[bolger] Re: sharpie stability/recovery
BO>Another aspect of all this, namely high freeboard. I had long objected
BO>to high sided boats as being such for the sake of too much "downstairs"
BO>at the cost of excessive windage topside.
<snip>
BO>I became convinced that high freeboard was not a bad idea from a
BO>windage standpoint, and from there to Bolger's statement that shallow
BO>draft requires high freeboard.
BO>Ed Haile
I was originally alarmed at the windage possibilities of the AS29 hull,
particularly given the necessity to get out of tight and narrow marinas
(and back in) at dead slow speeds with vicious crosswinds. We did have
windage problems, in particular the bow falling off, but all to do with
the windage of the mainmast (which is quite respectable). The hull
itself, with boards down, is close to neutral.
Now, if they'd allow us to sail in and out of marina, we wouldnt have
any trouble at all....
Tim & Lady Kate
BO>to high sided boats as being such for the sake of too much "downstairs"
BO>at the cost of excessive windage topside.
<snip>
BO>I became convinced that high freeboard was not a bad idea from a
BO>windage standpoint, and from there to Bolger's statement that shallow
BO>draft requires high freeboard.
BO>Ed Haile
I was originally alarmed at the windage possibilities of the AS29 hull,
particularly given the necessity to get out of tight and narrow marinas
(and back in) at dead slow speeds with vicious crosswinds. We did have
windage problems, in particular the bow falling off, but all to do with
the windage of the mainmast (which is quite respectable). The hull
itself, with boards down, is close to neutral.
Now, if they'd allow us to sail in and out of marina, we wouldnt have
any trouble at all....
Tim & Lady Kate
How about this concept? Sail power is only required for those long hauls from
Bermuda to the Azores, Canaries to Carribean - all down-hill sailing. Why use
a conventional rig, requiring a substantial righting moment (ballast or beam
= expense), if there was an alternative? My thought is of a reasonably long,
narrow, lightly balanced "box" suitable for low-powered internal combustion
engine operation in coastal waters, inland waters and canals, just
sufficiently ballasted for self-righting, with hatches amidship, etc. for
off-shore survivability. For the ocean crossings, one would use some form of
traction kites. Thrust from the kite could be taken at the rail by snatch
blocks. ( very low c.e. = low stability requirement for thrust developed).
Sail area ( I get the impression that projecting adequate non-chafing
downwind sail area in the Trades can be a problem with conventional boats)
would be independent of mast dimensions (low windage, low cost, low clearance
in canals). My perusal of traction kiting websites (e.g.
DaveCulpSpeedSailing) hasn't done much to dispel my ignorance of how such
kites are deployed and managed, but it does seem to me that they could
develop as much power as one could desire on courses up to at least a broad
reach with minimal heeling force. A buttoned-up hull of "Tennessee" or
"Wyoming" type dimensions (provided with some appendage to provide a suitable
CLR) might be one hell of a downwind sled.
Bill Page in the land of HARD water (MN)
Bermuda to the Azores, Canaries to Carribean - all down-hill sailing. Why use
a conventional rig, requiring a substantial righting moment (ballast or beam
= expense), if there was an alternative? My thought is of a reasonably long,
narrow, lightly balanced "box" suitable for low-powered internal combustion
engine operation in coastal waters, inland waters and canals, just
sufficiently ballasted for self-righting, with hatches amidship, etc. for
off-shore survivability. For the ocean crossings, one would use some form of
traction kites. Thrust from the kite could be taken at the rail by snatch
blocks. ( very low c.e. = low stability requirement for thrust developed).
Sail area ( I get the impression that projecting adequate non-chafing
downwind sail area in the Trades can be a problem with conventional boats)
would be independent of mast dimensions (low windage, low cost, low clearance
in canals). My perusal of traction kiting websites (e.g.
DaveCulpSpeedSailing) hasn't done much to dispel my ignorance of how such
kites are deployed and managed, but it does seem to me that they could
develop as much power as one could desire on courses up to at least a broad
reach with minimal heeling force. A buttoned-up hull of "Tennessee" or
"Wyoming" type dimensions (provided with some appendage to provide a suitable
CLR) might be one hell of a downwind sled.
Bill Page in the land of HARD water (MN)
> 2) Tacking: how often do you tack your LM on a trip from France toI think the issue here is maneuverability, something you don't give up
> Jamaica?
lightly.
>The limit is sail size vs crew. Not mast height. Clippers had masts
> 3) Multi-masts/Aero efficiency. As I understand it, multiple masts
> are an answer to the practical limits of mast height, i.e. clippers
> couldn't got as high as they wanted, so they went wide. Is this a
> correct understanding? If it isn't, what is correct. If it is, where
> are the practical lower limits (of hull size) of many small masts vs.
> one big one?
plenty high. But compare them to what went before and you see much
taller masts together with much smaller sails. They furled more than
they reefed and some prefer that on our-size boats. I think the Jochems
schooner has a lot of sails for an under-25 footer. Some might think
the main on a Loose Moose is a monster.
>You might consider comfort important too, after a couple of blows. But
> What I am envisioning is a very long, very lean cruiser. She'd have
> less sail, less beam, and more waterline. Doesn't tack very well? Who
> cares, I'm on a beam reach for the next 1500 miles! No deep heavy
> keel? If I can't get the nose into the wind and a sea anchor out,
> I'll ride out the blow on my side (like Kerby's timber carrying
> schooner,) confident my topsides will keep my from going any further.
maneuverability.
>The very question I put to PCB years ago: how about a long low-rig
> Has Bolger or anyone else designed such a beast? If so, what are her
> strengths? faults?
>
> YIBB,
sailing canoe? He referred me to the folding schooner. If he has
designed a proa since then, he might now mention that.
> David Ryan
> Minister of Information and Culture
> Crumbling Empire Productions
> (212) 247-0296
FBBB --
I'm glad I asked. My understanding continues to grow.
A couple of thoughts/questions:
1) As I said before, I am convinced that *most* boats are designed
with salability, not sailabilitly as their primary design
consideration. I think what has impressed my most about BWAOM is that
PCB is willing to realistically consider the way a boat will actually
be used. His comment about LM spending more time in port than in
ocean crossing, and then the resulting design really spoke to me. On
the other hand, since most boats spend most of their time tied up,
maybe a imitation offshore racer sponsors (that you don't actually
sail) sponsors more satisfying fantasies than a big Bolger box (that
you don't actually sail.) People sure get a big kick out of driving
SUVs will never see a dirt trail.
2) Tacking: Given similiar waterlines/rocker, is a narrower boat
harder to tack? Or is it simply that longer boats are harder to turn?
And besides, how often do you tack your LM on a trip from France to
Jamaica?
3) Multi-masts/Aero efficiency. As I understand it, multiple masts
are an answer to the practical limits of mast height, i.e. clippers
couldn't got as high as they wanted, so they went wide. Is this a
correct understanding? If it isn't, what is correct. If it is, where
are the practical lower limits (of hull size) of many small masts vs.
one big one?
What I am envisioning is a very long, very lean cruiser. She'd have
less sail, less beam, and more waterline. Doesn't tack very well? Who
cares, I'm on a beam reach for the next 1500 miles! No deep heavy
keel? If I can't get the nose into the wind and a sea anchor out,
I'll ride out the blow on my side (like Kerby's timber carrying
schooner,) confident my topsides will keep my from going any further.
Has Bolger or anyone else designed such a beast? If so, what are her
strengths? faults?
YIBB,
David Ryan
Minister of Information and Culture
Crumbling Empire Productions
(212) 247-0296
I'm glad I asked. My understanding continues to grow.
A couple of thoughts/questions:
1) As I said before, I am convinced that *most* boats are designed
with salability, not sailabilitly as their primary design
consideration. I think what has impressed my most about BWAOM is that
PCB is willing to realistically consider the way a boat will actually
be used. His comment about LM spending more time in port than in
ocean crossing, and then the resulting design really spoke to me. On
the other hand, since most boats spend most of their time tied up,
maybe a imitation offshore racer sponsors (that you don't actually
sail) sponsors more satisfying fantasies than a big Bolger box (that
you don't actually sail.) People sure get a big kick out of driving
SUVs will never see a dirt trail.
2) Tacking: Given similiar waterlines/rocker, is a narrower boat
harder to tack? Or is it simply that longer boats are harder to turn?
And besides, how often do you tack your LM on a trip from France to
Jamaica?
3) Multi-masts/Aero efficiency. As I understand it, multiple masts
are an answer to the practical limits of mast height, i.e. clippers
couldn't got as high as they wanted, so they went wide. Is this a
correct understanding? If it isn't, what is correct. If it is, where
are the practical lower limits (of hull size) of many small masts vs.
one big one?
What I am envisioning is a very long, very lean cruiser. She'd have
less sail, less beam, and more waterline. Doesn't tack very well? Who
cares, I'm on a beam reach for the next 1500 miles! No deep heavy
keel? If I can't get the nose into the wind and a sea anchor out,
I'll ride out the blow on my side (like Kerby's timber carrying
schooner,) confident my topsides will keep my from going any further.
Has Bolger or anyone else designed such a beast? If so, what are her
strengths? faults?
YIBB,
David Ryan
Minister of Information and Culture
Crumbling Empire Productions
(212) 247-0296
Hello Ed,
I never quite saw it that way but it sure does make a whole lot of sense,thanks!Now I have a wonderful arguement to give to all of my infidel friends without having to take them out for a sail on my Micro.
Despite the high sides of my Micro,I have never felt blown sideways since that lovely long keel just keeps on biting and biting long after the centerboarders and finkeelers have blown out of range!
Regards
Peter Lenihan
--- ed haile <bolger@egroups.com> wrote:
the BoatBuilding.Communityhttp://boatbuilding.com/
the Internet boatbuilding, design and repair resource
I never quite saw it that way but it sure does make a whole lot of sense,thanks!Now I have a wonderful arguement to give to all of my infidel friends without having to take them out for a sail on my Micro.
Despite the high sides of my Micro,I have never felt blown sideways since that lovely long keel just keeps on biting and biting long after the centerboarders and finkeelers have blown out of range!
Regards
Peter Lenihan
--- ed haile <bolger@egroups.com> wrote:
>David,_____________________________________________________________
>
>Another aspect of all this, namely high freeboard. I had long objected
>to high sided boats as being such for the sake of too much "downstairs"
>at the cost of excessive windage topside. A look at the oldtime
>galleons and it's obvious they were exclusively downwind sailers. But
>then something struck me in the Bolger boats. Look at the X-section of
>a box boat. It's just about square. That means that windage (despite
>the high sides) does not substantially increase or diminish with heel.
>What's more, a square section (vertical sides) becomes more streamlined
>when it heels (angled side facing the wind). Now look at your standard
>dinghy, fin keel yacht. On an even keel most of them are very low. But
>when they heel they throw up that ole weather rail and effectively have
>the same windage as one of your box boats, if not more, and, since you
>can see underneath, are much less streamlined.
>
>Ever notice how in yacht photos you almost never see a picture of a
>heeling yacht taken from windward.
>
>Hull windage is an advantage downwind, precisely where standard brands
>have the least, riding on an even keel. Windage is a disadvantage
>upwind, precisely where standard brands develop it when they heel. So,
>I became convinced that high freeboard was not a bad idea from a
>windage standpoint, and from there to Bolger's statement that shallow
>draft requires high freeboard.
>
>To say nothing of rigging windage.
>
>I am not yacht designer, and I admit in my lifetime on the water in
>boats I have learned next to nothing. The above simply reasons from
>facts & lines on paper. On the other hand, my Martha Jane pretty much
>bears it all out.
>
>Ed Haile
>
>
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David,
Another aspect of all this, namely high freeboard. I had long objected
to high sided boats as being such for the sake of too much "downstairs"
at the cost of excessive windage topside. A look at the oldtime
galleons and it's obvious they were exclusively downwind sailers. But
then something struck me in the Bolger boats. Look at the X-section of
a box boat. It's just about square. That means that windage (despite
the high sides) does not substantially increase or diminish with heel.
What's more, a square section (vertical sides) becomes more streamlined
when it heels (angled side facing the wind). Now look at your standard
dinghy, fin keel yacht. On an even keel most of them are very low. But
when they heel they throw up that ole weather rail and effectively have
the same windage as one of your box boats, if not more, and, since you
can see underneath, are much less streamlined.
Ever notice how in yacht photos you almost never see a picture of a
heeling yacht taken from windward.
Hull windage is an advantage downwind, precisely where standard brands
have the least, riding on an even keel. Windage is a disadvantage
upwind, precisely where standard brands develop it when they heel. So,
I became convinced that high freeboard was not a bad idea from a
windage standpoint, and from there to Bolger's statement that shallow
draft requires high freeboard.
To say nothing of rigging windage.
I am not yacht designer, and I admit in my lifetime on the water in
boats I have learned next to nothing. The above simply reasons from
facts & lines on paper. On the other hand, my Martha Jane pretty much
bears it all out.
Ed Haile
Another aspect of all this, namely high freeboard. I had long objected
to high sided boats as being such for the sake of too much "downstairs"
at the cost of excessive windage topside. A look at the oldtime
galleons and it's obvious they were exclusively downwind sailers. But
then something struck me in the Bolger boats. Look at the X-section of
a box boat. It's just about square. That means that windage (despite
the high sides) does not substantially increase or diminish with heel.
What's more, a square section (vertical sides) becomes more streamlined
when it heels (angled side facing the wind). Now look at your standard
dinghy, fin keel yacht. On an even keel most of them are very low. But
when they heel they throw up that ole weather rail and effectively have
the same windage as one of your box boats, if not more, and, since you
can see underneath, are much less streamlined.
Ever notice how in yacht photos you almost never see a picture of a
heeling yacht taken from windward.
Hull windage is an advantage downwind, precisely where standard brands
have the least, riding on an even keel. Windage is a disadvantage
upwind, precisely where standard brands develop it when they heel. So,
I became convinced that high freeboard was not a bad idea from a
windage standpoint, and from there to Bolger's statement that shallow
draft requires high freeboard.
To say nothing of rigging windage.
I am not yacht designer, and I admit in my lifetime on the water in
boats I have learned next to nothing. The above simply reasons from
facts & lines on paper. On the other hand, my Martha Jane pretty much
bears it all out.
Ed Haile
David,
Moderation in all things. Note that despite its boxy shape, the AS-29
is petty close to ordinary beam and weight for its length. The overall
beam is perhaps less than average (due to having no flare), but the
waterline beam is in the ordinary range.
I think of these sharpies as being sort of like a banana, floating
'convex down.' The rocker, which has virtues Mr. Bolger talks about
with respect to flow, works with respect to stability by giving the
boat a low belly, in which to put some ballast, and high ends. In a
knockdown, the high ends move the center of buoyancey away from the
ballast, giving a high righting moment (i.e. high reserve stability).
However, this sort of stability does not give much sail carrying power
at small angles of heel.
The sail carrying power comes from hull sections with a lot of form
stability, i.e. the box cross section, which depends on having adequate
beam.
If you take a small boat, and simply build it longer with the same
beam, the resulting hull can carry more sail area in proportion to its
length, but it can not carry it higher. As the boat gets longer and
longer, the rig must stay the same height. As you go from one mast to
two or three masts (remember Rondo II?), the aerodynamic effeciency
suffers.
That's my view, anyway.
Peter
Moderation in all things. Note that despite its boxy shape, the AS-29
is petty close to ordinary beam and weight for its length. The overall
beam is perhaps less than average (due to having no flare), but the
waterline beam is in the ordinary range.
I think of these sharpies as being sort of like a banana, floating
'convex down.' The rocker, which has virtues Mr. Bolger talks about
with respect to flow, works with respect to stability by giving the
boat a low belly, in which to put some ballast, and high ends. In a
knockdown, the high ends move the center of buoyancey away from the
ballast, giving a high righting moment (i.e. high reserve stability).
However, this sort of stability does not give much sail carrying power
at small angles of heel.
The sail carrying power comes from hull sections with a lot of form
stability, i.e. the box cross section, which depends on having adequate
beam.
If you take a small boat, and simply build it longer with the same
beam, the resulting hull can carry more sail area in proportion to its
length, but it can not carry it higher. As the boat gets longer and
longer, the rig must stay the same height. As you go from one mast to
two or three masts (remember Rondo II?), the aerodynamic effeciency
suffers.
That's my view, anyway.
Peter
>
> I've been thinking a lot about stability and recovery, and studying
> BWAOM very hard, especially the AS29 and LooseMoose. I think I'm
> finally starting to get the shallow draft/high freeboard concept.
>
>very stable right side up, very stable upside down.
>
>
> You'll end up with a multihull ;-)
>
>Ron
>Kismet 31 "Big Bird" (trimaran, building a cat)
David Ryan
Minister of Information and Culture
Crumbling Empire Productions
(212) 247-0296
David,
you may want to read this nice article by Bruce Kirby
http://www.coastalcruising.com/shallow.htm
Very instructive!
Best, Pippo
david ryan <davi-@...> wrote:
original article:http://www.egroups.com/group/bolger/?start=2150
you may want to read this nice article by Bruce Kirby
http://www.coastalcruising.com/shallow.htm
Very instructive!
Best, Pippo
david ryan <davi-@...> wrote:
original article:http://www.egroups.com/group/bolger/?start=2150
> FBBB --
>
> I've been thinking a lot about stability and recovery, and studying
> BWAOM very hard, especially the AS29 and LooseMoose. I think I'm
> finally starting to get the shallow draft/high freeboard concept.
>
> Having spent my whole life sailing dingies, I have always equated
> stability with hiking over the side, and maybe a weighed
> centerboard. Recovery meant standing on the centerboard and prying
> the thing back to upright. In a larger boat, this seemed to
> *obviously* indicate the necessity of deep keels and heavy ballast.
>
> The AS29 and LM (if I understand correctly,) seem to prove otherwise,
> and I am very intrigued.
>
> I've spent the weekend imaging a crusing sharpie that takes the
> concept to extremes -- a very long, very slender craft sporting a low
> sail plan and high freeboard: sort of like an extrastretched
> tarantula (minus the keel) with a multi-mast sail plan and high
> topsides. At what point is the beam to freeboard ratio optimized?
>
> Why this? The more I read, the more beaminess seems like a liability.
> I'm beginning to suspect boat are made wide so as to make them easy
> to sell, not easy to sail. I can't help but wonder what you end up
> with if you design for maximum, rather than minimum waterline.
>
> Anyone want to kick this around?
>
> YIBB,
>
> David Ryan
> Minister of Information and Culture
> Crumbling Empire Productions
> (212) 247-0296
>From: David Ryan <david@...>Snip
> FBBB --
>
> I've been thinking a lot about stability and recovery, and studying
> BWAOM very hard, especially the AS29 and LooseMoose. I think I'm
> finally starting to get the shallow draft/high freeboard concept.
> Why this? The more I read, the more beaminess seems like a liability.You'll end up with a multihull ;-)
> I'm beginning to suspect boat are made wide so as to make them easy
> to sell, not easy to sail. I can't help but wonder what you end up
> with if you design for maximum, rather than minimum waterline.
>
> Anyone want to kick this around?
Ron
Kismet 31 "Big Bird" (trimaran, building a cat)
> YIBB,
>
> David Ryan
> Minister of Information and Culture
> Crumbling Empire Productions
> (212) 247-0296
FBBB --
I've been thinking a lot about stability and recovery, and studying
BWAOM very hard, especially the AS29 and LooseMoose. I think I'm
finally starting to get the shallow draft/high freeboard concept.
Having spent my whole life sailing dingies, I have always equated
stability with hiking over the side, and maybe a weighed
centerboard. Recovery meant standing on the centerboard and prying
the thing back to upright. In a larger boat, this seemed to
*obviously* indicate the necessity of deep keels and heavy ballast.
The AS29 and LM (if I understand correctly,) seem to prove otherwise,
and I am very intrigued.
I've spent the weekend imaging a crusing sharpie that takes the
concept to extremes -- a very long, very slender craft sporting a low
sail plan and high freeboard: sort of like an extrastretched
tarantula (minus the keel) with a multi-mast sail plan and high
topsides. At what point is the beam to freeboard ratio optimized?
Why this? The more I read, the more beaminess seems like a liability.
I'm beginning to suspect boat are made wide so as to make them easy
to sell, not easy to sail. I can't help but wonder what you end up
with if you design for maximum, rather than minimum waterline.
Anyone want to kick this around?
YIBB,
David Ryan
Minister of Information and Culture
Crumbling Empire Productions
(212) 247-0296
I've been thinking a lot about stability and recovery, and studying
BWAOM very hard, especially the AS29 and LooseMoose. I think I'm
finally starting to get the shallow draft/high freeboard concept.
Having spent my whole life sailing dingies, I have always equated
stability with hiking over the side, and maybe a weighed
centerboard. Recovery meant standing on the centerboard and prying
the thing back to upright. In a larger boat, this seemed to
*obviously* indicate the necessity of deep keels and heavy ballast.
The AS29 and LM (if I understand correctly,) seem to prove otherwise,
and I am very intrigued.
I've spent the weekend imaging a crusing sharpie that takes the
concept to extremes -- a very long, very slender craft sporting a low
sail plan and high freeboard: sort of like an extrastretched
tarantula (minus the keel) with a multi-mast sail plan and high
topsides. At what point is the beam to freeboard ratio optimized?
Why this? The more I read, the more beaminess seems like a liability.
I'm beginning to suspect boat are made wide so as to make them easy
to sell, not easy to sail. I can't help but wonder what you end up
with if you design for maximum, rather than minimum waterline.
Anyone want to kick this around?
YIBB,
David Ryan
Minister of Information and Culture
Crumbling Empire Productions
(212) 247-0296
Ron Badley wrote:
have an interesting time turning it, to say nothing of trying to go through
stays.
The beaminess is what give it the stability, that's why the hulls of a cat
are so far apart. Mine is 5 ft wide and 20 ft long, for a 4:1 length to beam
ratio. Say you went to the extreme, 3 feet wide and 30 feet long. Basicaly a
very long canoe. It would be pretty fast, but very hard to turn. If you
increase rocker to improve turning, you loose waterline....
>A long, narrow, flat bottom boat would be very fast. Of course, you would
> > Why this? The more I read, the more beaminess seems like a liability.
> > I'm beginning to suspect boat are made wide so as to make them easy
> > to sell, not easy to sail. I can't help but wonder what you end up
> > with if you design for maximum, rather than minimum waterline.
> >
> > Anyone want to kick this around?
>
>
have an interesting time turning it, to say nothing of trying to go through
stays.
The beaminess is what give it the stability, that's why the hulls of a cat
are so far apart. Mine is 5 ft wide and 20 ft long, for a 4:1 length to beam
ratio. Say you went to the extreme, 3 feet wide and 30 feet long. Basicaly a
very long canoe. It would be pretty fast, but very hard to turn. If you
increase rocker to improve turning, you loose waterline....