Re: keel
Hi Grant, Frankly I think this project is a disaster waiting to happen
and I don't mean it figuratively.
Put the ballast keel back on if you can. You don't need the
centerboard since you don't have a mast and sails. The ballast keel
would not badly impact performance since you are only looking for hull
speed. As has already been suggested you need the ballast to float the
hull on its lines.
If you can't put the ballast keel back on then junk the whole project
and build a motor boat.
Bob Chamberland
and I don't mean it figuratively.
Put the ballast keel back on if you can. You don't need the
centerboard since you don't have a mast and sails. The ballast keel
would not badly impact performance since you are only looking for hull
speed. As has already been suggested you need the ballast to float the
hull on its lines.
If you can't put the ballast keel back on then junk the whole project
and build a motor boat.
Bob Chamberland
Hi Nels,
To answer your questions:
on 1/12/04 11:19 AM, Nels atarvent@...wrote:
If you sliced the boat in half what would the cross-
section look like
At the beamiest cross section the bottom of the hull is quite flat with soft
chines of course.
I would think an oak keel runner on the outside, through bolted to an inner
keelson ( not sure of the right terms here) might be the strongest.
I like your idea. It would give the hull some protection in a grounding and
help it to track better. Great advice
Best, Grant
To answer your questions:
on 1/12/04 11:19 AM, Nels atarvent@...wrote:
If you sliced the boat in half what would the cross-
section look like
At the beamiest cross section the bottom of the hull is quite flat with soft
chines of course.
I would think an oak keel runner on the outside, through bolted to an inner
keelson ( not sure of the right terms here) might be the strongest.
I like your idea. It would give the hull some protection in a grounding and
help it to track better. Great advice
Best, Grant
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--- Inbolger@yahoogroups.com, "Richard Spelling" <richard@c...>
wrote:
Richard,
That is indeed perhaps the most important function of ballast
on a sailboat,however it is also needed to bring the hull down to its
designed lines from which all other calculations derive,including
stability.
My thinking of this comes mainly from trying to imagine a
Micro,relieved of its' 420+ lbs of ballast and rig.Because of its
square cross section,it will exhibit great form stability at rest but
will become rather flighty,relative to its ballasted state,if it
motors along in choppy conditions and will lose its self-righting
capability.
We have yet to see a photo of the boat in question but,being a
production boat in GRP,I suspect it will have wine-glass type
sections and thus want to float up rather high on its lines,if
relieved of its' ballast, thereby reducing its' effective water plane
area and static stability.
Hopefully,we'll all have more info soon to chew over and offer
up loads of free advice :-) Of course,had he bought/built a Chebacco
or Micro,in the first place, he wouldn't be in this quandry..... :-D
Sincerely,
Peter Lenihan,whose sum knowledge of keels could be written onto the
proverbial head of a pin.......and in my case,with lots of room left
over for the abridged version of War and Peace too!
wrote:
> The ballast on a sailboat is to counteract the heeling forces fromthe sails. No such thing on power boats.
Richard,
That is indeed perhaps the most important function of ballast
on a sailboat,however it is also needed to bring the hull down to its
designed lines from which all other calculations derive,including
stability.
My thinking of this comes mainly from trying to imagine a
Micro,relieved of its' 420+ lbs of ballast and rig.Because of its
square cross section,it will exhibit great form stability at rest but
will become rather flighty,relative to its ballasted state,if it
motors along in choppy conditions and will lose its self-righting
capability.
We have yet to see a photo of the boat in question but,being a
production boat in GRP,I suspect it will have wine-glass type
sections and thus want to float up rather high on its lines,if
relieved of its' ballast, thereby reducing its' effective water plane
area and static stability.
Hopefully,we'll all have more info soon to chew over and offer
up loads of free advice :-) Of course,had he bought/built a Chebacco
or Micro,in the first place, he wouldn't be in this quandry..... :-D
Sincerely,
Peter Lenihan,whose sum knowledge of keels could be written onto the
proverbial head of a pin.......and in my case,with lots of room left
over for the abridged version of War and Peace too!
--- Inbolger@yahoogroups.com, grant corson <corson@a...> wrote:
times as being about the best for the ordinary person. Do a search on
the title and/or check it out at your library.
It is hard to visualize what might be required without seeing the
actual hull. If you sliced the boat in half what would the cross-
section look like? The flatter the bottom the less likely it will
require much ballest, but if it is for example 'wine glass' in shape
or even round, it may require more ballest. Otherwise it may sit too
high in the water and not be all that stable when in a beam sea.
Also if there is a strong shear then having floatation in the bow and
stern is really a good idea, so that just in case it flipped it would
roll back up and float high enough to drain or pump out.
Peter Lenihan is pretty knowledgeable with installing keels. I would
think an oak keel runner on the outside, through bolted to an inner
keelson ( not sure of the right terms here) might be the strongest.
It would clamp the entire keel line into one solid beam. All would
have to be properly bedded and sealed of course.
Cheers, Nels
> Hi Nels, the book is a great idea, hopefully it is simple enoughfor me to
> understand. Interesting that you should mention floatation, theboat in
> it's former life had none at all.I don't have the book myself, but have heard it referred to many
times as being about the best for the ordinary person. Do a search on
the title and/or check it out at your library.
It is hard to visualize what might be required without seeing the
actual hull. If you sliced the boat in half what would the cross-
section look like? The flatter the bottom the less likely it will
require much ballest, but if it is for example 'wine glass' in shape
or even round, it may require more ballest. Otherwise it may sit too
high in the water and not be all that stable when in a beam sea.
Also if there is a strong shear then having floatation in the bow and
stern is really a good idea, so that just in case it flipped it would
roll back up and float high enough to drain or pump out.
Peter Lenihan is pretty knowledgeable with installing keels. I would
think an oak keel runner on the outside, through bolted to an inner
keelson ( not sure of the right terms here) might be the strongest.
It would clamp the entire keel line into one solid beam. All would
have to be properly bedded and sealed of course.
Cheers, Nels
on 1/12/04 10:49 AM, Richard Spelling atrichard@...wrote:
the one hand I have been told that I must reinstall the keel or the boat
would capsize and at the other extreme, no keel, no ballast required. I
suppose the right answer is somewhere in between. To help the boat track a
keel is a necessity, but I don't believe I need one as deep as the original
for the reasons you stated. Ballast would bring the boat down in the water
to it's original water line, but if it is mostly internal ballast it would
make the boat more of a shoal draft cruiser. I would like to fit a wooden
keel to the hull to aid in tracking and to protect the hull if it should run
aground.
I will be using the boat in Lake Champlain.
I just ordered a used copy of Dave Gerr's The Nature of Baots and hopefully
I will find some answers there.
> Why are you sure you need ballast of some kind?A good question Richard, I have had advice on both ends of the question. On
>
> The ballast on a sailboat is to counteract the heeling forces from the sails.
> No such thing on power boats.
>
> You may need ballast, it depends on the hull shape and the center of gravity,
> where you put the motor, etc. However, just because it
> had ballast in sailboat mode, doesn't mean it must have it in power boat mode.
>
> Depends on where you are going to use it, as well.
the one hand I have been told that I must reinstall the keel or the boat
would capsize and at the other extreme, no keel, no ballast required. I
suppose the right answer is somewhere in between. To help the boat track a
keel is a necessity, but I don't believe I need one as deep as the original
for the reasons you stated. Ballast would bring the boat down in the water
to it's original water line, but if it is mostly internal ballast it would
make the boat more of a shoal draft cruiser. I would like to fit a wooden
keel to the hull to aid in tracking and to protect the hull if it should run
aground.
I will be using the boat in Lake Champlain.
I just ordered a used copy of Dave Gerr's The Nature of Baots and hopefully
I will find some answers there.
>
> ----- Original Message -----
> From: "grant corson" <corson@...>
> To: <bolger@yahoogroups.com>
> Sent: Sunday, January 11, 2004 3:25 PM
> Subject: [bolger] keel
>
>
>> I have purchased an abandoned 22' x 8' sail boat and am in the process of
>> converting it into a replica of a 1929 weekend power cruiser (no mast or
>> sails). What I have now is really only a hull, I have removed the keel
>> because I want the boat to be beachable but I am sure that I will need
>> ballast of some sort. I want to put the ballast inside the hull and glass
>> over the slot where the centerboard fit down through the split keel. Any
>> ideas or suggestions?
>> Grant Corson
>>
>>
>> Bolger rules!!!
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>> - 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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>
>
> Bolger rules!!!
> - no cursing, flaming, trolling, spamming, 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
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Why are you sure you need ballast of some kind?
The ballast on a sailboat is to counteract the heeling forces from the sails. No such thing on power boats.
You may need ballast, it depends on the hull shape and the center of gravity, where you put the motor, etc. However, just because it
had ballast in sailboat mode, doesn't mean it must have it in power boat mode.
Depends on where you are going to use it, as well.
The ballast on a sailboat is to counteract the heeling forces from the sails. No such thing on power boats.
You may need ballast, it depends on the hull shape and the center of gravity, where you put the motor, etc. However, just because it
had ballast in sailboat mode, doesn't mean it must have it in power boat mode.
Depends on where you are going to use it, as well.
----- Original Message -----
From: "grant corson" <corson@...>
To: <bolger@yahoogroups.com>
Sent: Sunday, January 11, 2004 3:25 PM
Subject: [bolger] keel
> I have purchased an abandoned 22' x 8' sail boat and am in the process of
> converting it into a replica of a 1929 weekend power cruiser (no mast or
> sails). What I have now is really only a hull, I have removed the keel
> because I want the boat to be beachable but I am sure that I will need
> ballast of some sort. I want to put the ballast inside the hull and glass
> over the slot where the centerboard fit down through the split keel. Any
> ideas or suggestions?
> Grant Corson
>
>
> Bolger rules!!!
> - no cursing, flaming, trolling, spamming, 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
>
> To visit your group on the web, go to:
>http://groups.yahoo.com/group/bolger/
>
> To unsubscribe from this group, send an email to:
>bolger-unsubscribe@yahoogroups.com
>
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>http://docs.yahoo.com/info/terms/
>
>
>
Hi Nels, the book is a great idea, hopefully it is simple enough for me to
understand. Interesting that you should mention floatation, the boat in
it's former life had none at all. I do plan to put the boat in and out at
the beginning and end of the season using the trailer to move and launch the
boat, another reason for removing the keel (now 18 inches high) and lowering
the boat on the trailer. I still don't know how heavy the keel is, I could
not begin to move it and had to use a come-along to drag it out from under
the boat and even that took quite a bit of effort.
Thanks again, Grant
understand. Interesting that you should mention floatation, the boat in
it's former life had none at all. I do plan to put the boat in and out at
the beginning and end of the season using the trailer to move and launch the
boat, another reason for removing the keel (now 18 inches high) and lowering
the boat on the trailer. I still don't know how heavy the keel is, I could
not begin to move it and had to use a come-along to drag it out from under
the boat and even that took quite a bit of effort.
Thanks again, Grant
>
> Bolger rules!!!
> - no cursing, flaming, trolling, spamming, 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
>
> To visit your group on the web, go to:
>http://groups.yahoo.com/group/bolger/
>
> To unsubscribe from this group, send an email to:
>bolger-unsubscribe@yahoogroups.com
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> Your use of Yahoo! Groups is subject to:
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>
>
--- Inbolger@yahoogroups.com, grant corson <corson@a...> wrote:
book that Derek Waters suggested. Probably it will be pretty
seaworthy by the sounds of it, but you will have to look at enough
floatation I would guess and that information should be there. You
might want the floatation up high under those side decks I would
guess.
Perhaps somebody else might be able to suggest the best way to close
the slot in the bottom. Do you plan to trailer it or take it
offshore at all? Those two options might have to be considered when
adding ballest. Invite a bunch of friends when you go out the first
time and stay close to shore to see how she sits in the water. May
take quite a load to get her down to near her designed lines. Did you
find out how heavy the keel was?
Cheers, Nels
> Hi Nels, the boat in question is a 1980? Universal Sailing Yacht(never
> heard of it before). The hull is a bit unusual in that it isbeamier than
> most 22 footers, 8'.Sounds pretty interesting. Perhaps the best idea would be to get the
book that Derek Waters suggested. Probably it will be pretty
seaworthy by the sounds of it, but you will have to look at enough
floatation I would guess and that information should be there. You
might want the floatation up high under those side decks I would
guess.
Perhaps somebody else might be able to suggest the best way to close
the slot in the bottom. Do you plan to trailer it or take it
offshore at all? Those two options might have to be considered when
adding ballest. Invite a bunch of friends when you go out the first
time and stay close to shore to see how she sits in the water. May
take quite a load to get her down to near her designed lines. Did you
find out how heavy the keel was?
Cheers, Nels
Hi Nels, the boat in question is a 1980? Universal Sailing Yacht (never
heard of it before). The hull is a bit unusual in that it is beamier than
most 22 footers, 8'. The original keel was a split lead keel with a swing
keel that could be cranked up into a centerboard well. The hull itself is
GRP. I have removed everything above decks except for the fordeck and a 6"
sidedeck. The plan is to build a cabin with full headroom which would make
the new cabin about 8" higher than the original and an open cockpit with a
steel framed canvas canopy over it. The finished design would be a replica
(nearly) of a 1929 power cruiser. I don't expect or look for anything more
than hull speed and plan to power the boat with a 9.9 high thrust OB in a
well. The helm would be on the aft side of the cabin bulkhead. I don't
have any pictures that would be much help right now. I do plan to replace
the original keel with one that would give me a shallower draft than the
original but need to make up the loss of weight. Of course I will no longer
be ofsetting the effect of a mast and sail.
Thanks for you and others input. I would gladly consult a naval architect
but don't know where to find one around these parts.
Grant
on 1/11/04 7:07 PM, Nels atarvent@...wrote:
heard of it before). The hull is a bit unusual in that it is beamier than
most 22 footers, 8'. The original keel was a split lead keel with a swing
keel that could be cranked up into a centerboard well. The hull itself is
GRP. I have removed everything above decks except for the fordeck and a 6"
sidedeck. The plan is to build a cabin with full headroom which would make
the new cabin about 8" higher than the original and an open cockpit with a
steel framed canvas canopy over it. The finished design would be a replica
(nearly) of a 1929 power cruiser. I don't expect or look for anything more
than hull speed and plan to power the boat with a 9.9 high thrust OB in a
well. The helm would be on the aft side of the cabin bulkhead. I don't
have any pictures that would be much help right now. I do plan to replace
the original keel with one that would give me a shallower draft than the
original but need to make up the loss of weight. Of course I will no longer
be ofsetting the effect of a mast and sail.
Thanks for you and others input. I would gladly consult a naval architect
but don't know where to find one around these parts.
Grant
on 1/11/04 7:07 PM, Nels atarvent@...wrote:
> --- Inbolger@yahoogroups.com, grant corson <corson@a...> wrote:
>> I have purchased an abandoned 22' x 8' sail boat and am in the
> process of
>> converting it into a replica of a 1929 weekend power cruiser (no
> mast or
>> sails). What I have now is really only a hull, I have removed the
> keel
>> because I want the boat to be beachable but I am sure that I will
> need
>> ballast of some sort. I want to put the ballast inside the hull
> and glass
>> over the slot where the centerboard fit down through the split
> keel. Any
>> ideas or suggestions?
>> Grant Corson
>
> Hi Grant,
>
> Could you give us some more details and perhaps post a few photos? Is
> it a wooden hull? (Obviously if it was built in 1929 it is - but you
> say it is a replica?) How much does it weigh? What was the weight of
> the original keel and what was the original displacement? Where do
> you intend to use, how do you intent to move it once you are finished
> and what is the intended use? What is your background experience in
> restoring old boats? Did you get a survey?
>
> The reason I am asking it that some of these projects can become a
> real burden - both on your time, pocket book and patience - and if
> and when you do get it completed - you may have something that isn't
> really all that effective. Sailboat hulls do not necessarily make
> good motor vessels and vice versa.
>
> In other words do you have a plan and do you know what it is going to
> cost and how long it will take?
>
> In my opinion, building a completely new boat is often easier than
> restoring an old one.
>
> Nels
>
>
> Bolger rules!!!
> - no cursing, flaming, trolling, spamming, 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
>
> To visit your group on the web, go to:
>http://groups.yahoo.com/group/bolger/
>
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>
>
Hi Grant
You may have to chew pretty hard to deal with what you've bitten off. A
casual approach could drown people.
Along with the good advice already given by others I'd offer the following
2c worth. Get hold of a copy of Dave Gerr's "The Nature of Boats" and look
at the chapters dealing with 'theory', where he covers the basics of
stability, ballast and trim.
Good Luck
Derek
You may have to chew pretty hard to deal with what you've bitten off. A
casual approach could drown people.
Along with the good advice already given by others I'd offer the following
2c worth. Get hold of a copy of Dave Gerr's "The Nature of Boats" and look
at the chapters dealing with 'theory', where he covers the basics of
stability, ballast and trim.
Good Luck
Derek
--- grant corson wrote:
around until you find some boat
designers.
One thing I recall reading,
is that a classic problem with
inside ballast, is that when the
day comes that you ground out
in the boat [and it is only a matter
of time until that happens], the
interior ballast has much greater
destructive impact on the planking
and framing than exterior ballast
would.
Presumably the planking and
framing of your boat was designed
to withstand the forces from exterior
ballast, and not made stronger to
handle the greater forces imposed
by interior ballast.
> in the process ofYou probably should keep asking
> converting it ... I
> have removed the keel
> I want to put the ballast
> inside the hull
around until you find some boat
designers.
One thing I recall reading,
is that a classic problem with
inside ballast, is that when the
day comes that you ground out
in the boat [and it is only a matter
of time until that happens], the
interior ballast has much greater
destructive impact on the planking
and framing than exterior ballast
would.
Presumably the planking and
framing of your boat was designed
to withstand the forces from exterior
ballast, and not made stronger to
handle the greater forces imposed
by interior ballast.
--- Inbolger@yahoogroups.com, grant corson <corson@a...> wrote:
Could you give us some more details and perhaps post a few photos? Is
it a wooden hull? (Obviously if it was built in 1929 it is - but you
say it is a replica?) How much does it weigh? What was the weight of
the original keel and what was the original displacement? Where do
you intend to use, how do you intent to move it once you are finished
and what is the intended use? What is your background experience in
restoring old boats? Did you get a survey?
The reason I am asking it that some of these projects can become a
real burden - both on your time, pocket book and patience - and if
and when you do get it completed - you may have something that isn't
really all that effective. Sailboat hulls do not necessarily make
good motor vessels and vice versa.
In other words do you have a plan and do you know what it is going to
cost and how long it will take?
In my opinion, building a completely new boat is often easier than
restoring an old one.
Nels
> I have purchased an abandoned 22' x 8' sail boat and am in theprocess of
> converting it into a replica of a 1929 weekend power cruiser (nomast or
> sails). What I have now is really only a hull, I have removed thekeel
> because I want the boat to be beachable but I am sure that I willneed
> ballast of some sort. I want to put the ballast inside the hulland glass
> over the slot where the centerboard fit down through the splitkeel. Any
> ideas or suggestions?Hi Grant,
> Grant Corson
Could you give us some more details and perhaps post a few photos? Is
it a wooden hull? (Obviously if it was built in 1929 it is - but you
say it is a replica?) How much does it weigh? What was the weight of
the original keel and what was the original displacement? Where do
you intend to use, how do you intent to move it once you are finished
and what is the intended use? What is your background experience in
restoring old boats? Did you get a survey?
The reason I am asking it that some of these projects can become a
real burden - both on your time, pocket book and patience - and if
and when you do get it completed - you may have something that isn't
really all that effective. Sailboat hulls do not necessarily make
good motor vessels and vice versa.
In other words do you have a plan and do you know what it is going to
cost and how long it will take?
In my opinion, building a completely new boat is often easier than
restoring an old one.
Nels
--- Inbolger@yahoogroups.com, grant corson <corson@a...> wrote:
I'm no designer and haven't a clue exactly which design you have
purchased but,it would seem to me that,if the ballast weight was
replaced by an inboard engine,fuel tanks,and other interior structure
( read: weight equal to that of ballast keel) and you did not over-do
it with a new higher cabin structure/weight, then you won't come to
much harm.
For sure-fire certainty and 100% confidence in all the work and
money you will put into her conversion,then perhaps a few hundred
dollars given to a navel architech would be very much worth the peace
of mind factor:-)
Sorry I couldn't be more helpful.....
Sincerely,
Peter Lenihan,who once saw a sailboat conversion to powerboat but
they kept their keel for easier motion in a seaway and excellent low
speed cross wind tracking in tight quarters instead of looking for
anying beaching advantage(that's what the dinghy is for:-
) )...........
> I have purchased an abandoned 22' x 8' sail boat and am in theprocess of
> converting it into a replica of a 1929 weekend power cruiser (nomast or
> sails). What I have now is really only a hull, I have removed thekeel
> because I want the boat to be beachable but I am sure that I willneed
> ballast of some sort. I want to put the ballast inside the hulland glass
> over the slot where the centerboard fit down through the splitkeel. Any
> ideas or suggestions?Grant,
> Grant Corson
I'm no designer and haven't a clue exactly which design you have
purchased but,it would seem to me that,if the ballast weight was
replaced by an inboard engine,fuel tanks,and other interior structure
( read: weight equal to that of ballast keel) and you did not over-do
it with a new higher cabin structure/weight, then you won't come to
much harm.
For sure-fire certainty and 100% confidence in all the work and
money you will put into her conversion,then perhaps a few hundred
dollars given to a navel architech would be very much worth the peace
of mind factor:-)
Sorry I couldn't be more helpful.....
Sincerely,
Peter Lenihan,who once saw a sailboat conversion to powerboat but
they kept their keel for easier motion in a seaway and excellent low
speed cross wind tracking in tight quarters instead of looking for
anying beaching advantage(that's what the dinghy is for:-
) )...........
I have purchased an abandoned 22' x 8' sail boat and am in the process of
converting it into a replica of a 1929 weekend power cruiser (no mast or
sails). What I have now is really only a hull, I have removed the keel
because I want the boat to be beachable but I am sure that I will need
ballast of some sort. I want to put the ballast inside the hull and glass
over the slot where the centerboard fit down through the split keel. Any
ideas or suggestions?
Grant Corson
converting it into a replica of a 1929 weekend power cruiser (no mast or
sails). What I have now is really only a hull, I have removed the keel
because I want the boat to be beachable but I am sure that I will need
ballast of some sort. I want to put the ballast inside the hull and glass
over the slot where the centerboard fit down through the split keel. Any
ideas or suggestions?
Grant Corson
Hi there. The answer in principle is "yes" (see George Buehler's book
on boatbuilding), but, if the shape of the keel remains constant,
then
the boat will come out much more tender or possibly totally unstable
(i.e., stable upside down). The problem here is that a lower density
of the material makes for a lighter keel which in turn raises the
center of gravity of the boat. Now, if you had a boat with a deep
canoe body draft (submerged hull depth), you could supplement the
concrete keel with some inside ballast. The problem is much tougher
with shallow draft hulls.
In any case, you should use rebar-reinforced concrete, and try to
increase its density by embedding scrap metal into it...
Best, Pippo
on boatbuilding), but, if the shape of the keel remains constant,
then
the boat will come out much more tender or possibly totally unstable
(i.e., stable upside down). The problem here is that a lower density
of the material makes for a lighter keel which in turn raises the
center of gravity of the boat. Now, if you had a boat with a deep
canoe body draft (submerged hull depth), you could supplement the
concrete keel with some inside ballast. The problem is much tougher
with shallow draft hulls.
In any case, you should use rebar-reinforced concrete, and try to
increase its density by embedding scrap metal into it...
Best, Pippo
--- Inbolger@egroups.com, fung42@h... wrote:
> greetings,
> can concrete be used instead of cast iron or lead for castiong a
> keel.any ideas?
greetings,
can concrete be used instead of cast iron or lead for castiong a
keel.any ideas?
can concrete be used instead of cast iron or lead for castiong a
keel.any ideas?