Re: [bolger] Hull Shapes and "Flattie" Thinking
Excellent reply
Stuart Crawford
on 9/10/01 5:09 PM, thomas dalzell atproaconstrictor@...wrote:
pg> "
pg> "
Stuart Crawford
on 9/10/01 5:09 PM, thomas dalzell atproaconstrictor@...wrote:
> The traditional sharpies are largely regarded as beingsrc="http://us.a1.yimg.com/us.yimg.com/a/1-/flash/overstock_com/osyahooalt.j
> anacronisms now, because they were designed to go out
> and get a huge load of oysters or whatnot, and as a
> result they were designed with a variable waterline in
> mind.
>
> Your last comment is where Bolger is at. He is
> designing his sharpies with the idea that the two
> curves of bottom and side should be equal so that the
> boat when heeled will not have a heavy helm. A
> sharpie with that much curve to the bottom is going to
> have the stem out of the water.
>
> If you have done any canoeing, you know that you can
> induce a fairly fast carved turn by doing nothing but
> rolling the hull under you until one rail nears the
> water. The keel is relatively straight, and the side
> curved, so if you heel down on the right, she will
> turn sharply to the left. That is what the advanced
> sharpie design is intended to neutralize.
>
> A number of Bolger Sharpie owners have complained of
> the banging, and some have felt compeled to hang nets
> off the bow etc... in order to sleep quietly at
> anchor. Bolger lived aboard a large plywood sharpie
> for a while, so I guess he has the experience, and has
> come up with the best compromise as he sees it.
>
> I have rowed a number of his tenders with short
> waterlines, and stems well out of the water, these
> things move. At the wooden boat school I was able to
> compare them to any number of sweeter looking hulls,
> and they were in all cases faster, if one include his
> dory. The waterline length stuff is highly variable.
> As multihulls prove this is only a useful formula when
> comparing very simmilar boats to start with. Even
> then, hull speed may have little to do with the actual
> efficiency of a design. What matters is how it
> performs within the speed envelope it is designed for,
> not whether the hull might perform better, at speeds
> it is not designed to make, if its hull were drawn
> differently.
>
> TD
>
>
>
>
> ---PseudoDion3@...wrote:
>
> <HR>
> <html><body>
> <tt>
> Hi, All. I've just finished reading Stambaugh's
> "Good Skiffs." I'm <BR>
> trying to figure out the different theories of hull
> design and <BR>
> perhaps someone out there can help me understand them
> better.<BR>
> <BR>
> Let me preface my remarks by
> saying that I favor "sharpie" hull <BR>
> forms. At the moment, I am considering building a
> "traditional" <BR>
> sharpie for my next boat. Consequently, in reading
> Chapelle and <BR>
> others, I note that traditional sharpies are trimmed
> to keep the stem <BR>
> out of the water. Even the modified sharpie designs
> (e.g., Micro) <BR>
> show the "stem" slightly out of the water.
> Stambaugh claims that such <BR>
> an approach increases pounding and decreases hull
> efficiency (speed <BR>
> and the like). The flatties in his "Skiffs"
> invariably show the stems <BR>
> immersed which he claims decreases the pounding,
> increases water line <BR>
> length and possibly even hull speed since speed is
> related to water <BR>
> line length.Now Michalak has an interesting prototype
> called "Vector" <BR>
> which is a V hull sharpie (at least that is what its
> profile suggests <BR>
> if this is not a contradiction in terms) and he claims
> that such a <BR>
> hull will be more efficient than the flattie though it
> might be a <BR>
> little more tiddly than the flattie.<BR>
> Is there anyone out there who
> can clue me in on the trade offs <BR>
> between these design approaches. At least share your
> experiences with <BR>
> me so that I can understand a little better. Since I
> sail a $200 <BR>
> sailboat, I am familiar with the pounding of the flat
> bottom although <BR>
> sailing heeled over mitigates that problem somewhat.
> What is your <BR>
> experience with skiff and v bottom?<BR>
> <BR>
> Thanks,<BR>
> <BR>
> Dennis Marshall<BR>
> <BR>
> <BR>
> <BR>
> </tt>
>
> <br>
>
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> dead horses<BR>
> - pls take "personals" off-list, stay on
> topic, and punctuate<BR>
> - add your comments at the TOP and SIGN your posts,
> snip all you like<BR>
> - To order plans: Mr. Philip C. Bolger, P.O. Box 1209,
> Gloucester, MA, 01930, Fax: (978) 282-1349<BR>
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>
>
> Bolger rules!!!
> - no cursing, flaming, trolling, spamming, or flogging dead horses
> - pls take "personals" off-list, stay on topic, and punctuate
> - add your comments at the TOP and SIGN your posts, snip all you like
> - To order plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA, 01930,
> Fax: (978) 282-1349
> - Unsubscribe:bolger-unsubscribe@yahoogroups.com
>
> Your use of Yahoo! Groups is subject tohttp://docs.yahoo.com/info/terms/
>
>
>
The traditional sharpies are largely regarded as being
anacronisms now, because they were designed to go out
and get a huge load of oysters or whatnot, and as a
result they were designed with a variable waterline in
mind.
Your last comment is where Bolger is at. He is
designing his sharpies with the idea that the two
curves of bottom and side should be equal so that the
boat when heeled will not have a heavy helm. A
sharpie with that much curve to the bottom is going to
have the stem out of the water.
If you have done any canoeing, you know that you can
induce a fairly fast carved turn by doing nothing but
rolling the hull under you until one rail nears the
water. The keel is relatively straight, and the side
curved, so if you heel down on the right, she will
turn sharply to the left. That is what the advanced
sharpie design is intended to neutralize.
A number of Bolger Sharpie owners have complained of
the banging, and some have felt compeled to hang nets
off the bow etc... in order to sleep quietly at
anchor. Bolger lived aboard a large plywood sharpie
for a while, so I guess he has the experience, and has
come up with the best compromise as he sees it.
I have rowed a number of his tenders with short
waterlines, and stems well out of the water, these
things move. At the wooden boat school I was able to
compare them to any number of sweeter looking hulls,
and they were in all cases faster, if one include his
dory. The waterline length stuff is highly variable.
As multihulls prove this is only a useful formula when
comparing very simmilar boats to start with. Even
then, hull speed may have little to do with the actual
efficiency of a design. What matters is how it
performs within the speed envelope it is designed for,
not whether the hull might perform better, at speeds
it is not designed to make, if its hull were drawn
differently.
TD
---PseudoDion3@...wrote:
<HR>
<html><body>
<tt>
Hi, All. I've just finished reading Stambaugh's
"Good Skiffs." I'm <BR>
trying to figure out the different theories of hull
design and <BR>
perhaps someone out there can help me understand them
better.<BR>
<BR>
Let me preface my remarks by
saying that I favor "sharpie" hull <BR>
forms. At the moment, I am considering building a
"traditional" <BR>
sharpie for my next boat. Consequently, in reading
Chapelle and <BR>
others, I note that traditional sharpies are trimmed
to keep the stem <BR>
out of the water. Even the modified sharpie designs
(e.g., Micro) <BR>
show the "stem" slightly out of the water.
Stambaugh claims that such <BR>
an approach increases pounding and decreases hull
efficiency (speed <BR>
and the like). The flatties in his "Skiffs"
invariably show the stems <BR>
immersed which he claims decreases the pounding,
increases water line <BR>
length and possibly even hull speed since speed is
related to water <BR>
line length.Now Michalak has an interesting prototype
called "Vector" <BR>
which is a V hull sharpie (at least that is what its
profile suggests <BR>
if this is not a contradiction in terms) and he claims
that such a <BR>
hull will be more efficient than the flattie though it
might be a <BR>
little more tiddly than the flattie.<BR>
Is there anyone out there who
can clue me in on the trade offs <BR>
between these design approaches. At least share your
experiences with <BR>
me so that I can understand a little better. Since I
sail a $200 <BR>
sailboat, I am familiar with the pounding of the flat
bottom although <BR>
sailing heeled over mitigates that problem somewhat.
What is your <BR>
experience with skiff and v bottom?<BR>
<BR>
Thanks,<BR>
<BR>
Dennis Marshall<BR>
<BR>
<BR>
<BR>
</tt>
<br>
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Bolger rules!!!<BR>
- no cursing, flaming, trolling, spamming, or flogging
dead horses<BR>
- pls take "personals" off-list, stay on
topic, and punctuate<BR>
- add your comments at the TOP and SIGN your posts,
snip all you like<BR>
- To order plans: Mr. Philip C. Bolger, P.O. Box 1209,
Gloucester, MA, 01930, Fax: (978) 282-1349<BR>
- Unsubscribe:
bolger-unsubscribe@yahoogroups.com</tt>
<br>
<br>
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anacronisms now, because they were designed to go out
and get a huge load of oysters or whatnot, and as a
result they were designed with a variable waterline in
mind.
Your last comment is where Bolger is at. He is
designing his sharpies with the idea that the two
curves of bottom and side should be equal so that the
boat when heeled will not have a heavy helm. A
sharpie with that much curve to the bottom is going to
have the stem out of the water.
If you have done any canoeing, you know that you can
induce a fairly fast carved turn by doing nothing but
rolling the hull under you until one rail nears the
water. The keel is relatively straight, and the side
curved, so if you heel down on the right, she will
turn sharply to the left. That is what the advanced
sharpie design is intended to neutralize.
A number of Bolger Sharpie owners have complained of
the banging, and some have felt compeled to hang nets
off the bow etc... in order to sleep quietly at
anchor. Bolger lived aboard a large plywood sharpie
for a while, so I guess he has the experience, and has
come up with the best compromise as he sees it.
I have rowed a number of his tenders with short
waterlines, and stems well out of the water, these
things move. At the wooden boat school I was able to
compare them to any number of sweeter looking hulls,
and they were in all cases faster, if one include his
dory. The waterline length stuff is highly variable.
As multihulls prove this is only a useful formula when
comparing very simmilar boats to start with. Even
then, hull speed may have little to do with the actual
efficiency of a design. What matters is how it
performs within the speed envelope it is designed for,
not whether the hull might perform better, at speeds
it is not designed to make, if its hull were drawn
differently.
TD
---PseudoDion3@...wrote:
<HR>
<html><body>
<tt>
Hi, All. I've just finished reading Stambaugh's
"Good Skiffs." I'm <BR>
trying to figure out the different theories of hull
design and <BR>
perhaps someone out there can help me understand them
better.<BR>
<BR>
Let me preface my remarks by
saying that I favor "sharpie" hull <BR>
forms. At the moment, I am considering building a
"traditional" <BR>
sharpie for my next boat. Consequently, in reading
Chapelle and <BR>
others, I note that traditional sharpies are trimmed
to keep the stem <BR>
out of the water. Even the modified sharpie designs
(e.g., Micro) <BR>
show the "stem" slightly out of the water.
Stambaugh claims that such <BR>
an approach increases pounding and decreases hull
efficiency (speed <BR>
and the like). The flatties in his "Skiffs"
invariably show the stems <BR>
immersed which he claims decreases the pounding,
increases water line <BR>
length and possibly even hull speed since speed is
related to water <BR>
line length.Now Michalak has an interesting prototype
called "Vector" <BR>
which is a V hull sharpie (at least that is what its
profile suggests <BR>
if this is not a contradiction in terms) and he claims
that such a <BR>
hull will be more efficient than the flattie though it
might be a <BR>
little more tiddly than the flattie.<BR>
Is there anyone out there who
can clue me in on the trade offs <BR>
between these design approaches. At least share your
experiences with <BR>
me so that I can understand a little better. Since I
sail a $200 <BR>
sailboat, I am familiar with the pounding of the flat
bottom although <BR>
sailing heeled over mitigates that problem somewhat.
What is your <BR>
experience with skiff and v bottom?<BR>
<BR>
Thanks,<BR>
<BR>
Dennis Marshall<BR>
<BR>
<BR>
<BR>
</tt>
<br>
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Bolger rules!!!<BR>
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- pls take "personals" off-list, stay on
topic, and punctuate<BR>
- add your comments at the TOP and SIGN your posts,
snip all you like<BR>
- To order plans: Mr. Philip C. Bolger, P.O. Box 1209,
Gloucester, MA, 01930, Fax: (978) 282-1349<BR>
- Unsubscribe:
bolger-unsubscribe@yahoogroups.com</tt>
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Hi, All. I've just finished reading Stambaugh's "Good Skiffs." I'm
trying to figure out the different theories of hull design and
perhaps someone out there can help me understand them better.
Let me preface my remarks by saying that I favor "sharpie" hull
forms. At the moment, I am considering building a "traditional"
sharpie for my next boat. Consequently, in reading Chapelle and
others, I note that traditional sharpies are trimmed to keep the stem
out of the water. Even the modified sharpie designs (e.g., Micro)
show the "stem" slightly out of the water. Stambaugh claims that such
an approach increases pounding and decreases hull efficiency (speed
and the like). The flatties in his "Skiffs" invariably show the stems
immersed which he claims decreases the pounding, increases water line
length and possibly even hull speed since speed is related to water
line length.Now Michalak has an interesting prototype called "Vector"
which is a V hull sharpie (at least that is what its profile suggests
if this is not a contradiction in terms) and he claims that such a
hull will be more efficient than the flattie though it might be a
little more tiddly than the flattie.
Is there anyone out there who can clue me in on the trade offs
between these design approaches. At least share your experiences with
me so that I can understand a little better. Since I sail a $200
sailboat, I am familiar with the pounding of the flat bottom although
sailing heeled over mitigates that problem somewhat. What is your
experience with skiff and v bottom?
Thanks,
Dennis Marshall
trying to figure out the different theories of hull design and
perhaps someone out there can help me understand them better.
Let me preface my remarks by saying that I favor "sharpie" hull
forms. At the moment, I am considering building a "traditional"
sharpie for my next boat. Consequently, in reading Chapelle and
others, I note that traditional sharpies are trimmed to keep the stem
out of the water. Even the modified sharpie designs (e.g., Micro)
show the "stem" slightly out of the water. Stambaugh claims that such
an approach increases pounding and decreases hull efficiency (speed
and the like). The flatties in his "Skiffs" invariably show the stems
immersed which he claims decreases the pounding, increases water line
length and possibly even hull speed since speed is related to water
line length.Now Michalak has an interesting prototype called "Vector"
which is a V hull sharpie (at least that is what its profile suggests
if this is not a contradiction in terms) and he claims that such a
hull will be more efficient than the flattie though it might be a
little more tiddly than the flattie.
Is there anyone out there who can clue me in on the trade offs
between these design approaches. At least share your experiences with
me so that I can understand a little better. Since I sail a $200
sailboat, I am familiar with the pounding of the flat bottom although
sailing heeled over mitigates that problem somewhat. What is your
experience with skiff and v bottom?
Thanks,
Dennis Marshall