Re: curved boom?
--- Inbolger@yahoogroups.com, "Lincoln Ross" <lincolnr@...> wrote:
Province of Saskatchewan during the developmental phase of their
wind generation project.
However measuring windflow over land is not the same as measuring it
over water. (Thus the fuzz factor) Over land, friction and
topography throw the whole thing out of wack and ground effects may
extend thousands of feet above the surface - mountains of course
being the extreme example.
But that is of little concern for a sailor - unless he is sailing
near mountains. Windflow over water tends to pretty much follow
parallel to the isobars on a surface weather map. You can easily
check this by observing the winds at buoys that have wind sensors or
by conferring with any meteorologist.
I believe the turbulent layer next to the surface of the earth is
called the boundary layer in meteorlogical terms. Over land it can
extend (on average) to about 3000 ft above the ground on a hot day.
Over water it is much less - in the order of 15- 50 feet at most,
depending on wave heights. Also there is very little diurnal
variation of air temperature over water as compared to land, so the
air flow is more constant and stable.
When I used the term "laminar" I was referring to the flow of wind
over the sea surface and not the sail.
Nels
> It would be interesting to see data on average wind speeds (andI did that for a living for awhile:-) Did wind studies for the
> directions) at various heights on a given day.
Province of Saskatchewan during the developmental phase of their
wind generation project.
However measuring windflow over land is not the same as measuring it
over water. (Thus the fuzz factor) Over land, friction and
topography throw the whole thing out of wack and ground effects may
extend thousands of feet above the surface - mountains of course
being the extreme example.
But that is of little concern for a sailor - unless he is sailing
near mountains. Windflow over water tends to pretty much follow
parallel to the isobars on a surface weather map. You can easily
check this by observing the winds at buoys that have wind sensors or
by conferring with any meteorologist.
I believe the turbulent layer next to the surface of the earth is
called the boundary layer in meteorlogical terms. Over land it can
extend (on average) to about 3000 ft above the ground on a hot day.
Over water it is much less - in the order of 15- 50 feet at most,
depending on wave heights. Also there is very little diurnal
variation of air temperature over water as compared to land, so the
air flow is more constant and stable.
When I used the term "laminar" I was referring to the flow of wind
over the sea surface and not the sail.
Nels
Sigh. Laminar is a technical term. It does not mean "relatively
smooth". It means that flow is as if in laybers. A nitrogen molecule
10 feet off the surface will not cross paths with one 15 feet off the
surface, if the flow is laminar. But if you've watched fuzzy stuff in
the air on light days, you can often see that this is not true.
Now, relative the a mast or something, flow might be laminar for a
little while, but if you want it to stay that way you had better make
a wing foil like a C cat, but with a laminar airfoil shape, and sand
the bejesus out of it. Still, by the time it gets to the wing sail,
the flow will be turbulent.
Standing rigging is a lousy shape, is at very low Reynolds numbers,
and it's high up. So it creates LOTS of drag. A thin wire will
probably have the same drag as a hypothetical C cat laminar foil
dozens of times thicker. (That laminar foil is probably just
hypothetical. A real life foil might only be sixes of times thicker
for the same drag.
BTW, turbulent is not the same as separated. In some cases, you can
have an airfoil that iss turbulent pretty much all over, which has
much less drag and more lift than an airfoil which has a fair amount
of laminar flow followed by complete separation, or even just a
separation "bubble". There are various tricks to show this kind of
stuff is not just mathematical hooey. A friend of mine has a tank
where you can see the transition from turbulent to separated flow very
easily. In the separated area, some of the flow even goes backwards.
We often put intentional rough spots or bumps on model airplanes,
because turbulent flow usually does a better job of staying stuck to
the plane. And it isn't ruined by little flyspecs, the way laminar
flow is. Or by one careless swipe of the sandpaper, or by little wavy
distortions in the surface. One of the easiest (except for your lungs)
ways to see the transition from laminar to turbulent is by watching
smoke rising off a cigarette in an ashtray in still air. Or a candle,
if something is added to make it smoke.
It would be interesting to see data on average wind speeds (and
directions) at various heights on a given day.
smooth". It means that flow is as if in laybers. A nitrogen molecule
10 feet off the surface will not cross paths with one 15 feet off the
surface, if the flow is laminar. But if you've watched fuzzy stuff in
the air on light days, you can often see that this is not true.
Now, relative the a mast or something, flow might be laminar for a
little while, but if you want it to stay that way you had better make
a wing foil like a C cat, but with a laminar airfoil shape, and sand
the bejesus out of it. Still, by the time it gets to the wing sail,
the flow will be turbulent.
Standing rigging is a lousy shape, is at very low Reynolds numbers,
and it's high up. So it creates LOTS of drag. A thin wire will
probably have the same drag as a hypothetical C cat laminar foil
dozens of times thicker. (That laminar foil is probably just
hypothetical. A real life foil might only be sixes of times thicker
for the same drag.
BTW, turbulent is not the same as separated. In some cases, you can
have an airfoil that iss turbulent pretty much all over, which has
much less drag and more lift than an airfoil which has a fair amount
of laminar flow followed by complete separation, or even just a
separation "bubble". There are various tricks to show this kind of
stuff is not just mathematical hooey. A friend of mine has a tank
where you can see the transition from turbulent to separated flow very
easily. In the separated area, some of the flow even goes backwards.
We often put intentional rough spots or bumps on model airplanes,
because turbulent flow usually does a better job of staying stuck to
the plane. And it isn't ruined by little flyspecs, the way laminar
flow is. Or by one careless swipe of the sandpaper, or by little wavy
distortions in the surface. One of the easiest (except for your lungs)
ways to see the transition from laminar to turbulent is by watching
smoke rising off a cigarette in an ashtray in still air. Or a candle,
if something is added to make it smoke.
It would be interesting to see data on average wind speeds (and
directions) at various heights on a given day.
--- Inbolger@yahoogroups.com, "Nels" <arvent@...> wrote:
>
> --- Inbolger@yahoogroups.com, "Phillip Lea" <phillip_lea@> wrote:
> > I suspect that there is
> > more difference in light winds when you need all the area you can
> > get.
>
> I would agree. Once winds drop to under about 10 knots the ground
> effect becomes negligable so that the lower area of the sail becomes
> more effective. Usually over water the air flow does not become
> laminar until levels above about 15 feet unless the water is really
> smooth. This is due to the friction and disturbance of the air over
> the waves as well as the boat structure itself.
>
> I think that may be one reason that Bolger does not worry much
> about "windage" from higher topsides and considers standing rigging to
> be more of a factor since standing rigging interferes with the laminar
> wind flow well above the ground effect layer.
>
> Nels
>
On the Brick, I never noticed the difference. Light air or heavy.
--- Inbolger@yahoogroups.com, "Phillip Lea" <phillip_lea@...> wrote:
>
> In my Junebug, the sprit boom on the leeward side has a very
> noticeable effect, experienced in 5 seasons of sailing her, boom on
> port, or boom on starboard (to eliminate effect of off-center
> leeboard). The corollary is that the off-center board has an
> unnoticable effect on my Junebug.
>
> snip
Actually, having an opinion on which choice of boom is supported by
the technical merits is like comparing apples and oranges. What is the
conversion factor between aerodynamic drag and pain???
I would definitely use a wishbone boom on a windsurfer, and would
consider it on a boat where the boom would always be well above my head.
the technical merits is like comparing apples and oranges. What is the
conversion factor between aerodynamic drag and pain???
I would definitely use a wishbone boom on a windsurfer, and would
consider it on a boat where the boom would always be well above my head.
--- Inbolger@yahoogroups.com, "Bruce Hallman" <bruce@...> wrote:
>
> > BTW, I have often seen Bolger say things that are technically
> > incorrect, but he still designs excellent boats.
>
> Every question has a set of assumptions at its base.
> In the case of the set of a sprit boom versus a wishbone,
> or a curved spare with its required topping lift.
>
> A wind tunnel test could be the assumption, or a race,
> or a day-in-day-out reality. I think Bolger factors in the
> cost and awkward handling of the wishbone or curved spar,
> and decides that the windtunnel improvement is too
> small to offset the simple elegance of handing a
> smaller, lighter stick.
>
> Both answers are technically correct, relative to their
> base assumptions.
>
While I don't doubt the theoretical improvement which a curved sprit or wishbone sprit may offer, my experience has been that the performance of a standard sprit boom is so close to identical on either tack that I can't tell the difference (based on a couple of years sailing a Dovekie). My conclusion is that a curved sprit solves a problem that doesn't exist!
John T
John T
----- Original Message -----
From: Bruce Hallman
To:bolger@yahoogroups.com
Sent: Monday, March 27, 2006 10:37 AM
Subject: Re: [bolger] Re: curved boom?
> BTW, I have often seen Bolger say things that are technically
> incorrect, but he still designs excellent boats.
Every question has a set of assumptions at its base.
In the case of the set of a sprit boom versus a wishbone,
or a curved spare with its required topping lift.
A wind tunnel test could be the assumption, or a race,
or a day-in-day-out reality. I think Bolger factors in the
cost and awkward handling of the wishbone or curved spar,
and decides that the windtunnel improvement is too
small to offset the simple elegance of handing a
smaller, lighter stick.
Both answers are technically correct, relative to their
base assumptions.
Bolger rules!!!
- NO "GO AWAY SPAMMER!" posts!!! Please!
- no cursing, flaming, trolling, spamming, respamming, or flogging dead horses
- stay on topic, stay on thread, punctuate, no 'Ed, thanks, Fred' posts
- Pls add your comments at the TOP, SIGN your posts, and snip away
- Plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA, 01930, Fax: (978) 282-1349
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--- Inbolger@yahoogroups.com, "Phillip Lea" <phillip_lea@...> wrote:
effect becomes negligable so that the lower area of the sail becomes
more effective. Usually over water the air flow does not become
laminar until levels above about 15 feet unless the water is really
smooth. This is due to the friction and disturbance of the air over
the waves as well as the boat structure itself.
I think that may be one reason that Bolger does not worry much
about "windage" from higher topsides and considers standing rigging to
be more of a factor since standing rigging interferes with the laminar
wind flow well above the ground effect layer.
Nels
> I suspect that there isI would agree. Once winds drop to under about 10 knots the ground
> more difference in light winds when you need all the area you can
> get.
effect becomes negligable so that the lower area of the sail becomes
more effective. Usually over water the air flow does not become
laminar until levels above about 15 feet unless the water is really
smooth. This is due to the friction and disturbance of the air over
the waves as well as the boat structure itself.
I think that may be one reason that Bolger does not worry much
about "windage" from higher topsides and considers standing rigging to
be more of a factor since standing rigging interferes with the laminar
wind flow well above the ground effect layer.
Nels
In my Junebug, the sprit boom on the leeward side has a very
noticeable effect, experienced in 5 seasons of sailing her, boom on
port, or boom on starboard (to eliminate effect of off-center
leeboard). The corollary is that the off-center board has an
unnoticable effect on my Junebug.
In fact when there were two 200 pound guys aboard with the wind
dropping to ~2 mph, on the bad tack, almost lost steerage, with a
mile to go that we didn't want to paddle, we swapped the boom while
underway. Result was real improvement in boat speed, steerage and
got back before the wind and sun were gone. I suspect that there is
more difference in light winds when you need all the area you can
get.
Bolger draws a boom constructed like an isosceles triangle that has
two straight sides that stand out from the sail with the short base
of the triangle in front of the mast in "Build the New Instant
Boats" I think. He didn't recommend a wishbone boom with two curved
sidessaid it was a bear to handle.
I have considered building another boom BUT:
1) I have gotten used to the difference in performance,
2) there is nobody to race,
3) it is a very simple rig that works very very well,
4) I am working on another boat
But don't be afraid to experiment. Do your homework. Pay your
nickels and take your chances. Let us know how it works. And if it
fails, blame yourself, not the designer.
Phil Lea
noticeable effect, experienced in 5 seasons of sailing her, boom on
port, or boom on starboard (to eliminate effect of off-center
leeboard). The corollary is that the off-center board has an
unnoticable effect on my Junebug.
In fact when there were two 200 pound guys aboard with the wind
dropping to ~2 mph, on the bad tack, almost lost steerage, with a
mile to go that we didn't want to paddle, we swapped the boom while
underway. Result was real improvement in boat speed, steerage and
got back before the wind and sun were gone. I suspect that there is
more difference in light winds when you need all the area you can
get.
Bolger draws a boom constructed like an isosceles triangle that has
two straight sides that stand out from the sail with the short base
of the triangle in front of the mast in "Build the New Instant
Boats" I think. He didn't recommend a wishbone boom with two curved
sidessaid it was a bear to handle.
I have considered building another boom BUT:
1) I have gotten used to the difference in performance,
2) there is nobody to race,
3) it is a very simple rig that works very very well,
4) I am working on another boat
But don't be afraid to experiment. Do your homework. Pay your
nickels and take your chances. Let us know how it works. And if it
fails, blame yourself, not the designer.
Phil Lea
--- Inbolger@yahoogroups.com, "Nels" <arvent@...> wrote:
>
> --- Inbolger@yahoogroups.com, "Bruce Hallman" <bruce@> wrote:
> >
> > > BTW, I have often seen Bolger say things that are technically
> > > incorrect, but he still designs excellent boats.
> >
> > Every question has a set of assumptions at its base.
> > In the case of the set of a sprit boom versus a wishbone,
> > or a curved spare with its required topping lift.
> >
> I would go even further than that and say. "Every *truth* has a
set
> of assumptions at its base."
>
> It is assumed true that the leg-o-mutton sailplan has a "good tack
> and a bad tack" because of the air flow being interuppted by the
> straight sprit boom on the bad tack. Yet in actual experience some
> have experienced the opposite to this assumed truth.
>
> I think this photo at Chuck Merrell's website is interesting in
that
> regard. The area of sail about the boom seems to be working very
> well. The area below the boom is actually in the "ground effect"
> region (an aerodynamic term.) - which is often filled with eddying
> air that is not creating power anyway. In fact the sprit boom may
be
> creating an "end plate" effect as is mentioned in some of Bolgers
> writings.
>
>http://www.boatdesign.com/micro/index.html
>
> Nels
>
I think there was another reason Bolger didn't use the wishbone. Him and I talked about it for the Wolftrap and he told me it was patented by, I think the people that built the Freedom forty. I'm sure the patent has long since run out.
Doug
Doug
----- Original Message -----
From: Bruce Hallman
To:bolger@yahoogroups.com
Sent: Monday, March 27, 2006 10:37 AM
Subject: Re: [bolger] Re: curved boom?
> BTW, I have often seen Bolger say things that are technically
> incorrect, but he still designs excellent boats.
Every question has a set of assumptions at its base.
In the case of the set of a sprit boom versus a wishbone,
or a curved spare with its required topping lift.
A wind tunnel test could be the assumption, or a race,
or a day-in-day-out reality. I think Bolger factors in the
cost and awkward handling of the wishbone or curved spar,
and decides that the windtunnel improvement is too
small to offset the simple elegance of handing a
smaller, lighter stick.
Both answers are technically correct, relative to their
base assumptions.
Bolger rules!!!
- NO "GO AWAY SPAMMER!" posts!!! Please!
- no cursing, flaming, trolling, spamming, respamming, or flogging dead horses
- stay on topic, stay on thread, punctuate, no 'Ed, thanks, Fred' posts
- Pls add your comments at the TOP, SIGN your posts, and snip away
- Plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA, 01930, Fax: (978) 282-1349
- Unsubscribe:bolger-unsubscribe@yahoogroups.com
- Open discussion:bolger_coffee_lounge-subscribe@yahoogroups.com
------------------------------------------------------------------------------
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a.. Visit your group "bolger" on the web.
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c.. Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
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--- Inbolger@yahoogroups.com, "Bruce Hallman" <bruce@...> wrote:
of assumptions at its base."
It is assumed true that the leg-o-mutton sailplan has a "good tack
and a bad tack" because of the air flow being interuppted by the
straight sprit boom on the bad tack. Yet in actual experience some
have experienced the opposite to this assumed truth.
I think this photo at Chuck Merrell's website is interesting in that
regard. The area of sail about the boom seems to be working very
well. The area below the boom is actually in the "ground effect"
region (an aerodynamic term.) - which is often filled with eddying
air that is not creating power anyway. In fact the sprit boom may be
creating an "end plate" effect as is mentioned in some of Bolgers
writings.
http://www.boatdesign.com/micro/index.html
Nels
>I would go even further than that and say. "Every *truth* has a set
> > BTW, I have often seen Bolger say things that are technically
> > incorrect, but he still designs excellent boats.
>
> Every question has a set of assumptions at its base.
> In the case of the set of a sprit boom versus a wishbone,
> or a curved spare with its required topping lift.
>
of assumptions at its base."
It is assumed true that the leg-o-mutton sailplan has a "good tack
and a bad tack" because of the air flow being interuppted by the
straight sprit boom on the bad tack. Yet in actual experience some
have experienced the opposite to this assumed truth.
I think this photo at Chuck Merrell's website is interesting in that
regard. The area of sail about the boom seems to be working very
well. The area below the boom is actually in the "ground effect"
region (an aerodynamic term.) - which is often filled with eddying
air that is not creating power anyway. In fact the sprit boom may be
creating an "end plate" effect as is mentioned in some of Bolgers
writings.
http://www.boatdesign.com/micro/index.html
Nels
> BTW, I have often seen Bolger say things that are technicallyEvery question has a set of assumptions at its base.
> incorrect, but he still designs excellent boats.
In the case of the set of a sprit boom versus a wishbone,
or a curved spare with its required topping lift.
A wind tunnel test could be the assumption, or a race,
or a day-in-day-out reality. I think Bolger factors in the
cost and awkward handling of the wishbone or curved spar,
and decides that the windtunnel improvement is too
small to offset the simple elegance of handing a
smaller, lighter stick.
Both answers are technically correct, relative to their
base assumptions.
Bill,
I built a wishbone boom for my Bolger Gypsy in 1998. I had seen
windsurfers and Nonsuch's and thought I could improve my boat. I didn't
bend wood but instead made a diamond shaped wishbone from 2x2's. I
scarphed the "corner joints" and reinforced them with fiberglass tape. I
was pleased with the strength of the whole thing, although it was heavier
than my standard, Gypsy 2x2 sprit boom.
The wishbone now sits in storage in the attic of my garage. I only tried
it once and was not pleased. I can echo some of the comments already
provided by list members. First, it's ungainly. Ideally you should have a
topping lift to keep the boom "up" for it's a whole lotta wood when it's
flopping about on the deck. It also has a tendency to tip (list?) when
it's deployed and thus it can still touch the sail (if you haven't made the
wish bones far enough apart). I suspect you could make it work, and with
time and tinkering you could make it work well. But I found it was far
more trouble than it was worth with my Gypsy and my Long Micro will have
standard sprit booms.
Bill, in Ohio
I built a wishbone boom for my Bolger Gypsy in 1998. I had seen
windsurfers and Nonsuch's and thought I could improve my boat. I didn't
bend wood but instead made a diamond shaped wishbone from 2x2's. I
scarphed the "corner joints" and reinforced them with fiberglass tape. I
was pleased with the strength of the whole thing, although it was heavier
than my standard, Gypsy 2x2 sprit boom.
The wishbone now sits in storage in the attic of my garage. I only tried
it once and was not pleased. I can echo some of the comments already
provided by list members. First, it's ungainly. Ideally you should have a
topping lift to keep the boom "up" for it's a whole lotta wood when it's
flopping about on the deck. It also has a tendency to tip (list?) when
it's deployed and thus it can still touch the sail (if you haven't made the
wish bones far enough apart). I suspect you could make it work, and with
time and tinkering you could make it work well. But I found it was far
more trouble than it was worth with my Gypsy and my Long Micro will have
standard sprit booms.
Bill, in Ohio
>Hi,[Non-text portions of this message have been removed]
>I've been wondering if anyone has experience with a curved boom sprit
>(using or
>making)? It seems like the benefit of improved sail shape could be worth a
>bit of
>laminating. I've even been daydreaming about possibly sandwiching some curved
>pieces of foam with a couple wooden strips and wrapping the length with
>epoxy and
>glass.
>
>Any input from the wiser mass?
>
>Thanks,
>Bill
You must live in a different universe. I've been chewed out a
gazillion times for it. All depends on delivery, and the disposition
of those in a position to disagree with the truth. For that matter,
who gets to say what right is? Mind you, I would like to live
someplace where people didn't get mad at others for being right. In
this one, if you make a correct prediction before it's obvous and
fashoinable, and it shows someone in a negative light, you're probably
going to get fired. And God help you if you remember something that
everyone else wants to forget, or never bothered to learn. A somewhat
better situation is when everyone says you're the prophet of doom,
admits you're often right, and ignores you anyway. I've been there.
Anyway, don't disagree with those people who say your Bolger boat will
never sail correctly. Just beat them going upwind. They can't reach
you then. Unless they are in charge of the racing rules...
BTW, I have often seen Bolger say things that are technically
incorrect, but he still designs excellent boats.
If you're able to avoid anger at someone who is right when you are
wrong, I admire you.
I've been on a boat with a bowed boom, in this case double sided like
a Windsurfer boom. I kept feeling like the boom was going to push me
overboard. It was an awkward thing. Perhaps one trick would be to make
the snotter out of something like very wide seat belt webbing or with
two ropes so that it tended to keep the boom horizontal.
gazillion times for it. All depends on delivery, and the disposition
of those in a position to disagree with the truth. For that matter,
who gets to say what right is? Mind you, I would like to live
someplace where people didn't get mad at others for being right. In
this one, if you make a correct prediction before it's obvous and
fashoinable, and it shows someone in a negative light, you're probably
going to get fired. And God help you if you remember something that
everyone else wants to forget, or never bothered to learn. A somewhat
better situation is when everyone says you're the prophet of doom,
admits you're often right, and ignores you anyway. I've been there.
Anyway, don't disagree with those people who say your Bolger boat will
never sail correctly. Just beat them going upwind. They can't reach
you then. Unless they are in charge of the racing rules...
BTW, I have often seen Bolger say things that are technically
incorrect, but he still designs excellent boats.
If you're able to avoid anger at someone who is right when you are
wrong, I admire you.
I've been on a boat with a bowed boom, in this case double sided like
a Windsurfer boom. I kept feeling like the boom was going to push me
overboard. It was an awkward thing. Perhaps one trick would be to make
the snotter out of something like very wide seat belt webbing or with
two ropes so that it tended to keep the boom horizontal.
--- Inbolger@yahoogroups.com, "Douglas Pollard" <dougpol1@...> wrote:
"out of my shenanigans and of course I could feel my ears getting red.
But you can't get mad at a guy for being right."
>
Doug
I built a curved boom that was offset at the mast for Wolftrap. The forward end of the boom stood away from the mast about one foot. there was about another foot of curve to the boom. It worked ok but was a pain in the neck. It had to hang by a three line bridle. We put a bow in it first and tried that. The curvature in the boom made it want to rotate and required a line running from the top of the mast to the middle of the boom to keep the curvature from hang downward. The upper third of the sail wanted to chafe against the line. So we added the offset with a line going down to the bottom of the mast to stop the rotation. There had to be a pad on the offset to contact the mast along with a snotter. When hoisting the sail in bad weather until the boon was set tight in place with it's lines all snug the person up forward handling the thing was in danger of having his brains knocked out or being knocked overboard. We tried several other things all of which were equally a pain in the neck. We finally gave up and replaced the thing with a straight spar that weighed about a third as much. There were several of us sailing her at the time and not one would say they could tell any difference in the way she sailed on or off the wind or on either tack. This was exactly Bolgers prediction. He got a good laugh out of my shenanigans and of course I could feel my ears getting red. But you can't get mad at a guy for being right.
Doug
Doug
----- Original Message -----
From: pvanderwaart
To:bolger@yahoogroups.com
Sent: Sunday, March 26, 2006 2:33 PM
Subject: [bolger] Re: curved boom?
> I've been wondering if anyone has experience with a curved boom
> sprit (using or
> making)? Any input from the wiser mass?
No, I don't have any experience, but...
1) Bolger thinks a boom with an offset jaw is as good as a curved boom,
2) Curved spars are hard to stow,
3) Users don't report a big difference in performance from one tack to
the other, and
4) Having the curved boom rest proud to the lee side of the sail may
well upset the aerodynamics more than the gore caused by the straight
boom.
Peter
Bolger rules!!!
- NO "GO AWAY SPAMMER!" posts!!! Please!
- no cursing, flaming, trolling, spamming, respamming, or flogging dead horses
- stay on topic, stay on thread, punctuate, no 'Ed, thanks, Fred' posts
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If you are clever, you can curve the spar to match the curve of your boat's gunwale and it will store very nicely. I didn't think of this; some Brit built a boat for one of their "Raids" with this feature.
John T
John T
----- Original Message -----
From: pvanderwaart
To:bolger@yahoogroups.com
Sent: Sunday, March 26, 2006 2:33 PM
Subject: [bolger] Re: curved boom?
> I've been wondering if anyone has experience with a curved boom
> sprit (using or
> making)? Any input from the wiser mass?
No, I don't have any experience, but...
1) Bolger thinks a boom with an offset jaw is as good as a curved boom,
2) Curved spars are hard to stow,
3) Users don't report a big difference in performance from one tack to
the other, and
4) Having the curved boom rest proud to the lee side of the sail may
well upset the aerodynamics more than the gore caused by the straight
boom.
Peter
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- stay on topic, stay on thread, punctuate, no 'Ed, thanks, Fred' posts
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- Plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA, 01930, Fax: (978) 282-1349
- Unsubscribe:bolger-unsubscribe@yahoogroups.com
- Open discussion:bolger_coffee_lounge-subscribe@yahoogroups.com
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[Non-text portions of this message have been removed]
> I've been wondering if anyone has experience with a curved boomNo, I don't have any experience, but...
> sprit (using or
> making)? Any input from the wiser mass?
1) Bolger thinks a boom with an offset jaw is as good as a curved boom,
2) Curved spars are hard to stow,
3) Users don't report a big difference in performance from one tack to
the other, and
4) Having the curved boom rest proud to the lee side of the sail may
well upset the aerodynamics more than the gore caused by the straight
boom.
Peter
Hi,
I've been wondering if anyone has experience with a curved boom sprit (using or
making)? It seems like the benefit of improved sail shape could be worth a bit of
laminating. I've even been daydreaming about possibly sandwiching some curved
pieces of foam with a couple wooden strips and wrapping the length with epoxy and
glass.
Any input from the wiser mass?
Thanks,
Bill
I've been wondering if anyone has experience with a curved boom sprit (using or
making)? It seems like the benefit of improved sail shape could be worth a bit of
laminating. I've even been daydreaming about possibly sandwiching some curved
pieces of foam with a couple wooden strips and wrapping the length with epoxy and
glass.
Any input from the wiser mass?
Thanks,
Bill