexable it will tend to seal the hole. I would think one with more density rather than low sensity, but beware, the higher density pieces become hard and difficult to manipulate.
Pay no attention to Apex 1, he is talking out of the top of his head,
He's just giving you grief like all the muti hull owners always give the mono's grief.
Secretly he desires a nice fast cat but is too proud to admit it :D
Fanie
01-03-2010, 09:05 AM
Shouldn't the question be how to prevent capsizing.
Fast Fred, I fully agree with you. I have said it before and I'm going to say it again :D
A mono dumps the wind when it heels, hence it doesn't capsize so easy.
A multihull resist heeling due to it's stability, but when the force on the sails become enough to heel it over, the force is usually so much that the righting force is not enough to prevent the capsize. Keep in mind there is no heavy keel on a multi that constantly tends to pull it upright.
The more a mono heels the more is the righting force from the keel, in a multi the more it heels the less the force that try to keep it upright.
So I would suggest another system to prevent capsize on a multi. I think it would be very possible to make a round clam cleat that has an adjustable clutch. When the force on the sail exceeds the clutch setting, it release the line and the sail can dump the wind, the boat stays upright.
Also, if a similar release method is made that acts on heeling it should also work well. When a certain angle of heel is reached the line is released, the sail force drops and the boat can right itself.
Now I know the racers are on to me already, but keep in mind when you're racing you are persuing the maximums and are hends on the whole time.
I'm referring to cruisers that will typically sail somewhere. It's that sudden gail that offers a problem.
In either case if the line is let out one can simply trim the sail back, no harm done and 10 seconds was lost in time.
Fanie
01-03-2010, 09:19 AM
Anything specific? - no offence, but I think "not feasible" has been said about every new thing that has ever been made.
You are absolutely right. The other problem is to get someone gutsy enough to actually do it and test it. Most just want to critisize from their chair and pesrpective.
Itchy&Scratchy
01-03-2010, 09:30 AM
If they persist with these massive hydraulic swing keels -that keep on falling off, a mono is as dangerous as a multi.:eek: :mad:
I like both so not taking sides on this one, just watching.:p
I wonder why they cant the keel instead of the mast? Either one will help keep the sail upright.
I think it’s a good Idea, sort of like the pedal of a bicycle rotates around the shaft. I just might give it a try, and I would think that you would have to run the center beam through the full length of the central hull. I like it when people think out side the box!
Itchy&Scratchy
01-03-2010, 11:18 AM
As far as I know they cant the keels so that they can overload the rigs for maximum power imput.
I'm wondering if this will just be a fad, although its what? about ten years now they've been using these things in earnest and they are still falling off, or the rams blowing up etc. I am wondering how long theyll perservere with them. Maybe a designer of race boats will come along and let us know the benefits behind them.
I would be interested to know how much more loading is exerted on a boat with; as opposed to same size boat without a canting keel.
And
How much extra reinforcement is put into building a boat with a canting keel? :eek: apart from the obvious keel area.
Anybody in that game?
Justin
kim s
01-03-2010, 11:56 AM
I do believe that some one is trying to start up a mini transat for multihull.
Part of the brief for the design,is it must be rightable (not sure thats good english)without outside assistance.
The one idea I saw was the outerfloats being able to move through 180 deg vertically and also the mast has releasing rigging to assist the turning as well.
As far as safety is concernd, i will just sit smuggly back with my beer staying where I put it, knowing that I will be in port tied up and safe long before the others arrive. I can be in before them when bad weather is on its way,
Mono hulls might be more "Sea Kindly". They have to be as they are going to out there a flippin long time.:P :P :) :)
Kim
View Full Version : self righting motor trimaran