Re: Query about QUERY
Well, actually a fish's tail is made to take advantage of unsteady
vortexes, if I understood a couple of papers I read on fin propulsion a
while back when I was interested in that. A rudder is more steady state
unless you're pumping the tiller to get home in a calm.I think a more
appropriate model might be a landing airplane's wing. That is, you'd
have 3 or 4 segments so that the cross section was an approximation of
an arc. However, in order to take advantage of this amount of lift
without creating huge amounts of (induced, but I would rather not get
into it) drag you'd want a skinny, deep rudder, which, when it stalled,
would stall suddenly and might make it pretty easy to get into irons and
pretty hard to get out. It would also hit things. It would also probably
be the most complicated thing in the boat, short of the engine or the
electronics. Making the transition between the segments smooth would be
pretty tough, and if not smooth you might be better off with a wider
rudder with an airfoil cross section, which might be lower drag and
nicer handling. Model sailboats have deep fins and rudders, though not
segmented, and they stall sharply sometimes. Anyway, I think maybe the
airfoil cross section might be the best compromise but it's still a lot
harder to do than a nice flat plate as we usually use. If I was trying
to make a boat go faster and I had already made sure the sails were good
I think I'd work on the centerboard and rudder cross sections. I
actually did some back of the envelope calculations on this, but they
were for model boats and I don't really remember them very well.
vortexes, if I understood a couple of papers I read on fin propulsion a
while back when I was interested in that. A rudder is more steady state
unless you're pumping the tiller to get home in a calm.I think a more
appropriate model might be a landing airplane's wing. That is, you'd
have 3 or 4 segments so that the cross section was an approximation of
an arc. However, in order to take advantage of this amount of lift
without creating huge amounts of (induced, but I would rather not get
into it) drag you'd want a skinny, deep rudder, which, when it stalled,
would stall suddenly and might make it pretty easy to get into irons and
pretty hard to get out. It would also hit things. It would also probably
be the most complicated thing in the boat, short of the engine or the
electronics. Making the transition between the segments smooth would be
pretty tough, and if not smooth you might be better off with a wider
rudder with an airfoil cross section, which might be lower drag and
nicer handling. Model sailboats have deep fins and rudders, though not
segmented, and they stall sharply sometimes. Anyway, I think maybe the
airfoil cross section might be the best compromise but it's still a lot
harder to do than a nice flat plate as we usually use. If I was trying
to make a boat go faster and I had already made sure the sails were good
I think I'd work on the centerboard and rudder cross sections. I
actually did some back of the envelope calculations on this, but they
were for model boats and I don't really remember them very well.
>someone wrote:
>
> What if the rudder could be arranged so that it was segmented and could assume a more streamlined configuration against the fluid---as in a fishes tail?
>
>
Thanks for the reply. Yes, simpler is better in our case. The higher aspect rudder is fine . I use one in my Featherwind and it is remarkably effective. It is also in an airfoil shape. Judicious use of the tiller is always best anyway. Hard over is not usually necessary.
----- Original Message -----
From: Lincoln Ross
To:bolger@yahoogroups.com
Sent: Thursday, May 15, 2003 6:30 PM
Subject: [bolger] Re: Query about QUERY
Well, actually a fish's tail is made to take advantage of unsteady
vortexes, if I understood a couple of papers I read on fin propulsion a
while back when I was interested in that. A rudder is more steady state
unless you're pumping the tiller to get home in a calm.I think a more
appropriate model might be a landing airplane's wing. That is, you'd
have 3 or 4 segments so that the cross section was an approximation of
an arc. However, in order to take advantage of this amount of lift
without creating huge amounts of (induced, but I would rather not get
into it) drag you'd want a skinny, deep rudder, which, when it stalled,
would stall suddenly and might make it pretty easy to get into irons and
pretty hard to get out. It would also hit things. It would also probably
be the most complicated thing in the boat, short of the engine or the
electronics. Making the transition between the segments smooth would be
pretty tough, and if not smooth you might be better off with a wider
rudder with an airfoil cross section, which might be lower drag and
nicer handling. Model sailboats have deep fins and rudders, though not
segmented, and they stall sharply sometimes. Anyway, I think maybe the
airfoil cross section might be the best compromise but it's still a lot
harder to do than a nice flat plate as we usually use. If I was trying
to make a boat go faster and I had already made sure the sails were good
I think I'd work on the centerboard and rudder cross sections. I
actually did some back of the envelope calculations on this, but they
were for model boats and I don't really remember them very well.
>someone wrote:
>
> What if the rudder could be arranged so that it was segmented and could assume a more streamlined configuration against the fluid---as in a fishes tail?
>
>
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No doubt that a judicious use of the tiller is appropriate ---and I do remember that the rudder is an important part of the lateral resistance --as Phil mentions several times in some of his wisdom.
----- Original Message -----
From: James R. Pope
To:bolger@yahoogroups.com
Sent: Wednesday, May 14, 2003 9:58 PM
Subject: Re: [bolger] Re: Query about QUERY
> i cant think of a more crude device than a "barn door" on the back of a
> cat. It's a wonder that they don't come to a stop when the helm is put over.
>
My first real boat was a Beetle Cat (12' wooden, gaff rigged catboat) which
I raced for several years. Later I owned a 26 ft gaff rigged cat.
Your observation is about right.
Hang that barn door over hard and, while she doesn't actually stop dead,
its no way to make it home on time. On the other hand, I've been told that
you should figure the submerged area of the big rudder on a catboat as a
part of her lateral plane and use it in the balance calculations. The large
rudder gives real authority at slower speeds than a smaller one.
Jim
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> i cant think of a more crude device than a "barn door" on the back of aMy first real boat was a Beetle Cat (12' wooden, gaff rigged catboat) which
> cat. It's a wonder that they don't come to a stop when the helm is put over.
>
I raced for several years. Later I owned a 26 ft gaff rigged cat.
Your observation is about right.
Hang that barn door over hard and, while she doesn't actually stop dead,
its no way to make it home on time. On the other hand, I've been told that
you should figure the submerged area of the big rudder on a catboat as a
part of her lateral plane and use it in the balance calculations. The large
rudder gives real authority at slower speeds than a smaller one.
Jim
>As far as I know, there have been no other designs with aWell, maybe he hit a sandbar.
>bow rudder.
>
>Anyone know what happened ???
--
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_________________________________
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> What if the rudder could be arranged so that it was segmented andcould assume a more streamlined configuration against the fluid---as
in a fishes tail?
Halsey Herreshoff built a boat with a rudder that had a moveable
leading edge as well as the usual moveable trailing edge.
Peter
We simply need a turning fin at both ends. Sure it would make things more complicated and certainly more open to breakdown. Remember Murphy. However, it has definate merit as an experiment. Who knows where it would lead? For now, maybe just one appendage which is an acknowledged certain compromise is the best thing afterall. A boat is not a thing which is improved by additional complication.
Want to give the big gift to boating? Devise the way that directional control can be maintained and leeway can be resisted WITHOUT any increased drag from immersed appendages.
Bolger is simply recognizing that some sort of resistance is enevitable and that reducing it to it's least contribution may be the best that we can hope for. More area dragging as friction because of the two boards may not be the best. Reducing the time that a rudder needs to be turned against the flow would help. What if the time to tack could be halved by the more efficient placement of the same rudder area?
What if the rudder could be arranged so that it was segmented and could assume a more streamlined configuration against the fluid---as in a fishes tail? i cant think of a more crude device than a "barn door" on the back of a cat. It's a wonder that they don't come to a stop when the helm is put over.
Want to give the big gift to boating? Devise the way that directional control can be maintained and leeway can be resisted WITHOUT any increased drag from immersed appendages.
Bolger is simply recognizing that some sort of resistance is enevitable and that reducing it to it's least contribution may be the best that we can hope for. More area dragging as friction because of the two boards may not be the best. Reducing the time that a rudder needs to be turned against the flow would help. What if the time to tack could be halved by the more efficient placement of the same rudder area?
What if the rudder could be arranged so that it was segmented and could assume a more streamlined configuration against the fluid---as in a fishes tail? i cant think of a more crude device than a "barn door" on the back of a cat. It's a wonder that they don't come to a stop when the helm is put over.
----- Original Message -----
From: pvanderwaart
To:bolger@yahoogroups.com
Sent: Wednesday, May 14, 2003 2:13 PM
Subject: [bolger] Re: Query about QUERY
My feeling was that Bolger made a fundemental error in putting the
fin at one end of the boat and the rudder at the other because it
made steering difficult. I know he wanted to keep the middle of the
boat free of the centerboard, but it doesn't follow in any way that I
know that if you put the rudder at the bow, you can put the fin at
the back. In one of the places that he wrote about it, Bolger
suggested that he came to the same conclusion.
There are more comments about bow rudders in the Chapter on Nancy
Jack in 30-Odd Boats.
Peter
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[Non-text portions of this message have been removed]
My feeling was that Bolger made a fundemental error in putting the
fin at one end of the boat and the rudder at the other because it
made steering difficult. I know he wanted to keep the middle of the
boat free of the centerboard, but it doesn't follow in any way that I
know that if you put the rudder at the bow, you can put the fin at
the back. In one of the places that he wrote about it, Bolger
suggested that he came to the same conclusion.
There are more comments about bow rudders in the Chapter on Nancy
Jack in 30-Odd Boats.
Peter
fin at one end of the boat and the rudder at the other because it
made steering difficult. I know he wanted to keep the middle of the
boat free of the centerboard, but it doesn't follow in any way that I
know that if you put the rudder at the bow, you can put the fin at
the back. In one of the places that he wrote about it, Bolger
suggested that he came to the same conclusion.
There are more comments about bow rudders in the Chapter on Nancy
Jack in 30-Odd Boats.
Peter
As of 1982, the euphoria had evaporated a bit.... the catamaran was
eventually built and reports of its inability to get through stays "dashed
[Mr Bolger's] hopes".
Bow steering was further pursued (BWAOM, Canard). At that point the feeling
still seemed to be that bow and stern fins would need to be steerable.
cheers
Derek
eventually built and reports of its inability to get through stays "dashed
[Mr Bolger's] hopes".
Bow steering was further pursued (BWAOM, Canard). At that point the feeling
still seemed to be that bow and stern fins would need to be steerable.
cheers
Derek
I think there was a good reason for there being "suddenly nothing."
A chapter in Bolger's 30 Odd Boats called Bow-Steering Update dealt
with experiments on a Dovekie, another unballasted boat. The results
were considerably less than euphoric--in fact downright dismal.
Attempts at tacking in varying wind conditions all had the same
result: the boat ground to a halt and sat in irons.
Jack
A chapter in Bolger's 30 Odd Boats called Bow-Steering Update dealt
with experiments on a Dovekie, another unballasted boat. The results
were considerably less than euphoric--in fact downright dismal.
Attempts at tacking in varying wind conditions all had the same
result: the boat ground to a halt and sat in irons.
Jack
Wasn't a recent Bolger article in MAIB called "bow steering update"?
I'm home nursing the computer today and all my MAIBs are at the
office.
Bruce Hector
I'm home nursing the computer today and all my MAIBs are at the
office.
Bruce Hector
The hull for Windsprint started out as the hull for QUERY, an
experimental monohull that was built as a test for the proposed bow
rudder on a catamaran project. In INSTANT BOATS, Payson wrote that
it worked, "after a fashion." I always assumed that I didn't really
work very well, but at long last I have a copy of DIFFERENT BOATS
(minus the pages for Sweet Chariot, neatly removed with a very sharp
knife -- I hope she was built).
Bolger's take on the experiment (as of 1980, at least) is quite a bit
different than Payson's. Bolger writes that she went "beautifully,"
that she tacked and jibed "perfectly" with no handling vices at all,
and that she outsailed and outmaneuvered Paysn's ZEPHYR. "Let go the
tiller, and she'd fall off gently 'til she was steering herself on a
broad reach. Heel her sharply and the lee helm dimished to neutral .
. . She luffed on demand with sharp control and never missed stays."
And of course, the forward view, unobstructed by mast and sail, was
pleasant.
Bolger also notes that she would heave to with the leach of her sail
full, that she would lose way in tacking (like any light, flat boat),
and that several people who tried the boat got her hove to on the new
tack and had trouble working out the tiller movements needed to get
her underway again. (Payson among them, perhaps?)
So how well did QUERY really work? Bolger says that during the days
they tested QUERY, he walked around with a "euphoric grin," and had
the thought that he'd condemned a lot of boats to obsolescence. He
went so far as to draw up a proposed study for a proposed EGRET-type
sharpie cruiser, with a cockpit and helm position forward and the rig
and cabin aft, like sailing BLACK SKIMMER backwards without the
mizzen.
And then, nothing. The proposed cat was scuttled because it looked
to be too expensive. The cruiser apparently never went further than
the study. As far as I know, there have been no other designs with a
bow rudder.
Anyone know what happened ???
experimental monohull that was built as a test for the proposed bow
rudder on a catamaran project. In INSTANT BOATS, Payson wrote that
it worked, "after a fashion." I always assumed that I didn't really
work very well, but at long last I have a copy of DIFFERENT BOATS
(minus the pages for Sweet Chariot, neatly removed with a very sharp
knife -- I hope she was built).
Bolger's take on the experiment (as of 1980, at least) is quite a bit
different than Payson's. Bolger writes that she went "beautifully,"
that she tacked and jibed "perfectly" with no handling vices at all,
and that she outsailed and outmaneuvered Paysn's ZEPHYR. "Let go the
tiller, and she'd fall off gently 'til she was steering herself on a
broad reach. Heel her sharply and the lee helm dimished to neutral .
. . She luffed on demand with sharp control and never missed stays."
And of course, the forward view, unobstructed by mast and sail, was
pleasant.
Bolger also notes that she would heave to with the leach of her sail
full, that she would lose way in tacking (like any light, flat boat),
and that several people who tried the boat got her hove to on the new
tack and had trouble working out the tiller movements needed to get
her underway again. (Payson among them, perhaps?)
So how well did QUERY really work? Bolger says that during the days
they tested QUERY, he walked around with a "euphoric grin," and had
the thought that he'd condemned a lot of boats to obsolescence. He
went so far as to draw up a proposed study for a proposed EGRET-type
sharpie cruiser, with a cockpit and helm position forward and the rig
and cabin aft, like sailing BLACK SKIMMER backwards without the
mizzen.
And then, nothing. The proposed cat was scuttled because it looked
to be too expensive. The cruiser apparently never went further than
the study. As far as I know, there have been no other designs with a
bow rudder.
Anyone know what happened ???