Re: Summer Ease/Micro alteration
The addition of mizzen may help a little with the variable geometry
problem but this is not the major factor regarding cat boat weather
helm. The problem originates in the transfer of power from the sail
to the mast to the hull. Because the mast is above the hull it tends
to push the bow forward but it ends up rotating around the center of
buoyancy and there for tries to nose dive. This nose dive effect is
why most cat boat designers give there boats very full bow sections,
it needs the buoyancy up there. The problem occurs when the boat gets
knocked down, something we all try to avoid but it does happen. When
the hull is laying over on its side the mast force still tries to
rotate around the centre of buoyancy however now this force pushes the
bow up into the wind. To see this, take a small piece of 2*4 say
8"-10" long and drill a hole on the flat near on end and fit a 12"
piece of dowl in it. With the crude cat boat bolt upright push
forward on the top of the mast and see how the stern tends to lift;
next lay the boat on its side and push forward on the top of the mast
the boat will round up. This is not a problem for sloops, etc because
the mast a steped far enough back to reduce the effect. Sloops mast
is closer to the centre of buoyancy and therefore looses some of
mechanical advantage needed to do this it also places hull and
bouyancy forward of the mast which counters the effect.
Andy Moore
Nova Scotia
Canada
problem but this is not the major factor regarding cat boat weather
helm. The problem originates in the transfer of power from the sail
to the mast to the hull. Because the mast is above the hull it tends
to push the bow forward but it ends up rotating around the center of
buoyancy and there for tries to nose dive. This nose dive effect is
why most cat boat designers give there boats very full bow sections,
it needs the buoyancy up there. The problem occurs when the boat gets
knocked down, something we all try to avoid but it does happen. When
the hull is laying over on its side the mast force still tries to
rotate around the centre of buoyancy however now this force pushes the
bow up into the wind. To see this, take a small piece of 2*4 say
8"-10" long and drill a hole on the flat near on end and fit a 12"
piece of dowl in it. With the crude cat boat bolt upright push
forward on the top of the mast and see how the stern tends to lift;
next lay the boat on its side and push forward on the top of the mast
the boat will round up. This is not a problem for sloops, etc because
the mast a steped far enough back to reduce the effect. Sloops mast
is closer to the centre of buoyancy and therefore looses some of
mechanical advantage needed to do this it also places hull and
bouyancy forward of the mast which counters the effect.
Andy Moore
Nova Scotia
Canada
I bet Chebacco will sail circles aroung Gunkholer, blow high or blow
low. It's much lighter with a better hull shape.
low. It's much lighter with a better hull shape.
>I've also dreamed over Jaymainsail.
> Benford's 19 foot Gunkholer catboat with its comparatively huge
Thought I'd jump in here with my 2 bits. I can't give a reference,
unfortunately, but I believe the master wrote somewhere that the Chebacco
(my boat), or maybe it was cat yawls in general, could have significantly
more speed with a longer boom, but would give up manageability.
This makes me think that a conversion of a cat to cat yawl could improve
weather helm, but only because the mizzen area is less than the area cut off
the main. Don't know if I'd bother with a conversion -- I think I'd just
reef when steering becomes awkward as it seems a waste to lose sail area.
On my Chebacco I've occasionally wished for more square feet (I also wished
devoutly for a third reef on another occasion!). I've also dreamed over Jay
Benford's 19 foot Gunkholer catboat with its comparatively huge mainsail. I
never bought the plans, because it also has significant ballast, which takes
it out of the trailer sailor category for me.
Cheers,
Jamie Orr
-----Original Message-----
From: Peter Lenihan [mailto:ellengaest@...]
Sent: December 4, 2001 4:00 PM
To:bolger@yahoogroups.com
Subject: [bolger] Re: Summer Ease/Micro alteration
Hi Peter,
Well,I first think about the Cape Cod catboats which need those
huge barn door rudders and either long tillers or wheels to
control.And this despite the variable geometry of the centerboard.That
is,the ability to shift the CLR.
With a mizzen,especially in the yawl category,the CE can be brought
further back,the relative size of the main reduced and the rudder area
also reduced.This is perhaps most benificial to fixed geometry
underbody shapes which really can't shift their CLRs.
None of this is meant to suggest that Ellis did not know what he
was doing.I've long admired the three examples of the NONSUCH at my
club.They are beautiful boats,superbly built,incredibly roomy and very
expensive..............I wish I had one!
I suppose it is a tough act catering to a public brought up on
sloops and trying to sell them a catboat.Going with a familiar
underbody shape with something of a comprimise shoal keel and a spade
rudder,I'm sure,goes a long way toward winning them over.Add a ton of
square feet with high-tech reefing gizmos to calm any nervous thoughts
of dealing with one huge sail and toss in first class construction
standards and hey,you just about have them!
Anyway Peter,I'm no racer and I certainly do not have hard numbers
to back up my suggestion.It is more a broad general feeling I have
each time I grab onto my tiller,especially after once trying to sail
my MICRO without the mizzen........talk about frustration!
Sincerely,
Peter Lenihan,amateur lover of yawls,from the shores of the
St.Lawrence...........
unfortunately, but I believe the master wrote somewhere that the Chebacco
(my boat), or maybe it was cat yawls in general, could have significantly
more speed with a longer boom, but would give up manageability.
This makes me think that a conversion of a cat to cat yawl could improve
weather helm, but only because the mizzen area is less than the area cut off
the main. Don't know if I'd bother with a conversion -- I think I'd just
reef when steering becomes awkward as it seems a waste to lose sail area.
On my Chebacco I've occasionally wished for more square feet (I also wished
devoutly for a third reef on another occasion!). I've also dreamed over Jay
Benford's 19 foot Gunkholer catboat with its comparatively huge mainsail. I
never bought the plans, because it also has significant ballast, which takes
it out of the trailer sailor category for me.
Cheers,
Jamie Orr
-----Original Message-----
From: Peter Lenihan [mailto:ellengaest@...]
Sent: December 4, 2001 4:00 PM
To:bolger@yahoogroups.com
Subject: [bolger] Re: Summer Ease/Micro alteration
Hi Peter,
Well,I first think about the Cape Cod catboats which need those
huge barn door rudders and either long tillers or wheels to
control.And this despite the variable geometry of the centerboard.That
is,the ability to shift the CLR.
With a mizzen,especially in the yawl category,the CE can be brought
further back,the relative size of the main reduced and the rudder area
also reduced.This is perhaps most benificial to fixed geometry
underbody shapes which really can't shift their CLRs.
None of this is meant to suggest that Ellis did not know what he
was doing.I've long admired the three examples of the NONSUCH at my
club.They are beautiful boats,superbly built,incredibly roomy and very
expensive..............I wish I had one!
I suppose it is a tough act catering to a public brought up on
sloops and trying to sell them a catboat.Going with a familiar
underbody shape with something of a comprimise shoal keel and a spade
rudder,I'm sure,goes a long way toward winning them over.Add a ton of
square feet with high-tech reefing gizmos to calm any nervous thoughts
of dealing with one huge sail and toss in first class construction
standards and hey,you just about have them!
Anyway Peter,I'm no racer and I certainly do not have hard numbers
to back up my suggestion.It is more a broad general feeling I have
each time I grab onto my tiller,especially after once trying to sail
my MICRO without the mizzen........talk about frustration!
Sincerely,
Peter Lenihan,amateur lover of yawls,from the shores of the
St.Lawrence...........
--- In bolger@y..., pvanderw@o... wrote:
>
> I'm not sure why you think so, Peter. What is your reasoning?
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Hi Peter,
Well,I first think about the Cape Cod catboats which need those
huge barn door rudders and either long tillers or wheels to
control.And this despite the variable geometry of the centerboard.That
is,the ability to shift the CLR.
With a mizzen,especially in the yawl category,the CE can be brought
further back,the relative size of the main reduced and the rudder area
also reduced.This is perhaps most benificial to fixed geometry
underbody shapes which really can't shift their CLRs.
None of this is meant to suggest that Ellis did not know what he
was doing.I've long admired the three examples of the NONSUCH at my
club.They are beautiful boats,superbly built,incredibly roomy and very
expensive..............I wish I had one!
I suppose it is a tough act catering to a public brought up on
sloops and trying to sell them a catboat.Going with a familiar
underbody shape with something of a comprimise shoal keel and a spade
rudder,I'm sure,goes a long way toward winning them over.Add a ton of
square feet with high-tech reefing gizmos to calm any nervous thoughts
of dealing with one huge sail and toss in first class construction
standards and hey,you just about have them!
Anyway Peter,I'm no racer and I certainly do not have hard numbers
to back up my suggestion.It is more a broad general feeling I have
each time I grab onto my tiller,especially after once trying to sail
my MICRO without the mizzen........talk about frustration!
Sincerely,
Peter Lenihan,amateur lover of yawls,from the shores of the
St.Lawrence...........
Well,I first think about the Cape Cod catboats which need those
huge barn door rudders and either long tillers or wheels to
control.And this despite the variable geometry of the centerboard.That
is,the ability to shift the CLR.
With a mizzen,especially in the yawl category,the CE can be brought
further back,the relative size of the main reduced and the rudder area
also reduced.This is perhaps most benificial to fixed geometry
underbody shapes which really can't shift their CLRs.
None of this is meant to suggest that Ellis did not know what he
was doing.I've long admired the three examples of the NONSUCH at my
club.They are beautiful boats,superbly built,incredibly roomy and very
expensive..............I wish I had one!
I suppose it is a tough act catering to a public brought up on
sloops and trying to sell them a catboat.Going with a familiar
underbody shape with something of a comprimise shoal keel and a spade
rudder,I'm sure,goes a long way toward winning them over.Add a ton of
square feet with high-tech reefing gizmos to calm any nervous thoughts
of dealing with one huge sail and toss in first class construction
standards and hey,you just about have them!
Anyway Peter,I'm no racer and I certainly do not have hard numbers
to back up my suggestion.It is more a broad general feeling I have
each time I grab onto my tiller,especially after once trying to sail
my MICRO without the mizzen........talk about frustration!
Sincerely,
Peter Lenihan,amateur lover of yawls,from the shores of the
St.Lawrence...........
--- In bolger@y..., pvanderw@o... wrote:
>
> I'm not sure why you think so, Peter. What is your reasoning?
> The NONSUCHs weather helm would be much improved by the simpleI'm not sure why you think so, Peter. What is your reasoning?
> addition of a mizzen......
To some extent, weather helm comes with a cat rig at no extra charge.
The center of effort moves around too much as the boom swings for it
to be otherwise. On the other hand, off the wind you can reduce
weather helm quite a lot from what you get with optimum sail trim if
you are willing to trim the sail for the optimum of BOTH sail and
helm. It is somewhat counter-intuitive, at least to me, but over-
trimming reduces weather helm.
This is not true on a sloop. On a sloop, the main is behind the
center of lateral resistance and increasing side force increases
weather helm. On a cat, the main is in front of the CLR, and side
force reduces weather helm.
On the wind, the boat should be well balanced. If weather helm is
excessive, you probably have too much sail up and are heeling too
much. Reef.
Peter
Andy,
The NONSUCHs weather helm would be much improved by the simple
addition of a mizzen......like the MICRO family of boats.Our Hero
Phil thinks of everything and for a small fraction of the outrageous
price of the NONSUCH.
Sincerely,
Peter Lenihan,from the shores of the very mild St.Lawrence........
The NONSUCHs weather helm would be much improved by the simple
addition of a mizzen......like the MICRO family of boats.Our Hero
Phil thinks of everything and for a small fraction of the outrageous
price of the NONSUCH.
Sincerely,
Peter Lenihan,from the shores of the very mild St.Lawrence........
--- In bolger@y..., amoore@h... wrote:
> Don, sounds interesting I have looked at the Micro and Long Micro
but
> having sailed Nonsuchs and not been happy with the nock down weather
> helm I steered away from them.
>
> > I set it out roughly, and my sailing neighbour said.."What about
> > downwind tracking, should be interesting?" Meaning she may take
> > control downwind.
> A little extra bow up forward might reduce the nock down weather
helm
> problem alittle.
>
> Andy Moore
> Nova Scotia
> Canada
Don, sounds interesting I have looked at the Micro and Long Micro but
having sailed Nonsuchs and not been happy with the nock down weather
helm I steered away from them.
problem alittle.
Andy Moore
Nova Scotia
Canada
having sailed Nonsuchs and not been happy with the nock down weather
helm I steered away from them.
> I set it out roughly, and my sailing neighbour said.."What aboutA little extra bow up forward might reduce the nock down weather helm
> downwind tracking, should be interesting?" Meaning she may take
> control downwind.
problem alittle.
Andy Moore
Nova Scotia
Canada
I was very interested to see the file about Summer Ease in Bolger2.
My Micro is being changed to a Navigator, and I had already decided
to form a rounded vee-bow, very similar to Summer Ease, before re-
launching.
My main purpose is to reduce the death-pounding that Micro subjects
herself to on an exposed mooring.
I set it out roughly, and my sailing neighbour said.."What about
downwind tracking, should be interesting?" Meaning she may take
control downwind. I am not really worried about that however,
because she will still be a short and quite blunt bowed boat. The
extra "chest" I believe will actually force her to lift rather than
knife into the waves downwind.
I shall leave the original flat bottom in place, extend the stem down
and build a cedar and moulded ply rounded bottom between the chine
and the new keel line.
Should be interesting.
DonB
My Micro is being changed to a Navigator, and I had already decided
to form a rounded vee-bow, very similar to Summer Ease, before re-
launching.
My main purpose is to reduce the death-pounding that Micro subjects
herself to on an exposed mooring.
I set it out roughly, and my sailing neighbour said.."What about
downwind tracking, should be interesting?" Meaning she may take
control downwind. I am not really worried about that however,
because she will still be a short and quite blunt bowed boat. The
extra "chest" I believe will actually force her to lift rather than
knife into the waves downwind.
I shall leave the original flat bottom in place, extend the stem down
and build a cedar and moulded ply rounded bottom between the chine
and the new keel line.
Should be interesting.
DonB