Re: Wishbone Boom Performance?
I think the test you are talking about is on www.swallowboats.com
Go the the Storm Petrel, look for design considerations, and look up
the sail rig.
Stu.
Go the the Storm Petrel, look for design considerations, and look up
the sail rig.
Stu.
--- In bolger@y..., wmrpage@a... wrote:
> In a message dated 4/18/01 4:23:42 PM Central Daylight Time,
> kwilson800@a... writes:
>
>
> > Does anyone out there have experience with the relative
performance
> > of a wishbone boom and the straight sprit boom on the
> >
>
> I don't have any experience, but I recall reading about a trial
involving
> identically or similarly rigged sprit-boomed boats with their booms
rigged on
> opposite sides. I thought it was in one of Michalak's back issues,
but may be
> mistaken, as I can't find it now. There is probably a citation in
this
> group's archives somewhere. In any event, the experimenters found
no
> difference in upwind performance between the boat with the sprit on
the
> "good" (i.e. windward) side vs. the "bad" side. As I recall there
were some
> caveats expressed as to whether the same results would obtain on
larger sails
> than those tested, but the tests as performed seemed to have been
pretty
> conclusive within the limits of amateur scientific rigor. If
correct, using a
> wishbone boom would seem more of an aesthetic affectation than
anything else.
> (If I'm not mistaken, it would also require an extra line to hold
it up,
> compared to a sprit boom, which on top of the additional
construction
> complexity, puts a pretty fair "tax" on aesthetics.) Bolger
discusses the
> wishbone boom and a 1/2 variant in "Rig 4" of my paperback edition
of "100
> Small Boat Rigs", and probably elsewhere. I think it is safe to say
he's not
> very enthusiastic about them.
>
> I was rather surprised by the result of the trial, as some years
ago I sailed
> a purportedly Bolger-designed fiberglass sharpie (perhaps the hull
design was
> his, I doubt that its rigged form reflected any direct
participation) inside
> the Florida Keys. The boat seemed to me to point much higher on one
tack than
> on the other. However the frequent course changes required to keep
the boat
> in water deep enough for the centerboards made it difficult to
judge, and, if
> memory serves, the mainmast was stepped on deck on the center line,
while the
> mizzen was offset - which might explain a lot, if simple
incompetent
> sail-handling was not a more likely and perfectly adequate
explanation for
> the phenomena (if it actually existed).
>
> I'll post the citation for the comparative trial of sprits on
the "good" and
> "bad" tacks if I can locate it.
>
> Bill in MN
Yes, probably, but there's MDO and then there's MDO. I was looking at some
MDO at a locally owned home center yesterday and it was junk, just chock
full of voids! :ob I know there's better out there somewhere (Skiff Craft
and perhaps some other manufacturers make (made?) lapstrake motorboats out
of it). Try calling a local sign company, they probably know where to get
the Good Stuff.
You should have seen the s**t they were selling for "AA marine" plywood at
the home center!!
MDO at a locally owned home center yesterday and it was junk, just chock
full of voids! :ob I know there's better out there somewhere (Skiff Craft
and perhaps some other manufacturers make (made?) lapstrake motorboats out
of it). Try calling a local sign company, they probably know where to get
the Good Stuff.
You should have seen the s**t they were selling for "AA marine" plywood at
the home center!!
On Thu, 19 Apr 2001 16:39:53 -0500 (CDT), somebody wrote:
> Thank you for your prompt response.
>
> Might MDO be found at my local home center, or is it more specialized?
> ...
--
John <jkohnen@...>
http://www.boat-links.com/
The trouble with the school of experience
is that the graduates are too old to go to work. <Henry Ford>
I found MDO in both 3/8" and 1/2" at my local lumberyard. Being
in Arkansas, it was made of southern yellow pine plys, and had brown
kraft paper sides. 3/8" was one-sided at ~$22 a sheet, and 1/2" was
two-sided at ~$38. The plys were fairly even and there were no more
than two small voids (<1/8") to be seen along the edges. I didn't
know we had it in stock locally until I was looking for some ply to
make a drafting table and stumbled upon it. However, there were
some waves in the surface of the paper, following the heavy grain
of the pine ply underneath. This obvious problem can be seen in
all our billboards across the southern U.S. Just not like those
nice smooth billboards on the west coast.
Phil in Russellville
in Arkansas, it was made of southern yellow pine plys, and had brown
kraft paper sides. 3/8" was one-sided at ~$22 a sheet, and 1/2" was
two-sided at ~$38. The plys were fairly even and there were no more
than two small voids (<1/8") to be seen along the edges. I didn't
know we had it in stock locally until I was looking for some ply to
make a drafting table and stumbled upon it. However, there were
some waves in the surface of the paper, following the heavy grain
of the pine ply underneath. This obvious problem can be seen in
all our billboards across the southern U.S. Just not like those
nice smooth billboards on the west coast.
Phil in Russellville
--- In bolger@y..., <darus@v...> wrote:
> Thank you for your prompt response.
>
> Might MDO be found at my local home center, or is it more
specialized?
>
> > MDO stands for Medium Density Overlay. It is an
> > exterior plywood that has a phenolic resin impregnated
> > heavy kraft paper facing on one or both sides. It was
> > developed for road signs and the like. It is good
> > stuff.
Thank you for your prompt response.
Might MDO be found at my local home center, or is it more specialized?
Might MDO be found at my local home center, or is it more specialized?
> MDO stands for Medium Density Overlay. It is an
> exterior plywood that has a phenolic resin impregnated
> heavy kraft paper facing on one or both sides. It was
> developed for road signs and the like. It is good
> stuff.
MDO stands for Medium Density Overlay. It is an
exterior plywood that has a phenolic resin impregnated
heavy kraft paper facing on one or both sides. It was
developed for road signs and the like. It is good
stuff.
JB
---darus@...wrote:
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Yahoo! Auctions - buy the things you want at great prices
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exterior plywood that has a phenolic resin impregnated
heavy kraft paper facing on one or both sides. It was
developed for road signs and the like. It is good
stuff.
JB
---darus@...wrote:
>__________________________________________________
> Pardon my ignorance, but what is MDO?
>
> I see it talked about here occasionally but I've
> never seen it explained in detail.
>
> I gather that it is some sort of plywood variant but
> beyond that... ???
>
> Bolger rules!!!
> - no cursing, flaming, trolling, or spamming
> - no flogging dead horses
> - add something: take "thanks!" and "ditto!" posts
> off-list.
> - stay on topic and punctuate
> - add your comments at the TOP and SIGN your posts
> - To order plans: Mr. Philip C. Bolger, P.O. Box
> 1209, Gloucester, MA, 01930, Fax: (978) 282-1349
>
>
> Your use of Yahoo! Groups is subject to
>http://docs.yahoo.com/info/terms/
>
>
>
>
Do You Yahoo!?
Yahoo! Auctions - buy the things you want at great prices
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Pardon my ignorance, but what is MDO?
I see it talked about here occasionally but I've
never seen it explained in detail.
I gather that it is some sort of plywood variant but beyond that... ???
I see it talked about here occasionally but I've
never seen it explained in detail.
I gather that it is some sort of plywood variant but beyond that... ???
--- Chris Crandall <crandall@...> wrote:
for the bottom, transom and some of the bulkheads. Jim
says he'd do 1/2" for the bottom if he had to do it
over.
Mine is 3/8" for the topsides, all the bulkheads and
decks, and 1/2" for the transom and bottom. Jim did
not think the extra weight would be noticible. I don't
think my boat is going to be all that heavy compared
to more lightly constructed one, since my plywood is
much less dense compared to the heavy pine plywood I
normally use.
Best,
JB
__________________________________________________
Do You Yahoo!?
Yahoo! Auctions - buy the things you want at great prices
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> Speaking of MDO and AF4's, what's the ply thicknessAs designed, it is 1/4" for topsides and decks, 3/8"
> for the boat, as
> designed?
>
for the bottom, transom and some of the bulkheads. Jim
says he'd do 1/2" for the bottom if he had to do it
over.
Mine is 3/8" for the topsides, all the bulkheads and
decks, and 1/2" for the transom and bottom. Jim did
not think the extra weight would be noticible. I don't
think my boat is going to be all that heavy compared
to more lightly constructed one, since my plywood is
much less dense compared to the heavy pine plywood I
normally use.
Best,
JB
__________________________________________________
Do You Yahoo!?
Yahoo! Auctions - buy the things you want at great prices
http://auctions.yahoo.com/
Speaking of MDO and AF4's, what's the ply thickness for the boat, as
designed?
designed?
Clyde,
Yes, I'm using MDO (two sides) for my boat. Most of
the boat will just be painted. I will be putting a
layer of 6 oz glass on the bottom for abraision
resistance. The outside seams at the butts on the
topsides will have narrow layer of light glass in
hopes they won't show too much over time.
My boat is not a taped seam boat like Diablo. I've
never seen any information or heard anybodies
experience with using MDO in that application. I have
my concerns, though.
Every destruction test I've run shows that when a
glued joint fails, it is the wood that fails and not
the paper peeling off the wood. Nevertheless, I'm
still worried that the wood-paper interface is a
potential weak link and therefore all joints are
mechanically fastened as well as glued. Is this just
paranoia or a well founded fear? I don't know. It is
going to be interesting to see how my boat holds up
over the next couple of years, though. Aren't y'all
glad there are fools like me who want to be guinea
pigs for the rest of you? Maybe one day I'll make a
couple of sample taped seam joint to test my MDO for
it's suitablity for that type of construction.
One good thing I can say about MDO is that as I watch
this boat go together, it is very stisfying to know
that I'm not going to have to spend a couple weekends
sheathing, filling, and sanding the hull. It's ready
for paint right now.
Best,
JB in Kennesaw
--- "Clyde S. Wisner" <clydewis@...> wrote:
Do You Yahoo!?
Yahoo! Auctions - buy the things you want at great prices
http://auctions.yahoo.com/
Yes, I'm using MDO (two sides) for my boat. Most of
the boat will just be painted. I will be putting a
layer of 6 oz glass on the bottom for abraision
resistance. The outside seams at the butts on the
topsides will have narrow layer of light glass in
hopes they won't show too much over time.
My boat is not a taped seam boat like Diablo. I've
never seen any information or heard anybodies
experience with using MDO in that application. I have
my concerns, though.
Every destruction test I've run shows that when a
glued joint fails, it is the wood that fails and not
the paper peeling off the wood. Nevertheless, I'm
still worried that the wood-paper interface is a
potential weak link and therefore all joints are
mechanically fastened as well as glued. Is this just
paranoia or a well founded fear? I don't know. It is
going to be interesting to see how my boat holds up
over the next couple of years, though. Aren't y'all
glad there are fools like me who want to be guinea
pigs for the rest of you? Maybe one day I'll make a
couple of sample taped seam joint to test my MDO for
it's suitablity for that type of construction.
One good thing I can say about MDO is that as I watch
this boat go together, it is very stisfying to know
that I'm not going to have to spend a couple weekends
sheathing, filling, and sanding the hull. It's ready
for paint right now.
Best,
JB in Kennesaw
--- "Clyde S. Wisner" <clydewis@...> wrote:
> John, I want to ask: Are you using MDO for your AF4?__________________________________________________
> Are you going to put fiberglass and epoxy over
> the paper coating. I've never used MDO but was
> thinking about trying it for large Diablo, to save
> some money. Clyde
>
> John Bell wrote:
>
> > |
> > |
>
>
> Bolger rules!!!
> - no cursing, flaming, trolling, or spamming
> - no flogging dead horses
> - add something: take "thanks!" and "ditto!" posts
> off-list.
> - stay on topic and punctuate
> - add your comments at the TOP and SIGN your posts
> - To order plans: Mr. Philip C. Bolger, P.O. Box
> 1209, Gloucester, MA, 01930, Fax: (978) 282-1349
>
>
> Your use of Yahoo! Groups is subject to
>http://docs.yahoo.com/info/terms/
>
>
>
>
Do You Yahoo!?
Yahoo! Auctions - buy the things you want at great prices
http://auctions.yahoo.com/
John, I want to ask: Are you using MDO for your AF4? Are you going to put fiberglass and epoxy over
the paper coating. I've never used MDO but was thinking about trying it for large Diablo, to save
some money. Clyde
John Bell wrote:
the paper coating. I've never used MDO but was thinking about trying it for large Diablo, to save
some money. Clyde
John Bell wrote:
> |
> |
In a message dated 4/18/01 4:23:42 PM Central Daylight Time,
kwilson800@... writes:
kwilson800@... writes:
Does anyone out there have experience with the relative performance
of a wishbone boom and the straight sprit boom on the
standard "instant boat" rig
I don't have any experience, but I recall reading about a trial involving
identically or similarly rigged sprit-boomed boats with their booms rigged on
opposite sides. I thought it was in one of Michalak's back issues, but may be
mistaken, as I can't find it now. There is probably a citation in this
group's archives somewhere. In any event, the experimenters found no
difference in upwind performance between the boat with the sprit on the
"good" (i.e. windward) side vs. the "bad" side. As I recall there were some
caveats expressed as to whether the same results would obtain on larger sails
than those tested, but the tests as performed seemed to have been pretty
conclusive within the limits of amateur scientific rigor. If correct, using a
wishbone boom would seem more of an aesthetic affectation than anything else.
(If I'm not mistaken, it would also require an extra line to hold it up,
compared to a sprit boom, which on top of the additional construction
complexity, puts a pretty fair "tax" on aesthetics.) Bolger discusses the
wishbone boom and a 1/2 variant in "Rig 4" of my paperback edition of "100
Small Boat Rigs", and probably elsewhere. I think it is safe to say he's not
very enthusiastic about them.
I was rather surprised by the result of the trial, as some years ago I sailed
a purportedly Bolger-designed fiberglass sharpie (perhaps the hull design was
his, I doubt that its rigged form reflected any direct participation) inside
the Florida Keys. The boat seemed to me to point much higher on one tack than
on the other. However the frequent course changes required to keep the boat
in water deep enough for the centerboards made it difficult to judge, and, if
memory serves, the mainmast was stepped on deck on the center line, while the
mizzen was offset - which might explain a lot, if simple incompetent
sail-handling was not a more likely and perfectly adequate explanation for
the phenomena (if it actually existed).
I'll post the citation for the comparative trial of sprits on the "good" and
"bad" tacks if I can locate it.
Bill in MN
I sail a standing lug with a sprit boom on my sailing canoe. I
recently switched from a straight sprit boom to a wishbone. I didn't
notice any difference between the "bad" tack and the "good" tack with
the straight boom. For this reason, the wishbone boom doesn't seem
like an improvement over a straight boom. I like the way it looks,
though.
Regards
Andy Farquhar
recently switched from a straight sprit boom to a wishbone. I didn't
notice any difference between the "bad" tack and the "good" tack with
the straight boom. For this reason, the wishbone boom doesn't seem
like an improvement over a straight boom. I like the way it looks,
though.
Regards
Andy Farquhar
|
| 1) In racing Sunfish and Sailfish, the performance upwind is
| essentially equal on the two tacks, with perhaps a slight edge to
| what would be thought of as the 'bad' tack where sail blows against
| the mast. At least, so I have been told.
I always felt like my balanced lug Windsprint went to windward better when
the sail lay against the mast.
Given the option of a straight sprit or a wishbone, I'd go with the sprit
boom almost every time. The only reason I can see for the wishbone is in
cases where chafe and sail wear is a concern, like on a bluewater boat.
JB in Kennesaw
| 1) In racing Sunfish and Sailfish, the performance upwind is
| essentially equal on the two tacks, with perhaps a slight edge to
| what would be thought of as the 'bad' tack where sail blows against
| the mast. At least, so I have been told.
I always felt like my balanced lug Windsprint went to windward better when
the sail lay against the mast.
Given the option of a straight sprit or a wishbone, I'd go with the sprit
boom almost every time. The only reason I can see for the wishbone is in
cases where chafe and sail wear is a concern, like on a bluewater boat.
JB in Kennesaw
> Does anyone out there have experience with the relative performanceThe precise answer to your question is no, I don't have any such
> of a wishbone boom and the straight sprit boom on the
> standard "instant boat" rig.
experience. But I have two observations.
1) In racing Sunfish and Sailfish, the performance upwind is
essentially equal on the two tacks, with perhaps a slight edge to
what would be thought of as the 'bad' tack where sail blows against
the mast. At least, so I have been told.
2) The disturbance of the wind by the wishbone boom being essentially
proud on the lee surface of the sail must be at least as great as
that due to the gore in the sail due to the straight boom. But
invisible.
Peter
Keith --
I've got a wishbone rig on my teal, and if aesthetics are your
concern, do the straight sprit. I did a wishbone because I got one
for free. Traditional straight sprit is much better looking.
134 West 26th St. 12th Floor
New York, New York 10001
http://www.crumblingempire.com
(212) 247-0296
I've got a wishbone rig on my teal, and if aesthetics are your
concern, do the straight sprit. I did a wishbone because I got one
for free. Traditional straight sprit is much better looking.
>Does anyone out there have experience with the relative performanceCRUMBLING EMPIRE PRODUCTIONS
>of a wishbone boom and the straight sprit boom on the
>standard "instant boat" rig (the 60 sq. ft. sail used on on the
>Cartopper, Gypsy, Rubens Nymph, Sweet Pea, Elegant Punt, June Bug,
>Surf, and Teal)? I'm sure there's a slight loss of performance on
>the "bad" tack due to the boom deforming the lower part of the sail,
>but can you notice the difference unless you're racing against an
>identical boat? I'm trying to decide if it's worth the trouble to
>laminate a wishbone, and if there's any good reason to do it other
>than aesthetics. Thanks for you help.
>
>Keith Wilson
>
>
>Bolger rules!!!
>- no cursing, flaming, trolling, or spamming
>- no flogging dead horses
>- add something: take "thanks!" and "ditto!" posts off-list.
>- stay on topic and punctuate
>- add your comments at the TOP and SIGN your posts
>- To order plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester,
>MA, 01930, Fax: (978) 282-1349
>
>
>Your use of Yahoo! Groups is subject tohttp://docs.yahoo.com/info/terms/
134 West 26th St. 12th Floor
New York, New York 10001
http://www.crumblingempire.com
(212) 247-0296
Does anyone out there have experience with the relative performance
of a wishbone boom and the straight sprit boom on the
standard "instant boat" rig (the 60 sq. ft. sail used on on the
Cartopper, Gypsy, Rubens Nymph, Sweet Pea, Elegant Punt, June Bug,
Surf, and Teal)? I'm sure there's a slight loss of performance on
the "bad" tack due to the boom deforming the lower part of the sail,
but can you notice the difference unless you're racing against an
identical boat? I'm trying to decide if it's worth the trouble to
laminate a wishbone, and if there's any good reason to do it other
than aesthetics. Thanks for you help.
Keith Wilson
of a wishbone boom and the straight sprit boom on the
standard "instant boat" rig (the 60 sq. ft. sail used on on the
Cartopper, Gypsy, Rubens Nymph, Sweet Pea, Elegant Punt, June Bug,
Surf, and Teal)? I'm sure there's a slight loss of performance on
the "bad" tack due to the boom deforming the lower part of the sail,
but can you notice the difference unless you're racing against an
identical boat? I'm trying to decide if it's worth the trouble to
laminate a wishbone, and if there's any good reason to do it other
than aesthetics. Thanks for you help.
Keith Wilson