Re: Bolger, Sharpie Catamaran Concept 24ft6in x 14 ft

Looks like it would be great WITHOUT the deckhouse, at least as a sport/day sailer. The deck would have to have some depth for strength though. Maybe deck over the sponsoons as well? Would be similar to a large hard deck Hobie Cat, would it not?

Someone made a comment about the centerboard. I'm not a sailer, but what would be wrong with a hinged centerboard centered in each sponsoon? I understand the turning for tacks, but would it be much different from a sharpie with lee boards? Or are both leeboards not down all the time? Seems like it would be a big PITA to lift and lower the correct side leeboard when tacking if that's the case... can't be!!

--- Inbolger@yahoogroups.com, BruceHallman <hallman@...> wrote:
>
> Bolger, Sharpie Catamaran Concept 24ft6in x 14 ft
>
> I was just studying this Bolger design concept, and thought I
> would share. This design was a concept study, and never reached
> fruition. Bolger admitted that it was ugly, but to my eye, the
> function in concept seems sound.
>
>http://hallman.org/bolger/SharpieCatamaranConcept/
>

More curves for improved looks?

This'n will still be terribly draggy - superstructure so high, so broad. Ross Turner designed a cat about this size that's a trailerable speedster, but for camp-cruising a detachable curve-fronted full-width cuddy-box-thingo mounts across the forward third of the deck. Come to think of it I don't think it has decks, just some catwalks and netting.

A rectangular immersed cross-section is not all bad:

http://www.rclandsailing.com/catamaran/design.html#hull

OTOH here's some other conceptual issues:

The immersed rectangular cross-section with rocker shown grant a low L/Disp, &etc, limiting at higher S/L, so relatively slow (planing is out of course).

There must be doubts about bridge clearance in chop. (This boat isn't going anywhere near waves!)

The rig could be further aft.

Surprising for PCB on a mono, but maybe not here: the sailing ergonomics are quite poor. Reaching and beating - it's a multi so there's more of this - anyway, when reaching and beating the crew are seated to weather facing too far away from the direction of travel and trouble - sore necks all round - with a rubber neck or mirror required for checking sail trim! A further twist is presented by the tiller sited inboard and behind. All those blind spots and twisting would also extend to hand the sheet. And hand the foils pendants. Yoga anyone? Another surprise reaching and beating is the seated crew weight sited inboard! This lowers righting moment and stability markedly. Note that crew can't sit in the weather footwell - too narrow. They can't stand there either - anyway, that verticle weight shift would be little better than as they are seated.

If slender semi-dory box hulls are out, then Eeek type hulls might be better for a flatwater camper-kinda-beachcat.

Wharram, has spoken/published only complimentary words regarding Bolger design. What was this design concept about?

--- Inbolger@yahoogroups.com, Kent <kent@...> wrote:
>
> Bruce, thanks for posting this. I couldn't find anything else about
> this design on the Web. Where can I learn more?
>
> I think this is a fascinating concept. Its looks could be improved a
> lot by designing some curves and non-90-degree angles into the
> deckhouse. But I see some possible problems:
>
> - I'm not sure if a sharpie hull is the best for a catamaran. Some
> of the sharpie's advantages only apply when it heels, and cats don't
> do much of that. The shape doesn't look easier to build than a
> V-shaped Wharram type. I'm not expert enough to know how the
> performance compares.
>
> - A single keel and rudder in the middle is simpler than having one
> in each hull ... or is it? Which is easier to build, really? I
> don't see any clear advantage for the central appendage. Also, it
> increases the draft quite a bit, unless perhaps it's meant to rotate
> sideways and up? But if it did that, the rudder would go with it, so
> you lose your steering.
>
> Any thoughts?
>
> -- Kent

I Like that take apart concept in this age of high storage fees. I hope
some day you do in Free!ship that 40 ft,take apart, water ballast,
sharpie schooner. I saw that from afar on Howe Sound,BC He was flying!

BruceHallman wrote:

> I am sure that the box section sponson would be fine in a catamaran,
> even when heeled. It is funny you mention Wharram as a baseline
> expectation, because that was the punch line in the Bolger writeup as
> to the disappointment of the commissioning client. Published June 1,
> 1996 MAIB. (Bob Hicks sells reprints.) Yes, I believe that the
> centered board is hinged and intended to be swung up flat against the
> underside of the dance floor for beaching. I don't quite know why PCB
> chose the centered board, but one guess is that a hinged assembly
> would be elegant in a way, and would need to be centered to accept the
> purchase point for the mainsheet, (and perhaps, that a centerboard in
> the exact center of the boat might make tacking rotation easier, which
> is a concern with catamarans) This model was created using Free!ship
> version 2.6.
>
>
>
> On Wed, Feb 16, 2011 at 1:06 PM, Kent <kent@...> wrote:
>
>>
>> Bruce, thanks for posting this. I couldn't find anything else about
>> this design on the Web. Where can I learn more?
>>
>> I think this is a fascinating concept. Its looks could be improved a
>> lot by designing some curves and non-90-degree angles into the
>> deckhouse. But I see some possible problems:
>>
>> - I'm not sure if a sharpie hull is the best for a catamaran. Some
>> of the sharpie's advantages only apply when it heels, and cats don't
>> do much of that. The shape doesn't look easier to build than a
>> V-shaped Wharram type. I'm not expert enough to know how the
>> performance compares.
>>
>> - A single keel and rudder in the middle is simpler than having one
>> in each hull ... or is it? Which is easier to build, really? I
>> don't see any clear advantage for the central appendage. Also, it
>> increases the draft quite a bit, unless perhaps it's meant to rotate
>> sideways and up? But if it did that, the rudder would go with it, so
>> you lose your steering.
>>
>> Any thoughts?
>>
>> -- Kent
>>
>>
>>> Bolger, Sharpie Catamaran Concept 24ft6in x 14 ft
>>>
>>> I was just studying this Bolger design concept, and thought I
>>> would share. This design was a concept study, and never reached
>>> fruition. Bolger admitted that it was ugly, but to my eye, the
>>> function in concept seems sound. The mast is 41 feet, with 280 sf
>>> sail. Judging from the displacment calcs, overall it is a light weight
>>> thing, meaning that the superstructure would be 1/4" plywood,
>>> plexiglass/lexan windows, etc.. That superstructure serves double
>>> duty, as "box beam" structure giving rigidity to the hull form and
>>> mast stays, with it also serving as a real 'patio dance floor' for
>>> this cruiser (with camping space using aluminum lawn furniture, I
>>> presume). Heck, you could rig up a disco-ball too. Port-a-potty stows
>>> in one of the sponsons. The boat is sailed with the crew sitting on
>>> deck with their feet hanging down in the sponsons. The whole thing
>>> could be fabricated in three assemblies, two sponsons, and the
>>> deck/superstructure, so it could be broken down and trucked to the
>>> summer vacation destination, lake, etc.. The centerboard, rudder for
>>> lateral plane (I deduce) is hinged, pinned, and cable stayed, so it
>>> can be swung 90 degrees up under the deck for beaching.
>>> URL for slideshow...
>>>
>>>http://hallman.org/bolger/SharpieCatamaranConcept/
>>>
>>>
>>
>
>
> ------------------------------------
>
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>
>
>

I am sure that the box section sponson would be fine in a catamaran,
even when heeled. It is funny you mention Wharram as a baseline
expectation, because that was the punch line in the Bolger writeup as
to the disappointment of the commissioning client. Published June 1,
1996 MAIB. (Bob Hicks sells reprints.) Yes, I believe that the
centered board is hinged and intended to be swung up flat against the
underside of the dance floor for beaching. I don't quite know why PCB
chose the centered board, but one guess is that a hinged assembly
would be elegant in a way, and would need to be centered to accept the
purchase point for the mainsheet, (and perhaps, that a centerboard in
the exact center of the boat might make tacking rotation easier, which
is a concern with catamarans) This model was created using Free!ship
version 2.6.

On Wed, Feb 16, 2011 at 1:06 PM, Kent <kent@...> wrote:
>
>
>
> Bruce, thanks for posting this. I couldn't find anything else about
> this design on the Web. Where can I learn more?
>
> I think this is a fascinating concept. Its looks could be improved a
> lot by designing some curves and non-90-degree angles into the
> deckhouse. But I see some possible problems:
>
> - I'm not sure if a sharpie hull is the best for a catamaran. Some
> of the sharpie's advantages only apply when it heels, and cats don't
> do much of that. The shape doesn't look easier to build than a
> V-shaped Wharram type. I'm not expert enough to know how the
> performance compares.
>
> - A single keel and rudder in the middle is simpler than having one
> in each hull ... or is it? Which is easier to build, really? I
> don't see any clear advantage for the central appendage. Also, it
> increases the draft quite a bit, unless perhaps it's meant to rotate
> sideways and up? But if it did that, the rudder would go with it, so
> you lose your steering.
>
> Any thoughts?
>
> -- Kent
>
> >Bolger, Sharpie Catamaran Concept 24ft6in x 14 ft
> >
> > I was just studying this Bolger design concept, and thought I
> >would share. This design was a concept study, and never reached
> >fruition. Bolger admitted that it was ugly, but to my eye, the
> >function in concept seems sound. The mast is 41 feet, with 280 sf
> >sail. Judging from the displacment calcs, overall it is a light weight
> >thing, meaning that the superstructure would be 1/4" plywood,
> >plexiglass/lexan windows, etc.. That superstructure serves double
> >duty, as "box beam" structure giving rigidity to the hull form and
> >mast stays, with it also serving as a real 'patio dance floor' for
> >this cruiser (with camping space using aluminum lawn furniture, I
> >presume). Heck, you could rig up a disco-ball too. Port-a-potty stows
> >in one of the sponsons. The boat is sailed with the crew sitting on
> >deck with their feet hanging down in the sponsons. The whole thing
> >could be fabricated in three assemblies, two sponsons, and the
> >deck/superstructure, so it could be broken down and trucked to the
> >summer vacation destination, lake, etc.. The centerboard, rudder for
> >lateral plane (I deduce) is hinged, pinned, and cable stayed, so it
> >can be swung 90 degrees up under the deck for beaching.
> > URL for slideshow...
> >
> >http://hallman.org/bolger/SharpieCatamaranConcept/
> >
>
>

Bruce, thanks for posting this. I couldn't find anything else about
this design on the Web. Where can I learn more?

I think this is a fascinating concept. Its looks could be improved a
lot by designing some curves and non-90-degree angles into the
deckhouse. But I see some possible problems:

- I'm not sure if a sharpie hull is the best for a catamaran. Some
of the sharpie's advantages only apply when it heels, and cats don't
do much of that. The shape doesn't look easier to build than a
V-shaped Wharram type. I'm not expert enough to know how the
performance compares.

- A single keel and rudder in the middle is simpler than having one
in each hull ... or is it? Which is easier to build, really? I
don't see any clear advantage for the central appendage. Also, it
increases the draft quite a bit, unless perhaps it's meant to rotate
sideways and up? But if it did that, the rudder would go with it, so
you lose your steering.

Any thoughts?

-- Kent

>Bolger, Sharpie Catamaran Concept 24ft6in x 14 ft
>
> I was just studying this Bolger design concept, and thought I
>would share. This design was a concept study, and never reached
>fruition. Bolger admitted that it was ugly, but to my eye, the
>function in concept seems sound. The mast is 41 feet, with 280 sf
>sail. Judging from the displacment calcs, overall it is a light weight
>thing, meaning that the superstructure would be 1/4" plywood,
>plexiglass/lexan windows, etc.. That superstructure serves double
>duty, as "box beam" structure giving rigidity to the hull form and
>mast stays, with it also serving as a real 'patio dance floor' for
>this cruiser (with camping space using aluminum lawn furniture, I
>presume). Heck, you could rig up a disco-ball too. Port-a-potty stows
>in one of the sponsons. The boat is sailed with the crew sitting on
>deck with their feet hanging down in the sponsons. The whole thing
>could be fabricated in three assemblies, two sponsons, and the
>deck/superstructure, so it could be broken down and trucked to the
>summer vacation destination, lake, etc.. The centerboard, rudder for
>lateral plane (I deduce) is hinged, pinned, and cable stayed, so it
>can be swung 90 degrees up under the deck for beaching.
> URL for slideshow...
>
>http://hallman.org/bolger/SharpieCatamaranConcept/
>

."It's the tides, man.  They can either work for you or they can work against you...

Confidentially, I've had this problem with the tides before."

--Captain Ron

Bolger, Sharpie Catamaran Concept 24ft6in x 14 ft

I was just studying this Bolger design concept, and thought I
would share. This design was a concept study, and never reached
fruition. Bolger admitted that it was ugly, but to my eye, the
function in concept seems sound. The mast is 41 feet, with 280 sf
sail. Judging from the displacment calcs, overall it is a light weight
thing, meaning that the superstructure would be 1/4" plywood,
plexiglass/lexan windows, etc.. That superstructure serves double
duty, as "box beam" structure giving rigidity to the hull form and
mast stays, with it also serving as a real 'patio dance floor' for
this cruiser (with camping space using aluminum lawn furniture, I
presume). Heck, you could rig up a disco-ball too. Port-a-potty stows
in one of the sponsons. The boat is sailed with the crew sitting on
deck with their feet hanging down in the sponsons. The whole thing
could be fabricated in three assemblies, two sponsons, and the
deck/superstructure, so it could be broken down and trucked to the
summer vacation destination, lake, etc.. The centerboard, rudder for
lateral plane (I deduce) is hinged, pinned, and cable stayed, so it
can be swung 90 degrees up under the deck for beaching.
URL for slideshow...

http://hallman.org/bolger/SharpieCatamaranConcept/