Re: [bolger] Re: Daggerboard vs. Centerboard
On Wed, 28 Jan 2004 09:47:37 +0800,fountainb@...wrote:
http://www.boatplans-online.com/proddetail.php?prod=CK17
If you click on the 'Study plans' link, they mention it there...
Interesting concept -- with the space I have behind the daggerboard, I'll
bet I could do something like that also.
Thanks for the pointer,
Jon
--------------------------------------------------------------
Jon HylandsJon@...http://www.huv.com/jon
Project: Micro Seeker (Micro Autonomous Underwater Vehicle)
http://www.huv.com
> I believe that Jaques Mertens-Goosens (www.bateau.com) has aIt appears to be a feature of the plan...
> modified daggerboard on his CK17, which is able to pivot to some
> extent, reducing the impact on the case. Might be worth asking on
> the bateau boards.
http://www.boatplans-online.com/proddetail.php?prod=CK17
If you click on the 'Study plans' link, they mention it there...
Interesting concept -- with the space I have behind the daggerboard, I'll
bet I could do something like that also.
Thanks for the pointer,
Jon
--------------------------------------------------------------
Jon HylandsJon@...http://www.huv.com/jon
Project: Micro Seeker (Micro Autonomous Underwater Vehicle)
http://www.huv.com
I believe that Jaques Mertens-Goosens (www.bateau.com) has a
modified daggerboard on his CK17, which is able to pivot to some
extent, reducing the impact on the case. Might be worth asking on
the bateau boards.
Bruce Fountain
Senior Software Engineer
Union Switch & Signal
Perth, Western Australia
modified daggerboard on his CK17, which is able to pivot to some
extent, reducing the impact on the case. Might be worth asking on
the bateau boards.
Bruce Fountain
Senior Software Engineer
Union Switch & Signal
Perth, Western Australia
On Tue, 27 Jan 2004 16:58:00 -0000,cha62759@...wrote:
It might be interesting to turn around the diagonal brace, to allow for it
to collapse a little in case of grounding.
The forward end of the daggerboard case has a 1/2" wide piece of fir for
the headboard, and then the 1/2" plywood frame.
In any case, I think I'm going to switch to a centerboard -- the kick-up
ability will save me in the spots where a daggerboard wouldn't, and if I
hit something sideways, it will be no different than a daggerboard.
I'm planning on having a closed-top centerboard trunk, so the centerboard
will be completely outside the dry side of the cabin. I will lead the
control lines to the cockpit, so I can raise or lower the board while I'm
sailing.
The pivot pin will probably be an inch in diameter, and rotate inside a
larger bushing, so hopefully there will be less chance of binding on a
sideways hit. I'll machine the whole assembly so that I can remove the pin
from inside the cabin if I need to remove the board, but it will still be
fully sealed while operational.
and then use 3" tape on the fore and aft edges after filleting them.
Later,
Jon
--------------------------------------------------------------
Jon HylandsJon@...http://www.huv.com/jon
Project: Micro Seeker (Micro Autonomous Underwater Vehicle)
http://www.huv.com
> I should have looked at all of your site. It would be easy to installBob,
> a shock absorber in your trunk. I'm concerned with your daggerboard
> trunk design. I may not be reading it properly but it looks to me like
> it is pretty flimsy. If you had a hard grounding I would be concerned
> that the forward head of the d board will go right through the
> bulkhead. I don't think the plywood bulkheads should be an integral
> part of the case. That diagonal reinforces the pivot point and
> increases the force against the forward bulkhead at the top of the
> case.
It might be interesting to turn around the diagonal brace, to allow for it
to collapse a little in case of grounding.
The forward end of the daggerboard case has a 1/2" wide piece of fir for
the headboard, and then the 1/2" plywood frame.
In any case, I think I'm going to switch to a centerboard -- the kick-up
ability will save me in the spots where a daggerboard wouldn't, and if I
hit something sideways, it will be no different than a daggerboard.
I'm planning on having a closed-top centerboard trunk, so the centerboard
will be completely outside the dry side of the cabin. I will lead the
control lines to the cockpit, so I can raise or lower the board while I'm
sailing.
The pivot pin will probably be an inch in diameter, and rotate inside a
larger bushing, so hopefully there will be less chance of binding on a
sideways hit. I'll machine the whole assembly so that I can remove the pin
from inside the cabin if I need to remove the board, but it will still be
fully sealed while operational.
> Also how do you finish glassing the inside of the case after itThe plans say to glass the inside of the panels before you put it together,
> is assembled or am I reading it wrong?
and then use 3" tape on the fore and aft edges after filleting them.
Later,
Jon
--------------------------------------------------------------
Jon HylandsJon@...http://www.huv.com/jon
Project: Micro Seeker (Micro Autonomous Underwater Vehicle)
http://www.huv.com
On Tue, 27 Jan 2004 16:32:37 -0000,cha62759@...wrote:
Thanks for the advice. A couple questions...
I assume the main point for leaks is the pivot pin, and the spot where the
pull-up/pull-down lines come out?
I have a Sherline lathe and mill in my basement, so I can machine very
close tolerance pieces (complete with o-rings) to make up a sealed pivot
pin. The lines can be routed through a pipe that is attached to the case,
and led up along the cabin bulkhead, and then outside.
I don't mind more complicated construction, as long as it is within my
means, if it produces a better result.
-- that is, when the centerboard is down, it will be in the same spot and
be the same length as the daggerboard was.
necessary at 5 knots, but I have his study plans for a couple boats, and
the information is there.
Thanks,
Jon
--------------------------------------------------------------
Jon HylandsJon@...http://www.huv.com/jon
Project: Micro Seeker (Micro Autonomous Underwater Vehicle)
http://www.huv.com
> The other problems with a centerboard case are leaks, more complicatedBob,
> construction and more turbulence.
Thanks for the advice. A couple questions...
I assume the main point for leaks is the pivot pin, and the spot where the
pull-up/pull-down lines come out?
I have a Sherline lathe and mill in my basement, so I can machine very
close tolerance pieces (complete with o-rings) to make up a sealed pivot
pin. The lines can be routed through a pipe that is attached to the case,
and led up along the cabin bulkhead, and then outside.
I don't mind more complicated construction, as long as it is within my
means, if it produces a better result.
> For what it's worth I would recommend that you stay with the designI can position a centerboard in exactly the same spot as the daggerboard is
> you have. If you change to a centerboard it will probably have to move
> forward or aft. I'm certainly not a designer but I can see that the
> forces are different with certain positions of a centerboard. Maybe it
> doesn't matter.
-- that is, when the centerboard is down, it will be in the same spot and
be the same length as the daggerboard was.
> Also you might consider (with a daggerboard) a "shockFarrier uses those on his tris as well. I'm not entirely sure it would be
> absorber" such as I had on my Tri. If you need a picture let me know.
necessary at 5 knots, but I have his study plans for a couple boats, and
the information is there.
> Also if you are going to be beaching your boat you will want a kick upYeah, the rudder is already designed to be kick-up.
> rudder.
Thanks,
Jon
--------------------------------------------------------------
Jon HylandsJon@...http://www.huv.com/jon
Project: Micro Seeker (Micro Autonomous Underwater Vehicle)
http://www.huv.com
Hi again Jon,
I should have looked at all of your site. It would be easy to install
a shock absorber in your trunk. I'm concerned with your daggerboard
trunk design. I may not be reading it properly but it looks to me like
it is pretty flimsy. If you had a hard grounding I would be concerned
that the forward head of the d board will go right through the
bulkhead. I don't think the plywood bulkheads should be an integral
part of the case. That diagonal reinforces the pivot point and
increases the force against the forward bulkhead at the top of the
case. Also how do you finish glassing the inside of the case after it
is assembled or am I reading it wrong?
Bob Chamberland
I should have looked at all of your site. It would be easy to install
a shock absorber in your trunk. I'm concerned with your daggerboard
trunk design. I may not be reading it properly but it looks to me like
it is pretty flimsy. If you had a hard grounding I would be concerned
that the forward head of the d board will go right through the
bulkhead. I don't think the plywood bulkheads should be an integral
part of the case. That diagonal reinforces the pivot point and
increases the force against the forward bulkhead at the top of the
case. Also how do you finish glassing the inside of the case after it
is assembled or am I reading it wrong?
Bob Chamberland
--- Inbolger@yahoogroups.com, Jon Hylands <jon@h...> wrote:
>
> Hi everyone,
>
> Nels' post regarding shallow water cruising got me thinking. I had
> previously thought about converting the K15 to a centerboard design,
but I
> was planning on doing it after sailing for a year, once I decided if a
> daggerboard didn't really work.
>
> Obviously, it would be much simpler to do the conversion while the
boat is
> in the design phase, and simply build a centerboard to begin with.
>
> What are your thoughts on this?
>
> Boat drawings can be found athttp://www.huv.com/sailing
>
> Later,
> Jon
>
> --------------------------------------------------------------
> Jon Hylands Jon@h...http://www.huv.com/jon
>
> Project: Micro Seeker (Micro Autonomous Underwater Vehicle)
>http://www.huv.com
Hi Jon,
I've had centerboard boats and I've had daggerboard boats. Either has
its evils or benefits.
The essential benefits of a D board is simpler construction. Less
likelihood of leaks. A smaller opening so less turbulence.
I sailed a Snipe for a number of years. The daggerboard for that
design when fully up (for beaching maybe) was in the way of the boom.
With your design the boom seems high enough and totally within the
cabin so that is not a problem. One of the hazards of a D board is the
resultant damage if you hit bottom or an underwater obstruction at
speed. I had a Dick Newick Trimaran, the Tremolino. With this design
there was a crushable insert aft of the D board that would take up the
shock of a "landing". I had the unfortunate experience of hitting
bottom at speed with this boat. Without the insert I would have been
rebuilding the case and that would have been a most unfortunate
project. The tri was capable of 20 knots or more in a blow so you can
see the potential. Your craft is probably capable of less than 5 knots
so perhaps that is not a problem.
There is a tendency to leave a daggerboard down on all points of sail
just to keep it out of the way. This doesn't seem to be a problem with
your project but having it in the cabin means that you will probably
leave it down because of the inconvenient location. On the other hand
a centerboard is more likely to be adjusted for point of sail.
The other problems with a centerboard case are leaks, more complicated
construction and more turbulence.
For what it's worth I would recommend that you stay with the design
you have. If you change to a centerboard it will probably have to move
forward or aft. I'm certainly not a designer but I can see that the
forces are different with certain positions of a centerboard. Maybe it
doesn't matter. Also you might consider (with a daggerboard) a "shock
absorber" such as I had on my Tri. If you need a picture let me know.
Also if you are going to be beaching your boat you will want a kick up
rudder.
Bob Chamberland
I've had centerboard boats and I've had daggerboard boats. Either has
its evils or benefits.
The essential benefits of a D board is simpler construction. Less
likelihood of leaks. A smaller opening so less turbulence.
I sailed a Snipe for a number of years. The daggerboard for that
design when fully up (for beaching maybe) was in the way of the boom.
With your design the boom seems high enough and totally within the
cabin so that is not a problem. One of the hazards of a D board is the
resultant damage if you hit bottom or an underwater obstruction at
speed. I had a Dick Newick Trimaran, the Tremolino. With this design
there was a crushable insert aft of the D board that would take up the
shock of a "landing". I had the unfortunate experience of hitting
bottom at speed with this boat. Without the insert I would have been
rebuilding the case and that would have been a most unfortunate
project. The tri was capable of 20 knots or more in a blow so you can
see the potential. Your craft is probably capable of less than 5 knots
so perhaps that is not a problem.
There is a tendency to leave a daggerboard down on all points of sail
just to keep it out of the way. This doesn't seem to be a problem with
your project but having it in the cabin means that you will probably
leave it down because of the inconvenient location. On the other hand
a centerboard is more likely to be adjusted for point of sail.
The other problems with a centerboard case are leaks, more complicated
construction and more turbulence.
For what it's worth I would recommend that you stay with the design
you have. If you change to a centerboard it will probably have to move
forward or aft. I'm certainly not a designer but I can see that the
forces are different with certain positions of a centerboard. Maybe it
doesn't matter. Also you might consider (with a daggerboard) a "shock
absorber" such as I had on my Tri. If you need a picture let me know.
Also if you are going to be beaching your boat you will want a kick up
rudder.
Bob Chamberland
--- Inbolger@yahoogroups.com, Jon Hylands <jon@h...> wrote:
>
> Hi everyone,
>
> Nels' post regarding shallow water cruising got me thinking. I had
> previously thought about converting the K15 to a centerboard design,
but I
> was planning on doing it after sailing for a year, once I decided
if a
> daggerboard didn't really work.
>
> Obviously, it would be much simpler to do the conversion while the
boat is
> in the design phase, and simply build a centerboard to begin with.
>
> What are your thoughts on this?
>
> Boat drawings can be found athttp://www.huv.com/sailing
>
> Later,
> Jon
>
> --------------------------------------------------------------
> Jon Hylands Jon@h...http://www.huv.com/jon
>
> Project: Micro Seeker (Micro Autonomous Underwater Vehicle)
>http://www.huv.com
Having spent some hundreds of hours sailing with a daggerboard, I'm not sure
they're as bad as you all make them out to be. There are a couple of tricks
to it.
1) You have to be able to adjust the amount of board protruding below the
hull. With the Sunfish, a piece of shock cord works well. Either run it
across from side to side of the spray shield, or add a screw eye to the
front of the board and hook to the front center of the spray shield.
2) I found it very useful to have an indication of the protrusion. Painted
the board white and used a felt tip marker to label the 3", 6", 9", 12",
etc. settings. Since the Sunfish has no other keel, 3" is the minimum for
the rudder to work against. Full extension is only for working to windward.
On the other hand, popping the board out lets you pivot about the rudder and
avoid whatever you were about to hit.
3) The board, at its highest setting, must NOT snag on the boom. Otherwise
a jibe can be quite upsetting.
On the larger centerboards, I've read many tales of their jamming in the
case. Some boats used a rigid rod to control them so that it could be
hammered down when necessary.
When running aground, which I did often, the centerboard would only help if
you were not making any leeway. Hitting the mud, sand, rock, or manatee
sideways will jam either CB or dagger board. (Manatees are tough. You
don't know they're there. You just know that you were hung out to the side
beating to windward when the boat stopped dead. No steerage way. Let the
sheet fly quickly, and then hope you don't rupture yourself getting your CG
back inside the boat.)
Fun!
Roger
derbyrm at starband.net
http://derbyrm.mystarband.net
they're as bad as you all make them out to be. There are a couple of tricks
to it.
1) You have to be able to adjust the amount of board protruding below the
hull. With the Sunfish, a piece of shock cord works well. Either run it
across from side to side of the spray shield, or add a screw eye to the
front of the board and hook to the front center of the spray shield.
2) I found it very useful to have an indication of the protrusion. Painted
the board white and used a felt tip marker to label the 3", 6", 9", 12",
etc. settings. Since the Sunfish has no other keel, 3" is the minimum for
the rudder to work against. Full extension is only for working to windward.
On the other hand, popping the board out lets you pivot about the rudder and
avoid whatever you were about to hit.
3) The board, at its highest setting, must NOT snag on the boom. Otherwise
a jibe can be quite upsetting.
On the larger centerboards, I've read many tales of their jamming in the
case. Some boats used a rigid rod to control them so that it could be
hammered down when necessary.
When running aground, which I did often, the centerboard would only help if
you were not making any leeway. Hitting the mud, sand, rock, or manatee
sideways will jam either CB or dagger board. (Manatees are tough. You
don't know they're there. You just know that you were hung out to the side
beating to windward when the boat stopped dead. No steerage way. Let the
sheet fly quickly, and then hope you don't rupture yourself getting your CG
back inside the boat.)
Fun!
Roger
derbyrm at starband.net
http://derbyrm.mystarband.net
----- Original Message -----
From: "Jon Hylands" <jon@...>
> Nels' post regarding shallow water cruising got me thinking. I had
> previously thought about converting the K15 to a centerboard design, but I
> was planning on doing it after sailing for a year, once I decided if a
> daggerboard didn't really work.
>
> Obviously, it would be much simpler to do the conversion while the boat is
> in the design phase, and simply build a centerboard to begin with.
>
> What are your thoughts on this?
>
> Boat drawings can be found athttp://www.huv.com/sailing
Hi Jon
I don't know a lot about the design issues involved but I've always
had a leaning towards off centre centreboards - often located inside
the bunk housing. (Did I get that right?) Alternatively I've seen
small daggerboard shaped centreboards installed on both starboard and
port bunks so that you'd use one or the other depending on your point
of sail. Probably fussy but I'm sure there's some advantage. Or to
play Devil's advocate, what about long, narrow bilge keels?
Bryant
I don't know a lot about the design issues involved but I've always
had a leaning towards off centre centreboards - often located inside
the bunk housing. (Did I get that right?) Alternatively I've seen
small daggerboard shaped centreboards installed on both starboard and
port bunks so that you'd use one or the other depending on your point
of sail. Probably fussy but I'm sure there's some advantage. Or to
play Devil's advocate, what about long, narrow bilge keels?
Bryant
--- Inbolger@yahoogroups.com, Jon Hylands <jon@h...> wrote:
>
> Hi everyone,
>
> Nels' post regarding shallow water cruising got me thinking. I had
> previously thought about converting the K15 to a centerboard
design,
Hi everyone,
Nels' post regarding shallow water cruising got me thinking. I had
previously thought about converting the K15 to a centerboard design, but I
was planning on doing it after sailing for a year, once I decided if a
daggerboard didn't really work.
Obviously, it would be much simpler to do the conversion while the boat is
in the design phase, and simply build a centerboard to begin with.
What are your thoughts on this?
Boat drawings can be found athttp://www.huv.com/sailing
Later,
Jon
--------------------------------------------------------------
Jon HylandsJon@...http://www.huv.com/jon
Project: Micro Seeker (Micro Autonomous Underwater Vehicle)
http://www.huv.com
Nels' post regarding shallow water cruising got me thinking. I had
previously thought about converting the K15 to a centerboard design, but I
was planning on doing it after sailing for a year, once I decided if a
daggerboard didn't really work.
Obviously, it would be much simpler to do the conversion while the boat is
in the design phase, and simply build a centerboard to begin with.
What are your thoughts on this?
Boat drawings can be found athttp://www.huv.com/sailing
Later,
Jon
--------------------------------------------------------------
Jon HylandsJon@...http://www.huv.com/jon
Project: Micro Seeker (Micro Autonomous Underwater Vehicle)
http://www.huv.com