Re: Aluminum centerboard in Cartopper?
--- Inbolger@yahoogroups.com, "John" <oneillparker@...> wrote:
> But I would not recommend it one way or the other for the simplePrecisely, the most distinguishing and sometimes copied Cartopper feature. If adopted, perhaps trim might be maintained by also increasing rudder weight - at cost of excessive pitching. Less wet, instead an under-floor water ballast tank perhaps?
> reason that Cartopper's board is placed fairly far forward. The
> weight would be in the bow.
--- Inbolger@yahoogroups.com, "figoni" <dc_3@...> wrote:
Comment two is just that Cartopper should rightly be pretty tender. It's a boat for alert live ballast, like a lot of other car-toppable sailboats. Put in a heavy centerboard and maybe it isn't a cartopper any more. Older I get (75th year now) less I seem to sail boats that require so much agility but it's no fault of the boats.
>It's interesting to note that Mike O'Brien, old Bolger friend and fan and the publisher of Boat Design Quarterly, has regularly been advocating wooden centerboards, weighted just enough to sink, as being much easier on their boats than heavy ones. I have rebuiltenough centerboard trunks and the adjacent planks and frames to see merit in this (many centerboard trunks not being well braced, nor keeping enough board up in the trunk when lowered.
> Has anyone experimented with a heavier centerboard in the Cartopper for the purpose of increasing stability in what some have called a slightly tender design?
>
Comment two is just that Cartopper should rightly be pretty tender. It's a boat for alert live ballast, like a lot of other car-toppable sailboats. Put in a heavy centerboard and maybe it isn't a cartopper any more. Older I get (75th year now) less I seem to sail boats that require so much agility but it's no fault of the boats.
--- Inbolger@yahoogroups.com, "figoni" <dc_3@...> wrote:
But I would not recommend it one way or the other for the simple reason that Cartopper's board is placed fairly far forward. The weight would be in the bow. One of the joys of Cartopper is how dry she is. She floats up and over virtually everything. Singlehanded, even upwind in a big breeze with a steep chop I only have very occasional sprinkles come aft. With two on the boat that changes, and whoever is sitting forward will take some spray, but only when it's really breezing on.
If you are used to a stiff boat Cartopper will not be fun. At first. Once you get used to having to shift your body weight, get quick on the sheet and come to appreciate the boat's personality, it won't be a problem. And btw, it's never a problem with two aboard, unless one is very small.
John O'Neill
>I experimented with water ballast under the midships platform in my Cartopper. Put it in collapsible plastic bottles. My imagination said it made a difference, but barely. A steel board especially probably would make a difference. It's as much a function of where the weight is placed in relation to the rest of the boat as the ratio of ballast to displacement. But, even with steel the difference would be slight.
> Has anyone experimented with a heavier centerboard in the Cartopper for the purpose of increasing stability in what some have called a slightly tender design?
>
But I would not recommend it one way or the other for the simple reason that Cartopper's board is placed fairly far forward. The weight would be in the bow. One of the joys of Cartopper is how dry she is. She floats up and over virtually everything. Singlehanded, even upwind in a big breeze with a steep chop I only have very occasional sprinkles come aft. With two on the boat that changes, and whoever is sitting forward will take some spray, but only when it's really breezing on.
If you are used to a stiff boat Cartopper will not be fun. At first. Once you get used to having to shift your body weight, get quick on the sheet and come to appreciate the boat's personality, it won't be a problem. And btw, it's never a problem with two aboard, unless one is very small.
John O'Neill
True, the density of aluminum is greater, but what difference will it make overall?
If you calculate the mass of the wood centerboard vs entire boat, then do the same with a hypothetical aluminum board, what is the difference between the two ratios? If the difference overall is fairly slight, as I suspect it would be, then little advantage is gained.
On the other hand, some folks find the cartopper tender and others do not, so maybe it is a little tender and folks who are adding extra weight through passengers or seating arrangement or heavier floorboards are overcoming that slight tenderness?
There is nothing like diving in and finding out. So many designs that are mathematically efficient are entirely crap on the water. I'd build one and try it and then either brag to us about how great your idea was or quietly dump the failure at the recycling center!
Sounds like a fun project/investigation.
John "Chris" Balch
Balch Boats
www.explorearth.org
If you calculate the mass of the wood centerboard vs entire boat, then do the same with a hypothetical aluminum board, what is the difference between the two ratios? If the difference overall is fairly slight, as I suspect it would be, then little advantage is gained.
On the other hand, some folks find the cartopper tender and others do not, so maybe it is a little tender and folks who are adding extra weight through passengers or seating arrangement or heavier floorboards are overcoming that slight tenderness?
There is nothing like diving in and finding out. So many designs that are mathematically efficient are entirely crap on the water. I'd build one and try it and then either brag to us about how great your idea was or quietly dump the failure at the recycling center!
Sounds like a fun project/investigation.
Balch Boats
www.explorearth.org
Travelin' Light
Tanzer 22 #668
Tanzer 22 #668
Torneremo #96
Chrysler Mutineer
Chrysler Mutineer
ALF II (A Little Fun)
Super Snark
From:sirdarnell <sirdarnell@...>
To:bolger@yahoogroups.com
Sent:Mon, February 21, 2011 11:16:24 AM
Subject:[bolger] Re: Aluminum centerboard in Cartopper?
Super Snark
From:sirdarnell <sirdarnell@...>
To:bolger@yahoogroups.com
Sent:Mon, February 21, 2011 11:16:24 AM
Subject:[bolger] Re: Aluminum centerboard in Cartopper?
A solid aluminum board the same size and shape would weight more. After all a wooden board will float and an aluminum one will not. This means the aluminum one weights more than water of the same size and shape.
David
--- Inbolger@yahoogroups.com, Dan Burrill <dan@...> wrote:
>
> Would an aluminium centreboard be significantly heavier than the plywood
> one in the original design?
>
> If you're going to go for a heavier option then galvanised steel would
> seem like the way to go, although you may need to strengthen the pivot
> and centreboard case, and the increased weight may be too much to
> car-top her as the designer intended. She may also float a bit deeper,
> though whether or not this would significantly change her
> characteristics I don't know.
>
> Dan Burrill
>
> On 20/02/2011 16:30, figoni wrote:
> >
> > Has anyone experimented with a heavier centerboard in the Cartopper
> > for the purpose of increasing stability in what some have called a
> > slightly tender design?
> >
> >
>
A solid aluminum board the same size and shape would weight more. After all a wooden board will float and an aluminum one will not. This means the aluminum one weights more than water of the same size and shape.
David
David
--- Inbolger@yahoogroups.com, Dan Burrill <dan@...> wrote:
>
> Would an aluminium centreboard be significantly heavier than the plywood
> one in the original design?
>
> If you're going to go for a heavier option then galvanised steel would
> seem like the way to go, although you may need to strengthen the pivot
> and centreboard case, and the increased weight may be too much to
> car-top her as the designer intended. She may also float a bit deeper,
> though whether or not this would significantly change her
> characteristics I don't know.
>
> Dan Burrill
>
> On 20/02/2011 16:30, figoni wrote:
> >
> > Has anyone experimented with a heavier centerboard in the Cartopper
> > for the purpose of increasing stability in what some have called a
> > slightly tender design?
> >
> >
>
When I made our cartopper we put some very heavy floorboards in it rather than the ply in the plans. The floorboards were made from 19mm Spotted Gum and weigh around 18kg. The idea was that the boards look nice, I had them on hand and the extra weight would make the boat more stable.
Well, I wouldn't say our Cartopper is tender, you can sit wherever you like without risk of capsizing. When sailing you don't need to hike out, just sit on the windward side. I think because you are sitting so low it adds to stability. We have often swapped skipper and crew positions while sailing, my son stands up and walks, I shuffle on my knees.
But I have decided that the weight of the floorboards is too much to lug around on the car or the trailer. I am in the process of making duplicates in Cedar and saving 9kg or more. I am confident that we will not be complaining of it being tender when we try it out. As it sails well at the moment I am not expecting a big increase in speed either.
Lastly, the centreboard is not that big and doesn't go down very deep - it would add very little stability if it was made of aluminium. Mine has lead shot and epoxy moulded in to help the board sink (as per the plans) but it isn't that heavy.
Andrew
http://sites.google.com/site/warrandytewoodenboat/Warrandyte-Wooden-Boats
Well, I wouldn't say our Cartopper is tender, you can sit wherever you like without risk of capsizing. When sailing you don't need to hike out, just sit on the windward side. I think because you are sitting so low it adds to stability. We have often swapped skipper and crew positions while sailing, my son stands up and walks, I shuffle on my knees.
But I have decided that the weight of the floorboards is too much to lug around on the car or the trailer. I am in the process of making duplicates in Cedar and saving 9kg or more. I am confident that we will not be complaining of it being tender when we try it out. As it sails well at the moment I am not expecting a big increase in speed either.
Lastly, the centreboard is not that big and doesn't go down very deep - it would add very little stability if it was made of aluminium. Mine has lead shot and epoxy moulded in to help the board sink (as per the plans) but it isn't that heavy.
Andrew
http://sites.google.com/site/warrandytewoodenboat/Warrandyte-Wooden-Boats
--- Inbolger@yahoogroups.com, "figoni" <dc_3@...> wrote:
>
> Has anyone experimented with a heavier centerboard in the Cartopper for the purpose of increasing stability in what some have called a slightly tender design?
>
On 02/20/2011 02:11 PM, figoni wrote:A heavier center board will offer almost no added stability. Most of that kind of boat gets it's stability from it's hull shape and the weight of it's crew. The boat may be a tiny bit more stable but I would think it would take a mighty fine instrument to measure it. Mostly, the increased weight will just make it harder to get the boat on the car. Heavy ballasted boats are usully built that way because the deep narrow hull is very unstable because of it's shape. Boats designed to be unballasted are stable because of their shape and ballast adds very little in stability. I Think! DougThanks Dan.
Yeah, I was wondering about steel too.
Maybe a better question would be: 'How many of you have found the Cartopper overly tender?'
If no one sees it here and responds, I'll start a new thread.
fig
--- Inbolger@yahoogroups.com, Dan Burrill<dan@...>wrote:
>
> Would an aluminium centreboard be significantly heavier than the plywood
> one in the original design?
>
> If you're going to go for a heavier option then galvanised steel would
> seem like the way to go, although you may need to strengthen the pivot
> and centreboard case, and the increased weight may be too much to
> car-top her as the designer intended. She may also float a bit deeper,
> though whether or not this would significantly change her
> characteristics I don't know.
>
> Dan Burrill
>
> On 20/02/2011 16:30, figoni wrote:
> >
> > Has anyone experimented with a heavier centerboard in the Cartopper
> > for the purpose of increasing stability in what some have called a
> > slightly tender design?
> >
> >
>
Thanks Dan.
Yeah, I was wondering about steel too.
Maybe a better question would be: 'How many of you have found the Cartopper overly tender?'
If no one sees it here and responds, I'll start a new thread.
fig
Yeah, I was wondering about steel too.
Maybe a better question would be: 'How many of you have found the Cartopper overly tender?'
If no one sees it here and responds, I'll start a new thread.
fig
--- Inbolger@yahoogroups.com, Dan Burrill <dan@...> wrote:
>
> Would an aluminium centreboard be significantly heavier than the plywood
> one in the original design?
>
> If you're going to go for a heavier option then galvanised steel would
> seem like the way to go, although you may need to strengthen the pivot
> and centreboard case, and the increased weight may be too much to
> car-top her as the designer intended. She may also float a bit deeper,
> though whether or not this would significantly change her
> characteristics I don't know.
>
> Dan Burrill
>
> On 20/02/2011 16:30, figoni wrote:
> >
> > Has anyone experimented with a heavier centerboard in the Cartopper
> > for the purpose of increasing stability in what some have called a
> > slightly tender design?
> >
> >
>
Would an aluminium centreboard be significantly heavier than the
plywood one in the original design?
If you're going to go for a heavier option then galvanised steel would seem like the way to go, although you may need to strengthen the pivot and centreboard case, and the increased weight may be too much to car-top her as the designer intended. She may also float a bit deeper, though whether or not this would significantly change her characteristics I don't know.
Dan Burrill
If you're going to go for a heavier option then galvanised steel would seem like the way to go, although you may need to strengthen the pivot and centreboard case, and the increased weight may be too much to car-top her as the designer intended. She may also float a bit deeper, though whether or not this would significantly change her characteristics I don't know.
Dan Burrill
On 20/02/2011 16:30, figoni wrote:Has anyone experimented with a heavier centerboard in the Cartopper for the purpose of increasing stability in what some have called a slightly tender design?
Has anyone experimented with a heavier centerboard in the Cartopper for the purpose of increasing stability in what some have called a slightly tender design?