Re: Champlain Speed
>1) Joy probably weighed a fraction of the (at a guess) two adults in
> Something obviously going on for a 7'9" Elegant Punt to
> win a race with a 15'6" Thomaston Galley, flow lines or not.
>
the Galley.
2) If the wind was light, the advantage of the extra length might not
count for much.
3) Perhaps she held the windward guage, or got a favorable puff.
4) Based on no sails in an EP (though I built one), and one sail in a
TG, I think the rig of the EP is better. The TG does not have a boom.
If there was tacking involved, the EP would be favored because the
sheet of a Payson TG has to be shifted to a thumb cleat on the new
leeward quarter: not a racing move.
Peter
> Yet Joy Payson in an EP is said to have outsailed her father in aSomething obviously going on for a 7'9" Elegant Punt to
> much more pretentious boat that he was demonstrating to a customer.
> My guess is the more pretentious boat was a Thomaston Galley, a boat
> designed to have good flow lines, but when level.
win a race with a 15'6" Thomaston Galley, flow lines or not.
Yet Joy Payson in an EP is said to have outsailed her father in a
much more pretentious boat that he was demonstrating to a customer.
My guess is the more pretentious boat was a Thomaston Galley, a boat
designed to have good flow lines, but when level.
much more pretentious boat that he was demonstrating to a customer.
My guess is the more pretentious boat was a Thomaston Galley, a boat
designed to have good flow lines, but when level.
--- Inbolger@yahoogroups.com, Bruce Hallman <bruce@h...> wrote:
>
> > Good compromise, or just good?
> >
> > "This shape and construction seem to me to make about as good a
boat
> > as anything it's practical to build out of wood; in fact, better
than
> > most of the more complex shapes." PCB from page 1, Chapter 1,
Folding
> > Schooner - on the Elegant Punt,
>
> Perhaps what he was thinking included the benefit of higher
> displacment capacity in a given length made possible with boxy
chines?
> The purpose of an Elegant Punt is more likely to be carrying
things
> short distances.
>
> For Kotick, a curvy hull, which I recall Bolger saying could not be
> improved, reducing flow resistance is a much higher design
criteria,
> because it is intended for longer distance cruising.
>
> Good compromise, or just good?Perhaps what he was thinking included the benefit of higher
>
> "This shape and construction seem to me to make about as good a boat
> as anything it's practical to build out of wood; in fact, better than
> most of the more complex shapes." PCB from page 1, Chapter 1, Folding
> Schooner - on the Elegant Punt,
displacment capacity in a given length made possible with boxy chines?
The purpose of an Elegant Punt is more likely to be carrying things
short distances.
For Kotick, a curvy hull, which I recall Bolger saying could not be
improved, reducing flow resistance is a much higher design criteria,
because it is intended for longer distance cruising.
Good compromise, or just good?
"This shape and construction seem to me to make about as good a boat
as anything it's practical to build out of wood; in fact, better than
most of the more complex shapes." PCB from page 1, Chapter 1, Folding
Schooner - on the Elegant Punt, and the 'simply wrap the sides around
a flared midships mold, sharpie style, to get yourself a good boat'
method.
Of course elsewhere in numerous places he says this type needs to be
sailed well heeled to cut through the chop (and get better flow).
Looking at him personally demonstrating how it's to be done in the
photo on page 114 of BWAOM while sailing 'Canard' I recall that
elsewhere he has said this also helps performance by substantially
reducing waterline beam. I guess for Canard the level approximate LWL
of 18'8" and LWB of 3'10" giving a L/B of around 4.8 shift when
heeled to a LWL of 17'10" and LWB of 2'4" yeilding a much greater L/B
at around 7.6. A ~158% increase. Good enough conventionally for the
main hull of a trimaran and just short of the minimum L/B required for
a catamaran.
Of course there always has to be some headscratching contrariness and
here is no exception, as PCB says sometimes that he believes that
sharpies should sail on their bottom. However, I think this is said
mostly in relation to those designs that more or less conform to his
flow theory, which may be plumb sided deriving sheer and rocker only
from the side profile and not from any flare.
Graeme
"This shape and construction seem to me to make about as good a boat
as anything it's practical to build out of wood; in fact, better than
most of the more complex shapes." PCB from page 1, Chapter 1, Folding
Schooner - on the Elegant Punt, and the 'simply wrap the sides around
a flared midships mold, sharpie style, to get yourself a good boat'
method.
Of course elsewhere in numerous places he says this type needs to be
sailed well heeled to cut through the chop (and get better flow).
Looking at him personally demonstrating how it's to be done in the
photo on page 114 of BWAOM while sailing 'Canard' I recall that
elsewhere he has said this also helps performance by substantially
reducing waterline beam. I guess for Canard the level approximate LWL
of 18'8" and LWB of 3'10" giving a L/B of around 4.8 shift when
heeled to a LWL of 17'10" and LWB of 2'4" yeilding a much greater L/B
at around 7.6. A ~158% increase. Good enough conventionally for the
main hull of a trimaran and just short of the minimum L/B required for
a catamaran.
Of course there always has to be some headscratching contrariness and
here is no exception, as PCB says sometimes that he believes that
sharpies should sail on their bottom. However, I think this is said
mostly in relation to those designs that more or less conform to his
flow theory, which may be plumb sided deriving sheer and rocker only
from the side profile and not from any flare.
Graeme
--- Inbolger@yahoogroups.com, Bruce Hallman <bruce@h...> wrote:
>
> Bolger power sharpies are shapes that are formed easily from sheets
of
> plywood (or steel) that have good flow characteristics.
>
> A long curvy hull, [versus a Bolger box], could have even better flow
> characteristics but would be harder to build from sheet materials
like
> plywood.
> All in all, many people agree that Bolger boxes are a pretty good
compromise.
>
> The Bolger power sharpies displace the waterThe weight = displacement, doesn't it? And the minimum length boat
> about the minimum amount for a boat of their length and weight,
would be 1/8 inch long and a mile wide and deep.
Or, are you thinking of minimum surface area? That would be half a
sphere, though tests show that such a form causes lots of turbulence
when moved through the water.
Bolger power sharpies are shapes that are formed easily from sheets of
plywood (or steel) that have good flow characteristics.
A long curvy hull, [versus a Bolger box], could have even better flow
characteristics but would be harder to build from sheet materials like
plywood.
A very long shape has lots of wetted surface causing drag. And, a
short shape has lots of turbulence which causes drag. I think, Bolger
tries to find the 'sweet spot' in between these two extremes [plus
some others].
All in all, many people agree that Bolger boxes are a pretty good compromise.
James,
I don't think it's a "bad" formula, but it is an "average" formula for
"average" (cruising) boats where the water line length / water line
beam is less that about 6 to 1. Somewhere around the 6 to 1 ratio and
above you get into the very murky world of semi-displacement or
semi-planing hulls and I have yet to find a good formula to predict
expected speed with X amount of horsepower. If your Banka has a water
line length of 20" 6", then you have a length/beam ratio of a whopping
13.6 to one! Dave Greer in "The Nature of Boats" talks about this
subject and has some good examples of "skinny" boats.
I also don't think a 200' submarine is limited to around 19.7 knots,
and there is no way it is a planing hull, but it sure is skinny!
JMHO,
Lewis
I don't think it's a "bad" formula, but it is an "average" formula for
"average" (cruising) boats where the water line length / water line
beam is less that about 6 to 1. Somewhere around the 6 to 1 ratio and
above you get into the very murky world of semi-displacement or
semi-planing hulls and I have yet to find a good formula to predict
expected speed with X amount of horsepower. If your Banka has a water
line length of 20" 6", then you have a length/beam ratio of a whopping
13.6 to one! Dave Greer in "The Nature of Boats" talks about this
subject and has some good examples of "skinny" boats.
I also don't think a 200' submarine is limited to around 19.7 knots,
and there is no way it is a planing hull, but it sure is skinny!
JMHO,
Lewis
--- Inbolger@yahoogroups.com, James Greene <jg6892@g...> wrote:
>
> >> My Philippine banka boat is the same length (22')
> >> and it goes at least twice this fast on an 8 hp Briggs and Stratton
> >> gas engine ... and if there's one thing I know for a fact,
> >> it's that my boat is not planing when it runs at this speed.
> >
> > James, I assume this is a dory-style main hull no?
> > Beam at WL and max. beam? Draft?
>
> No, it's nothing like a dory hull. The bottom is semi-circular
because it's cut from a log, then hollowed out to a thickness of 2-3
inches. The waterline width is about 18 inches and the maximum beam
is only 24 inches. Draft is about 8 inches when I'm the only one in
it, or as much as 18 inches or more when loaded heavily.
>
> I don't have any pictures of my boat online, but there are a couple
of pictures of Philippine bankas on this page. Mine is very much like
the small one painted dark red with yellow letters and 9 people aboard:
>
>http://www.sfacef.org/photo.htm
>
> Here's another page with a couple more banka photos:
>
>http://www.travelphoto.com/showphoto.php/photo/47
>
> It doesn't take much of an engine to drive one of these skinny boats
faster that the so-called "theoretical hull speed" which is why I
think that formula is a total waste of time. Let's face it, it's a
bad formula that doesn't work in the real world.
>
> James Greene
>
From another list, Bruce Hallman has mentioned using these on his
lapstrake construction.
HJ
-------------
I came across some disposable plastic cake decorating bags that work pretty
well to lay down a bead of epoxy with filler for edge gluing or filleting.
These allow you to quickly lay down a bead to a desired size by adjusting
how much of the tip you cut off. I haven't found it necessary to use a
tip--but if you want to make epoxy roses you may!
Thought these may be of some interest to the group. I am using the 18 inch
HYGO Bags, 100 bags on a roll for $26 plus shipping.
If you are interested check out www.sugarcraft.com.
lapstrake construction.
HJ
-------------
I came across some disposable plastic cake decorating bags that work pretty
well to lay down a bead of epoxy with filler for edge gluing or filleting.
These allow you to quickly lay down a bead to a desired size by adjusting
how much of the tip you cut off. I haven't found it necessary to use a
tip--but if you want to make epoxy roses you may!
Thought these may be of some interest to the group. I am using the 18 inch
HYGO Bags, 100 bags on a roll for $26 plus shipping.
If you are interested check out www.sugarcraft.com.
> Show me a hull that creates significant bow and stern wakes and goesAs I see it, the real issue is how far the water is displaced. In a
> significantly beyond hull speed (displacement, not planing or diving!)
> with reasonable power, and I will agree that the formula doesn't work.
very light boat, it is not displaced far, and can rush back in place
in time to support the stern. The Bolger power sharpies displace the
water about the minimum amount for a boat of their length and weight,
so they have high "hull speed" for their length.
Skinny hulls, like multihulls, benefit in the same way.
--- James Greene <jg6892@g...> wrote:
I think if one understands the background for that formula, then it
does make sense. This is how I understand it:
Total drag is mainly from surface friction and wave making.
Surface friction goes steadily up with increase of speed. More or less
just a function of wetted surface and speed. Apply more power and you
can increase speed.
Wave making depends on hull form and speed. That drag increases at
around "hull speed" (BTW, I think this "1.34" suggest a higher
precision than is in real world. "Somewhere between 1.3 and 1.4 is at
least same reasonable.). If the hull is formed in such a way that it
creates significant waves, then the increase at "hullspeed" will be
significant. If the hull creates little waves, then the total "wave
making drag" is low, and the increase at hull speed is low to not
noticeable.
Show me a hull that creates significant bow and stern wakes and goes
significantly beyond hull speed (displacement, not planing or diving!)
with reasonable power, and I will agree that the formula doesn't work ;)
Thanks for the info on your banka. Looks like your hull has more in
common with a racing rowboat than a cruiser ;)
Cheers,
Stefan
> It doesn't take much of an engine to drive one of these skinny boatsHi James,
> faster that the so-called "theoretical hull speed" which is why I
> think that formula is a total waste of time.
> Let's face it, it's a bad formula that doesn't work
> in the real world.
I think if one understands the background for that formula, then it
does make sense. This is how I understand it:
Total drag is mainly from surface friction and wave making.
Surface friction goes steadily up with increase of speed. More or less
just a function of wetted surface and speed. Apply more power and you
can increase speed.
Wave making depends on hull form and speed. That drag increases at
around "hull speed" (BTW, I think this "1.34" suggest a higher
precision than is in real world. "Somewhere between 1.3 and 1.4 is at
least same reasonable.). If the hull is formed in such a way that it
creates significant waves, then the increase at "hullspeed" will be
significant. If the hull creates little waves, then the total "wave
making drag" is low, and the increase at hull speed is low to not
noticeable.
Show me a hull that creates significant bow and stern wakes and goes
significantly beyond hull speed (displacement, not planing or diving!)
with reasonable power, and I will agree that the formula doesn't work ;)
Thanks for the info on your banka. Looks like your hull has more in
common with a racing rowboat than a cruiser ;)
Cheers,
Stefan
>> My Philippine banka boat is the same length (22')No, it's nothing like a dory hull. The bottom is semi-circular because it's cut from a log, then hollowed out to a thickness of 2-3 inches. The waterline width is about 18 inches and the maximum beam is only 24 inches. Draft is about 8 inches when I'm the only one in it, or as much as 18 inches or more when loaded heavily.
>> and it goes at least twice this fast on an 8 hp Briggs and Stratton
>> gas engine ... and if there's one thing I know for a fact,
>> it's that my boat is not planing when it runs at this speed.
>
> James, I assume this is a dory-style main hull no?
> Beam at WL and max. beam? Draft?
I don't have any pictures of my boat online, but there are a couple of pictures of Philippine bankas on this page. Mine is very much like the small one painted dark red with yellow letters and 9 people aboard:
http://www.sfacef.org/photo.htm
Here's another page with a couple more banka photos:
http://www.travelphoto.com/showphoto.php/photo/47
It doesn't take much of an engine to drive one of these skinny boats faster that the so-called "theoretical hull speed" which is why I think that formula is a total waste of time. Let's face it, it's a bad formula that doesn't work in the real world.
James Greene
--- "donschultz8275" <donschultz@i...> wrote:
I read that planing means
a) that at least half of the weight is supported by dynamic lift, not
by displacement.
b) that the water at the transom doesn't flow back, but the transom
is clear.
And then it is said, that the Sneakeasy basically planes while at
rest. Obviously not all can be true at the same time.
they are much bothered by the "normal" hullspeed" I should have been
more specific: "They operate in displacement mode, ..."
I don't doubt that the design is a planing design. But that doesn't
say that you need to plane when going beyond the theoretical
hullspeed. See the example of the Banka. OTOH, you can get many non-
planing hulls to plane, if you propel them with sufficient power...
So, the question still is: how to estimate drag of such hulls?
Stefan
> Stefan, you must have spent time at the "Bill Clinton" school ofTo be or not to be/is or not is, that's the question ...
> debate. ["It depends on the definition of "is""]
I read that planing means
a) that at least half of the weight is supported by dynamic lift, not
by displacement.
b) that the water at the transom doesn't flow back, but the transom
is clear.
And then it is said, that the Sneakeasy basically planes while at
rest. Obviously not all can be true at the same time.
> Look at the aft runWhen I wrote "They are displacement hulls, but I don't think that
> of Wyoming's chine, and read the original design essays by Bolger.
> Wyoming is a planing design.
they are much bothered by the "normal" hullspeed" I should have been
more specific: "They operate in displacement mode, ..."
I don't doubt that the design is a planing design. But that doesn't
say that you need to plane when going beyond the theoretical
hullspeed. See the example of the Banka. OTOH, you can get many non-
planing hulls to plane, if you propel them with sufficient power...
So, the question still is: how to estimate drag of such hulls?
Stefan
I agree, that Tenne' is planing. HOWEVER, that boat in that
circumstance, is very lightly loaded. At anything approaching a full
load, she will be a displacement hull. I find the aft rocker being
the characteristic that defines a planing, vs displacement sharpie.
Don
circumstance, is very lightly loaded. At anything approaching a full
load, she will be a displacement hull. I find the aft rocker being
the characteristic that defines a planing, vs displacement sharpie.
Don
--- Inbolger@yahoogroups.com, Harry James <welshman@p...> wrote:
>
> However Tennessee will plane
>
>http://www.boatdesign.com/jumps/dixtenn/tenn3.jpg
>
>http://www.boatdesign.com/jumps/dixtenn/tenn4.jpg
>
--- James Greene <jg6892@g...> wrote:
Beam at WL and max. beam? Draft?
Thanks!
Stefan
> My Philippine banka boat is the same length (22')James, I assume this is a dory-style main hull no?
> and it goes at least twice this fast on an 8 hp Briggs and Stratton
> gas engine ... and if there's one thing I know for a fact,
> it's that my boat is not planing when it runs at this speed.
Beam at WL and max. beam? Draft?
Thanks!
Stefan
--- "donschultz8275" <donschultz@i...> wrote:
Just that a boat lifts its stem out of the water doesn't make it
plane. If you move all the weight aft and start the outboard you
might get the stem clear of the water, since the outboard produces
some torque (its thrust times the distance of the propeller to the
transom mount), at very low speed, no?
reasonable ;) speed supported by dynamic forces, not by its
displacement?
If so: at what speed?
meaning of hullspeed. Would be interesting to know the drag vs. speed
diagram of such hulls.
Stefan
> Actually the Wyoming is a planing design.How do you define "planing"?
Just that a boat lifts its stem out of the water doesn't make it
plane. If you move all the weight aft and start the outboard you
might get the stem clear of the water, since the outboard produces
some torque (its thrust times the distance of the propeller to the
transom mount), at very low speed, no?
> Actually the Wyoming is a planing design.Do you mean, that at least half of its weight is at a certain,
reasonable ;) speed supported by dynamic forces, not by its
displacement?
If so: at what speed?
> The only "completed" version I'm aware of is an AussieHullspeed is an effect of the bow wake. No/little wake, no/little
> with a highly modified cabin structure and a pair of 9.9s.
> While it is propelled at displacement speeds,
> the original design called for BIG motor(s) and planing
> speeds.
meaning of hullspeed. Would be interesting to know the drag vs. speed
diagram of such hulls.
Stefan
Hi Bruce,
My Philippine banka boat is the same length (22') and it goes at least twice this fast on an 8 hp Briggs and Stratton gas engine ... and if there's one thing I know for a fact, it's that my boat is not planing when it runs at this speed. If the formula is nothing more than "1.34 X square root of the LWL" then it is very flawed indeed ...
James Greene
My Philippine banka boat is the same length (22') and it goes at least twice this fast on an 8 hp Briggs and Stratton gas engine ... and if there's one thing I know for a fact, it's that my boat is not planing when it runs at this speed. If the formula is nothing more than "1.34 X square root of the LWL" then it is very flawed indeed ...
James Greene
On Fri, 18 Nov 2005 07:36:58 -0800, Bruce Hallman wrote:
> On 11/17/05, captainbws <captainbws@...> wrote:
>> Hi ya'll! I'm not familiar enough with Bolger hulls to figure the
>> upper speed of Champlain should one need it. I realize it was not
>> meant to be a speed demon. Any help? Thanks!
>
> It is not limited to Bolger Hulls, but any hull that ploughs
> through the water and doesn't rise up and slide
> across the top has a theoretical maximum based on
> its length. Which is 6.29 knots (7.2 miles per hour) for a
> 22 foot hull like Champlain.
>
>
>
> Bolger rules!!!
> - 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
> Yahoo! Groups Links
>
>
>
>
>
>
--- Inbolger@yahoogroups.com, "Peter Lenihan" <peterlenihan@h...>
wrote:
I've been looking at Devlin Czarinnas and his faster power boats,
kinda hoping for something in between. Like to go fast sometimes.
Schedules, outrun weather, etc. I mostly go slow, but want
flexibility. I have a Nimble Nomad now, which is similar to Champlain
in many ways. Don't know that I could justify the change; although
Champlain has some flavors I prefer over my Nomad.....Happy boating,
Tim
wrote:
>sometime
> --- Inbolger@yahoogroups.com, "captainbws" <captainbws@h...> wrote:
> >
> > Hi ya'll! I'm not familiar enough with Bolger hulls to figure the
> > upper speed of Champlain should one need it. I realize it was not
> > meant to be a speed demon. Any help? Thanks!
>
>
> Now that you have the conventional formuli for displacement
> hulls,from Bruce,Peter et.al.,consider this;
> with Windermere(31' foot model like Champlain) Bolger calls for one
> 50hp 4 stroke big foot to drive her.She does not need this much
> power to attain her hull speed(7kts) but rather to a) operate at
> lower rpms for longer engine life. b)lots of reserve power in hand
> for dealing with strong river currents and c) superior"braking"
> power when put into reverse.The back-up/emergency power plant,btw,
> is a 9.9 4 stroke which he also states can be used whenever I want
> to just retard my return to civilization a bit longer or go poking
> along interesting shorelines.These are Bolgers reasons for the 50hp
> called for.However,he also states that mounting something like twin
> 50's off her stern will drive her into the high teens and into the
> realm of planing.
> Thus,alot will depend on whether you wish to use a Champlain as it
> was intended or to push an envelope somewhere.... along with the
> associated higher operating costs:-)
>
> Have you started building a Champlain? Pictures?
>
>
> Sincerely,
>
> Peter Lenihan, looking forward to some good "poking around"
> next summer..........!Interesting Peter, and thanks. Not building Champlain at this time.
>
I've been looking at Devlin Czarinnas and his faster power boats,
kinda hoping for something in between. Like to go fast sometimes.
Schedules, outrun weather, etc. I mostly go slow, but want
flexibility. I have a Nimble Nomad now, which is similar to Champlain
in many ways. Don't know that I could justify the change; although
Champlain has some flavors I prefer over my Nomad.....Happy boating,
Tim
However Tennessee will plane
http://www.boatdesign.com/jumps/dixtenn/tenn3.jpg
http://www.boatdesign.com/jumps/dixtenn/tenn4.jpg
HJ
donschultz8275 wrote:
http://www.boatdesign.com/jumps/dixtenn/tenn3.jpg
http://www.boatdesign.com/jumps/dixtenn/tenn4.jpg
HJ
donschultz8275 wrote:
>>Consider hulls like the Wyo and similar "no wake sharpies". They[Non-text portions of this message have been removed]
>>
>>
>are
>
>
>>displacement hulls, but I don't think that they are much bothered
>>
>>
>by
>
>
>>the "normal" hullspeed.
>>
>>
>>
>
>
>Actually the Wyoming is a planing design. The only "completed"
>version I'm aware of is an Aussie with a highly modified cabin
>structure and a pair of 9.9s. While it is propelled at displacement
>speeds, the original design called for BIG motor(s) and planing
>speeds.
>
>Whew!! Can you imagine a pile of CDX that big going 25+ mph?? How
>fast can one turn/stop a house?
>
>Other similar sharpies by Bolger include Sneakeasy, Idaho, and
>Minnesota.
>
>Displacement hull sharpies include Tennesee, Champlain, Dakota, and
>others I've forgotten. These feature "rocker" in the hull design.
>
>All the above have hard single chines, and I've purposely avoided
>the box keel and multichine boats, keeping it to the single chine
>versions.
>
>Don
>
>Don Schultz
>
>
>
>
>
>
>Bolger rules!!!
>- 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
>Yahoo! Groups Links
>
>
>
>
>
>
>
>
>
> Consider hulls like the Wyo and similar "no wake sharpies". Theyare
> displacement hulls, but I don't think that they are much botheredby
> the "normal" hullspeed.Actually the Wyoming is a planing design. The only "completed"
>
version I'm aware of is an Aussie with a highly modified cabin
structure and a pair of 9.9s. While it is propelled at displacement
speeds, the original design called for BIG motor(s) and planing
speeds.
Whew!! Can you imagine a pile of CDX that big going 25+ mph?? How
fast can one turn/stop a house?
Other similar sharpies by Bolger include Sneakeasy, Idaho, and
Minnesota.
Displacement hull sharpies include Tennesee, Champlain, Dakota, and
others I've forgotten. These feature "rocker" in the hull design.
All the above have hard single chines, and I've purposely avoided
the box keel and multichine boats, keeping it to the single chine
versions.
Don
Don Schultz
--- Inbolger@yahoogroups.com, "captainbws" <captainbws@h...> wrote:
hulls,from Bruce,Peter et.al.,consider this;
with Windermere(31' foot model like Champlain) Bolger calls for one
50hp 4 stroke big foot to drive her.She does not need this much
power to attain her hull speed(7kts) but rather to a) operate at
lower rpms for longer engine life. b)lots of reserve power in hand
for dealing with strong river currents and c) superior"braking"
power when put into reverse.The back-up/emergency power plant,btw,
is a 9.9 4 stroke which he also states can be used whenever I want
to just retard my return to civilization a bit longer or go poking
along interesting shorelines.These are Bolgers reasons for the 50hp
called for.However,he also states that mounting something like twin
50's off her stern will drive her into the high teens and into the
realm of planing.
Thus,alot will depend on whether you wish to use a Champlain as it
was intended or to push an envelope somewhere.... along with the
associated higher operating costs:-)
Have you started building a Champlain? Pictures?
Sincerely,
Peter Lenihan, looking forward to some good "poking around" sometime
next summer..........!
>Now that you have the conventional formuli for displacement
> Hi ya'll! I'm not familiar enough with Bolger hulls to figure the
> upper speed of Champlain should one need it. I realize it was not
> meant to be a speed demon. Any help? Thanks!
hulls,from Bruce,Peter et.al.,consider this;
with Windermere(31' foot model like Champlain) Bolger calls for one
50hp 4 stroke big foot to drive her.She does not need this much
power to attain her hull speed(7kts) but rather to a) operate at
lower rpms for longer engine life. b)lots of reserve power in hand
for dealing with strong river currents and c) superior"braking"
power when put into reverse.The back-up/emergency power plant,btw,
is a 9.9 4 stroke which he also states can be used whenever I want
to just retard my return to civilization a bit longer or go poking
along interesting shorelines.These are Bolgers reasons for the 50hp
called for.However,he also states that mounting something like twin
50's off her stern will drive her into the high teens and into the
realm of planing.
Thus,alot will depend on whether you wish to use a Champlain as it
was intended or to push an envelope somewhere.... along with the
associated higher operating costs:-)
Have you started building a Champlain? Pictures?
Sincerely,
Peter Lenihan, looking forward to some good "poking around" sometime
next summer..........!
I am not sure what you are referring to.
The Wyo is 51'6" (i.e. 9.6 knots theoretical hull speed). Approx.
10,000 lbs. Bolger writes that one Aussie built her heavier than
designed and drove her with two 9.9 hp outborders at "full
displacement speed". Two 9.9 hp engines might make a bit more than one
15 hp engine, no?
I think that's pretty amazing. Seems like most of the power is needed
for frictional resistance. Little wave making resistance. But what
formula could predict/estimate that?
Stefan
--- "John Bell" <smallboatdesigner@m...> wrote:
The Wyo is 51'6" (i.e. 9.6 knots theoretical hull speed). Approx.
10,000 lbs. Bolger writes that one Aussie built her heavier than
designed and drove her with two 9.9 hp outborders at "full
displacement speed". Two 9.9 hp engines might make a bit more than one
15 hp engine, no?
I think that's pretty amazing. Seems like most of the power is needed
for frictional resistance. Little wave making resistance. But what
formula could predict/estimate that?
Stefan
--- "John Bell" <smallboatdesigner@m...> wrote:
>
> As designed, she's only got a 9.9 horse on her transom.
> As heavy as she is, you aren't going very fast with such meager
> power. The difference between 6
> knots and 6.3 knots isn't worth worrying about. Relax. Enjoy a quiet
> conversation with your companion as the scenery slides easily by...
>
>
>
> ----- Original Message -----
> | I am not aware of drag/speed estimations/predictions for typical
> | Bolger box boats:
> | a) very high Prismatic Coefficient Cp
> | and/or
> | b) very low Draft/Beam ratio
> |
> | Consider hulls like the Wyo and similar "no wake sharpies".
> | They are displacement hulls, but I don't think that they are
> | much bothered by the "normal" hullspeed.
> |
> | Most drag/speed formulas that I saw are for fairly round hulls....
> |
> | Anybody has pointers for "box estimations"?
> |
> | TIA,
> | Stefan
As designed, she's only got a 9.9 horse on her transom. As heavy as she is,
you aren't going very fast with such meager power. The difference between 6
knots and 6.3 knots isn't worth worrying about. Relax. Enjoy a quiet
conversation with your companion as the scenery slides easily by...
you aren't going very fast with such meager power. The difference between 6
knots and 6.3 knots isn't worth worrying about. Relax. Enjoy a quiet
conversation with your companion as the scenery slides easily by...
----- Original Message -----
From: "Stefan Probst" <stefan.probst@opticom.v-nam.net>
To: <bolger@yahoogroups.com>
Sent: Friday, November 18, 2005 9:18 PM
Subject: [bolger] Re: Champlain Speed
| --- Inbolger@yahoogroups.com, "captainbws" <captainbws@h...> wrote:
| >
| > Hi ya'll! I'm not familiar enough with Bolger hulls to figure the
| > upper speed of Champlain should one need it. I realize it was not
| > meant to be a speed demon. Any help? Thanks!
|
| I second that question ;)
|
| I am not aware of drag/speed estimations/predictions for typical
| Bolger box boats:
| a) very high Prismatic Coefficient Cp
| and/or
| b) very low Draft/Beam ratio
|
| Consider hulls like the Wyo and similar "no wake sharpies". They are
| displacement hulls, but I don't think that they are much bothered by
| the "normal" hullspeed.
|
| Most drag/speed formulas that I saw are for fairly round hulls....
|
| Anybody has pointers for "box estimations"?
|
| TIA,
| Stefan
|
|
|
|
|
|
|
| Bolger rules!!!
| - 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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| - Open discussion:bolger_coffee_lounge-subscribe@yahoogroups.com
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|
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|
|
|
|
|
--- Inbolger@yahoogroups.com, "captainbws" <captainbws@h...> wrote:
I am not aware of drag/speed estimations/predictions for typical
Bolger box boats:
a) very high Prismatic Coefficient Cp
and/or
b) very low Draft/Beam ratio
Consider hulls like the Wyo and similar "no wake sharpies". They are
displacement hulls, but I don't think that they are much bothered by
the "normal" hullspeed.
Most drag/speed formulas that I saw are for fairly round hulls....
Anybody has pointers for "box estimations"?
TIA,
Stefan
>I second that question ;)
> Hi ya'll! I'm not familiar enough with Bolger hulls to figure the
> upper speed of Champlain should one need it. I realize it was not
> meant to be a speed demon. Any help? Thanks!
I am not aware of drag/speed estimations/predictions for typical
Bolger box boats:
a) very high Prismatic Coefficient Cp
and/or
b) very low Draft/Beam ratio
Consider hulls like the Wyo and similar "no wake sharpies". They are
displacement hulls, but I don't think that they are much bothered by
the "normal" hullspeed.
Most drag/speed formulas that I saw are for fairly round hulls....
Anybody has pointers for "box estimations"?
TIA,
Stefan
--- Inbolger@yahoogroups.com, "pvanderwaart" <pvanderwaart@y...>
wrote:
wrote:
>Thanks Peter and Bruce.......Grist for the mill
> > Champlain looks
> > like it has a ruduced form of forward hull similar to the fast
> > motorsailer.
>
> As noted, the weight prohibits planning, but the key part of the hull
> is the stern, not the bow (which would be out of the water in any
> planning or semi-planning condition). The curve as the lines rise to
> (and above) the lwl aft will keep here from planning. A fast boat has
> to have straight lines there. PCB's similar-sized Retriever and, as
> you noted, Fast Motorsailer, are examples.
>
> Peter
>
> Champlain looksAs noted, the weight prohibits planning, but the key part of the hull
> like it has a ruduced form of forward hull similar to the fast
> motorsailer.
is the stern, not the bow (which would be out of the water in any
planning or semi-planning condition). The curve as the lines rise to
(and above) the lwl aft will keep here from planning. A fast boat has
to have straight lines there. PCB's similar-sized Retriever and, as
you noted, Fast Motorsailer, are examples.
Peter
> Bolger physics.Oh, good point. One thing that isn't obvious when looking at
the drawings and photos of Champlain is that 500+ lbs of
ballast is necessary to get her to float down on her
waterline. Four 'industrial sized' 216AH lead acid batteries
are used for the ballast. Champlain is a low powered
displacement boat.
Four of these
http://www.apexbattery.com/8a4d-agm-12v-216ah-rv-battery.html
--- Inbolger@yahoogroups.com, Bruce Hallman <bruce@h...> wrote:
Bolger hulls, Champlain included aren't the usual. Champlain looks
like it has a ruduced form of forward hull similar to the fast
motorsailer. I thought maybe it is semi-planing. Kinda talking through
my hat here cause I don't understand Bolger physics.
>Thanks, I'm aware of the whole 1.34 X square root of the LWL, but some
> On 11/17/05, captainbws <captainbws@h...> wrote:
> > Hi ya'll! I'm not familiar enough with Bolger hulls to figure the
> > upper speed of Champlain should one need it. I realize it was not
> > meant to be a speed demon. Any help? Thanks!
>
> It is not limited to Bolger Hulls, but any hull that ploughs
> through the water and doesn't rise up and slide
> across the top has a theoretical maximum based on
> its length. Which is 6.29 knots (7.2 miles per hour) for a
> 22 foot hull like Champlain.
>
Bolger hulls, Champlain included aren't the usual. Champlain looks
like it has a ruduced form of forward hull similar to the fast
motorsailer. I thought maybe it is semi-planing. Kinda talking through
my hat here cause I don't understand Bolger physics.
On 11/17/05, captainbws <captainbws@...> wrote:
through the water and doesn't rise up and slide
across the top has a theoretical maximum based on
its length. Which is 6.29 knots (7.2 miles per hour) for a
22 foot hull like Champlain.
> Hi ya'll! I'm not familiar enough with Bolger hulls to figure theIt is not limited to Bolger Hulls, but any hull that ploughs
> upper speed of Champlain should one need it. I realize it was not
> meant to be a speed demon. Any help? Thanks!
through the water and doesn't rise up and slide
across the top has a theoretical maximum based on
its length. Which is 6.29 knots (7.2 miles per hour) for a
22 foot hull like Champlain.
Hi ya'll! I'm not familiar enough with Bolger hulls to figure the
upper speed of Champlain should one need it. I realize it was not
meant to be a speed demon. Any help? Thanks!
upper speed of Champlain should one need it. I realize it was not
meant to be a speed demon. Any help? Thanks!