Re: [bolger] Safety of ballasted vs. unbalasted open boats
Chris,
I'm glad that you mentioned this:
the only one who didn't "get it", the one who didn't understand how the
weight of the crew would be distributed to contribute to self righting.
There is a big difference between the theory and what can be counted on
when you are cold, wet, tired and in a bad chop as it is getting on toward
dusk. But I would like to hear from the folks in Chebaccos (or other
non-ballasted boats) who have been surprised by bigger than expected gusts
of wind.
Regards, Warren
I'm glad that you mentioned this:
>Using passenger weight to make a boat self-righting, like Birdwatcher,For a long time I thought that maybe the answer was obvious... and I was
>doesn't seem to make sense to me.
>In a 90 degree knockdown, the passengers shift from the bottom to the hull
>sides--they don't velcro their butts to what is now a vertical surface.
>Their weight shifts to *hold the boat down*, not help it right.>
the only one who didn't "get it", the one who didn't understand how the
weight of the crew would be distributed to contribute to self righting.
There is a big difference between the theory and what can be counted on
when you are cold, wet, tired and in a bad chop as it is getting on toward
dusk. But I would like to hear from the folks in Chebaccos (or other
non-ballasted boats) who have been surprised by bigger than expected gusts
of wind.
Regards, Warren
On Wed, 2 Aug 2000, GHC wrote:
hardly to be considered self-righting.
> At 90 degrees (sail in the water), the crew usually sits on theYes. Alas, when one goes outside and hauls on the centerboard, it's
> centerboard...
hardly to be considered self-righting.
My son, a friend and I did some capsize testing on Michalak's Scram Pram.
Yes, In a capsize, the crew tends to aggregrate on the side of the hull. It
is possible to move back towords the bottom. This does shift the c/g of the
capsized hull. In the Scram Pram and I assume the B/W, the windowed portion
of the topsides does provide a lot of flotation. With the Scram Pram, any
water ballast was enuff to right the boat when this movement occurred. In
an actual capsize, my wife (chivalry is not dead, but I'm doing my part!!!)
was able to right the hull with only 10 lbs of pressure on the lee board -
no ballast in the tanks at all.
On Birdwatcher, Scram Pram, IMB, Jewel Box and similar, it helps to turn
the plans sideways and "guestimate" where the center of bouyancy(sp) is and
judge for yourself what additional righting moment is created by crew
movement. Sometimes in a 90 degree capsize, the crew must be settled down a
bit before they will move!
Tim - the one near Houston
At 10:49 AM 08/02/2000 -0500, you wrote:
Yes, In a capsize, the crew tends to aggregrate on the side of the hull. It
is possible to move back towords the bottom. This does shift the c/g of the
capsized hull. In the Scram Pram and I assume the B/W, the windowed portion
of the topsides does provide a lot of flotation. With the Scram Pram, any
water ballast was enuff to right the boat when this movement occurred. In
an actual capsize, my wife (chivalry is not dead, but I'm doing my part!!!)
was able to right the hull with only 10 lbs of pressure on the lee board -
no ballast in the tanks at all.
On Birdwatcher, Scram Pram, IMB, Jewel Box and similar, it helps to turn
the plans sideways and "guestimate" where the center of bouyancy(sp) is and
judge for yourself what additional righting moment is created by crew
movement. Sometimes in a 90 degree capsize, the crew must be settled down a
bit before they will move!
Tim - the one near Houston
At 10:49 AM 08/02/2000 -0500, you wrote:
>On Wed, 2 Aug 2000, Michael Surface wrote:
>> Self righting is possible in a non-ballasted boat. Bolger's
>> Birdwatcher design is a good example. With the Birdwatcher high
>> freeboard and low passenger weight is used to make the boat self
>> righting from a nearly 90 degree knockdown. Jim Michalak has several
>> designs that use the birdwatcher approach to provide self-righting
>> with little or no ballast.
>
>I guess this is the right place to mention my concerns about this.
>
>Using passenger weight to make a boat self-righting, like Birdwatcher,
>doesn't seem to make sense to me.
>
>In a 90 degree knockdown, the passengers shift from the bottom to the hull
>sides--they don't velcro their butts to what is now a vertical surface.
>Their weight shifts to *hold the boat down*, not help it right.
>
At 90 degrees (sail in the water), the crew usually sits on the centerboard...
GHC
At 10:52 AM 8/2/2000 -0500, you wrote:
GHC
At 10:52 AM 8/2/2000 -0500, you wrote:
>I've had the same thoughts. I imagine you have the crew lean up against the
>floor to right the boat.
>
>Richard Spelling,http://www.spellingbusiness.com/boats
>From the muddy waters of Oklahoma
>
>----- Original Message -----
>From: "Chris Crandall" <crandall@...>
>To: <bolger@egroups.com>
>Sent: Wednesday, August 02, 2000 10:49 AM
>Subject: Re: [bolger] Safety of ballasted vs. unbalasted open boats
>
>
>> On Wed, 2 Aug 2000, Michael Surface wrote:
>> > Self righting is possible in a non-ballasted boat. Bolger's
>> > Birdwatcher design is a good example. With the Birdwatcher high
>> > freeboard and low passenger weight is used to make the boat self
>> > righting from a nearly 90 degree knockdown. Jim Michalak has several
>> > designs that use the birdwatcher approach to provide self-righting
>> > with little or no ballast.
>>
>> I guess this is the right place to mention my concerns about this.
>>
>> Using passenger weight to make a boat self-righting, like Birdwatcher,
>> doesn't seem to make sense to me.
>>
>> In a 90 degree knockdown, the passengers shift from the bottom to the hull
>> sides--they don't velcro their butts to what is now a vertical surface.
>> Their weight shifts to *hold the boat down*, not help it right.
>>
>> I have always wondered what in he** Bolger meant by this.
>>
>>
>>
>>
>> Bolger rules!!!
>> - no cursing
>> - stay on topic
>> - use punctuation
>> - add your comments at the TOP and SIGN your posts
>> - add some content: send "thanks!" and "ditto!" posts off-list.
>>
>
>
>
>
>Bolger rules!!!
>- no cursing
>- stay on topic
>- use punctuation
>- add your comments at the TOP and SIGN your posts
>- add some content: send "thanks!" and "ditto!" posts off-list.
>
>
I've had the same thoughts. I imagine you have the crew lean up against the
floor to right the boat.
Richard Spelling,http://www.spellingbusiness.com/boats
From the muddy waters of Oklahoma
floor to right the boat.
Richard Spelling,http://www.spellingbusiness.com/boats
From the muddy waters of Oklahoma
----- Original Message -----
From: "Chris Crandall" <crandall@...>
To: <bolger@egroups.com>
Sent: Wednesday, August 02, 2000 10:49 AM
Subject: Re: [bolger] Safety of ballasted vs. unbalasted open boats
> On Wed, 2 Aug 2000, Michael Surface wrote:
> > Self righting is possible in a non-ballasted boat. Bolger's
> > Birdwatcher design is a good example. With the Birdwatcher high
> > freeboard and low passenger weight is used to make the boat self
> > righting from a nearly 90 degree knockdown. Jim Michalak has several
> > designs that use the birdwatcher approach to provide self-righting
> > with little or no ballast.
>
> I guess this is the right place to mention my concerns about this.
>
> Using passenger weight to make a boat self-righting, like Birdwatcher,
> doesn't seem to make sense to me.
>
> In a 90 degree knockdown, the passengers shift from the bottom to the hull
> sides--they don't velcro their butts to what is now a vertical surface.
> Their weight shifts to *hold the boat down*, not help it right.
>
> I have always wondered what in he** Bolger meant by this.
>
>
>
>
> Bolger rules!!!
> - no cursing
> - stay on topic
> - use punctuation
> - add your comments at the TOP and SIGN your posts
> - add some content: send "thanks!" and "ditto!" posts off-list.
>
On Wed, 2 Aug 2000, Michael Surface wrote:
Using passenger weight to make a boat self-righting, like Birdwatcher,
doesn't seem to make sense to me.
In a 90 degree knockdown, the passengers shift from the bottom to the hull
sides--they don't velcro their butts to what is now a vertical surface.
Their weight shifts to *hold the boat down*, not help it right.
I have always wondered what in he** Bolger meant by this.
> Self righting is possible in a non-ballasted boat. Bolger'sI guess this is the right place to mention my concerns about this.
> Birdwatcher design is a good example. With the Birdwatcher high
> freeboard and low passenger weight is used to make the boat self
> righting from a nearly 90 degree knockdown. Jim Michalak has several
> designs that use the birdwatcher approach to provide self-righting
> with little or no ballast.
Using passenger weight to make a boat self-righting, like Birdwatcher,
doesn't seem to make sense to me.
In a 90 degree knockdown, the passengers shift from the bottom to the hull
sides--they don't velcro their butts to what is now a vertical surface.
Their weight shifts to *hold the boat down*, not help it right.
I have always wondered what in he** Bolger meant by this.
Hi All
Self righting is possible in a non-ballasted boat. Bolger's Birdwatcher
design is a good example. With the Birdwatcher high freeboard and low
passenger weight is used to make the boat self righting from a nearly 90
degree knockdown. Jim Michalak has several designs that use the birdwatcher
approach to provide self-righting with little or no ballast.
Michael Surface Still building
Get Your Private, Free E-mail from MSN Hotmail athttp://www.hotmail.com
Self righting is possible in a non-ballasted boat. Bolger's Birdwatcher
design is a good example. With the Birdwatcher high freeboard and low
passenger weight is used to make the boat self righting from a nearly 90
degree knockdown. Jim Michalak has several designs that use the birdwatcher
approach to provide self-righting with little or no ballast.
Michael Surface Still building
>From:KF4call@...________________________________________________________________________
>Reply-To:bolger@egroups.com
>To:bolger@egroups.com
>Subject: Re: [bolger] Safety of ballasted vs. unballasted open boats
>Date: Tue, 1 Aug 2000 19:07:16 EDT
>
>To all,
> There is another safety related design characteristic that is not yet
>been mentioned here...it is the "self righting" capacity of the boat. When
>I
>was faced with the choice, I went with a weighted keel design. This was
>because the boat was also described as "self righting". (Bolger designed
>Oldshoe) Is it possible to get "self righting" capability that will work
>in
>most conditions in an unballasted boat? Here in Florida , USA, we must be
>prepared for sudden afternoon thunderstorms with winds that have
>substantial
>strength and unpredictable direction , but (in my sailing area) not
>especially large seas.
>Regards, Warren
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