Re: Gypsy with centerboard
> One way of avoiding this is to cover the slot with a long strip ofthin, stiffish rubber, with a slit all the way along for the CB to
emerge. When the CB is down, the rubber springs back to cover the rest
of the slot. (Hope that makes sense - needs a pic!)
>and eliminate drag from that source.
> This trick has been used on racing dinghies for many years, to try
>Yep, I wound up doing something like that on the 30 footer & I think it
> Bill
>
> [Non-text portions of this message have been removed]
added a knot to the speed....
Gary
>>----- Original Message -----From: gbship
To:bolger@yahoogroups.com
Sent: Tuesday, September 27, 2005 11:05 PM
Subject: [bolger] Re: Gypsy with centerboard
One consideration. If you use a long, narow board, there will be a
considerable gap when the board is fully down between the aft edge of
the board and the aft face of the trunk, and the face, perpenducular
to the movement of the boat, will add drag.>>
One way of avoiding this is to cover the slot with a long strip of thin, stiffish rubber, with a slit all the way along for the CB to emerge. When the CB is down, the rubber springs back to cover the rest of the slot. (Hope that makes sense - needs a pic!)
This trick has been used on racing dinghies for many years, to try and eliminate drag from that source.
Bill
[Non-text portions of this message have been removed]
Gordon: FWIW, our 30-footer (design #459) is basically a doubled
Gypsy - with the same hull shape. It started life with a fixed fin
keel like a dagger board and Bolger himself came up with the plans to
convert it to a centerboard-like pivoting keel, albeit with a 1000-
pound wing at the bottom.
One consideration. If you use a long, narow board, there will be a
considerable gap when the board is fully down between the aft edge of
the board and the aft face of the trunk, and the face, perpenducular
to the movement of the boat, will add drag. (I suspect, but without
any real evidence, that the greater the gap, the greater the drag.) I
think that's why Bolger uses so many wedge shaped centerboards
because up or down, they fill the gap in the bottom of the hull and
improve flow around the slot and particularly that back face.
Gary Blankenship
Gypsy - with the same hull shape. It started life with a fixed fin
keel like a dagger board and Bolger himself came up with the plans to
convert it to a centerboard-like pivoting keel, albeit with a 1000-
pound wing at the bottom.
One consideration. If you use a long, narow board, there will be a
considerable gap when the board is fully down between the aft edge of
the board and the aft face of the trunk, and the face, perpenducular
to the movement of the boat, will add drag. (I suspect, but without
any real evidence, that the greater the gap, the greater the drag.) I
think that's why Bolger uses so many wedge shaped centerboards
because up or down, they fill the gap in the bottom of the hull and
improve flow around the slot and particularly that back face.
Gary Blankenship
--- Inbolger@yahoogroups.com, "paulthober" <paulthober@y...> wrote:
> This doesn't sound like a bad idea at all. I built a Gypsy with the
> designed daggerboard and it was rather clumsy and inconvenient, i.e.
> the mast and sail would interfere with inserting and withdrawing it.
> Also its angle forward meant pulling it up quite difficult,
especially
> when sailing alone. The points I would bear in mind are that the
> centerboard center and area be the same as the original daggerboard
> and that the trunk not interfere with sailing the boat - or rowing
if
> you intend to do that. I think the angling of the board was to
allow a
> single rower to sit over the center of boyancy. If you do this
> modification it would be nice if you could post a drawing so that
> others building this boat would have the option.
>
> Paul
>
> --- Inbolger@yahoogroups.com, "Gordon Snapp" <grsnapp@c...> wrote:
> > I'm considering building a Gypsy, using "Build the New Instant
Boats."
> > However, I'm thinking it would be nice if it had a centerboard
instead
> > of a dagger board. My sailing would be in shallow Morro Bay,
where the
> > chance of running "aground" into the yucky, silty bottom is
always
> > there. Are there any Gypsy builders who can give me advice in
general,
> > and specific thoughts on the centerboard idea? Thanks in advance.
> >
> > -Gordon Snapp
> > Central Coast of California
This doesn't sound like a bad idea at all. I built a Gypsy with the
designed daggerboard and it was rather clumsy and inconvenient, i.e.
the mast and sail would interfere with inserting and withdrawing it.
Also its angle forward meant pulling it up quite difficult, especially
when sailing alone. The points I would bear in mind are that the
centerboard center and area be the same as the original daggerboard
and that the trunk not interfere with sailing the boat - or rowing if
you intend to do that. I think the angling of the board was to allow a
single rower to sit over the center of boyancy. If you do this
modification it would be nice if you could post a drawing so that
others building this boat would have the option.
Paul
designed daggerboard and it was rather clumsy and inconvenient, i.e.
the mast and sail would interfere with inserting and withdrawing it.
Also its angle forward meant pulling it up quite difficult, especially
when sailing alone. The points I would bear in mind are that the
centerboard center and area be the same as the original daggerboard
and that the trunk not interfere with sailing the boat - or rowing if
you intend to do that. I think the angling of the board was to allow a
single rower to sit over the center of boyancy. If you do this
modification it would be nice if you could post a drawing so that
others building this boat would have the option.
Paul
--- Inbolger@yahoogroups.com, "Gordon Snapp" <grsnapp@c...> wrote:
> I'm considering building a Gypsy, using "Build the New Instant Boats."
> However, I'm thinking it would be nice if it had a centerboard instead
> of a dagger board. My sailing would be in shallow Morro Bay, where the
> chance of running "aground" into the yucky, silty bottom is always
> there. Are there any Gypsy builders who can give me advice in general,
> and specific thoughts on the centerboard idea? Thanks in advance.
>
> -Gordon Snapp
> Central Coast of California
I'm considering building a Gypsy, using "Build the New Instant Boats."
However, I'm thinking it would be nice if it had a centerboard instead
of a dagger board. My sailing would be in shallow Morro Bay, where the
chance of running "aground" into the yucky, silty bottom is always
there. Are there any Gypsy builders who can give me advice in general,
and specific thoughts on the centerboard idea? Thanks in advance.
-Gordon Snapp
Central Coast of California
However, I'm thinking it would be nice if it had a centerboard instead
of a dagger board. My sailing would be in shallow Morro Bay, where the
chance of running "aground" into the yucky, silty bottom is always
there. Are there any Gypsy builders who can give me advice in general,
and specific thoughts on the centerboard idea? Thanks in advance.
-Gordon Snapp
Central Coast of California