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Old 15-11-2012, 12:50   #76
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Re: Following Seas Dangers?

I have found my eyes rolling into the back of their sockets on the last few posts as well.
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Old 15-11-2012, 13:25   #77
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Fair enough, Andrew and I will take our discussion offline since it is really between us anyway...
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Old 15-11-2012, 15:52   #78
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Re: Following Seas Dangers?

Its OK, some sailors look at the sea in awe, others see numbers. I am kinda an analog guy myself...
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Old 15-11-2012, 15:59   #79
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When in it i am in awe and sometimes fearful, when looking back i try to rationalize and comparmentalize by disecting and analyizing...

Funny how after not doing any real passagemakin for the last 2 years suddenly i have become an armchair cruiser.
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Old 15-11-2012, 16:23   #80
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Re: Following Seas Dangers?

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Originally Posted by foolishsailor View Post
Parachute anchor is designed to stop the boat as close to dead in the water as possible.
I would say that is accurate as applied to multi-hull storm tactics but not for monohulls. The use of a para-anchor described by the Pardeys (and maybe Beth and Evans too) is different and much closer to the use of the "drogue off the bow" which you describe. The para anchor is used (sometimes in conjunction with a sail) to hold the bow @50' off the wind and create a slick directly upwind of the boat as it makes leeway.
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Old 15-11-2012, 16:23   #81
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Re: Following Seas Dangers?

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Fair enough, Andrew and I will take our discussion offline since it is really between us anyway...
Please don't -- I enjoy reading it. Or perhaps just cc me offline .

I've read about a dozen non-specialist books on yacht design, and I am enjoying the rare balance here between offshore experience and theoretical models.

Most conversations are either one or the other, which is fine, but, to me, I don't trust models made up by people who have little experience, and experiences without a model eventually reduce to a collection of anecdotal trivia that must be seen from the perspective of the person and equipment that produced it.

For example, I found Dashew's few chapters on design much more interesting than all of Marchaij, just because I felt he had a philosophy, made a model, made a boat, and iterated on all three of those over and over again.
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Old 15-11-2012, 22:00   #82
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Originally Posted by Ship2210
Does anyone have actual repeat experience of a particular design of boat as to when (what sorts of speeds too), to deploy the drogue in following seas. I know it is dependent on the following sea conditions, wind etc etc but it would just be interesting to note a few speeds at which deploying the drogue was considered prudent. I am particularly interested in the production type boats like the Beneteau's, Jeanneau's, Hunter's etc but any other actual experience on any design will be welcomed.
For what its worth: our beneteau oc 393 did about 5 kts under full sail in 15kts on the beam with the engine at max cruising revs towing a 30L seabrake. It was flat water. We just wanted a feel for the drag it gave.
We had about 20m chain and 40m rode out.
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Old 16-11-2012, 01:28   #83
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Re: Following Seas Dangers?

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Originally Posted by roscoep View Post
For what its worth: our beneteau oc 393 did about 5 kts under full sail in 15kts on the beam with the engine at max cruising revs towing a 30L seabrake. It was flat water. We just wanted a feel for the drag it gave.
We had about 20m chain and 40m rode out.
Thanks for that info ... the sort of info I am looking for.
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Old 16-11-2012, 04:49   #84
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Re: Following Seas Dangers?

I'm away for a day or two, why doesn't someone who is interested in this particular interface between theory and practice start a new thread on capsize dynamics or whatever.

I don't personally see that it's an offensive line of discussion, but I can see that it might be seen as having derailed this thread.

I'm not sure what happened to the guy who persuaded me to elaborate on something I was pretty sure would bore the average forum participant; maybe he's out of town too.

ON EDIT:
Just spotted the post a couple up from this one - glad you're still hanging in there, msponer.

I entirely agree about Marchaj ; it seemed to me that on that particular subtopic, he let himself be driven by answers rather than questions.

Furthermore while he's undoubtedly brilliant on the aerodynamic side, I got the feeling, way back when he wrote it, that he just didn't have sufficient variety and depth of experience in many different styles of boat, in severe enough conditions, to be able to do reality checks on his thinking about how the style of boat affects handling characteristics.

And the experiences I've had and heard about since have only served to solidify those early reservations.
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Old 25-02-2017, 04:51   #85
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Re: Following Seas Dangers?

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Originally Posted by DeepFrz View Post
Kind of like this?
By the way the Vendee Globe 2012/13 kicks of on Sat. Nov. 10...

I've been in something like this one winter out in the mid atlantic. I was in a wood ketch at the time, but I am wondering what it would be like in one of those newer catamarans with the reverse bows? I think there would be too little buoyancy to keep them from digging on the way down the slope of the wave??
Any cat sailor with that experience??
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Old 25-02-2017, 04:58   #86
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Re: Following Seas Dangers?

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....

Aboard a cruising cat: Speed control is a much more important issue aboard cats (and mutli's in general) they tend to be directionally quite stable off the wind, but speed control becomes an issue sooner. This is why I don't head offshore in a cat without at least a drogue aboard. This concerns me less on a mono. The above events are not as likely on a cat, but they can accelerate quite quickly coming off the back of a wave, and surf much easier, thus you are more likely to surf into the back of the wave ahead of you. This results in sudden deceleration, wave behind you catches you and lifts the stern (rather than pooping you), ... and bad stuff may happen after that depending upon wave size. I've been aboard cruising cats and tri's when the bows got stuffed in moderately heavy conditions and they were surprisingly well behaved...dramatic deceleration, followed by a pucker factor increasing lift of the stern, and then...all calm and off sailing again, but I would not want to try that in really heavy conditions (or ever again even in moderately heavy conditions for that matter!).

Oh, and there are lots of broaching images and videos on the net just Google-Fu them up.
Any experiences on cats with reverse/plumb bows?
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Old 25-02-2017, 05:42   #87
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Re: Following Seas Dangers?

May I enquire what reverse Plum bows means, Thanks,
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Old 25-02-2017, 06:01   #88
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Re: Following Seas Dangers?

Quote:
Originally Posted by beiland View Post
I've been in something like this one winter out in the mid atlantic. I was in a wood ketch at the time, but I am wondering what it would be like in one of those newer catamarans with the reverse bows? I think there would be too little buoyancy to keep them from digging on the way down the slope of the wave??
Any cat sailor with that experience??
I have a little Gemini, And I sail about 30 Degrees off the wave line top, That keeps my speed down, Im about 4 .1/4 Ton fully loaded and 14 feet wide,
2 foot Draught, 7 feet with the centre board fully down,

I use only a small bit of Genoa, Maybe two feet out at the bottom, 6 to 12 knots, average,
I do keep my windward side centre board fully down and the Lee board fully up,
With both boards down it has a tendency to dig in and not let the boat slip sideways down the wave,
I learnt that the hard way as the self steering dropped out and I came around beam on, I almost went over sideways, Quickly turned it down the wave and saved it, But it was a very scary moment,

I do prefer the bigger waves as its a lot easier to sail in, Less effort on all the gear, and comfortable, No bouncing around, 100 to 120 degrees down wind,
I avoid going upwind, The boat slams under the bridge deck, Its quite unsettling with things jumping off the Salon table, The bangs travel up the table leg,
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Old 25-02-2017, 06:14   #89
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Re: Following Seas Dangers?

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Originally Posted by Mr B View Post
May I enquire what reverse Plum bows means, Thanks,
They're where the bow at the waterline is further forward than at deck level. Kind of like reversed transoms on monos, only facing the other direction, & at the cat's bows.

In theory they're supposed to reduce the dangers of stuffing the bows when things get wild. Since they're designed to be wave piercing. So that the boat won't decelerate nearly so much when it plows into waves. Though because they have so little buoyancy as compared to normal bows, the boat's bows may not rise up quickly enough once stuffed in order to avoid pitchpoling, if the bows stay buried for too long.

Some folks describe such boats this way. Picture a 35' boat with conventional vertical bows, & then add on 5' of wave piercing bow to those hulls, thus giving you a 40' boat. So that the extra 5' functions (in theory) only to assist in reducing the drag caused when the boat punches through seas in front of it. With the rest of the hull, the 35' functioning to resist pitchpoling via the buoyancy associated with them.

Design wise, I'm sure that it's a balancing act. And for anyone used to normal sailing, the idea (& experience) of seeing one's bows submarining is more than a little disconcerting.
Personally I'd rather never see the bows submerge on a multi, as since childhood the idea of one's bows going under has firmly fallen into the Bad Juju category.

Also, to a fairly large degree, such bows are driven by marketing. Folks with money see them on things like America's Cup catamarans, & want them on their personal "cruising" boats. And since yacht designers need to eat, they draw them on racer/cruisers that get built for the well funded masses. Much as the automobile companies put Corvette level horsepower in family grocery getters... needlessly.
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Old 25-02-2017, 06:49   #90
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Re: Following Seas Dangers?

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Originally Posted by UNCIVILIZED View Post
They're where the bow at the waterline is further forward than at deck level. Kind of like reversed transoms on monos, only facing the other direction, & at the cat's bows.

In theory they're supposed to reduce the dangers of stuffing the bows when things get wild. Since they're designed to be wave piercing. So that the boat won't decelerate nearly so much when it plows into waves. Though because they have so little buoyancy as compared to normal bows, the boat's bows may not rise up quickly enough once stuffed in order to avoid pitchpoling, if the bows stay buried for too long.

Some folks describe such boats this way. Picture a 35' boat with conventional vertical bows, & then add on 5' of wave piercing bow to those hulls, thus giving you a 40' boat. So that the extra 5' functions (in theory) only to assist in reducing the drag caused when the boat punches through seas in front of it. With the rest of the hull, the 35' functioning to resist pitchpoling via the buoyancy associated with them.

Design wise, I'm sure that it's a balancing act. And for anyone used to normal sailing, the idea (& experience) of seeing one's bows submarining is more than a little disconcerting.
Personally I'd rather never see the bows submerge on a multi, as since childhood the idea of one's bows going under has firmly fallen into the Bad Juju category.

Also, to a fairly large degree, such bows are driven by marketing. Folks with money see them on things like America's Cup catamarans, & want them on their personal "cruising" boats. And since yacht designers need to eat, they draw them on racer/cruisers that get built for the well funded masses. Much as the automobile companies put Corvette level horsepower in family grocery getters... needlessly.
Thanks for that,
I had a 14 paper tiger, When its offside bow dug in I was ten feet in the air,
It was like a big brake as the water came over the bow and it dug in, It stopped it dead in the water,
The flat top of the deck made it instantly Pitch Pole, Like hitting a brick wall,

My Gemini has a forward sloping Bow and it very rarely ever goes under,
When it does,It not very much, Its more like punching thru the crest of the wave, and a bit of water on the front of the boat,
If mine had a tendency to Pitch Pole, I would sell it,
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