Micro scantlings
[newcomer to the LIST]
I strongly recommend increasing both the bottom and cabin top
scantlings of the Micro. Only the sides of my Micro are of the
specified one-quarter ply; all else is three-eighths. Moreover, I
glassed the bottom, and six inches up the hull's side, with 10 oz.
cloth and everything else--exterior surfaces, that is--with 6 oz.
cloth. (All joints are heavily radiused.) In addition, I attached the
two optional runner skegs as further insurance against the rocky bits
of our New England coastline. And I have had several groundings, one
of which happened on a falling tide in a good sloppy blow! Gosh,
there was an awful lot of bump-bumping until the boat was fully
grounded.Yet the hull has never sustained any damage that I have been
able to
detect.
The cabin roof really should be three-eighths. Who knows about
that heavy person who's going to rush forward in the wet and windy to
fend off? Further, I added radiused laminated "beams" (1x2) to the
inside of the roof for additional strength, with handholds so that
one can easily pull oneself up out of the bunks.
Finally, I added some "frames" to the upper hull sides of the
cockpit, to reinforce those sections that people lean and push
against, and in retrospect, I probably should have built up the
rail-cap in that area.
But it really has to do with where and how you're going to
sail the boat: if in protected waters, I'd probably go with the
original scantlings. But if in open waters with substantial seas and
rocky coastline, I'd recommend an increase. I don't feel that the
increases have compromised the boat's speed that much (I admit, my
boat IS heavy), but if I'd wanted fast-with-minimal-safety, I would
have built an International-14.
Wishing you fair winds=eric
Eric Schoonover
eric@...
I strongly recommend increasing both the bottom and cabin top
scantlings of the Micro. Only the sides of my Micro are of the
specified one-quarter ply; all else is three-eighths. Moreover, I
glassed the bottom, and six inches up the hull's side, with 10 oz.
cloth and everything else--exterior surfaces, that is--with 6 oz.
cloth. (All joints are heavily radiused.) In addition, I attached the
two optional runner skegs as further insurance against the rocky bits
of our New England coastline. And I have had several groundings, one
of which happened on a falling tide in a good sloppy blow! Gosh,
there was an awful lot of bump-bumping until the boat was fully
grounded.Yet the hull has never sustained any damage that I have been
able to
detect.
The cabin roof really should be three-eighths. Who knows about
that heavy person who's going to rush forward in the wet and windy to
fend off? Further, I added radiused laminated "beams" (1x2) to the
inside of the roof for additional strength, with handholds so that
one can easily pull oneself up out of the bunks.
Finally, I added some "frames" to the upper hull sides of the
cockpit, to reinforce those sections that people lean and push
against, and in retrospect, I probably should have built up the
rail-cap in that area.
But it really has to do with where and how you're going to
sail the boat: if in protected waters, I'd probably go with the
original scantlings. But if in open waters with substantial seas and
rocky coastline, I'd recommend an increase. I don't feel that the
increases have compromised the boat's speed that much (I admit, my
boat IS heavy), but if I'd wanted fast-with-minimal-safety, I would
have built an International-14.
Wishing you fair winds=eric
Eric Schoonover
eric@...
Peter,
I have decided to go with 3/8" and a 3/4" bottom, per imput from
you and Pippo, and a closer reading of the plans.
Thanks for the advice,
david
(who, following present list convention, is looking out at the clouds
over the melting snow of the late winter wonderland that is the
western Catskills. Last night a coyote pissed on my lawn, I think.
_Sic transit gloria nivis_.)
peter lenihan wrote:
I have decided to go with 3/8" and a 3/4" bottom, per imput from
you and Pippo, and a closer reading of the plans.
Thanks for the advice,
david
(who, following present list convention, is looking out at the clouds
over the melting snow of the late winter wonderland that is the
western Catskills. Last night a coyote pissed on my lawn, I think.
_Sic transit gloria nivis_.)
peter lenihan wrote:
> David,
> I built my Micro with half inch bottom and three-eights everywhere
> else.If I had to do it again,I would go with half inch everywhere!Micro
> is an incredibly stable little boat and with that 450 lbs on the
> bottom,the moment she starts to heal over,you begin generating one hell
> of a lever arm!!!!
> I am unable to detect any particular difference with my Micro as
> she sits right on her designed lines and that with the boat loaded for
> a weeks cruise!So I really would not fret too much about a slight
> weight increase especially as that weight is spread out over the WHOLE
> boat and not concentrated in one area.
> I seem to recall Bernie telling me how his Micro bottom lasted a
> season or two before developing a wee problem.........rot.(If you read
> this Bernie,please correct me if I misunderstood you!)
> Bolger seems to have designed the Micro with a slight error in
> favour of us amateur builders and our propensity to"modify" a design
> and NOT stick religeously to the plans.......lucky for us!!!
> Sincerely,
>
> Peter,in the midst of another bit of frozen rain fall,looking at it all
> through frosted glasses,on the snow-bound shores of the
> St.Lawrence.....
>
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Pippo,
That does it. Now I have an excuse to go to Italy. The Okoume is cheaper there! Now how do I fit eleven sheets into my carryon bag?<g>
Thanks,
david
That does it. Now I have an excuse to go to Italy. The Okoume is cheaper there! Now how do I fit eleven sheets into my carryon bag?<g>
Thanks,
david
Giuseppe 'Pippo' Bianco wrote:
Hi David
I think your decision of using 3/8" stuff and going for double bottom
is a wise one. True, you add weight, but look, the difference would be
less noticeable than having one more crew aboard...
My okoumé is not certified "marine" (that would cost at least 3 times
as much), but it's pretty much used in workboats all over Italy. I
still have to find one void in my panels. My total cost was about 550
US$, delivered to my garage, for 11 sheets of 3/8" ply, 5 plies. My
sheets are 5'x10' instead of 4'x8', so the total surface is the same of
17.5 standard US sheets. I can easily handle one whole panel by myself.
Best
Pippo
david <galvin-@...> wrote:
original article:http://www.egroups.com/group/bolger/?start=2815
> Pippo,
> Thanks for your imput. 1/4" (6mm) plywood is pretty skinny stuff,
no
matter
> what species. Occume is pretty pricey up here, as it is everywhere,
and I
> would have to have it trucked in from Boston or NYC, adding to the
cost. It is
> delightful looking stuff, though not very rot resistant, I
understand. Knowing
> me, I'll probably go with 3/8" (9mm) fir or MDO, and a double bottom.
I can
> save weight by building spruce spars and using lighter glass cloth
on
the
> topsides, I suppose. Right now I'm just waiting for the four feet
of
snow to
> melt from in front of my shop so I can get the Saturn out and sell
it. Too
> many cars and too many boats....
> david
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david <galvin-@...> wrote:
original article:http://www.egroups.com/group/bolger/?start=2785
I built my Micro with half inch bottom and three-eights everywhere
else.If I had to do it again,I would go with half inch everywhere!Micro
is an incredibly stable little boat and with that 450 lbs on the
bottom,the moment she starts to heal over,you begin generating one hell
of a lever arm!!!!
I am unable to detect any particular difference with my Micro as
she sits right on her designed lines and that with the boat loaded for
a weeks cruise!So I really would not fret too much about a slight
weight increase especially as that weight is spread out over the WHOLE
boat and not concentrated in one area.
I seem to recall Bernie telling me how his Micro bottom lasted a
season or two before developing a wee problem.........rot.(If you read
this Bernie,please correct me if I misunderstood you!)
Bolger seems to have designed the Micro with a slight error in
favour of us amateur builders and our propensity to"modify" a design
and NOT stick religeously to the plans.......lucky for us!!!
Sincerely,
Peter,in the midst of another bit of frozen rain fall,looking at it all
through frosted glasses,on the snow-bound shores of the
St.Lawrence.....
original article:http://www.egroups.com/group/bolger/?start=2785
> Micro, as designed, is of 1/4" plywood. A long time ago Bernie Wolfardalthough
> built one of 3/8", and I see that Pippo is now doing the same,
> most folks still seem to follow the original plans. Increasing thebeing
> thickness of the ply by 1/8" would increase the boat's weight by about
> 120 Lb. if done in fir or luan, with about 80 lb. of the increase
> above to waterline. What are the advantages of going this route, anddo
> they offset the obvious disadvantages of reduced stability andincreased
> cost?David,
> david
>
I built my Micro with half inch bottom and three-eights everywhere
else.If I had to do it again,I would go with half inch everywhere!Micro
is an incredibly stable little boat and with that 450 lbs on the
bottom,the moment she starts to heal over,you begin generating one hell
of a lever arm!!!!
I am unable to detect any particular difference with my Micro as
she sits right on her designed lines and that with the boat loaded for
a weeks cruise!So I really would not fret too much about a slight
weight increase especially as that weight is spread out over the WHOLE
boat and not concentrated in one area.
I seem to recall Bernie telling me how his Micro bottom lasted a
season or two before developing a wee problem.........rot.(If you read
this Bernie,please correct me if I misunderstood you!)
Bolger seems to have designed the Micro with a slight error in
favour of us amateur builders and our propensity to"modify" a design
and NOT stick religeously to the plans.......lucky for us!!!
Sincerely,
Peter,in the midst of another bit of frozen rain fall,looking at it all
through frosted glasses,on the snow-bound shores of the
St.Lawrence.....
Hi David
I think your decision of using 3/8" stuff and going for double bottom
is a wise one. True, you add weight, but look, the difference would be
less noticeable than having one more crew aboard...
My okoumé is not certified "marine" (that would cost at least 3 times
as much), but it's pretty much used in workboats all over Italy. I
still have to find one void in my panels. My total cost was about 550
US$, delivered to my garage, for 11 sheets of 3/8" ply, 5 plies. My
sheets are 5'x10' instead of 4'x8', so the total surface is the same of
17.5 standard US sheets. I can easily handle one whole panel by myself.
Best
Pippo
david <galvin-@...> wrote:
original article:http://www.egroups.com/group/bolger/?start=2815
I think your decision of using 3/8" stuff and going for double bottom
is a wise one. True, you add weight, but look, the difference would be
less noticeable than having one more crew aboard...
My okoumé is not certified "marine" (that would cost at least 3 times
as much), but it's pretty much used in workboats all over Italy. I
still have to find one void in my panels. My total cost was about 550
US$, delivered to my garage, for 11 sheets of 3/8" ply, 5 plies. My
sheets are 5'x10' instead of 4'x8', so the total surface is the same of
17.5 standard US sheets. I can easily handle one whole panel by myself.
Best
Pippo
david <galvin-@...> wrote:
original article:http://www.egroups.com/group/bolger/?start=2815
> Pippo,matter
> Thanks for your imput. 1/4" (6mm) plywood is pretty skinny stuff, no
> what species. Occume is pretty pricey up here, as it is everywhere,and I
> would have to have it trucked in from Boston or NYC, adding to thecost. It is
> delightful looking stuff, though not very rot resistant, Iunderstand. Knowing
> me, I'll probably go with 3/8" (9mm) fir or MDO, and a double bottom.I can
> save weight by building spruce spars and using lighter glass cloth onthe
> topsides, I suppose. Right now I'm just waiting for the four feet ofsnow to
> melt from in front of my shop so I can get the Saturn out and sellit. Too
> many cars and too many boats....
> david
Pippo,
Thanks for your imput. 1/4" (6mm) plywood is pretty skinny stuff, no matter
what species. Occume is pretty pricey up here, as it is everywhere, and I
would have to have it trucked in from Boston or NYC, adding to the cost. It is
delightful looking stuff, though not very rot resistant, I understand. Knowing
me, I'll probably go with 3/8" (9mm) fir or MDO, and a double bottom. I can
save weight by building spruce spars and using lighter glass cloth on the
topsides, I suppose. Right now I'm just waiting for the four feet of snow to
melt from in front of my shop so I can get the Saturn out and sell it. Too
many cars and too many boats....
david
Giuseppe 'Pippo' Bianco wrote:
Thanks for your imput. 1/4" (6mm) plywood is pretty skinny stuff, no matter
what species. Occume is pretty pricey up here, as it is everywhere, and I
would have to have it trucked in from Boston or NYC, adding to the cost. It is
delightful looking stuff, though not very rot resistant, I understand. Knowing
me, I'll probably go with 3/8" (9mm) fir or MDO, and a double bottom. I can
save weight by building spruce spars and using lighter glass cloth on the
topsides, I suppose. Right now I'm just waiting for the four feet of snow to
melt from in front of my shop so I can get the Saturn out and sell it. Too
many cars and too many boats....
david
Giuseppe 'Pippo' Bianco wrote:
> David,
> I asked exactly the same question to Bernie about one year ago.
> Micro is designed for either 1/4" or 3/8" ply: see PCB's building key,
> 2nd row of the introductory paragraph. Bernie was (and I guess he still
> is) a strong advocate of 3/8" thick ply for Micro, and that was the
> basis for CSD Micro kits.
> Now, I understand that the weight calculation for Micro has been done
> having fir plywood in mind. I use okoumé plywood, which weighs
> substantially less than fir, so the difference in overall weight is
> going to be marginal. Just to be more precise, fir plywood has a density
> of 650 kg/m^3 (from Glen L. Witt's book), while okoume's density
> (measured by me) is about 490 kg/m^3.
> Moreover, I'm going to build a double thickness bottom. As PCB himself
> writes in the same building key, #12, "the weight will not hurt her
> performance".
> I really believe that 6 mm "cheapo" ply is marginal for a boat that
> displaces 750 kg, in particular for the botton that, is such case,
> reportedly does "oil can". By the way, 6 mm is the same plywood
> specified for much smaller boats (Bobcat, Gypsy, etc). The Chebacco has
> a nominal displacement very similar to Micro's, but uses 12 mm ply...
> And finally, Sam Devlin's scantlings for a boat displacing like Micro
> specify 10 mm ply. Look at what John Morrice has done to stiffen his
> Micro's sides...
> I don't know how fir plywood looks like, but 6 mm thick okoumé (medium
> quality stuff, 3 plies) is really, really too flimsy...
> Best, Pippo
>
> david ha scritto:
> >
> > Micro, as designed, is of 1/4" plywood. A long time ago Bernie Wolfard
> > built one of 3/8", and I see that Pippo is now doing the same, although
> > most folks still seem to follow the original plans. Increasing the
> > thickness of the ply by 1/8" would increase the boat's weight by about
> > 120 Lb. if done in fir or luan, with about 80 lb. of the increase being
> > above to waterline. What are the advantages of going this route, and do
> > they offset the obvious disadvantages of reduced stability and increased
> > cost?
>
David,
I asked exactly the same question to Bernie about one year ago.
Micro is designed for either 1/4" or 3/8" ply: see PCB's building key,
2nd row of the introductory paragraph. Bernie was (and I guess he still
is) a strong advocate of 3/8" thick ply for Micro, and that was the
basis for CSD Micro kits.
Now, I understand that the weight calculation for Micro has been done
having fir plywood in mind. I use okoumé plywood, which weighs
substantially less than fir, so the difference in overall weight is
going to be marginal. Just to be more precise, fir plywood has a density
of 650 kg/m^3 (from Glen L. Witt's book), while okoume's density
(measured by me) is about 490 kg/m^3.
Moreover, I'm going to build a double thickness bottom. As PCB himself
writes in the same building key, #12, "the weight will not hurt her
performance".
I really believe that 6 mm "cheapo" ply is marginal for a boat that
displaces 750 kg, in particular for the botton that, is such case,
reportedly does "oil can". By the way, 6 mm is the same plywood
specified for much smaller boats (Bobcat, Gypsy, etc). The Chebacco has
a nominal displacement very similar to Micro's, but uses 12 mm ply...
And finally, Sam Devlin's scantlings for a boat displacing like Micro
specify 10 mm ply. Look at what John Morrice has done to stiffen his
Micro's sides...
I don't know how fir plywood looks like, but 6 mm thick okoumé (medium
quality stuff, 3 plies) is really, really too flimsy...
Best, Pippo
david ha scritto:
I asked exactly the same question to Bernie about one year ago.
Micro is designed for either 1/4" or 3/8" ply: see PCB's building key,
2nd row of the introductory paragraph. Bernie was (and I guess he still
is) a strong advocate of 3/8" thick ply for Micro, and that was the
basis for CSD Micro kits.
Now, I understand that the weight calculation for Micro has been done
having fir plywood in mind. I use okoumé plywood, which weighs
substantially less than fir, so the difference in overall weight is
going to be marginal. Just to be more precise, fir plywood has a density
of 650 kg/m^3 (from Glen L. Witt's book), while okoume's density
(measured by me) is about 490 kg/m^3.
Moreover, I'm going to build a double thickness bottom. As PCB himself
writes in the same building key, #12, "the weight will not hurt her
performance".
I really believe that 6 mm "cheapo" ply is marginal for a boat that
displaces 750 kg, in particular for the botton that, is such case,
reportedly does "oil can". By the way, 6 mm is the same plywood
specified for much smaller boats (Bobcat, Gypsy, etc). The Chebacco has
a nominal displacement very similar to Micro's, but uses 12 mm ply...
And finally, Sam Devlin's scantlings for a boat displacing like Micro
specify 10 mm ply. Look at what John Morrice has done to stiffen his
Micro's sides...
I don't know how fir plywood looks like, but 6 mm thick okoumé (medium
quality stuff, 3 plies) is really, really too flimsy...
Best, Pippo
david ha scritto:
>
> Micro, as designed, is of 1/4" plywood. A long time ago Bernie Wolfard
> built one of 3/8", and I see that Pippo is now doing the same, although
> most folks still seem to follow the original plans. Increasing the
> thickness of the ply by 1/8" would increase the boat's weight by about
> 120 Lb. if done in fir or luan, with about 80 lb. of the increase being
> above to waterline. What are the advantages of going this route, and do
> they offset the obvious disadvantages of reduced stability and increased
> cost?
> david
>
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Micro, as designed, is of 1/4" plywood. A long time ago Bernie Wolfard
built one of 3/8", and I see that Pippo is now doing the same, although
most folks still seem to follow the original plans. Increasing the
thickness of the ply by 1/8" would increase the boat's weight by about
120 Lb. if done in fir or luan, with about 80 lb. of the increase being
above to waterline. What are the advantages of going this route, and do
they offset the obvious disadvantages of reduced stability and increased
cost?
david
built one of 3/8", and I see that Pippo is now doing the same, although
most folks still seem to follow the original plans. Increasing the
thickness of the ply by 1/8" would increase the boat's weight by about
120 Lb. if done in fir or luan, with about 80 lb. of the increase being
above to waterline. What are the advantages of going this route, and do
they offset the obvious disadvantages of reduced stability and increased
cost?
david
I would go with the 5 ply, as the Okoume is probably pretty light anyway. I
single-planked my Micro bottom for the lake (I can swim to the edge), but
it does oil-can. I would double the bottom if it's a concern at all.
Gregg
At 02:11 PM 8/21/1999 -0700, you wrote:
single-planked my Micro bottom for the lake (I can swim to the edge), but
it does oil-can. I would double the bottom if it's a concern at all.
Gregg
At 02:11 PM 8/21/1999 -0700, you wrote:
>Dear all - the Micro scantlings specify either 1/4" or 3/8" plywood.
>Here in Europe we deal with millimeters instead. My supplier sells
>marine okoume in many thicknesses, including 6, 8 and 10 mm. The 6 mm
>is questionable: 3 plies, baulk core and very thin outside venners.
>Both the 8 and the 10 mm have 5 plies, and the 8 mm costs 10% less.
>Which one would you use for the Micro? And what about the bottom:
>single or double? Thanks all, Pippo
>
>
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Dear all - the Micro scantlings specify either 1/4" or 3/8" plywood.
Here in Europe we deal with millimeters instead. My supplier sells
marine okoume in many thicknesses, including 6, 8 and 10 mm. The 6 mm
is questionable: 3 plies, baulk core and very thin outside venners.
Both the 8 and the 10 mm have 5 plies, and the 8 mm costs 10% less.
Which one would you use for the Micro? And what about the bottom:
single or double? Thanks all, Pippo
Here in Europe we deal with millimeters instead. My supplier sells
marine okoume in many thicknesses, including 6, 8 and 10 mm. The 6 mm
is questionable: 3 plies, baulk core and very thin outside venners.
Both the 8 and the 10 mm have 5 plies, and the 8 mm costs 10% less.
Which one would you use for the Micro? And what about the bottom:
single or double? Thanks all, Pippo