Lapstrake dinghy made from foam ????

With stryofoam, the best way to shape it is not by sanding, but by
cutting -- preferably with a hot wire knife. They are fairly easy to make,
but I don't have the relevant source material at hand. Should be easy enough
to find on the net though.

--
Karin Conover-Lewis
klc dot lewis at gte dot net


"Dave W" <woodwind.RemoveThis@suscom-maine.net> wrote in message
news:5ImcnV39sv5jj2qjXTWJhA@suscom-maine.net...
 > You have hit the nail on the head, the only problem will be sanding the
 > laps.
 > "RichH" <RhmpL33.RemoveThis@NOSPAM.net> wrote in message
 > news:3EF4F8D1.9070809@NOSPAM.net...
  > > Am contemplating a large lapstrake dinghy (wherry) made from styrofoam
  > > sheet and FRG ... as a male plug - in the manufacturing fashion of a
  > > surfboard. The obvious attempt would be to keep the boat in the
  > > ultra-light range.
  > >
  > > The sanding, finishing of a male plug fashion boat seems at first glance
  > > to be no problem .... except the sanding of the joints of the strakes,
  > > etc.
  > > (if I can find pure white stryofoam, I wont even have to paint!)
  > >
  > > Any references, comments, etc. would be appreciated.
  > > Sources of quality, white, long, fine grained styrofoam sheets would be
  > > appreciated. '
  > >
  > > Am I nuts?
  > >
 >
 ><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Lapstrake dinghy made from foam ???? 

RichH <RhmpL33.RemoveThis@NOSPAM.net> wrote in message
news:3EF4F8D1.9070809@NOSPAM.net...

is the lapstrake design aesthetic or because of an engineering reason? My
understanding was that in FRP construction, mock lapstrake represented extra
weight and reduced strength for a given weight.

I'm curious about the lapstrake, is there something I've missed?

thanks

Al
 >> Stay informed about: Lapstrake dinghy made from foam ???? 

Yah! It looks cool!

"Al" <Almann.DeleteThis@mygaff.fsnet.co.ukdontspamme> wrote in message
news:bd7ia6$vs9$1@newsg2.svr.pol.co.uk...
 > RichH <RhmpL33.DeleteThis@NOSPAM.net> wrote in message
 > news:3EF4F8D1.9070809@NOSPAM.net...
 >
 > is the lapstrake design aesthetic or because of an engineering reason? My
 > understanding was that in FRP construction, mock lapstrake represented
extra
 > weight and reduced strength for a given weight.
 >
 > I'm curious about the lapstrake, is there something I've missed?
 >
 > thanks
 >
 > Al
 >
 ><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Lapstrake dinghy made from foam ???? 

Al says:

 >My
 >understanding was that in FRP construction, mock lapstrake represented extra
 >weight and reduced strength for a given weight.

The "laps" (i.e. the little flats perpendicular to the hull surface) actually
form a whole bunch of built-in stringers, allowing the skins to be thinner, or
the frames to be spaced further apart, or both.

Steve<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Lapstrake dinghy made from foam ???? 

Steve has it.
The minute laps should act as mini-stringers; therefore, might enable
usage of thinner laminate schedule & should give better form resistance
to buckling failure.

Why lapstrake? I want the boat to be a 'modernized' reproduction of the
BEAUTIFUL whitehall/wherries of the 1890s.... I may be just a romantic;
but, a smooth hull wherry would look 'awful'.

Commercial FRG wherry/whitehall versions are tooooo heavy and tooooo
pricey.

Surfboards have been built for quite a long time with styrofoam cores. A
wherry requires quite complicated lofting (errors) and I though the
easiest way to produce a light weight one was with foam as the 'form' as
well as the laminate core. Inotherwords, ... loft/build the boat first
with foam (as a male plug) then laminate the exterior and interior
surfaces with epoxy, etc. I envision rabbeting the foam strake joints
for precise fit; the keel, etc. can be FRG box beam or tube
construction, etc. ... plus a mahogany veneer stern.

Want I definitely dont want is a 17-18 ft. boat that weighs several
hundred pounds (I can always add 'ballast' for rowing momentum in rough
water). Just like you dont put a surfboard between two chairs then jump
in the middle, such a lightweight foam cored boat would have 'special
strength considerations' when using, landing, etc.
 >> Stay informed about: Lapstrake dinghy made from foam ???? 

RichH wrote:

 > ...Just like you dont put a surfboard between two chairs then jump
 > in the middle, such a lightweight foam cored boat would have 'special
 > strength considerations' when using, landing, etc.

Funny you should say that, well made foam core panels can be incredibly
strong. I should think that if you wanted to put a foam core surfboard
between two chairs and jump on it (odd behavior, but to his each his own),
and the board was built half-decently, that it would come out just fine
except for maybe a few scratches from the chairs and/or floor.

Also, there are some commercially built lapstrake wherries in fiberglass.
It's not as much fun as building it yourself, perhaps, but then you'd have
one to use & study while you work on your own design....

Fresh Breezes- Doug King<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Lapstrake dinghy made from foam ???? 

RichH says:

 >Why lapstrake? I want the boat to be a 'modernized' reproduction of the
 >BEAUTIFUL whitehall/wherries of the 1890s....

Which were mostly built carvel-planked...

<ducks and runs>



Steve<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Lapstrake dinghy made from foam ???? 

Wonder if you could use a vacuum form and a large sheet of polyethylene (or
???) to form the "skins" around the plug. Inner skin could be formed
directly, then you could add a filler to get to appropriate dimensions and
re do the outer... Taking this to the next level, if you had an inner plug
and an outer plug, you could vacuum form both skins and hold them apart by
the eventual thickness of the foam. This would allow you to use a expanded
polyurethane foam to fill the void. All you'd have to do them is trim and
cap the gunwale.. You'd have to be a bit inventive on the wand required to
get the foam to the bottom of the hull but....it could be done.

Only problem would be heating up the skins enough to form them, and then
handling the hot sheets without destroying them. You could probably do the
vacuum with a simple ShopVac if the numbers all worked out...

Rob


"RichH" <RhmpL33.TakeThisOut@NOSPAM.net> wrote in message
news:3EF75ECB.9040205@NOSPAM.net...
 > Steve has it.
 > The minute laps should act as mini-stringers; therefore, might enable
 > usage of thinner laminate schedule & should give better form resistance
 > to buckling failure.
 >
 > Why lapstrake? I want the boat to be a 'modernized' reproduction of the
 > BEAUTIFUL whitehall/wherries of the 1890s.... I may be just a romantic;
 > but, a smooth hull wherry would look 'awful'.
 >
 > Commercial FRG wherry/whitehall versions are tooooo heavy and tooooo
 > pricey.
 >
 > Surfboards have been built for quite a long time with styrofoam cores. A
 > wherry requires quite complicated lofting (errors) and I though the
 > easiest way to produce a light weight one was with foam as the 'form' as
 > well as the laminate core. Inotherwords, ... loft/build the boat first
 > with foam (as a male plug) then laminate the exterior and interior
 > surfaces with epoxy, etc. I envision rabbeting the foam strake joints
 > for precise fit; the keel, etc. can be FRG box beam or tube
 > construction, etc. ... plus a mahogany veneer stern.
 >
 > Want I definitely dont want is a 17-18 ft. boat that weighs several
 > hundred pounds (I can always add 'ballast' for rowing momentum in rough
 > water). Just like you dont put a surfboard between two chairs then jump
 > in the middle, such a lightweight foam cored boat would have 'special
 > strength considerations' when using, landing, etc.
 ><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Lapstrake dinghy made from foam ???? 

Steve's right. Clinker boats were considered rude work. A gentleman would
certainly not use one.

Furthermore, IMHO, the most practical way to build a light one-off rowing
boat is cedar strip composite. Use (a real structural) foam in place of
cedar if you must, but the heavier skin layup it needs will eat up most of
the foam's weight savings.

If you want that fake lapstrake look, there's tape.
<ducks and runs>


Jim

Stephen Baker wrote:

 > RichH says:
 >
  > >Why lapstrake? I want the boat to be a 'modernized' reproduction of the
  > >BEAUTIFUL whitehall/wherries of the 1890s....
 >
 > Which were mostly built carvel-planked...
 >
 > <ducks and runs>
 >
 >
 >
 > Steve<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Lapstrake dinghy made from foam ???? 

 > The "laps" (i.e. the little flats perpendicular to the hull surface)
actually
 > form a whole bunch of built-in stringers, allowing the skins to be
thinner, or
 > the frames to be spaced further apart, or both.

I've seen this argument used successfuly by CLC in reference to their
lapstitch technology, using plywood, basically making use of the fact that
when you laminate two bits of wood they become one very stiff bit of wood.
I can't see it working as well with foam. I can see where your argument is
coming from, the flaw as I see it, is that you're looking at lots of little
near 90 degree corners, which to me says "stress riser" in big letters when
looking at the FRP skin.

I guess you'll just have to prove me wrong!

(which won't be hard)

Al<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Lapstrake dinghy made from foam ???? 

Hi

"Al" <Almann.DeleteThis@mygaff.fsnet.co.ukdontspamme> skrev i en meddelelse
news:bd7pl8$67o$1@newsg2.svr.pol.co.uk...
  > > The "laps" (i.e. the little flats perpendicular to the hull surface)
 > actually
  > > form a whole bunch of built-in stringers, allowing the skins to be
 > thinner, or
  > > the frames to be spaced further apart, or both.
 >
 > I've seen this argument used successfuly by CLC in reference to their
 > lapstitch technology, using plywood, basically making use of the fact that
 > when you laminate two bits of wood they become one very stiff bit of wood.
 > I can't see it working as well with foam. I can see where your argument is
 > coming from, the flaw as I see it, is that you're looking at lots of little
 > near 90 degree corners, which to me says "stress riser" in big letters when
 > looking at the FRP skin.
 >
 > I guess you'll just have to prove me wrong!
 >
 > (which won't be hard)
 >
 > Al
 >

Whatever you want you need to build it, then forming a thick shell of 3D-H will
provide the form to be laminated. , a Lapstrake structure is easy produced as a
3D intergrated framework, ---------- I agrea that I recon first quality Ply
better than the mahogony it is produced from , still a framework in this ,and
paneling in Crome plated Gold )
Anyway this is what I don't understand ; you could do the top technology in a
rational Design, then you want to replace Lapstrake with foam, ------------ I
don't mind but acturly there acturly are modern building methods that do better
than a Lapstrake pram ; what if you for the same money could get an ocean going
sailboard.
Click
<a style='text-decoration: underline;' href="http://groups.yahoo.com/group/Cyber-Boat-Longboat-5meter/" target="_blank">http://groups.yahoo.com/group/Cyber-Boat-Longboat-5meter/</a>

P.C.
Have a nice day<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Lapstrake dinghy made from foam ???? 

P.c., on a total tangent, the current edition of woodenboat magazine
contains an article about a V bottom built onto a flat skiff using a method
that looks similar to what you propose. You might like to hunt down a copy.
Or find someone to scan it and mail it to you (I can't, the computer with
the scanner attached is down at the moment).

Al
 >> Stay informed about: Lapstrake dinghy made from foam ???? 

Hi

"Al" <Almann.DeleteThis@mygaff.fsnet.co.ukdontspamme> skrev i en meddelelse
news:bda1j7$ma0$1@newsg2.svr.pol.co.uk...
 > P.c., on a total tangent, the current edition of woodenboat magazine
 > contains an article about a V bottom built onto a flat skiff using a method
 > that looks similar to what you propose. You might like to hunt down a copy.
 > Or find someone to scan it and mail it to you (I can't, the computer with
 > the scanner attached is down at the moment).
 >

I wouldn't mind 3D-H being used for building boats, acturly that is what it is
develobed for. But building structures , vessel fuselages and all scale 3D
formwork, is there if you ask it in an assembly framework. If you then add
panels there are a honeycomb structure m With buildings the feets is alway's
well on ground when all forces are distribuated, in a self carrying framework,
so offcaurse boats is an option with a modern 2D building method, that produce
nice round 3D things from sheet material )

Now as I been promoting the methods for documented years , I wonder if this
realy is 3D-H and if so, if the inventers name is published.

P.C.
Have a nice day.
The Longboat would anyway be better, still that you can produce in chip wood ,an
foam filled hull leaving the paneling leaking no problem, wonder of any Roman
bookstore ever seen other mahogony than interiours , Anyway this is what I
realy think 3D-H shuld produce ;
<a style='text-decoration: underline;' href="http://groups.yahoo.com/group/structure-testbench/" target="_blank">http://groups.yahoo.com/group/structure-testbench/</a>

I love mahogony just check some furnitures I once produced ;
<a style='text-decoration: underline;' href="http://www.designcommunity.com/scrapbook/2498.html" target="_blank">http://www.designcommunity.com/scrapbook/2498.html</a>

Today you can ask all the claims about a center in a city, and have everything
formes just perfect. I stopped boat design years ago and acturly do no
boatbuilding at all, but develobing new Digital building methods, funny if a
boat will be the first object produced with an idear that need a computer to
even be an option, as almost impossible without. Buuuut I am quite sure, that
once again, somthing not at all a true 3D-H shell, is what is there )

P.C.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Lapstrake dinghy made from foam ????