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Go Back   SailNet Community > On Board > Boat Review and Purchase Forum > Sailboat Design and Construction > Multihull
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  #221  
Old 03-17-2014
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Re: How do you feel about catamarans?

Quote:
Originally Posted by jzk View Post
Are you aware of such an instance of damage to the stern of a catamaran deploying a Jordan Series Drogue?
No...

Quote:
Originally Posted by jzk View Post
I am not saying that the concern is illegitimate, but the drogue acts to minimize the forces acting on the boat while a sea anchor tends to present shock loads. Do you agree with that part?
Yes...

Quote:
Originally Posted by jzk View Post
I remember some test video on the Jordan site or linked to by it, but I am not finding it. It shows the effect of a large breaking wave on the boat. The idea is to maintain some forward motion, but not allow the boat to surf down the wave and crash out of control. Instead, the boat continues forward with the drogue providing a retarding force increasing with the square of the speed of the boat. That allows the boat to be lifted up under the wave with the breaking wave impacting the boat as gently as possible, under the circumstances.
I believe quite the opposite occurs, actually, and it was expressed by Steve Dashew in my original cite. One of the problems with the JSD it that it can exert a powerful DOWNWARD pull on the stern - which is only increased as the attitude of the boat changes as it begins to surf down the face of a wave, and the 'bungee' effect of the drogue only increases as the crest of the wave approaches the boat...

Anyone deploying a series drogue in storm conditions had better be prepared for being pooped routinely, and have a bulletproof companionway and a cockpit that drains quickly... Many cats are extremely vulnerable to a breaking sea from astern, hence my own reluctance to consider lying to a drogue in heavy weather in a typical cruising cat... Well, aside from the fact that I will likely never find myself offshore aboard one, to begin with... :-)

Quote:
Originally Posted by jzk View Post
Here is another question. Are you aware of an unsuccessful deployment of a jordan series drogue on a catamaran? If so, I would like to read it. I remember reading that the concern about presenting the stern is common, but it never really ends up being an issue in practice.
Again, such accounts are few and far between, I'm not sure the absence of any disaster stories re multihulls streaming a drogue is proof that it will necessarily be a successful tactic...

Quote:
Originally Posted by jzk View Post
As far as the swinging doors, what if they fit recessed into the sides of the companionway such that they did not catch or snag on passers by? I like the idea of being able to seal it up quickly. And, crew can quickly come and go minimizing the time that it is open.
Creating such recesses would be a more expensive way to build a companionway, of course, and I've yet to see it on any boat I've run... Last boat that had them was a Cabo Rico 42, but at least they were set on take-apart hinges so that the doors could be removed, and stowed elsewhere...

Drop-down 'window shade' style drop boards are a pretty slick way to go, and are becoming more common, particularly on Euro boats... But they can also have 'issues', I once had the boards on a Trintella 50 get stuck in the recess below the sill, and it required a bit of taking apart of some finely finished cabinetry below to get them out... KISS, conventional drop boards with a convenient and secure rack for stowing them is still the best way to go on most boats, in my opinion...

Quote:
Originally Posted by jzk View Post
I was speaking to a Jeanneau engineer at a boat show about the windows. I will see if I can get some data on their strength. Again, it is a valid concern, but let's see what the engineering data says.

Thanks.
Well, this wasn't a Jeanneau... But, I'll rely upon what I saw with my own eyes, and heard with my own ears this day, rather than waiting for what the "engineering data" says about the seaworthiness of putting picture windows in the hulls to today's production boats built primarily to a price point... :-)



Last edited by JonEisberg; 03-17-2014 at 07:59 PM.
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  #222  
Old 03-17-2014
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Re: How do you feel about catamarans?

Quote:
Originally Posted by JonEisberg View Post
No...



Yes...



I believe quite the opposite occurs, actually, and it was expressed by Steve Dashew in my original cite. One of the problems with the JSD it that it can exert a powerful DOWNWARD pull on the stern - which is only increased as the attitude of the boat changes as it begins to surf down the face of a wave, and the 'bungee' effect of the drogue only increases as the crest of the wave approaches the boat...

Anyone deploying a series drogue in storm conditions had better be prepared for being pooped routinely, and have a bulletproof companionway and a cockpit that drains quickly... Many cats are extremely vulnerable to a breaking sea from astern, hence my own reluctance to consider lying to a drogue in heavy weather in a typical cruising cat... Well, aside from the fact that I will likely never find myself offshore aboard one, to begin with... :-)



Again, such accounts are few and far between, I'm not sure the absence of any disaster stories re multihulls streaming a drogue is proof that it will necessarily be a successful tactic...



Creating such recesses would be a more expensive way to build a companionway, of course, and I've yet to see it on any boat I've run... Last boat that had them was a Cabo Rico 42, but at least they were set on take-apart hinges so that the doors could be removed, and stowed elsewhere...

Drop-down 'window shade' style drop boards are a pretty slick way to go, and are becoming more common, particularly on Euro boats... But they can also have 'issues', I once had the boards on a Trintella 50 get stuck in the recess below the sill, and it required a bit of taking apart of some finely finished cabinetry below to get them out... KISS, conventional drop boards with a convenient and secure rack for stowing them is still the best way to go on most boats, in my opinion...



Well, this wasn't a Jeanneau... But, I'll rely upon what I saw with my own eyes, and heard with my own ears this day, rather than waiting for what the "engineering data" says about the seaworthiness of putting picture windows in the hulls to today's production boats built primarily to a price point... :-)


Most of the boats I've seen that have those windows in the sides of the hull are suppose to be more performance oriented aren't they? I've often wondered how on earth you could keep them water tight and just how screwed you may be if they blew out? I sure wouldn't want a big square hole in the side of my hull if the rail was finding itself taking a bath!

I'm a little off topic there but what the hey!
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  #223  
Old 03-17-2014
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Re: How do you feel about catamarans?

Do you have an account of Steve Dashew deploying a JSD? The sites I found just have him talking about it, but not actually using one.(Other than just deploying it in non-storm conditions).

On the Jordan website, there is this statement:

"It should be noted here that the drogue has been through many storms at sea including several of hurricane strength and there are no reports of the cockpit filling. The reason for this is that the waves at sea are large and have a low frequency. The boat has time to rise with the wave."

Is this just BS?

Thanks.

Quote:
Originally Posted by JonEisberg View Post
No...



Yes...



I believe quite the opposite occurs, actually, and it was expressed by Steve Dashew in my original cite. One of the problems with the JSD it that it can exert a powerful DOWNWARD pull on the stern - which is only increased as the attitude of the boat changes as it begins to surf down the face of a wave, and the 'bungee' effect of the drogue only increases as the crest of the wave approaches the boat...

Anyone deploying a series drogue in storm conditions had better be prepared for being pooped routinely, and have a bulletproof companionway and a cockpit that drains quickly... Many cats are extremely vulnerable to a breaking sea from astern, hence my own reluctance to consider lying to a drogue in heavy weather in a typical cruising cat... Well, aside from the fact that I will likely never find myself offshore aboard one, to begin with... :-)



Again, such accounts are few and far between, I'm not sure the absence of any disaster stories re multihulls streaming a drogue is proof that it will necessarily be a successful tactic...



Creating such recesses would be a more expensive way to build a companionway, of course, and I've yet to see it on any boat I've run... Last boat that had them was a Cabo Rico 42, but at least they were set on take-apart hinges so that the doors could be removed, and stowed elsewhere...

Drop-down 'window shade' style drop boards are a pretty slick way to go, and are becoming more common, particularly on Euro boats... But they can also have 'issues', I once had the boards on a Trintella 50 get stuck in the recess below the sill, and it required a bit of taking apart of some finely finished cabinetry below to get them out... KISS, conventional drop boards with a convenient and secure rack for stowing them is still the best way to go on most boats, in my opinion...



Well, this wasn't a Jeanneau... But, I'll rely upon what I saw with my own eyes, and heard with my own ears this day, rather than waiting for what the "engineering data" says about the seaworthiness of putting picture windows in the hulls to today's production boats built primarily to a price point... :-)



Last edited by jzk; 03-17-2014 at 08:54 PM.
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  #224  
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Re: How do you feel about catamarans?

Quote:
Originally Posted by jzk View Post
Do you have an account of Steve Dashew deploying a JSD? The sites I found just have him talking about it, but not actually using one.(Other than just deploying it in non-storm conditions).
No, in roughly 250,000 miles of voyaging, Dashew says he's never resorted to using a JSD 'in anger'...

Quote:
Originally Posted by jzk View Post
On the Jordan website, there is this statement:

"It should be noted here that the drogue has been through many storms at sea including several of hurricane strength and there are no reports of the cockpit filling. The reason for this is that the waves at sea are large and have a low frequency. The boat has time to rise with the wave."

Is this just BS?

Thanks.
No, I wouldn't call it BS, but it is an overly broad statement that doesn't take varying conditions into account... In a place like the Gulf Stream, or the Aghulas Current, the waves can be large, and yet quite the opposite of "having a low frequency"...

The notion that getting pooped while lying to a drogue in storm force conditions is not likely, however, seems laughable...

Quote:

John , I had the chance to use my Jordan drogue on 3 occasions over the last 3 years , on a 21,000 mile trip from Vancouver Island to Cp. Horn and then north to the Aleutians and back to Vancouver Island. The boat is a 36′ steel 10 ton Swain design cutter.

...

The 3rd opportunity was this past June , 90 miles south of Adak in the Aleutians. A much more powerful system approached from Kamchatka, and we had lots of warning, but could not make shelter safely.

We rode to the Jordan drogue for 3 days and certainly encountered conditions that were the worst I’ve seen . My crewman had never been offshore .

We had lots of breaking seas coming aboard aft and on the cabin top and sides. Our semi-centre cockpit was filled and emptied a number of times. The companion door was dogged inside, and vents were shuttered.

We were dry and relatively comfortable.

Jordan Series Drogue Deployment System On Expedition Sailboat



Almost everyone who I speak to about this drogue thinks that it puts you in peril from oncoming waves. That is far from the truth. The boat just rides on the oncoming waves like a duck and the wave passes under the boat. Since the drogue is longer than a wavelength there is always resistance to motion and you are not relying on one device in the water to slow you down.

Driving a submarine

Of course, if the oncoming wave is breaking, you are going to get wet. The Amel Super Maramu has a center cockpit. On every watch we were pooped at least once. One crewmember was up to his armpits in water in the cockpit. Amel has unusually large scuppers and the center cockpit drains in less than 30 seconds. On a few of my watches, the boat was totally invisible being completely under water. It was more like driving a submarine than a sailboat. As far as I know the Jordan is the only drogue actually tested and approved in a wave tank. You might think that I have some financial interest in Jordan but I am just a fanatic about it, having launched it too many times.

Prepare for survival conditions - Ocean Navigator - May/June 2011
So, in the sort of conditions where seas were routinely sweeping the deck and filling the cockpit of a boat like an 53' Amel Super Maramu, I don't believe lying to a series drogue in a boat such as this even bears thinking about... :-)



Last edited by JonEisberg; 03-17-2014 at 10:31 PM.
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  #225  
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Re: How do you feel about catamarans?

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That ugly statement is just a sailing snob spouting off and showing his limited amount of ability for flexibility for other views
One assumes that you got the irony of your own statement?
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Old 03-17-2014
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Re: How do you feel about catamarans?

I actually quite enjoy being a spouting sailing snob.
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  #227  
Old 03-17-2014
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Re: How do you feel about catamarans?

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Originally Posted by smj View Post
That's precisely the type of observation I'm referring to.

Half way down that web page there is a graph that you are presumably based your statement on.

It compares a 35 foot multihull with a 35 foot monohull. Why is length on deck used for an equivalent craft comparison? A 35 foot mono is clearly a much smaller cheaper craft not at all comparable with a 35 foot cat.

I suggested before comparing a cat with a mono that is 10 feet longer on the waterline as being more sensible.

It would be no more sensible to compare the craft on beam alone than to compare them on length.

Multiplying waterline beam by waterline length for both craft would produce a more sensible figure for comparison.

Then we get significantly different results. Most importantly the monohull will be longer, safer, and be a better performing (over all conditions & headings) passage maker.
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Old 03-18-2014
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Re: How do you feel about catamarans?

I submit that getting wet or even pooped is not the same as causing damage. It would seem that the JSD allows the wave to hit as gently as possible which is about all one can ask for under the circumstances while the crew remains "dry and relatively comfortable."
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Old 03-18-2014
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Re: How do you feel about catamarans?

Quote:
Originally Posted by MikeJohns View Post
That's precisely the type of observation I'm referring to.

Half way down that web page there is a graph that you are presumably based your statement on.

It compares a 35 foot multihull with a 35 foot monohull. Why is length on deck used for an equivalent craft comparison? A 35 foot mono is clearly a much smaller cheaper craft not at all comparable with a 35 foot cat.

I suggested before comparing a cat with a mono that is 10 feet longer on the waterline as being more sensible.

It would be no more sensible to compare the craft on beam alone than to compare them on length.

Multiplying waterline beam by waterline length for both craft would produce a more sensible figure for comparison.

Then we get significantly different results. Most importantly the monohull will be longer, safer, and be a better performing (over all conditions & headings) passage maker.
It is what it is. It takes 50% more force to knock a 35' cat down to 90 degrees than it does to knock a 35' monohull down to 135 degrees. Your question has been answered. If you need more info to satisfy yourself I suggest you start beating on the keyboards. Infact show me an article that would prove a 40' mono will be safer and faster than a 35' cat, I just think that's poppy ****. How would you make that comparison?
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  #230  
Old 03-18-2014
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Re: How do you feel about catamarans?

MikeJohns, I am still waiting for you to cite your sources for the assertions you're making, as I asked in this post:

How do you feel about catamarans?

Mr Eisberg is glad to cite. I still await yours, Mr Johns
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