Re: Departing from original plans
Kieron: I wouldn't worry one bit about the frame spacing -- with
sawn frames at 18 inch intervals, you've got more than enough
strength and support. For comparison, Edson I. Schock, who
designed and built a number of plywood on frame boats in the
1940s, specified 3/8 ply on 16 inch stations for a 16-foot v-
bottomed daysailor.
In either case it's probably overkill -- Reuel Parker's sharpies in
the 16 to 18 foot size range typically use only 3 frames (with 3/8
ply for the sides and 1/2 for the bottom). However, I wouldn't
recommend eliminating any frames from Monk's design.
Steve Paskey
sawn frames at 18 inch intervals, you've got more than enough
strength and support. For comparison, Edson I. Schock, who
designed and built a number of plywood on frame boats in the
1940s, specified 3/8 ply on 16 inch stations for a 16-foot v-
bottomed daysailor.
In either case it's probably overkill -- Reuel Parker's sharpies in
the 16 to 18 foot size range typically use only 3 frames (with 3/8
ply for the sides and 1/2 for the bottom). However, I wouldn't
recommend eliminating any frames from Monk's design.
Steve Paskey
--- In bolger@y..., "K WALSH" <kieron.walsh@p...> wrote:
> His "planks" are bent around 9 sawn frames on 18-in. stations
(3-part 3/4" oak) . . .
>
> Given all that, I have a hard time understanding why I would
want to change frame spacing (terra incognita for me) or why I
should be concerned with plywood not bending in two directions.
Isn't 3/8-in. plywood is usually OK for hard chine lay up?
> Kieron Walsh - Dublin, NH
V-bottom designs are notorious for _looking_ like they'll plank easily with
ply when in actuality the panels can't be made to fit. :o( When you try to
twist plywood and at the same time bend it around the frames it can protest
and bulge away from the frames. The lines of Curlew show very little twist
in the planks. I'd guess that plywood would work fine, but before going
to all the trouble of erecting the strongback and frames only to discover
that plywood _doesn't_ want to fit make a simple model using cardboard for
the planking.
ply when in actuality the panels can't be made to fit. :o( When you try to
twist plywood and at the same time bend it around the frames it can protest
and bulge away from the frames. The lines of Curlew show very little twist
in the planks. I'd guess that plywood would work fine, but before going
to all the trouble of erecting the strongback and frames only to discover
that plywood _doesn't_ want to fit make a simple model using cardboard for
the planking.
On Sun, 27 Jan 2002 12:12:55 -0500, Kieron Walsh wrote:
> ...
> Given all that, I have a hard time understanding why I would want to change
> frame spacing (terra incognita for me) or why I should be concerned with
> plywood not bending in two directions. Isn't 3/8-in. plywood is usually OK
> for hard chine lay up?
--
John <jkohnen@...>
http://www.boat-links.com/
If perfection were needed for friendship the world
would be a wilderness for our love. <Thomas Jefferson>
In a message dated 1/27/02 11:10:41 AM Central Standard Time,
kieron.walsh@...writes:
substitution would cause in a boat this size. The displacement is going to be
indeterminate and variable, depending on weight of crew and paraphenalia.
I do think you should be concerned about whether plywood sheets will conform
to the boat's shape if you are planning to plank from chine-to-chine with
sheet plywood in the conventional manner what you describe as a hard-chined
boat. The planks in the original design (of which I am entirely ignorant) may
have taper, bend and twist to them, clearance for caulking, etc., that may
describe a shape not duplicable in sheets of plywood.
I believe you mentioned in an earlier posting that you made a model of
"Cartopper" before embarking on the full-sized version. This would not be a
bad idea for your proposed modification of this plan. It may not be
fool-proof, but if there any gross discrepancies with the sheets not
conforming to the desired shape and not landing on the frames as drafted,
building a model might save you some remorse and expense.
Good luck!
Ciao for Niao,
Bill in MN
[Non-text portions of this message have been removed]
kieron.walsh@...writes:
> I have a hard time understanding why I would want to changeI don't think I would worry much about any change in displacement that your
> frame spacing (terra incognita for me) or why I should be concerned with
> plywood not bending in two directions.
substitution would cause in a boat this size. The displacement is going to be
indeterminate and variable, depending on weight of crew and paraphenalia.
I do think you should be concerned about whether plywood sheets will conform
to the boat's shape if you are planning to plank from chine-to-chine with
sheet plywood in the conventional manner what you describe as a hard-chined
boat. The planks in the original design (of which I am entirely ignorant) may
have taper, bend and twist to them, clearance for caulking, etc., that may
describe a shape not duplicable in sheets of plywood.
I believe you mentioned in an earlier posting that you made a model of
"Cartopper" before embarking on the full-sized version. This would not be a
bad idea for your proposed modification of this plan. It may not be
fool-proof, but if there any gross discrepancies with the sheets not
conforming to the desired shape and not landing on the frames as drafted,
building a model might save you some remorse and expense.
Good luck!
Ciao for Niao,
Bill in MN
[Non-text portions of this message have been removed]
Thanks for your responses, Peter and Bob. But I see that inadequate info
about Curlew and the use of the word "plank" has perhaps made it difficult
to answer. Curlew is not carvel planked.
BTW Being a newbie to this group and noting that this thread centers around
a non-Bolger design I have to ask if this is OK? Having built Cartopper I've
been looking for a longer roomy trailerable daysailer, when I latched onto
Monk's Curlew. She looks pretty sweet.
Writing at a time (1932) before the advent of reliable marine plywood and
epoxy, Edwin Monk, N.A. thought plywood "might be ideal for bulkheads web
frames and stiffeners". His design for Curlew is a "hard chine" design of a
shallow vee bottom 15'6" day sailer. His writeup describes three "planks":
bottom plank 2 pcs. 5/8"x10"-15', 2 pcs. 5/8"x10"-13', and 2 pcs.
5/8"x8"-12'
bilge plank 2 pcs. 5/8"x10"-16' and 2 pcs. 5/8"x12"-16'
topsides plank 2 pcs. 5/8"x12"-16'6" or use dory lap and 2 pcs. 5/8"x8"-16'
and 2 pcs. 5/8"x6"-16'6"
His "planks" are bent around 9 sawn frames on 18-in. stations (3-part 3/4"
oak)
Seams on the bottom plank are covered on the wet side by 1-1/4"x1/2" battens
Seams on the bilge and side planks are a 1" glued dory lap
Given all that, I have a hard time understanding why I would want to change
frame spacing (terra incognita for me) or why I should be concerned with
plywood not bending in two directions. Isn't 3/8-in. plywood is usually OK
for hard chine lay up?
Kieron Walsh - Dublin, NH
"I wouldn't want to belong to a club that had someone like me as a member" -
Woody Allen
about Curlew and the use of the word "plank" has perhaps made it difficult
to answer. Curlew is not carvel planked.
BTW Being a newbie to this group and noting that this thread centers around
a non-Bolger design I have to ask if this is OK? Having built Cartopper I've
been looking for a longer roomy trailerable daysailer, when I latched onto
Monk's Curlew. She looks pretty sweet.
Writing at a time (1932) before the advent of reliable marine plywood and
epoxy, Edwin Monk, N.A. thought plywood "might be ideal for bulkheads web
frames and stiffeners". His design for Curlew is a "hard chine" design of a
shallow vee bottom 15'6" day sailer. His writeup describes three "planks":
bottom plank 2 pcs. 5/8"x10"-15', 2 pcs. 5/8"x10"-13', and 2 pcs.
5/8"x8"-12'
bilge plank 2 pcs. 5/8"x10"-16' and 2 pcs. 5/8"x12"-16'
topsides plank 2 pcs. 5/8"x12"-16'6" or use dory lap and 2 pcs. 5/8"x8"-16'
and 2 pcs. 5/8"x6"-16'6"
His "planks" are bent around 9 sawn frames on 18-in. stations (3-part 3/4"
oak)
Seams on the bottom plank are covered on the wet side by 1-1/4"x1/2" battens
Seams on the bilge and side planks are a 1" glued dory lap
Given all that, I have a hard time understanding why I would want to change
frame spacing (terra incognita for me) or why I should be concerned with
plywood not bending in two directions. Isn't 3/8-in. plywood is usually OK
for hard chine lay up?
Kieron Walsh - Dublin, NH
"I wouldn't want to belong to a club that had someone like me as a member" -
Woody Allen
> From: "pvanderwaart" <pvanderwaart@...>
> Subject: Re: Departing from original plans
>
> > I am about to start on Edwin Monk's 1934 design called
> > Curlew (a fast-looking, but roomy 15-foot daysailer), which calls
> for
> > 5/8-in. cedar planks and battens. I want to switch to 3/8-in.
> marine
> > plywood.
>
> To compare with the 15' Bolger Spartina, he uses 1/2" planking, and
> the planks are fairly narrow which means a greater area of double
> thickness. I assume that both Spartina and your boat will be glued
> lap.
>
> The other point to note is the frame (bulkhead) spacing. It looks to
> be abut 20" in Spartina. If I was going to use the lighter planking,
> I would think about a closer frame spacing. Ply is stronger, but also
> more pliable than natural stock.
>
> Peter
> From: "rdchamberland" <cha62759@...>
> Subject: Re: Departing from original plans
>
> Hi,
> A couple of things to think about if you are thinking of changing from
> carvel planking to plywood. I don't quite understand the process for
> making plywood work however the thing to remember is that plywood is
> not going to bend in two directions ( except minimally). Plywood
> planking, if I have it right, is a section of a cone. So the lines of
> your "Curlew" may have to be modified for plywood planking. I am not
> familiar with "Curlew" and have no idea of the construction method. Is
> it carvel planking or clinker construction. My guess is that merely
> going from 5/8 cedar to 3/8 plywood is reasonable considering the
> above. As to "Spartina", I have plans and the first question I asked
> Mr Bolger was "Can I substitute 1/4" for the specified 1/2". The
> answer was a definite "No!". I didn't ask about 3/8". Frames for
> "Spartina" are spaced from 21" to 24".
>
> Before sticking my neck out further I quess I need to ask about the
> construction of "Curlew"
>
> Bob Chamberland
Hi,
A couple of things to think about if you are thinking of changing from
carvel planking to plywood. I don't quite understand the process for
making plywood work however the thing to remember is that plywood is
not going to bend in two directions ( except minimally). Plywood
planking, if I have it right, is a section of a cone. So the lines of
your "Curlew" may have to be modified for plywood planking. I am not
familiar with "Curlew" and have no idea of the construction method. Is
it carvel planking or clinker construction. My guess is that merely
going from 5/8 cedar to 3/8 plywood is reasonable considering the
above. As to "Spartina", I have plans and the first question I asked
Mr Bolger was "Can I substitute 1/4" for the specified 1/2". The
answer was a definite "No!". I didn't ask about 3/8". Frames for
"Spartina" are spaced from 21" to 24".
Before sticking my neck out further I quess I need to ask about the
construction of "Curlew"
Bob Chamberland
A couple of things to think about if you are thinking of changing from
carvel planking to plywood. I don't quite understand the process for
making plywood work however the thing to remember is that plywood is
not going to bend in two directions ( except minimally). Plywood
planking, if I have it right, is a section of a cone. So the lines of
your "Curlew" may have to be modified for plywood planking. I am not
familiar with "Curlew" and have no idea of the construction method. Is
it carvel planking or clinker construction. My guess is that merely
going from 5/8 cedar to 3/8 plywood is reasonable considering the
above. As to "Spartina", I have plans and the first question I asked
Mr Bolger was "Can I substitute 1/4" for the specified 1/2". The
answer was a definite "No!". I didn't ask about 3/8". Frames for
"Spartina" are spaced from 21" to 24".
Before sticking my neck out further I quess I need to ask about the
construction of "Curlew"
Bob Chamberland
> > I am about to start on Edwin Monk's 1934 design calledalso
> > Curlew (a fast-looking, but roomy 15-foot daysailer), which calls
> for
> > 5/8-in. cedar planks and battens. I want to switch to 3/8-in.
> marine
> > plywood.
>
> To compare with the 15' Bolger Spartina, he uses 1/2" planking, and
> the planks are fairly narrow which means a greater area of double
> thickness. I assume that both Spartina and your boat will be glued
> lap.
>
> The other point to note is the frame (bulkhead) spacing. It looks to
> be abut 20" in Spartina. If I was going to use the lighter planking,
> I would think about a closer frame spacing. Ply is stronger, but
> more pliable than natural stock.
>
> Peter
> I am about to start on Edwin Monk's 1934 design calledfor
> Curlew (a fast-looking, but roomy 15-foot daysailer), which calls
> 5/8-in. cedar planks and battens. I want to switch to 3/8-in.marine
> plywood.To compare with the 15' Bolger Spartina, he uses 1/2" planking, and
the planks are fairly narrow which means a greater area of double
thickness. I assume that both Spartina and your boat will be glued
lap.
The other point to note is the frame (bulkhead) spacing. It looks to
be abut 20" in Spartina. If I was going to use the lighter planking,
I would think about a closer frame spacing. Ply is stronger, but also
more pliable than natural stock.
Peter
Hello all:
I am new to this group. Very interesting reading about what everyone
is building. I am about to start on Edwin Monk's 1934 design called
Curlew (a fast-looking, but roomy 15-foot daysailer), which calls for
5/8-in. cedar planks and battens. I want to switch to 3/8-in. marine
plywood. I write to solicit any ideas about how this will affect the
building and what affect it might have on the performance etc. (less
displacement? stability?).
When the subject of boat building comes up around the dinner table,
much discussion centers around my propensity to depart from
specifications in original plans.
I started my first boatbuilding project in the summer of 1999,
"Baidin" was launched in 2000 in Dublin Lake. She's a Bolger
Cartopper that we have sailed all ME and NH (and last Sept Lake Erie).
Departing from the plans I got from Dynamite Payson, I opted to cut
the frames from 1/2-in. plywood after I found that building his model
with frames from the same plywood thickness as the planks was beyond
my level of ability (the mahogany veneer plywood I used looks nicer
too). The second departure was to start sailing her that spring with a
lateen rig with wooden spars salvaged from an Old Town sailing rig
(the canoe rotted away long ago in someone's shed).
When I asked for his advice, PCB wrote back:
"The Old Town lateen sail looks as though it would work. The boom may
end up at an awkward angle, with the end likely to get in the water
when she heels sharply. Try it and see. Shift the boom parrel and
halyard attachment until it looks right, or as best you can.
Cartoppers aren't very sensitive as long as the sail isn't too far
forward. Probably there'll be no need to move the mast.
All those boats to take that standard rig, first used in the Elegant
Punt."
He was right. With her narrow bottom plank, gusty lake sailing
conditions caused the longer boom to dunk into the drink frequently.
She was also laterally shifty when running downwind. After that first
summer, I was ready to retire the lateen, but then I fell in love wtih
another (unauthorized) sail rig.
Last year I finished a new sliding gunter rig for her with the very
able assistance from a sailmaker friend. Though it was heavier, it
gave the height and approximate sail area of the sprit sail called for
in the plans. It is a great improvement, especially when I quit using
the sheet hooks called for in the plans in favor of a rope traveller
and small Harken swivel blocks. I also added a removable mast partner
across the gunwhales above the bow frame and moved the step aft about
two inches. Getting a taller and more "inboard" sail rig has made a
big difference. She's very fast and fun with a crew of one 200-pounder
(me) aboard. A little cramped for more than one though. So, aside from
the inevitable yearly touch-up and adding a few other refinements of
my own (I have a nifty wheelie thingie to single-handedly get her up
on the car fully loaded with sails spars and oars without a triple
hernia or wrenched back). I'm ready to start another a new boat
a-building. Any ideas/suggestions on changing this old design to
plywood construction. Are there others out there who can't stick to
the specs like me?
I am new to this group. Very interesting reading about what everyone
is building. I am about to start on Edwin Monk's 1934 design called
Curlew (a fast-looking, but roomy 15-foot daysailer), which calls for
5/8-in. cedar planks and battens. I want to switch to 3/8-in. marine
plywood. I write to solicit any ideas about how this will affect the
building and what affect it might have on the performance etc. (less
displacement? stability?).
When the subject of boat building comes up around the dinner table,
much discussion centers around my propensity to depart from
specifications in original plans.
I started my first boatbuilding project in the summer of 1999,
"Baidin" was launched in 2000 in Dublin Lake. She's a Bolger
Cartopper that we have sailed all ME and NH (and last Sept Lake Erie).
Departing from the plans I got from Dynamite Payson, I opted to cut
the frames from 1/2-in. plywood after I found that building his model
with frames from the same plywood thickness as the planks was beyond
my level of ability (the mahogany veneer plywood I used looks nicer
too). The second departure was to start sailing her that spring with a
lateen rig with wooden spars salvaged from an Old Town sailing rig
(the canoe rotted away long ago in someone's shed).
When I asked for his advice, PCB wrote back:
"The Old Town lateen sail looks as though it would work. The boom may
end up at an awkward angle, with the end likely to get in the water
when she heels sharply. Try it and see. Shift the boom parrel and
halyard attachment until it looks right, or as best you can.
Cartoppers aren't very sensitive as long as the sail isn't too far
forward. Probably there'll be no need to move the mast.
All those boats to take that standard rig, first used in the Elegant
Punt."
He was right. With her narrow bottom plank, gusty lake sailing
conditions caused the longer boom to dunk into the drink frequently.
She was also laterally shifty when running downwind. After that first
summer, I was ready to retire the lateen, but then I fell in love wtih
another (unauthorized) sail rig.
Last year I finished a new sliding gunter rig for her with the very
able assistance from a sailmaker friend. Though it was heavier, it
gave the height and approximate sail area of the sprit sail called for
in the plans. It is a great improvement, especially when I quit using
the sheet hooks called for in the plans in favor of a rope traveller
and small Harken swivel blocks. I also added a removable mast partner
across the gunwhales above the bow frame and moved the step aft about
two inches. Getting a taller and more "inboard" sail rig has made a
big difference. She's very fast and fun with a crew of one 200-pounder
(me) aboard. A little cramped for more than one though. So, aside from
the inevitable yearly touch-up and adding a few other refinements of
my own (I have a nifty wheelie thingie to single-handedly get her up
on the car fully loaded with sails spars and oars without a triple
hernia or wrenched back). I'm ready to start another a new boat
a-building. Any ideas/suggestions on changing this old design to
plywood construction. Are there others out there who can't stick to
the specs like me?