Re: Birdwatcher - centreboard question
Thank you Bob - Yes it is BW 1 that I was reading about regards
rudder, -will have to get hold of updated arrangement. Sounds like
best to go with CB. Am also considering trying out tacking crabclaw
first off (about 14m2 ) - could mount stubb mast on forward bulkhead,
this would enable a canting arrangement and the COE is maintained when
the boom is laid back a little, as in reaching setup. However, with
boom raised close to mast (as for w'ward work) it looks like the COE
moves forward and is raised a little higher than on the designed
setup. Any ideas on possible probs with this and would the canting
have any effect in this instance.
Thanks - Darrell
rudder, -will have to get hold of updated arrangement. Sounds like
best to go with CB. Am also considering trying out tacking crabclaw
first off (about 14m2 ) - could mount stubb mast on forward bulkhead,
this would enable a canting arrangement and the COE is maintained when
the boom is laid back a little, as in reaching setup. However, with
boom raised close to mast (as for w'ward work) it looks like the COE
moves forward and is raised a little higher than on the designed
setup. Any ideas on possible probs with this and would the canting
have any effect in this instance.
Thanks - Darrell
--- Inbolger@yahoogroups.com, "Bob Larkin" <boblark@...> wrote:
>
> Hello Darrell,
>
> I don't feel qualified to comment on your proposed design changes.
> But, a couple of comments, based on sailing the BW2 for the last year+.
>
> The weight of the centerboard (about 150 lb) provides about the same
> static moment as the mast. The bottom, even as designed with 1-1/4
> thickness does not provide a big righting moment, as it is only a few
> inches below the CG. The dynamic ballast of people sitting low is
> very effective, as the windward side is the place to put the ballast
> with a flat bottom. This is most obvious, when sailing.
>
> Form stability of the sharpie is limited by the narrow beam. On, the
> other hand, getting the boat up on the chine log reduces the wetted
> area, which is desirable.
>
> Are you looking at the BW or BW2? The BW2 has more sail area than the
> original BW. At 213 sq-ft (full main and jib) it ends up with SA/D
> around 30, which makes for a spirited sailboat. The centerboard, as
> drawn, makes for the windward performance you would want. I would be
> careful about giving that up.
>
> Relative to tacking, I am trying to remember if I have gotten into
> irons at all. Certainly not while tending to business. The thing to
> remember is that the boat is light, and as soon as you start to tack,
> it becomes upright, and rotates very fast. I might add that the fast
> tacking makes for a busy time for the crew!
>
> On the BW2, there is plenty of tiller range. One has plenty of range
> for tacking, and to stall it, for that matter. I am not with the
> plans or boat now, so I can't get you a number. If the Honda motor is
> up, it limits the rudder travel, by a few degrees in one direction.
> The tiller mechanism changed between BW versions.
>
> Bob
>
> --- Inbolger@yahoogroups.com, "hobyarr" <knic0014@> wrote:
> >
> > questions, wondering about centre board
> > whether it would be possible to do away with and use chine runners as
> > Matt Layden designs on Paradox and particularly Enigma as it is
> > designed a little closer to the BW build than Paradox is. What do you
> > reckon BW's draught would be heeled over - would it be enough to allow
> > chine runners to do there job - would adding weight to bottom overcome
> > loss of c.b weight Although I have read somewhere that BW can be a
> > little difficult to tack at times and perhaps the c'board is necessary
> > to assist Also thinking about rudder/tiller mods as it seems you can
> > only get about 20 degrees on rudder. Does anyone have any ideas or
> > knowledge on this.
> > Thank you - Darrell
> >
>
Hello Darrell,
I don't feel qualified to comment on your proposed design changes.
But, a couple of comments, based on sailing the BW2 for the last year+.
The weight of the centerboard (about 150 lb) provides about the same
static moment as the mast. The bottom, even as designed with 1-1/4
thickness does not provide a big righting moment, as it is only a few
inches below the CG. The dynamic ballast of people sitting low is
very effective, as the windward side is the place to put the ballast
with a flat bottom. This is most obvious, when sailing.
Form stability of the sharpie is limited by the narrow beam. On, the
other hand, getting the boat up on the chine log reduces the wetted
area, which is desirable.
Are you looking at the BW or BW2? The BW2 has more sail area than the
original BW. At 213 sq-ft (full main and jib) it ends up with SA/D
around 30, which makes for a spirited sailboat. The centerboard, as
drawn, makes for the windward performance you would want. I would be
careful about giving that up.
Relative to tacking, I am trying to remember if I have gotten into
irons at all. Certainly not while tending to business. The thing to
remember is that the boat is light, and as soon as you start to tack,
it becomes upright, and rotates very fast. I might add that the fast
tacking makes for a busy time for the crew!
On the BW2, there is plenty of tiller range. One has plenty of range
for tacking, and to stall it, for that matter. I am not with the
plans or boat now, so I can't get you a number. If the Honda motor is
up, it limits the rudder travel, by a few degrees in one direction.
The tiller mechanism changed between BW versions.
Bob
I don't feel qualified to comment on your proposed design changes.
But, a couple of comments, based on sailing the BW2 for the last year+.
The weight of the centerboard (about 150 lb) provides about the same
static moment as the mast. The bottom, even as designed with 1-1/4
thickness does not provide a big righting moment, as it is only a few
inches below the CG. The dynamic ballast of people sitting low is
very effective, as the windward side is the place to put the ballast
with a flat bottom. This is most obvious, when sailing.
Form stability of the sharpie is limited by the narrow beam. On, the
other hand, getting the boat up on the chine log reduces the wetted
area, which is desirable.
Are you looking at the BW or BW2? The BW2 has more sail area than the
original BW. At 213 sq-ft (full main and jib) it ends up with SA/D
around 30, which makes for a spirited sailboat. The centerboard, as
drawn, makes for the windward performance you would want. I would be
careful about giving that up.
Relative to tacking, I am trying to remember if I have gotten into
irons at all. Certainly not while tending to business. The thing to
remember is that the boat is light, and as soon as you start to tack,
it becomes upright, and rotates very fast. I might add that the fast
tacking makes for a busy time for the crew!
On the BW2, there is plenty of tiller range. One has plenty of range
for tacking, and to stall it, for that matter. I am not with the
plans or boat now, so I can't get you a number. If the Honda motor is
up, it limits the rudder travel, by a few degrees in one direction.
The tiller mechanism changed between BW versions.
Bob
--- Inbolger@yahoogroups.com, "hobyarr" <knic0014@...> wrote:
>
> questions, wondering about centre board
> whether it would be possible to do away with and use chine runners as
> Matt Layden designs on Paradox and particularly Enigma as it is
> designed a little closer to the BW build than Paradox is. What do you
> reckon BW's draught would be heeled over - would it be enough to allow
> chine runners to do there job - would adding weight to bottom overcome
> loss of c.b weight Although I have read somewhere that BW can be a
> little difficult to tack at times and perhaps the c'board is necessary
> to assist Also thinking about rudder/tiller mods as it seems you can
> only get about 20 degrees on rudder. Does anyone have any ideas or
> knowledge on this.
> Thank you - Darrell
>
questions, wondering about centre board
whether it would be possible to do away with and use chine runners as
Matt Layden designs on Paradox and particularly Enigma as it is
designed a little closer to the BW build than Paradox is. What do you
reckon BW's draught would be heeled over - would it be enough to allow
chine runners to do there job - would adding weight to bottom overcome
loss of c.b weight Although I have read somewhere that BW can be a
little difficult to tack at times and perhaps the c'board is necessary
to assist Also thinking about rudder/tiller mods as it seems you can
only get about 20 degrees on rudder. Does anyone have any ideas or
knowledge on this.
Thank you - Darrell
whether it would be possible to do away with and use chine runners as
Matt Layden designs on Paradox and particularly Enigma as it is
designed a little closer to the BW build than Paradox is. What do you
reckon BW's draught would be heeled over - would it be enough to allow
chine runners to do there job - would adding weight to bottom overcome
loss of c.b weight Although I have read somewhere that BW can be a
little difficult to tack at times and perhaps the c'board is necessary
to assist Also thinking about rudder/tiller mods as it seems you can
only get about 20 degrees on rudder. Does anyone have any ideas or
knowledge on this.
Thank you - Darrell