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Old 10-11-2016, 09:34   #46
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Re: Swing Keels -- Pros? Cons?

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Originally Posted by IdoraKeeper View Post
The further north you go the further you are from services. Keep the deep draft. spend money on forward looking sonar. Keep a bigger dink for the longer run to shore. You dont see high maintenance stuff like that pn fish boats.
Lifting keels are actually fairly common on high latitude adventure boats.
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Old 10-11-2016, 10:14   #47
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Re: Swing Keels -- Pros? Cons?

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Originally Posted by leftbrainstuff View Post
The shards have some good feedback from their Southerly ownership

Sent from my SM-N900T using Cruisers Sailing Forum mobile app
I don't know if they are very satisfied with their Southerly. They had two, firs a 42 and more recently a new 49, just some years ago, but they are already looking for another boat to substitute it.

They are interested in a swallow keel boat or one with a lifting one and Paul Shard visited recently Delphia shipyards to try their 46DS.

Curiously he says a lot of good things about the Delphia, namely that this 46 has more storage than his Southerly 49, a bigger galley, that sails better in light winds and offers a better interior pilot station. He says also that the boat has good quality all around.

The Delphia 46DS is not a very innovative boat, it has a shallow draft modified fin keel with wings and a centerboard to improve performance.

The Southerly 49 has some of the ballast on the keel, some on the boat interior. Here what he says about the Delphia 46DS on his facebook page:
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Old 10-11-2016, 10:22   #48
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Re: Swing Keels -- Pros? Cons?

The new Allures 45.9 will be available with either a centreboard or a swing keel.
According to the site of the German dealer;
Blue Yachting


the weight difference is significant,12.6 versus 10.6 tonnes.
I do not know yet whether the swing keel will easily dry out


regards,
JJ
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Old 10-11-2016, 15:35   #49
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Re: Swing Keels -- Pros? Cons?

DH, your interest in tungsten ballast stimulated me to do a brief check on price. I couldn't find much on pure tungsten, but ferro tungsten, an industrial alloy that is on the order of 80% W 20% Fe seems to go for around 24 USD/Kg. Could add up, but in a vessel as expensive as that which you plan, perhaps it isn't prohibitive.

Not sure how one would manufacture the ballast, nor how one would electrically isolate it from the aluminium, but I reckon that there are ways and means!

My limited experience with tungsten (in much, much smaller bits) is that it is really hard to machine, tends to crack, and in general not much fun. But it sure is dense!

On another aspect of swing keel usage: someone mentioned being able to utilize fishing boat slipways in out of the way places. Might be possible to slip with the keel fully withdrawn, but this would leave the hull resting on the carriage directly. Useful for some jobs, but not for swing keel issues. For such, a travel lift or crane would be required as usual!

Anyhow, an interesting discussion...

Jim
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Old 10-11-2016, 15:51   #50
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Re: Swing Keels -- Pros? Cons?

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DH, your interest in tungsten ballast stimulated me to do a brief check on price. I couldn't find much on pure tungsten, but ferro tungsten, an industrial alloy that is on the order of 80% W 20% Fe seems to go for around 24 USD/Kg. Could add up, but in a vessel as expensive as that which you plan, perhaps it isn't prohibitive.

Not sure how one would manufacture the ballast, nor how one would electrically isolate it from the aluminium, but I reckon that there are ways and means!

My limited experience with tungsten (in much, much smaller bits) is that it is really hard to machine, tends to crack, and in general not much fun. But it sure is dense!

. . .
Yes, it's about $24,000 a tonne. Probably impossible to justify the cost, but it sure is tempting in an application where you can't have a proper bulb.
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Old 10-11-2016, 16:01   #51
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Re: Swing Keels -- Pros? Cons?

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Yes, it's about $24,000 a tonne. Probably impossible to justify the cost, but it sure is tempting in an application where you can't have a proper bulb.
40+ years ago I was buying a folk boat moulding to fit-out. Factory told me their previous customer wanted a stiffer boat and ordered without ballast. Apparently, he worked for British Nuclear Fuels or whatever they were called then. Could source a supply of spent uranium. Sort-of makes a mockery of density differences with other options, but do not even think of the cost!
I have no idea if he did it or not. Sounds rather dubious to me, but a good story non the less
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Old 10-11-2016, 16:16   #52
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Re: Swing Keels -- Pros? Cons?

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40+ years ago I was buying a folk boat moulding to fit-out. Factory told me their previous customer wanted a stiffer boat and ordered without ballast. Apparently, he worked for British Nuclear Fuels or whatever they were called then. Could source a supply of spent uranium. Sort-of makes a mockery of density differences with other options, but do not even think of the cost!
I have no idea if he did it or not. Sounds rather dubious to me, but a good story non the less
Well, not really -- depleted uranium is slightly LESS dense than tungsten (18.95 g/c3 vs 19.25 g/c3). It is more expensive than ferro-tungsten, but less than double (about $40 vs about $24). It is cheaper than pure tungsten.

So uranium is theoretically possible, but it's a health hazard.

FWIW, tungsten and depleted uranium are actually the two materials used in anti-tank sabot projectiles.
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Old 10-11-2016, 17:35   #53
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Re: Swing Keels -- Pros? Cons?

Quote:
Originally Posted by Jim Cate View Post
DH, your interest in tungsten ballast stimulated me to do a brief check on price. I couldn't find much on pure tungsten, but ferro tungsten, an industrial alloy that is on the order of 80% W 20% Fe seems to go for around 24 USD/Kg. Could add up, but in a vessel as expensive as that which you plan, perhaps it isn't prohibitive.

Not sure how one would manufacture the ballast, nor how one would electrically isolate it from the aluminium, but I reckon that there are ways and means!

My limited experience with tungsten (in much, much smaller bits) is that it is really hard to machine, tends to crack, and in general not much fun. But it sure is dense!

On another aspect of swing keel usage: someone mentioned being able to utilize fishing boat slipways in out of the way places. Might be possible to slip with the keel fully withdrawn, but this would leave the hull resting on the carriage directly. Useful for some jobs, but not for swing keel issues. For such, a travel lift or crane would be required as usual!

Anyhow, an interesting discussion...

Jim
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Well, not really -- depleted uranium is slightly LESS dense than tungsten (18.95 g/c3 vs 19.25 g/c3). It is more expensive than ferro-tungsten, but less than double (about $40 vs about $24). It is cheaper than pure tungsten.

So uranium is theoretically possible, but it's a health hazard.

FWIW, tungsten and depleted uranium are actually the two materials used in anti-tank sabot projectiles.
Both have been used. Though in very limited numbers of boats, mostly due to cost. And it's been banned in racing boats primarily for that reason. I'd thought about mentioning it before, in the purely hypothetical, but since it is so rare, it's not worth the attention.

The cost isn't just due to those involved with sourcing the materials, but also because of some of the hazards involved with using it/being around it. Though by the time you have a glow in the dark keel, I'd reckon there's enough lead between it & the boat to be pretty safe for the crew. And on this, I'm referring to use in the very lower bits of a fin keel. Not in a hull, or lifting/swing keel.
IIRC one boat that it was used in may be mentioned by the Dashews.


On the broaching issue, it's so rare for boats of size to take a knock past 90 deg. that I'd not worry about it much, regardless of keel type. Well, unless you are spending a lot of time in the Southern Ocean, or similar, & have the huevos to routinely sail in the kind of weather that induces non-spinnaker type broaches.
Down south all bets are off.


Polux, I'm curious to see the new designs. I've been aware of such keels in a very few custom boats, & lust after them. But due to the engineering (& demand, read $) they haven't much been common before. Sadly.
How do they fair in areas where ice is an issue, or in boats that commonly beach in order to dry out with the tides? And does anyone have links to info on their internal structural hull bits?


Edit: The heavier than lead materials have been used in fin keels, though not in bulbs to my knowledge, due to issues with difficulties in casting them. And don't even think about trying to machine them. WAY too expensive, & even more toxic.
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Old 10-11-2016, 17:54   #54
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Re: Swing Keels -- Pros? Cons?

We love our French aluminum centerboard sailboat( Boreal44)2013. It is the sea kindliest boat we have sailed in 45 years of serious sailing. The places we have been able to go to get away from crowds is just amazing. Had her in 71 knots of wind on the way up from Panama last April when a major front came through and I was amazed just how she handled for that short period of time. We had her in 35 to 40 knots for almost 6 days on our Atlantic Crossing, huge seas. Reefed to full extent,centerboard up and very comfortable. We got whacked crossing the from Antigua to Panama with a wave that broke at 2 AM across the beam, white water to the boom and over the doghouse. Huge bang and shudder but the boat just slid sideways and then went back on course without rounding up or being knocked down. I don't even want to think about if we were in our previous boat a Mason 44 and that happened.

We are about to sell our Boreal because of illness in the family. We will miss her a whole lot. Best boat I ever sailed bar non! Centerboard boats are the way to go if you are thinking of being a serious cruiser.
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Old 10-11-2016, 18:52   #55
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Re: Swing Keels -- Pros? Cons?

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...

We are about to sell our Boreal because of illness in the family. We will miss her a whole lot. Best boat I ever sailed bar non! Centerboard boats are the way to go if you are thinking of being a serious cruiser.
Steve, I am very sorry to hear about that and even more with the problems in the family. I know how you love that boat and how you love your wife. I wish the best for both of you.

Paulo
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Old 10-11-2016, 19:06   #56
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Re: Swing Keels -- Pros? Cons?

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...
Polux, I'm curious to see the new designs. I've been aware of such keels in a very few custom boats, & lust after them. But due to the engineering (& demand, read $) they haven't much been common before. Sadly.
How do they fair in areas where ice is an issue, or in boats that commonly beach in order to dry out with the tides? And does anyone have links to info on their internal structural hull bits?
..
To be beached the boats have to be designed in a way that they can stand upright, the Malango and the Mojito do that with some tubes you deploy from the cockpit. It is late here, tomorrow I will post some more regarding your questions:










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Old 10-11-2016, 19:21   #57
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Re: Swing Keels -- Pros? Cons?

Cool. The keel on the Malango 10.45 very much reminds me of the one on our old Chrysler 22'. Which was a sweet sailing boat.

stevewrye, sorry to hear about the reasons for selling the boat. Rarely an easy thing when it's become part of the family. I hope that things work out at home.
Thanks for the info on how well your Boreal side slips, as well as handles things when Neptune throws a tantrum.

My lust for these new boats just keeps growing. Time for me to see about signing on at Boreal, & building a copy at home while working in the factory. As was done with Westsail 32's
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Old 10-11-2016, 20:13   #58
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Re: Swing Keels -- Pros? Cons?

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Steve, I am very sorry to hear about that and even more with the problems in the family. I know how you love that boat and how you love your wife. I wish the best for both of you.

Paulo
Thanks Paulo for your kind words, I've known you for a long time now. Still hope to visit you one of these days and eat seafood and talk modern boats till the cows come home. It was a hard thing to do, sell the boat, but we realize we had a great sail with SV RC LOUISE, met lot's of wonderful people all over the world. All ready have lots of invites from other Boreal owners to come sail with them. We have a small but great group of serious Boreal sailors throughout the world. We have one good sail left from DeltaVille Virginia to Annapolis coming up next week or so. Plan on gunkholing here and there for a week or so, turn on the Reflecks stove and enjoy a winter sail.

Cheers and what the hell are you doing up at this hour?

Steve and Tracy
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Old 10-11-2016, 20:42   #59
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Re: Swing Keels -- Pros? Cons?

I am sure there are some places like PNW where shoal draft is not necessary. I think a well designed keel CB boat is a great cruising compromise for most other places in the world where there are shallow nooks you want to tuck into. I wish my T40 was shallower but some people think with a nearly 5 foot draft that there is no need for CB. But put it down and get a good leading edge foil extension to nearly 9 foot depth. Makes huge difference in pointing ability especially in big breeze and waves where it doesn't get shoved to leeward at all. I'm biased like many others about my boat but was specifically looking for this tyoe of underbody for east coast US/chesapeake. And boat is 30 years old and as far as I can tell CB only has needed occasional pendant replacement. Otherwise pretty low maintenance. Difference is the fixed part of my keel can be lead so good ballast. The CB is weighted just enough to fall.
what I don't like about swing keels is that most are cast iron I think. Don't like cast iron keels...


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Old 11-11-2016, 00:26   #60
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Re: Swing Keels -- Pros? Cons?

One thing on CB's not yet mentioned is that they don't necessarily have to be shaped like daggerboards. The possible alternative is a board that is shaped like a quarter or third of a circle, so that when it's lowered, the case is still filled, thus reducing that drag.

It's foil shape will of course be different, & perhaps a bit less efficiient, depending on what section is chosen. Though it's projected area will be larger, so that may make up the difference in terms of generated lift.
Which, that & the part on foil sections I don't recall from my NA classes many years ago. But the basics shouldn't be all that hard to dig up online.

The board on my Searunner was similar to this, & it worked fairly well. And when you consider that a ballasted monohull isn't a fast vessel, & thus may not have the speed to take advantage of high aspect ratio foils, or the high performance foil sections such as you'd typically find on daggerboards, or deep, slim rudders.
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