Re: A real forgotten gem

> Wouldn't flare increase the pressure from the sides?


G'day Mark,

not if the panels are of equal curvature, ie s o p, ie the body plan view shows the chine line bisecting the angle between sides and bottom. Works where there's more than three panels too, such as for non-pareil sharpies, etc.

What if there's negative flare, ie panels joining at less than 90 degrees? This might happen in, say, a vee-tunneled scow. What if the panels aren't 2D flat, but are 3D with equal curvatures adjacent the chine? What if the hull shows a water shedding chine aft, but is otherwise molded with equal curvatures adjacent the chine?

Graeme
Hiya Graeme,

It causes wild steering.

"When it cuts through a wave crest, the pressure of water against the
sides of the bow is comparatively small. The pressure under the
forward bottom is still less, so water is forced downward across the
chine and breaks into turbulence. The turbulent flow reduces the
pressure underneath still more, allowing the bow to sink lower,
increasing the pressure against the sides - a vicious circle,
accounting for the erratic behavior of sharp bowed flat bottom boats
in rough water.
BWAOM pp 352

Matching plan and profile views moves the bow up and the waterline
further aft. What's not explained is that since the sides aren't
fully immersed, the extra comparative width of the bottom pushes up
disproportionately, making the front of the boat more buoyant - back
to the garvey.

The square boat bow may also help. Wouldn't flare increase the
pressure from the sides?

Mark



On Jun 13, 2010, at 7:50 PM, graeme19121984 wrote:
> As for that restricted to sharpies: the famous, simple, didactic
> 'seas of peas' demonstration about minimising cross chine flow
> doesn't let on much about why, according to his flow theory, the
> detrimental effects are just so important in the bow region.
> Similar to an airplane wing. The distance the water molecule has to
> travel relative to the boat depends on the curvature of the path
> traveled. A deep curvature causes the molecule spacing to stretches
> out (compared with a straight line), and this increased molecule (or
> pea) spacing makes the pressure decrease. But, if the panels on > two sides of a chine edge have equal curvature, they have equal
> pressure.

That's sort of the Bernoulli Principle. Part of the explanation of flight, but I think not at work here.

It's more like Newton's Third Law of Motion, ie, for any action there's an equal and opposite reaction. (This too is part of the explanation of flight (lift). In flight it works two ways at least: the fluid stream above the wing is bent downwards; and the fluid stream under the wing is forced downwards.)

As the flow of water impacts the sharpie SOP panels, sides and bottom, at the same speed and the same angle of incidence, then the glancing blow imparts the same force per unit area to the water - sides and bottom.
No, due to the pressures being equal. Though the total force exerted by the larger bottom area may be much larger than that of the sum of the sides, the force per unit of area, measured as pressure, is the same. It's not the relative areas causing the pressure, rather the speed and relative angle of the hull panels. The pressure at the SOP sides is the same as at the SOP bottom for the speed and angles of those panels are the same. And the net effect of the pressure increase lifts the hull.


--- Inbolger@yahoogroups.com, "Joe T" <scsbmsjoe@...> wrote:
> Back to the pressures, look at any chine design. If the underwater
> line of the chine in section bisects the adjacent panels then the
> water pressures on those panels es equal, no eddies.

> Now, the areas of the panels at each point along the chine are not
> equal. Does it matter.
--- Inbolger@yahoogroups.com, Fred Schumacher <fredschum@...> wrote:
> On Fri, Jun 11, 2010 at 10:58 PM, Joe T <scsbmsjoe@...> wrote:

> That's right. When looking at a lines drawing from bow or stern
> on, the chine line should describe a 45 degree angle.

What then if the chine angle is greater than 90 degrees, say as for Otter?

> This bottom curve problem can also be solved by adding a cutwater
> to the bow, allowing the boat to have a pointy end, while still
> maintaining good Sea of Peas flow and putting some displacement
> into the bow.

Yes, there's that, and there's "...the streamlining being effective as that of a torpedo. ...The blunt-pointed upper bow is mostly cosmetic... The origin of the concept was an attempt to do something about the plowing, skidding, and air ingestion of a garvey by adding bouyancy under the garvey's toboggan bow" (BWAOM, Microtrawler, pp 282, 283)

Graeme
I don't know about it's being dangerous to think too much about the Bolger stuff ;-) There's much to think on...

I believe "seas of peas" to be merely a didactic exercise, a way to communicate one aspect of a boat moving on water via an easy visualisation. The visualisation exercise is simplified to being about how different angles of oncoming hull panels may affect how water is pushed. It's about the bounce or acceleration of particles after striking with different angles of incidence. Differing angles means differing accelerations, or pressures. Differing pressures will cause water to flow from high to low. If the flow is around a sharpie hull then it will flow across a sharp chine. This is a bad thing, as much undesirable power sapping turbulence may occur. That's about it for the 'seas of peas' visualisation. It's very easy to visualise small models having different shaped bows moving through a plate of frozen peas, and get the idea that some sharpie shape more likely forces no pressure differential across the chine. There's a lot more to the flow theory though. There's a vast matrix of knowledge and empirical results, self originated and accumulated, that PCB used, let alone that as applied to his thinking on sharpie hulls.

As for that restricted to sharpies: the famous, simple, didactic 'seas of peas' demonstration about minimising cross chine flow doesn't let on much about why, according to his flow theory, the detrimental effects are just so important in the bow region. Further, there's no mention made of how, according to his theory, design innattention at the sharpie bow causes not only the chine induced turbulent eddies there to drag away power, but may cause the rudder to drag even more in a sea way. Crikey, PCB wrote he learnt much from Munroe, but that he sided with Hunt in believing sharpies ought sail on their bottoms, yet he agreed with Atkins on the advantageous qualities inherant in the heeling sharpie hull!!! Apparent contradictions, inconsistencies, incoherence? No, I don't think so. Mostly all is resolved in theory somewhere in writing, and by reference to the boats.

Graeme

--- Inbolger@yahoogroups.com, Bruce Hallman <hallman@...> wrote:
>
> > ISTR it being in one of the write-ups in BWaOM, and I've seen similar
> > commentary concerning traditional sharpies.
> >
> > -p
>
> When I get home later I will re-read BWAOM (for the 100th time) and
> see if I can find it.
>
> Thinking aloud, the classic Bolger "Sea of Peas" shouldn't care about
> the angle of heel. All that each "pea" sees is the tiny spot on the
> hull surface perpendicular to its place in space. Heel angle
> shouldn't have any effect. But, it is dangerous to think too much,
> what do I know!
>
Bruce,

I think you may have remembered pretty well the chapter in BWOAM on Wyoming - just in reverse. The higher pressure is on the sides of a flattie. The water flows down cross the chines; not up.

Cheers


On Jun 12, 2010, at 9:22 AM, Bruce Hallman wrote:

 



Enlightenment? Not me! In any case, this is how I rationalize it in my mind:


Like, in a "flat bottom boat", the sides are curved, and the bottom is
flat. Then the pressure along the side is less than the pressure
below the boat. And, water tries to flow from high pressure to low
pressure, (across the chine) and this causes turbulence which slows
you down.


IIRC, Martha Jane was commissioned as a trailerable Black Skimmer.  The long overhanging ends were seen as superfluous and truncated.
 
V/R
Chris
--- OnSat, 6/12/10, Fred Schumacher<fredschum@...>wrote:
This is the primary reason, I think, for Bolger's famous bow transoms. To get a pointy end on the front with the deep bellied rocker would require the bottom curve to come way out of the water at the bow.
On Fri, Jun 11, 2010 at 8:51 PM, eric14850 <eric14850@...> wrote:
>
>
>
> Whalewatcher Pg245 BWAOM last paragraph. And the winner is Prairiedog!

Actually the paragraph I was remember is just after that on page 246:

"The boat is supposed to be sail heeled. The ideal angle is 10 to 12
degrees, with the weather-side chine close to the waterline. At this
angle, the waterline length, nominally 20 feet when upright, lengthens
out 6 feet or more as the lee overhangs immerse. ... She'll also be a
good drifter since the short upright waterline length keeps the wetted
surface small."

Hmmm, pretty interesting!
On Fri, Jun 11, 2010 at 8:58 PM, Joe T <scsbmsjoe@...> wrote:
>
>
>
> I have given the Sea Of Peas, Bolger Flow Theory much thought. Here is my take on it. In a chine boat it is best to have the pressures on the panels equal in order to minimize eddying over the chines. Eddying causes turbulance that slows the boat and can create erratic swerving. I know this from experience with a flat bottom kayak. When testing it with it seemed to have a will of its own with no directional stability. Fixed it with skeg. Back to the pressures, look at any chine design. If the underwater line of the chine in section bisects the adjacent panels then the water pressures on those panels es equal, no eddies.
>
> Now, the areas of the panels at each point along the chine are not equal. Does it matter. Can one of you bright engineers enlighten me?
>


Enlightenment? Not me! In any case, this is how I rationalize it in my mind:

Similar to an airplane wing. The distance the water molecule has to
travel relative to the boat depends on the curvature of the path
traveled. A deep curvature causes the molecule spacing to stretches
out (compared with a straight line), and this increased molecule (or
pea) spacing makes the pressure decrease. But, if the panels on two
sides of a chine edge have equal curvature, they have equal pressure.

Like, in a "flat bottom boat", the sides are curved, and the bottom is
flat. Then the pressure along the side is less than the pressure
below the boat. And, water tries to flow from high pressure to low
pressure, (across the chine) and this causes turbulence which slows
you down.
On Fri, Jun 11, 2010 at 10:58 PM, Joe T<scsbmsjoe@...>wrote:

I have given the Sea Of Peas, Bolger Flow Theory much thought. Here is my take on it. In a chine boat it is best to have the pressures on the panels equal in order to minimize eddying over the chines.... If the underwater line of the chine in section bisects the adjacent panels then the water pressures on those panels es equal, no eddies.


That's right. When looking at a lines drawing from bow or stern on, the chine line should describe a 45 degree angle.

This is the primary reason, I think, for Bolger's famous bow transoms. To get a pointy end on the front with the deep bellied rocker would require the bottom curve to come way out of the water at the bow. Notice on Micro and AS series how the bottom curve flattens toward the bow. This bottom curve problem can also be solved by adding a cutwater to the bow, allowing the boat to have a pointy end, while still maintaining good Sea of Peas flow and putting some displacement into the bow.

fred s.
I have given the Sea Of Peas, Bolger Flow Theory much thought. Here is my take on it. In a chine boat it is best to have the pressures on the panels equal in order to minimize eddying over the chines. Eddying causes turbulance that slows the boat and can create erratic swerving. I know this from experience with a flat bottom kayak. When testing it with it seemed to have a will of its own with no directional stability. Fixed it with skeg. Back to the pressures, look at any chine design. If the underwater line of the chine in section bisects the adjacent panels then the water pressures on those panels es equal, no eddies.

Now, the areas of the panels at each point along the chine are not equal. Does it matter. Can one of you bright engineers enlighten me?

Joe T

--- Inbolger@yahoogroups.com, Bruce Hallman <hallman@...> wrote:
>
> On Fri, Jun 11, 2010 at 11:12 AM, Christopher C. Wetherill
> <wetherillc@...> wrote:
> >
> >
> >
> > By "flat" I meant 0 deadrise.  I recall seeing two bits of info that I lack sufficient time to search out for reference.
>
> I understand now, thanks. Part of my strong feelings about this come
> from sailing a Tortoise a few summers back in really stiff wind, and
> on the downwind leg of a couple miles of fetch, so with some pretty
> big waves. (Not advised unless warm water and close to shore, but
> this was that.)
>
> I was really shocked how the deep curvature (and 0 deadrise) of that
> hull was able to flow through the water when pressed hard. As far as
> the molecules of water were concerned, they just flowed around the
> boat. (A boat that didn't look like boat.) Stamping was not an
> issue. Exceeding hull speed was an issue!
>
> >One is the existence of "anti-stamp" pads for one of the AS series.
>
> You are right, MAIB V190N18, but I they were called "anti-phlumphing
> Bowshape", and the stated purpose was: "introduced for more restful
> nights in ripples and waves...when at rest", and also to provide body
> armor for "beaching-prowess".
>
> >The other is that PCB, in a write-up of an AS type boat, discussed at some length the fact that the hull shape was intended to heel so that the chine gave the behavior that a V bottom would otherwise.  He further mentioned that the boat would be noisy at anchor.
>
> I recall reading this too, but can't remember where. Does anybody remember?
>
> I think this comes up when there are discussions of the "sea of peas".
> I flagged an old email of graeme19121984 where he writes of this PCB
> theory is some detail, pasted below...
>
> =====pasted email below========
>
> graeme19121984 to bolger group 9/27/05
> ==
> A little while ago there was yet again some discussion here from
> message #46045 to #46078 wherein the question was again raised as to
> whether or not Mr Bolger had ever claimed SOP. Now, I think there is
> sufficient evidence including that of Jim Michalak's account
> (http://marina.fortunecity.com/breakwater/274/2004/0901/index.htm#Hull
> %20Shaping2 orhttp://tinyurl.com/bnks4) and Gary's account at
> message #46078 to safely conclude that Mr Bolger indeed had
> conceived, even written (and here we must remember Bolger's
> reputation for being a very careful author. Even his correspondence
> warrants study!), of a thought experiment: Seas of Peas. This to
> help envisage the movement of a boat hull through water.
>
> The idea of representing water molecules as peas may have been
> entirely original; or possibly may be an adaptation of a similar
> model, for example, the explanation of behaviour of airflow around a
> wing or sail is often seen depicted as moving 'particles'; also gas
> molecules were to be "visualised as a collection of perfectly hard
> spheres", when explaining the Ideal Gas Law
>http://tinyurl.com/aallolong ago when I went to high school.
>
> Now, if that is SOP, this visualisation exercise, then it is one
> thing and helpful; but it has always seemed to me to be inextricably
> linked, sometimes confusingly so, to ANOTHER fundamental Bolger
> concept or theory of design for boats in general and sharpie hull
> lines particularly. Frustratingly, Mr Bolger makes fleeting
> references and gingerly alludes to this theory in many of his
> writings without actually coming out and stating it fully and
> clearly. Here a bit, there a bit: a riddle, a tease. The elephant is
> in the room, yet mostly ignored.
>
> My favourite most obvious bit is about the lessened chine eddies of
> (Minimum) Proa in BWAOM, Chapter 24, p118, then there is the bit
> about a long series of experiments (testing what other hypothesis?)
> when explaining the seemingly excessive rocker in the bottom of
> Otter in SB, Chapter 22, p119. There are again, sharpie hull form
> plus exaggerated rocker plus chine eddies, all mentioned regarding
> Archaeopteryx in SB, Chapter 23, pp128+130; then there is the
> recently posted article on AS19; and on, and on. From more recent,
> to way back times.
>
> Why is Mr Bolger so reticent, if that is the correct
> characterisation? Why not elaborate the flow theory? Well, I recall
> reading articles linked or posted here, written by Mr Bolger some
> time ago, in which he lamented that he was not allowed to call
> himself a naval architect. People had said he had not the proper
> professional qualifications. He vigorously railed against this
> argument maintaining something along the lines that if someone loved
> doing something, did a lot of it, and did it well, indeed
> brilliantly, then that ought be sufficient "qualification". Perhaps
> attack from authorities and "professionals" jealously guarding their
> bailiwick prompts Mr Bolger's apparent discretion (his valour will
> be remembered; will theirs?).
>
> BFT
> Now and again Mr Bolger mentions Ralph Munroe and Ray Hunt, but
> while regarding the Gloucester Yawl in Small Boats, Chapter 10, p50,
> Mr Bolger writes at the page top:
>
> "It's an old observation that sharpies suffer from being wide for
> their length, and from having flaring sides. MY FLOW THEORY*
> accounts for this, but I've long thought that a sponson sharpie
> would produce the benefits of a flaring side without the drawbacks,
> or most of them." ( * no italics thus my capitals)
>
> Gotcha. There is the proclamation: " My flow theory", ie. His flow
> theory, ie. Bolger flow theory, ie. BFT.
>
> And it goes way back. Before the dinosaurs, way before the evolution
> of Archaeopteryx. How far? I don't know. And it will stretch into
> the future too, and via the Bolgerverse have an effect in many
> places. I hope one day Mr Bolger tells. I hope he simply reveals
> all, in published writing, and not only in design. 'Cause I want to
> know.
>
> When I figure out how, I have an idea to set up a database here of
> all the many Bolger references to SOP and BFT. They are too many and
> too deliberately low profile to recollect at will. If pulled
> together comprehensively in one easily accessible place a wider and
> better understanding of one Bolger theory (or two) may eventuate.
> Maybe someone else would like to set this up?
>
> forgive me this lengthy rave
> Graeme who would love to have over Bolger For Tea
>
Whalewatcher Pg245 BWAOM last paragraph. And the winner is Prairiedog! And Martha Jane is in BWAOM. I thought it was in Folding Schooner.

Eric


--- Inbolger@yahoogroups.com, "prairiedog2332" <arvent@...> wrote:
>
> I believe what you are referring to is the chapter on Whalewatcher.
>
> --- Inbolger@yahoogroups.com, Bruce Hallman <hallman@> wrote:
> >
> > > ISTR it being in one of the write-ups in BWaOM, and I've seen
> similar
> > > commentary concerning traditional sharpies.
> > >
> > > -p
> >
> > When I get home later I will re-read BWAOM (for the 100th time) and
> > see if I can find it.
> >
> > Thinking aloud, the classic Bolger "Sea of Peas" shouldn't care about
> > the angle of heel. All that each "pea" sees is the tiny spot on the
> > hull surface perpendicular to its place in space. Heel angle
> > shouldn't have any effect. But, it is dangerous to think too much,
> > what do I know!
> >
>
Re: Bolger flow theory

What I've taken away from his writing is that it is ideal if the curve in profile is the same as the curve in plan, so that the forces are balanced and there are no eddies around the chine.

If you look at the body shape of tropical boxfish (Ostraciidae spp.) the curves in plan and profile are the same. Daimler used this concept to design what they called the Bionic Car, which had a coefficient of drag of 0.19 while retaining an essentially boxy shape. Seehttp://www.ecofriend.org/entry/fish-inspired-mercedes-bionic-car-most-efficient-this-category-aerodynamic-vehicle/Some photos of a boxfish look like a Bolger Box.

fred s.
I thought the reference was from AS-29, but I skimmed AS-29 and Loose Moose and didn't find it. Therefore I think it is from Martha Jane (back when such things needed explaining) but I can't check that because the book is on loan.

Eric

--- Inbolger@yahoogroups.com, Bruce Hallman <hallman@...> wrote:
>
> On Fri, Jun 11, 2010 at 11:12 AM, Christopher C. Wetherill
> <wetherillc@...> wrote:
> >
> >
> >
> > By "flat" I meant 0 deadrise.  I recall seeing two bits of info that I lack sufficient time to search out for reference.
>
> I understand now, thanks. Part of my strong feelings about this come
> from sailing a Tortoise a few summers back in really stiff wind, and
> on the downwind leg of a couple miles of fetch, so with some pretty
> big waves. (Not advised unless warm water and close to shore, but
> this was that.)
>
> I was really shocked how the deep curvature (and 0 deadrise) of that
> hull was able to flow through the water when pressed hard. As far as
> the molecules of water were concerned, they just flowed around the
> boat. (A boat that didn't look like boat.) Stamping was not an
> issue. Exceeding hull speed was an issue!
>
> >One is the existence of "anti-stamp" pads for one of the AS series.
>
> You are right, MAIB V190N18, but I they were called "anti-phlumphing
> Bowshape", and the stated purpose was: "introduced for more restful
> nights in ripples and waves...when at rest", and also to provide body
> armor for "beaching-prowess".
>
> >The other is that PCB, in a write-up of an AS type boat, discussed at some length the fact that the hull shape was intended to heel so that the chine gave the behavior that a V bottom would otherwise.  He further mentioned that the boat would be noisy at anchor.
>
> I recall reading this too, but can't remember where. Does anybody remember?
>
> I think this comes up when there are discussions of the "sea of peas".
> I flagged an old email of graeme19121984 where he writes of this PCB
> theory is some detail, pasted below...
>
> =====pasted email below========
>
> graeme19121984 to bolger group 9/27/05
> ==
> A little while ago there was yet again some discussion here from
> message #46045 to #46078 wherein the question was again raised as to
> whether or not Mr Bolger had ever claimed SOP. Now, I think there is
> sufficient evidence including that of Jim Michalak's account
> (http://marina.fortunecity.com/breakwater/274/2004/0901/index.htm#Hull
> %20Shaping2 orhttp://tinyurl.com/bnks4) and Gary's account at
> message #46078 to safely conclude that Mr Bolger indeed had
> conceived, even written (and here we must remember Bolger's
> reputation for being a very careful author. Even his correspondence
> warrants study!), of a thought experiment: Seas of Peas. This to
> help envisage the movement of a boat hull through water.
>
> The idea of representing water molecules as peas may have been
> entirely original; or possibly may be an adaptation of a similar
> model, for example, the explanation of behaviour of airflow around a
> wing or sail is often seen depicted as moving 'particles'; also gas
> molecules were to be "visualised as a collection of perfectly hard
> spheres", when explaining the Ideal Gas Law
>http://tinyurl.com/aallolong ago when I went to high school.
>
> Now, if that is SOP, this visualisation exercise, then it is one
> thing and helpful; but it has always seemed to me to be inextricably
> linked, sometimes confusingly so, to ANOTHER fundamental Bolger
> concept or theory of design for boats in general and sharpie hull
> lines particularly. Frustratingly, Mr Bolger makes fleeting
> references and gingerly alludes to this theory in many of his
> writings without actually coming out and stating it fully and
> clearly. Here a bit, there a bit: a riddle, a tease. The elephant is
> in the room, yet mostly ignored.
>
> My favourite most obvious bit is about the lessened chine eddies of
> (Minimum) Proa in BWAOM, Chapter 24, p118, then there is the bit
> about a long series of experiments (testing what other hypothesis?)
> when explaining the seemingly excessive rocker in the bottom of
> Otter in SB, Chapter 22, p119. There are again, sharpie hull form
> plus exaggerated rocker plus chine eddies, all mentioned regarding
> Archaeopteryx in SB, Chapter 23, pp128+130; then there is the
> recently posted article on AS19; and on, and on. From more recent,
> to way back times.
>
> Why is Mr Bolger so reticent, if that is the correct
> characterisation? Why not elaborate the flow theory? Well, I recall
> reading articles linked or posted here, written by Mr Bolger some
> time ago, in which he lamented that he was not allowed to call
> himself a naval architect. People had said he had not the proper
> professional qualifications. He vigorously railed against this
> argument maintaining something along the lines that if someone loved
> doing something, did a lot of it, and did it well, indeed
> brilliantly, then that ought be sufficient "qualification". Perhaps
> attack from authorities and "professionals" jealously guarding their
> bailiwick prompts Mr Bolger's apparent discretion (his valour will
> be remembered; will theirs?).
>
> BFT
> Now and again Mr Bolger mentions Ralph Munroe and Ray Hunt, but
> while regarding the Gloucester Yawl in Small Boats, Chapter 10, p50,
> Mr Bolger writes at the page top:
>
> "It's an old observation that sharpies suffer from being wide for
> their length, and from having flaring sides. MY FLOW THEORY*
> accounts for this, but I've long thought that a sponson sharpie
> would produce the benefits of a flaring side without the drawbacks,
> or most of them." ( * no italics thus my capitals)
>
> Gotcha. There is the proclamation: " My flow theory", ie. His flow
> theory, ie. Bolger flow theory, ie. BFT.
>
> And it goes way back. Before the dinosaurs, way before the evolution
> of Archaeopteryx. How far? I don't know. And it will stretch into
> the future too, and via the Bolgerverse have an effect in many
> places. I hope one day Mr Bolger tells. I hope he simply reveals
> all, in published writing, and not only in design. 'Cause I want to
> know.
>
> When I figure out how, I have an idea to set up a database here of
> all the many Bolger references to SOP and BFT. They are too many and
> too deliberately low profile to recollect at will. If pulled
> together comprehensively in one easily accessible place a wider and
> better understanding of one Bolger theory (or two) may eventuate.
> Maybe someone else would like to set this up?
>
> forgive me this lengthy rave
> Graeme who would love to have over Bolger For Tea
>
I believe what you are referring to is the chapter on Whalewatcher.

--- Inbolger@yahoogroups.com, Bruce Hallman <hallman@...> wrote:
>
> > ISTR it being in one of the write-ups in BWaOM, and I've seen
similar
> > commentary concerning traditional sharpies.
> >
> > -p
>
> When I get home later I will re-read BWAOM (for the 100th time) and
> see if I can find it.
>
> Thinking aloud, the classic Bolger "Sea of Peas" shouldn't care about
> the angle of heel. All that each "pea" sees is the tiny spot on the
> hull surface perpendicular to its place in space. Heel angle
> shouldn't have any effect. But, it is dangerous to think too much,
> what do I know!
>
> ISTR it being in one of the write-ups in BWaOM, and I've seen similar
> commentary concerning traditional sharpies.
>
> -p

When I get home later I will re-read BWAOM (for the 100th time) and
see if I can find it.

Thinking aloud, the classic Bolger "Sea of Peas" shouldn't care about
the angle of heel. All that each "pea" sees is the tiny spot on the
hull surface perpendicular to its place in space. Heel angle
shouldn't have any effect. But, it is dangerous to think too much,
what do I know!
On Fri, Jun 11, 2010 at 12:53 PM, Bruce Hallman <hallman@...> wrote:

>>The other is that PCB, in a write-up of an AS type boat, discussed at some length the fact that the hull shape was intended to heel so that the chine gave the behavior that a V bottom would otherwise.  He further mentioned that the boat would be noisy at anchor.
>
> I recall reading this too, but can't remember where.  Does anybody remember?

ISTR it being in one of the write-ups in BWaOM, and I've seen similar
commentary concerning traditional sharpies.

-p
On Fri, Jun 11, 2010 at 11:12 AM, Christopher C. Wetherill
<wetherillc@...> wrote:
>
>
>
> By "flat" I meant 0 deadrise.  I recall seeing two bits of info that I lack sufficient time to search out for reference.

I understand now, thanks. Part of my strong feelings about this come
from sailing a Tortoise a few summers back in really stiff wind, and
on the downwind leg of a couple miles of fetch, so with some pretty
big waves. (Not advised unless warm water and close to shore, but
this was that.)

I was really shocked how the deep curvature (and 0 deadrise) of that
hull was able to flow through the water when pressed hard. As far as
the molecules of water were concerned, they just flowed around the
boat. (A boat that didn't look like boat.) Stamping was not an
issue. Exceeding hull speed was an issue!

>One is the existence of "anti-stamp" pads for one of the AS series.

You are right, MAIB V190N18, but I they were called "anti-phlumphing
Bowshape", and the stated purpose was: "introduced for more restful
nights in ripples and waves...when at rest", and also to provide body
armor for "beaching-prowess".

>The other is that PCB, in a write-up of an AS type boat, discussed at some length the fact that the hull shape was intended to heel so that the chine gave the behavior that a V bottom would otherwise.  He further mentioned that the boat would be noisy at anchor.

I recall reading this too, but can't remember where. Does anybody remember?

I think this comes up when there are discussions of the "sea of peas".
I flagged an old email of graeme19121984 where he writes of this PCB
theory is some detail, pasted below...

=====pasted email below========

graeme19121984 to bolger group 9/27/05
==
A little while ago there was yet again some discussion here from
message #46045 to #46078 wherein the question was again raised as to
whether or not Mr Bolger had ever claimed SOP. Now, I think there is
sufficient evidence including that of Jim Michalak's account
(http://marina.fortunecity.com/breakwater/274/2004/0901/index.htm#Hull
%20Shaping2 orhttp://tinyurl.com/bnks4) and Gary's account at
message #46078 to safely conclude that Mr Bolger indeed had
conceived, even written (and here we must remember Bolger's
reputation for being a very careful author. Even his correspondence
warrants study!), of a thought experiment: Seas of Peas. This to
help envisage the movement of a boat hull through water.

The idea of representing water molecules as peas may have been
entirely original; or possibly may be an adaptation of a similar
model, for example, the explanation of behaviour of airflow around a
wing or sail is often seen depicted as moving 'particles'; also gas
molecules were to be "visualised as a collection of perfectly hard
spheres", when explaining the Ideal Gas Law
http://tinyurl.com/aallolong ago when I went to high school.

Now, if that is SOP, this visualisation exercise, then it is one
thing and helpful; but it has always seemed to me to be inextricably
linked, sometimes confusingly so, to ANOTHER fundamental Bolger
concept or theory of design for boats in general and sharpie hull
lines particularly. Frustratingly, Mr Bolger makes fleeting
references and gingerly alludes to this theory in many of his
writings without actually coming out and stating it fully and
clearly. Here a bit, there a bit: a riddle, a tease. The elephant is
in the room, yet mostly ignored.

My favourite most obvious bit is about the lessened chine eddies of
(Minimum) Proa in BWAOM, Chapter 24, p118, then there is the bit
about a long series of experiments (testing what other hypothesis?)
when explaining the seemingly excessive rocker in the bottom of
Otter in SB, Chapter 22, p119. There are again, sharpie hull form
plus exaggerated rocker plus chine eddies, all mentioned regarding
Archaeopteryx in SB, Chapter 23, pp128+130; then there is the
recently posted article on AS19; and on, and on. From more recent,
to way back times.

Why is Mr Bolger so reticent, if that is the correct
characterisation? Why not elaborate the flow theory? Well, I recall
reading articles linked or posted here, written by Mr Bolger some
time ago, in which he lamented that he was not allowed to call
himself a naval architect. People had said he had not the proper
professional qualifications. He vigorously railed against this
argument maintaining something along the lines that if someone loved
doing something, did a lot of it, and did it well, indeed
brilliantly, then that ought be sufficient "qualification". Perhaps
attack from authorities and "professionals" jealously guarding their
bailiwick prompts Mr Bolger's apparent discretion (his valour will
be remembered; will theirs?).

BFT
Now and again Mr Bolger mentions Ralph Munroe and Ray Hunt, but
while regarding the Gloucester Yawl in Small Boats, Chapter 10, p50,
Mr Bolger writes at the page top:

"It's an old observation that sharpies suffer from being wide for
their length, and from having flaring sides. MY FLOW THEORY*
accounts for this, but I've long thought that a sponson sharpie
would produce the benefits of a flaring side without the drawbacks,
or most of them." ( * no italics thus my capitals)

Gotcha. There is the proclamation: " My flow theory", ie. His flow
theory, ie. Bolger flow theory, ie. BFT.

And it goes way back. Before the dinosaurs, way before the evolution
of Archaeopteryx. How far? I don't know. And it will stretch into
the future too, and via the Bolgerverse have an effect in many
places. I hope one day Mr Bolger tells. I hope he simply reveals
all, in published writing, and not only in design. 'Cause I want to
know.

When I figure out how, I have an idea to set up a database here of
all the many Bolger references to SOP and BFT. They are too many and
too deliberately low profile to recollect at will. If pulled
together comprehensively in one easily accessible place a wider and
better understanding of one Bolger theory (or two) may eventuate.
Maybe someone else would like to set this up?

forgive me this lengthy rave
Graeme who would love to have over Bolger For Tea
By "flat"I meant 0 deadrise.  I recall seeing two bits of info that I lack sufficient time to search out for reference.  One is the existence of "anti-stamp" pads for one of the AS series.  The other is that PCB, in a write-up of an AS type boat, discussed at some length the fact that the hull shape was intended to heel so that the chine gave the behavior that a V bottom would otherwise.  He further mentioned that the boat would be noisy at anchor.

V/R
Chris

On 6/11/2010 1:35 PM, Bruce Hallman wrote:
On Fri, Jun 11, 2010 at 10:14 AM, Christopher C. Wetherill<wetherillc@...>wrote:
The V bottom also is required because the boat will sail essentially
upright. A flat bottom would stamp something fierce. The AS series
sails heeled over so that the chine forms a V.

V/R
Chris
I partially agree.

Flat bottom boats can pound fiercely.  I agree.

Where I disagree is that the so called Bolger Box sailboats.  I am
speaking only of the "box" displacement hulls like the Advanced
Sharpies.  Those hulls have very deep bottom curvatures.  When viewed
on paper in two dimension this harder to see, but look at these hulls
in three dimensions, they have fat deeply curved bottoms.  They
certainly have hard very chines, but they that cannot be called flat.

The boxy river cruisers which are meant to plane, like Tennesee,
Wyoming, etc., do have relatively flat bottoms, but they aren't sail
boats.
On Fri, Jun 11, 2010 at 10:14 AM, Christopher C. Wetherill
<wetherillc@...> wrote:
>
>
>
> The V bottom also is required because the boat will sail essentially
> upright. A flat bottom would stamp something fierce. The AS series
> sails heeled over so that the chine forms a V.
>
> V/R
> Chris
>

I partially agree.

Flat bottom boats can pound fiercely. I agree.

Where I disagree is that the so called Bolger Box sailboats. I am
speaking only of the "box" displacement hulls like the Advanced
Sharpies. Those hulls have very deep bottom curvatures. When viewed
on paper in two dimension this harder to see, but look at these hulls
in three dimensions, they have fat deeply curved bottoms. They
certainly have hard very chines, but they that cannot be called flat.

The boxy river cruisers which are meant to plane, like Tennesee,
Wyoming, etc., do have relatively flat bottoms, but they aren't sail
boats.
The V bottom also is required because the boat will sail essentially
upright. A flat bottom would stamp something fierce. The AS series
sails heeled over so that the chine forms a V.

V/R
Chris

On 6/11/2010 11:59 AM, Bruce Hallman wrote:
>
> My guess is that the "V bottom" (four panel) hull was chosen over a
> "square bottom" (three panel) hull because the outriggers give
> overturning stability. A "V bottom" doesn't displace the water that a
> "square bottom" does, and the displacement affects the need for
> ballast. An outrigger boat doesn't need as much ballast because the
> pontoons resist overturning, therefor a "V bottom" makes sense in a
> trimaran. And, not having ballast (hard or water tank) makes
> trailer-boating more practical. Also, I imagine that there are some
> floorboards installed so you could stand easily in the cockpit. The
> berthing for four comes from removable and adjustable "old fashioned"
> pipe berths, which I image would be adjustable and converted for
> optimal positioning when seated versus optimal positioning when
> sleeping.
>
>
>
On Fri, Jun 11, 2010 at 6:39 AM, Mason Smith <masonsmith@...> wrote:
>
>
>
> Bruce, thanks for working up this 554 trimaran idea. Provided the amas do come in against the hull, so that it's trailerable, it tempts me greatly. So much boat for the time and money it would take! And what fun to use! Was it only from the sketches that you produced your images? I wonder whether the number indicate that it's a completed design and plans would be available? The eyes and teeth are a kick.


Back in 1992, the MAIB Bolger articles were shorter than the "Bolger
on Design" articles we are familiar with later. Fun thing about
working up models in Free!Ship, it allows a person to build the boat
in their mind plus it allows a person get a glimpse into the design
process in PCB's mind.

It is a fully developed complete design. Seeing these full plans
would reveal more, and Susanne writes in another recent email that the
plans are still for sale, great!

(I had to make a few guesses to fill in some details when I modeling her.)

My educated guess is that the Hobie pontoon support tubes are
removable and are sliding into plywood hollow beams mounted on the top
deck of the center hull. Probably fastened in with bolts, or perhaps
some ingenious PCB connection mechanism.

So, this boat is almost certainly intended to be trailer-able.

Answering another questions in nearby email...

My guess is that the "V bottom" (four panel) hull was chosen over a
"square bottom" (three panel) hull because the outriggers give
overturning stability. A "V bottom" doesn't displace the water that a
"square bottom" does, and the displacement affects the need for
ballast. An outrigger boat doesn't need as much ballast because the
pontoons resist overturning, therefor a "V bottom" makes sense in a
trimaran. And, not having ballast (hard or water tank) makes
trailer-boating more practical. Also, I imagine that there are some
floorboards installed so you could stand easily in the cockpit. The
berthing for four comes from removable and adjustable "old fashioned"
pipe berths, which I image would be adjustable and converted for
optimal positioning when seated versus optimal positioning when
sleeping.
Hello All,
     #554, 23'6" x 12'9" Camper Trimaran Sloop is laid out on five 17'x 22' sheets, includes expanded hull-panels and ply-sheet layout for the hull-components, and is available from Phil Bolger & Friends for $200.- to build one boat, sent first-class, rolled in a tube.

Buried deep in the preparations for boat-bulding project here in Gloucester,
Susanne Altenburger, PB&F 
----- Original Message -----
Sent:Friday, June 11, 2010 9:39 AM
Subject:[bolger] A real forgotten gem, Bolger 554 Camping Trimaran using Hobie Cat       parts!

 

Bruce, thanks for working up this 554 trimaran idea. Provided the amas do come in against the hull, so that it's trailerable, it tempts me greatly. So much boat for the time and money it would take! And what fun to use! Was it only from the sketches that you produced your images? I wonder whether the number indicate that it's a completed design and plans would be available? The eyes and teeth are a kick.
 
By the way I have a few more photos from Susanne of the Whalewatcher sailing her trials off the Naval Academy at Annapolis last spring, including one nice one of Phil at the helm, and will put them in the photo album shortly.
 
Mason Smith
Adirondack Goodboat
68 North Point Road
Long Lake, NY 12847
 

Bruce, thanks for working up this 554 trimaran idea. Provided the amas do come in against the hull, so that it's trailerable, it tempts me greatly. So much boat for the time and money it would take! And what fun to use! Was it only from the sketches that you produced your images? I wonder whether the number indicate that it's a completed design and plans would be available? The eyes and teeth are a kick.
 
By the way I have a few more photos from Susanne of the Whalewatcher sailing her trials off the Naval Academy at Annapolis last spring, including one nice one of Phil at the helm, and will put them in the photo album shortly.
 
Mason Smith
Adirondack Goodboat
68 North Point Road
Long Lake, NY 12847
 
518 624 6398
www.adirondackgoodboat.com