Catamaran Evolution

Navalers

What is your question? Are you looking for a good book? It is best to start your own thread. Put all your questions in your thread so that people have something to read. Then if they are interested, they will help you.

Regards
- Richard

 

thank's
this is my first post,.......
and I'm net verygood in English

 

Hello Navalers,

A little hijack attempt at my thread?

Been busy with work and travel so don't have much time lately.
Richard is right. The question is difficult to answer. Start by reading the pertinent posts on the site and then start a thread so everyone has a history to follow so they can best advise you. The construction section will be the best place start to read and to start the thread.

I don't think language will be a barrier in this diverse site, but if you find it difficult, there are many translators on the net to assist. Everyone is extremely knowlegeable and helpful and they will be candid so that you can get a hard reality check.

Best of luck,

J

 

Hi J
Where's that model

 

Hello Richard,

Well, the 1:12 prints are still on the table. Not a whole lot of time to do much right now between work and business. Come 2/15 we are going to be back on the plane to the Dominican Republic until 3/5. We've been negotiating the sale of two of the four lots we own there so the attorney wants us to go out there.

It looks like it could be a while before I can commit some time to this.
Sorry.

J

 

No problem dude Good to see you are still alive

 

Somebody Stop Me...Please!!!

Hello all...

Still busy as hell with little time but to travel and do "business". Not done yet, but it sure is good to spend a little time among the seekers of the sea.

Did some playing around while transiting between locations and "reworked" the "Green Lantern" into a trimaran. Yes I know...somebody stop me please.

Here it is for your perusal and comments. As always, they are appreciated although there will be little response regarding the drawing because no studies have been done. Nothing at all...just "dooodling".

J

 

Hello to all...

Still busy.

Anyway...I was thinking about all of this capsizing stuff for multihulls and was wondering if anyone had any thoughts about the following.

You capsize...for whatever reason.
The mast head can have a deployable "balloon" type apparatus which when inflated can float her on her beam ends or slightly higher and keep her there, if not dismasted.

Option 1: Attach a sea anchor outboard on the flying hull to hold her to the sea (she will be beam on anyway) and attach a line outboard to the submerged hull and attach it to the dinghy and pull until she rights herself. I believe that a significant bang may occur if it happens.

Option 2: Attach the dinghy outboard on the flying hull a couple of feet off the water and flood the dinghy (carefully) until she rights herself. A sea anchor should be tied to the dinghy to pull the dinghy away from the hull as she begins to right so that the dinghy isn't smashed. A bigger bang may be experience if the dinghy isn't in the water when she decides to swing over.

Option 3: Attach a bladder to the submerged side and fill with air, and attach another bladder to the flying hull and fill with water until she rights herself. This could be a little bit scary if the water bladder isn't cut away at the right time.

Option 4: To hell with it. Set off the beacon, layabout and do nothing until rescue, let the insurance pay the loss or pay to salvage the vessel. This may be hard for me because I would have a lot of time on my hands to feel sorry for myself and cry.

I have been giving some thought to this possibility and wanted to get serious thoughts, which I'm sure have been given to the situation, albeit it would be easier to say to hell with it. Obviously, both hulls would have to be hatched off and pumps working diligently in all cases. A combination of all options except 4 may be required.

I am also giving some thought to righting her longitudinally as oppossed to laterally, but it isn't clear in my head yet. It looks like it may be possible with controlled hull flooding?

Okay. There it is. Anybody given these any serious thought?

J

 

A capsized multihull floats. A monohull deep sixes. Your EPIRB will call the rescue services. Relax.

Pericles

 

Hello Pericles...
...good to hear from you again.

Well it appears that is the opinion favored. Relaxing sounds good.
However, what if you can't? Would you still think that it could be worth it to exploring a little bit more on getting righted in case of capsize or knockdown?

I did some reading and saw the Harry Proa by Bob. Did you read the explanation about how it is righted? Unfortunately it is unproven but I hope they can test it in static.

Thanks
J

 

Its been done but is not worth it

In 1976 a guy called carlos Ruiz showed a capsize retrieval method at the world mutlihull symposium. Later Gunter Ullrich really did re-right a large - 35ft ish - cat designed by Derek Kelsall. He tried it before it was fitted out.

None of these ideas have been taken up because of the huge problems of ridding the boat of water and getting the boat to float properly upside down. The problems are huge and make the boat's normal usability much compromised. It is good to think of capsize though.

To that end design in some inverted flotation that works well the right way up too. Cats are really bad in the inverted flotation stakes. Tris are much better with two hulls to hold you up.

Step one is to not use the bows for accomodation. Have water tight bulkheads about 1/4 of the way back from the bows and enter these from the deck - no water into the boat if opened and much safer if you hit an object. You will gain great stowage and lose a bad berth. This gives you inverted flotation. Also use the space between the typical berths in fron of the mast for nothing - just void it or if you have to use it do a deck hatch again.

Down the back you need something too. Again do the watertight bulkhead thing and maybe a bigger than really needed aft beam, although this does take up cockpit space.

My 38 footer was designed with these features by Robin Chamberlin - Australia's most experienced (sea miles) designer. He remarked how unusual it was to have people asking for safety features instade of cutting through bulkheads for an extra berth.

If you really want to know more about capzize methods search for "The capsize bugaboo" Published by Multihulls magazine. You may get it on a secondhand book site.

cheers

Phil Thompson

 

JCD, stop being sooo paranoid - - take your calming pills - else you will never fully enjoy the pleasures of "messing about in boats"

 

JCD,

We now know very well that a trimaran will turn turtle if an ama is lost, so on that basis a wide bridgedeck catamaran would seem to be the soundest vessel.

http://www.john-shuttleworth.com/Articles/52images/fig10.jpg

Reef early, stream drogue over stern or lift dagger boards and deploy sea anchor as necessary. Read Gary Pearce answering questions about Zazen at http://www.john-shuttleworth.com/owner.html

Pericles

 

Hi JCD. Good to hear from you again. I read somewhere that nearly all catamaran rescues are caused by sailor error...leading to pitchpole. I'm surprised the skippers are so honest about it (if they are).

If that is true, then I would havet to agree with the others....it's so rare to capsize that it should be a matter for the insurance companies.

 

Still worthwhile building safety in

Although capsize may be rare if it occurs in most bridgdeck cats it may be catastrophic if rescue is not prompt. Cats are much better than tris at resisting wave action capsize as they have much greater rotational inertia so they will be safer in many situations. Be that as it may there may be times when offshore that you could find your built in safety considerations worthwhile.

Making the bows and sterns watertight makes sense from a capsize and collision standpoint - safer all round. Cats do capsize - putting it down to driver error could be dangerous. We all make mistakes and being on the water doesn't stop this. If you keep your ear to the ground you will hear a lot more capsize stories than are well reported - cats blown over sideways in the Whitsundays, over their bows in the Gladstone race, over their nose on a bar. Cats do go over usually due to silly sailing but a cautious owner will want to guard against error by building in safety features into their boat. I liked having a safe boat carrying my family so that if the worst happened I would be able to get them safe and dry whilst the EPIRB did its job. It made my cruising time more enjoyable.

cheers

Phil Thompson