Re: (Prince William Sound Yawl isometric) Leeboard raised / canted?
Good day Will
My folding schooner was built with a single off-centreboard about a
foot deeper than the plans. It is 3/8" steel plate with rounded leading
edge and chamfered down to 1/8" over 2" of the trailing edge.
Performace-wise it stalls at low speeds and sometimes sucks air due to
being a bit small but once the breeze is above 12 knots it flies to
windward. Am glad I made it a centreboard as our bay has many shallows
and coral bommies. We hit them or run aground so often the board is
called the galvanized depth sounder.
Martin
My folding schooner was built with a single off-centreboard about a
foot deeper than the plans. It is 3/8" steel plate with rounded leading
edge and chamfered down to 1/8" over 2" of the trailing edge.
Performace-wise it stalls at low speeds and sometimes sucks air due to
being a bit small but once the breeze is above 12 knots it flies to
windward. Am glad I made it a centreboard as our bay has many shallows
and coral bommies. We hit them or run aground so often the board is
called the galvanized depth sounder.
Martin
--- Inbolger@yahoogroups.com, ANDREW AIREY <andyairey@...> wrote:
down,unless racing.Dutch leebords,which have something of an aerofoil
section,were thought to be superior to the English flat boards,but I
don't think many skippers bothered to change.On a trip along the
Brittany coast last summer my skipper left the boards up,apart from
having one down to assist manoevering in Paimpol harbour,but what wind
we had was following anyway
them. They are quite obviously slower if both boards are left down, no
matter what point of sail, but especially to windward. Thanks to all
who posted answers. The Bolgers may have tried to reply by fax ... I
discovered after the fact that the printing cartridge in our machine
needed replacing.
To those who asked about photos: Yes, I have a few, but haven't posted
any of our photos to a photo site. Will be happy to Email a couple of
shots directly to those who asked; just need to figure out the system.
I've lost the handle since we upgraded to the fast glass wire system.
Or maybe it's just the cantankerous Mac with which I struggle.
-- Will White
>skipper is quoted as saying that they would leave both boards
> I can only pass on what I've read on sailing barge practise.One
down,unless racing.Dutch leebords,which have something of an aerofoil
section,were thought to be superior to the English flat boards,but I
don't think many skippers bothered to change.On a trip along the
Brittany coast last summer my skipper left the boards up,apart from
having one down to assist manoevering in Paimpol harbour,but what wind
we had was following anyway
> cheershttp://uk.messenger.yahoo.com
> andy airey
>
> Send instant messages to your online friends
>In my initial inquiry I twice mentioned E-scows, because I have raced
them. They are quite obviously slower if both boards are left down, no
matter what point of sail, but especially to windward. Thanks to all
who posted answers. The Bolgers may have tried to reply by fax ... I
discovered after the fact that the printing cartridge in our machine
needed replacing.
To those who asked about photos: Yes, I have a few, but haven't posted
any of our photos to a photo site. Will be happy to Email a couple of
shots directly to those who asked; just need to figure out the system.
I've lost the handle since we upgraded to the fast glass wire system.
Or maybe it's just the cantankerous Mac with which I struggle.
-- Will White
I can only pass on what I've read on sailing barge practise.One skipper is quoted as saying that they would leave both boards down,unless racing.Dutch leebords,which have something of an aerofoil section,were thought to be superior to the English flat boards,but I don't think many skippers bothered to change.On a trip along the Brittany coast last summer my skipper left the boards up,apart from having one down to assist manoevering in Paimpol harbour,but what wind we had was following anyway
cheers
andy airey
Send instant messages to your online friendshttp://uk.messenger.yahoo.com
cheers
andy airey
Send instant messages to your online friendshttp://uk.messenger.yahoo.com
Will,
I think you've made two queries:
1)
On Folding Schooner as drawn, when going to windward: leave both
boards down.
A rule of thumb for fin type foil area is that it be about 4% of the
sail area (opinion is split on whether the rudder area is, or is not
included.)
Excluding the staysail the Folding Schooner sail area is given as
193.5sqft, so applying the rule would have the total foil area at 4%
of 193.5sqft: which is 7.74sqft.
Now, the bilgeboard measurements are given as being 4.25ft by 1.66ft
(4'3" by 1'8").
From the overall length can be deducted 0.25ft for the handles, plus
about 1' 9.5", or, let's say 1.75ft, for the height of the leeboard
case: 4.25ft - 0.25ft - 1.75ft = 2.25ft.
The exposed area of a fully lowered FS foil is then 2.25ft by 1.66ft,
or approximately 3.735sqft. This is only about half the area that is
needed according to the rule of thumb, so it would be safe to assume
that PCB drew it to be sailed with both boards down. Both boards when
down together give the required area, albeit with less
lifting/pointing ability than one larger board would have.
PCB was probably aiming for reasonable sailing in the shallow waters
that this fun "toy" trailer boat was likeley to be sailed on the
most.
Another related consideration PCB may have had, similarly as for the
schooner sail plan aloft (large sail area deployed at _low height_),
is the advantage obtained from the shorter lever arm to the centre of
effort of the relatively short twin bilgeboards directly affecting
how far the boat will heel, and how far the crew must hike out as
wind speed increases. (Heeling is in part a result of the turning
moment arising from the amount of force acting on the sail centre of
effort, which is countered by a similar force acting on the foil
centre of effort, and is multipied by the distance between them.)
So, if you are having trouble consistently beating another Folding
Schooner, and if the water you sail on is deep enough, then modify to
use one bilgeboard of double the draft at 4.5ft, or about 6.5ft
overall length (all else being equal this would be within the PCB
Gloucester schooner class racing rules). You will best them beating
and close reaching, then lift the long board and stow it when going
downwind in light air to remain well in the lead. When beating, you
and your crew will have to be more athletic in hiking out though -
signing on heavier crew might help!
Anyway, for a standard Folding Schooner query, you could phone
Dynamite Payson for an answer.
--------------------
2)
Regarding your more general query of whether or not Bolger leeboards
or (twin) bilgeboards should both be left down when going to
windward, or whether the weatherside one should be raised:
PCB is all over the place on this.
Generally, he has said that raising the weather board is not worth
the trouble, and has designed boards accordingly at times, eg Black
Skimmer. Yet he has experimented with all kinds of leeboard fastening
arrangements and geometries that both allow the board to be raised
easier, or to remain lowered with minimal consequence eg Martha Jane,
Pico - so take your pick.
Often he reckons there is little to gain from anything more than
rudimentary shaping, just a little rounding at the leading edge and
some tapering at the trailing edge, equal on both faces of a
thwartships symetrical board.
Sometimes he writes that the precision required for building any toe-
in of a board is too great, and so risks adverse performance rather
than improved performance, yet has designed toe-in, especially early
on.
Particularly he sometimes draws reasonably high aspect ratio leeboard
foils, yet at other times he has drawn extremely broad low aspect
ones, and then writes that this is the best shape for a leeboard, eg.
Pirate Racer.
Sometimes he draws assymetric boards, most likely with a NACA profile
and toe-in, that most obviously should be raised when on the weather
side, eg. the later Offshore Leeboarder, while at the same time
telling us that these are of the simplest possible type eg Japanese
Beach Cruiser!
The parsimony of PCB's pen in plan and print often generalises the
particular sometimes.
I'd say the query mostly needs to be answered case by case, and day
by day.
----------------------------
Nice to hear you're nearly finished building, Will. Any pics?
Graeme
I think you've made two queries:
1)
On Folding Schooner as drawn, when going to windward: leave both
boards down.
A rule of thumb for fin type foil area is that it be about 4% of the
sail area (opinion is split on whether the rudder area is, or is not
included.)
Excluding the staysail the Folding Schooner sail area is given as
193.5sqft, so applying the rule would have the total foil area at 4%
of 193.5sqft: which is 7.74sqft.
Now, the bilgeboard measurements are given as being 4.25ft by 1.66ft
(4'3" by 1'8").
From the overall length can be deducted 0.25ft for the handles, plus
about 1' 9.5", or, let's say 1.75ft, for the height of the leeboard
case: 4.25ft - 0.25ft - 1.75ft = 2.25ft.
The exposed area of a fully lowered FS foil is then 2.25ft by 1.66ft,
or approximately 3.735sqft. This is only about half the area that is
needed according to the rule of thumb, so it would be safe to assume
that PCB drew it to be sailed with both boards down. Both boards when
down together give the required area, albeit with less
lifting/pointing ability than one larger board would have.
PCB was probably aiming for reasonable sailing in the shallow waters
that this fun "toy" trailer boat was likeley to be sailed on the
most.
Another related consideration PCB may have had, similarly as for the
schooner sail plan aloft (large sail area deployed at _low height_),
is the advantage obtained from the shorter lever arm to the centre of
effort of the relatively short twin bilgeboards directly affecting
how far the boat will heel, and how far the crew must hike out as
wind speed increases. (Heeling is in part a result of the turning
moment arising from the amount of force acting on the sail centre of
effort, which is countered by a similar force acting on the foil
centre of effort, and is multipied by the distance between them.)
So, if you are having trouble consistently beating another Folding
Schooner, and if the water you sail on is deep enough, then modify to
use one bilgeboard of double the draft at 4.5ft, or about 6.5ft
overall length (all else being equal this would be within the PCB
Gloucester schooner class racing rules). You will best them beating
and close reaching, then lift the long board and stow it when going
downwind in light air to remain well in the lead. When beating, you
and your crew will have to be more athletic in hiking out though -
signing on heavier crew might help!
Anyway, for a standard Folding Schooner query, you could phone
Dynamite Payson for an answer.
--------------------
2)
Regarding your more general query of whether or not Bolger leeboards
or (twin) bilgeboards should both be left down when going to
windward, or whether the weatherside one should be raised:
PCB is all over the place on this.
Generally, he has said that raising the weather board is not worth
the trouble, and has designed boards accordingly at times, eg Black
Skimmer. Yet he has experimented with all kinds of leeboard fastening
arrangements and geometries that both allow the board to be raised
easier, or to remain lowered with minimal consequence eg Martha Jane,
Pico - so take your pick.
Often he reckons there is little to gain from anything more than
rudimentary shaping, just a little rounding at the leading edge and
some tapering at the trailing edge, equal on both faces of a
thwartships symetrical board.
Sometimes he writes that the precision required for building any toe-
in of a board is too great, and so risks adverse performance rather
than improved performance, yet has designed toe-in, especially early
on.
Particularly he sometimes draws reasonably high aspect ratio leeboard
foils, yet at other times he has drawn extremely broad low aspect
ones, and then writes that this is the best shape for a leeboard, eg.
Pirate Racer.
Sometimes he draws assymetric boards, most likely with a NACA profile
and toe-in, that most obviously should be raised when on the weather
side, eg. the later Offshore Leeboarder, while at the same time
telling us that these are of the simplest possible type eg Japanese
Beach Cruiser!
The parsimony of PCB's pen in plan and print often generalises the
particular sometimes.
I'd say the query mostly needs to be answered case by case, and day
by day.
----------------------------
Nice to hear you're nearly finished building, Will. Any pics?
Graeme
--- Inbolger@yahoogroups.com, "omegacubedtoo" <omegacubed@...> wrote:
>
> --- Inbolger@yahoogroups.com, "Bruce Hallman" <bruce@> wrote:
> >
> > Prince William Sound Yawl isometric
> >
> >http://flickr.com/photos/hallman/2711209606/
> >
> Bruce --
>
> Another beautiful set of isometrics.
>
> Question ... So many Bolger designs have leeboards or bilgeboards,
as
> does the Folding Schooner. I faxed some questions to Him and
Friends,
> the most vexing of which, to me, is whether the boat is designed to
go
> to windward with both boards down or just the leeward one, a la
> E-scow. Ths size of the boards on the Prince William Sound Yawl and
> Wisp would suggest that the efficient way is to raise the windward
> board, but those on the Folding Schooner seem relatively small, and
> are canted inward, parallel to the topsides, as opposed to canting
> out, like Wisp and, again, an E-scow. Anyone out there have an
> opinion, or better yet, certain knowledge from Bolger himself?
>
> I'm almost finished building one, only with a lot of brushwork to go
> ... I'm finishing the decks and interior bright (okoume mahogony),
and
> have done the filling and staining.
>
> -- Will
>
Just looked at the link.Does anyone have any information on the Antispray 48
cheers
andy airey
Send instant messages to your online friendshttp://uk.messenger.yahoo.com
cheers
andy airey
Send instant messages to your online friendshttp://uk.messenger.yahoo.com
> Anyone out there have anPhil Bolger has written about leeboards, in several places, for sure!
> opinion, or better yet, certain knowledge from Bolger himself?
Now to just remember where he wrote it...
I recall that he did not feel that keeping both boards down was that
bad. It varies depending on the specific board design.
> I'm almost finished building one,A folding schooner? Got any photos?
--- Inbolger@yahoogroups.com, "Bruce Hallman" <bruce@...> wrote:
Another beautiful set of isometrics.
Question ... So many Bolger designs have leeboards or bilgeboards, as
does the Folding Schooner. I faxed some questions to Him and Friends,
the most vexing of which, to me, is whether the boat is designed to go
to windward with both boards down or just the leeward one, a la
E-scow. Ths size of the boards on the Prince William Sound Yawl and
Wisp would suggest that the efficient way is to raise the windward
board, but those on the Folding Schooner seem relatively small, and
are canted inward, parallel to the topsides, as opposed to canting
out, like Wisp and, again, an E-scow. Anyone out there have an
opinion, or better yet, certain knowledge from Bolger himself?
I'm almost finished building one, only with a lot of brushwork to go
... I'm finishing the decks and interior bright (okoume mahogony), and
have done the filling and staining.
-- Will
>Bruce --
> Prince William Sound Yawl isometric
>
>http://flickr.com/photos/hallman/2711209606/
>
Another beautiful set of isometrics.
Question ... So many Bolger designs have leeboards or bilgeboards, as
does the Folding Schooner. I faxed some questions to Him and Friends,
the most vexing of which, to me, is whether the boat is designed to go
to windward with both boards down or just the leeward one, a la
E-scow. Ths size of the boards on the Prince William Sound Yawl and
Wisp would suggest that the efficient way is to raise the windward
board, but those on the Folding Schooner seem relatively small, and
are canted inward, parallel to the topsides, as opposed to canting
out, like Wisp and, again, an E-scow. Anyone out there have an
opinion, or better yet, certain knowledge from Bolger himself?
I'm almost finished building one, only with a lot of brushwork to go
... I'm finishing the decks and interior bright (okoume mahogony), and
have done the filling and staining.
-- Will
Usually you can determine the scale by looking at the station,
waterline and buttock lines, which are typically 1 foot spacing, (or 3
foot on larger designs).
The Prince William Sound Yawl is 16 feet long. The sizes of most
(probably all) of these boats is also found in the database section of
this Yahoo group, and also at :
http://en.wikipedia.org/wiki/Talk:Phil_Bolger
Almost always, I work out these renderings by interpreting the
drawings published in the magazine Messing About in Boats.
waterline and buttock lines, which are typically 1 foot spacing, (or 3
foot on larger designs).
The Prince William Sound Yawl is 16 feet long. The sizes of most
(probably all) of these boats is also found in the database section of
this Yahoo group, and also at :
http://en.wikipedia.org/wiki/Talk:Phil_Bolger
Almost always, I work out these renderings by interpreting the
drawings published in the magazine Messing About in Boats.
Bruce:
I'm a relative newcomer to the group and have been intrigued by the isometrics you post. I have a couple of questions if I may.
Is there a way for the viewer to determine the actual size of the boat presented in these isometrics? And, there are so many designs..where do you get the information to produce these images?
I have Mr Bolgers plans for Wisp, #411 and look forward to beginning construction fairly soon now that I have retired.
Sincerely:
Paul T
I'm a relative newcomer to the group and have been intrigued by the isometrics you post. I have a couple of questions if I may.
Is there a way for the viewer to determine the actual size of the boat presented in these isometrics? And, there are so many designs..where do you get the information to produce these images?
I have Mr Bolgers plans for Wisp, #411 and look forward to beginning construction fairly soon now that I have retired.
Sincerely:
Paul T
--- On Mon, 7/28/08, Bruce Hallman <bruce@...> wrote:
> From: Bruce Hallman <bruce@...>
> Subject: [bolger] Prince William Sound Yawl isometric
> To:bolger@yahoogroups.com
> Date: Monday, July 28, 2008, 1:55 PM
> Prince William Sound Yawl isometric
>
>http://flickr.com/photos/hallman/2711209606/
>
> ------------------------------------
>
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> - Pls add your comments at the TOP, SIGN your posts, and
> snip away
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