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Rod, I had a trim tab "locked" too and felt a heavy rudder. Turned out that the trim tab had moved slightly off center alignment due to slippage of trim tab shaft within a clamped fitting. You may note that the top edge of your rudder submerged while sailing, making it difficult to ascertain that the trim tab is in fact aligned with rudder. Good luck.
Mark
"Itchen"
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Rod, my trim tab is similar to yours but because of the system it uses, the tab can rotate freely(when disengaged). However, I do feel that it gives a little weather helm despite its ability to line up with the laminar water flow. I suppose a bare one inch diameter tube would have some effect, however slight.
As an indication of just how sensitive the presence of tab is, I at one time put a 3/4 inch leading edge ahead of the tab's vertical axel in an attempt to make the tab more powerful and quicker acting. It worked a little too well and caused the the tab to be too sensitive; so much so that the more turbulent flow of water when motoring threw a tremendous lee helm to the point where you could hardly hold the tiller against the pressure.
So I can imagine that your tab is contributing to the weather helm you're experiencing. Can the tab 'freewheel'?
I will usually throw in a first reef when the winds go much above 15 knots (estimated), which let's her stand up a little more and usually picks up a 1/4 to 1/2 knot in speed.
I see from your pic that you have a Sabb prop. Can you tell me which diameter it is?
Also, congratulations on your launch. Well worth the work, huh?
dry decks and warm seas,
Stan on Waxwing
Rod Bruckdorfer wrote:
Sunday we sailed IDUNA for the first time. Our destination was Harborview Marina in Baltimore's Inner Harbor - a distance of about 15 miles. Prior to launching the boat, I locked the trim tab in alignment with the rudder to prevent it from turning while we backed - see attached photo. The photo was taken prior to IDUNA's launch and before locking the trim tab. During our sail, we felt the rudder was a little heavy. We discussed the rudder and theorized the locked trim tab resulted in an increased rudder volume. We also experienced some weather helm as we broad reached for Baltimore. We would have taken a reef in the main, but had not had time to rig the reefing lines. Estimated wind speed was 10 knots. Sail combination was main, staysail and yankee or about 580 sq. ft. of canvas. Does anyone have a similar experience when the tim tab is locked?
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Stan;
for some reason your email didn’t load properly on my computer. As
I am currently deciding which kind of self steering to purchase for my
new BCC I’m very interested in learning about the freehand which seems
to be the most popular one. Does it introduce additional weather helm ?
Can it be tuned out ?
Jim Hiller
Stan Roeder wrote:
Rod, my trim tab is similar to yours but because of the system it uses, the tab can rotate freely(when disengaged). However, I do feel that it gives a little weather helm despite its ability to line up with the laminar water flow. I suppose a bare one inch diameter tube would have some effect, however slight.
As an indication of just how sensitive the presence of tab is, I at one time put a 3/4 inch leading edge ahead of the tab's vertical axel in an attempt to make the tab more powerful and quicker acting. It worked a little too well and caused the the tab to be too sensitive; so much so that the more turbulent flow of water when motoring threw a tremendous lee helm to the point where you could hardly hold the tiller against the pressure.
So I can imagine that your tab is contributing to the weather helm you're experiencing. Can the tab 'freewheel'?
I will usually throw in a first reef when the winds go much above 15 knots (estimated), which let's her stand up a little more and usually picks up a 1/4 to 1/2 knot in speed.
I see from your pic that you have a Sabb prop. Can you tell me which diameter it is?
Also, congratulations on your launch. Well worth the work, huh?
dry decks and warm seas,
Stan on Waxwing
Rod Bruckdorfer wrote:
Sunday we sailed IDUNA for the first time. Our destination was Harborview Marina in Baltimore's Inner Harbor - a distance of about 15 miles. Prior to launching the boat, I locked the trim tab in alignment with the rudder to prevent it from turning while we backed - see attached photo. The photo was taken prior to IDUNA's launch and before locking the trim tab. During our sail, we felt the rudder was a little heavy. We discussed the rudder and theorized the locked trim tab resulted in an increased rudder volume. We also experienced some weather helm as we broad reached for Baltimore. We would have taken a reef in the main, but had not had time to rig the reefing lines. Estimated wind speed was 10 knots. Sail combination was main, staysail and yankee or about 580 sq. ft. of canvas. Does anyone have a similar experience when the tim tab is locked?
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Stan:
Thanks for the insight. Our Sabb engines turns the larger of the two props available. Because previous owners had not set the propeller pitch stop screws, it is easy to over pitch the prop.
John Letcher, Jr. the author of Self-Steering for Sailing Craft discusses the size the tab in relationship to the rudder and states the tab lift X tab arm must equal the rudder lift X rudder arm to achieve effective steering. The effective tab area is called tab volume and is equal to the tab area X the tab arm. I believe what he means in our case is, The combined effect of the tab volume and rudder volume is approximately doubled when the tab is locked fore and aft. This must affect the balance of the boat, hence the early weather helm and the heaviness of the rudder. I suspect, if I did not lock the tab, the effect would be negligible. We need to lock the tab so we can back and when we dock the boat in her slip.
Fair Winds,
Rod
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Rod, I think I understand that your trim tab cannot
freewheel 360 degrees and that is the reason you
must have it locked fore and aft when you back down?
Okay, mine has a lever arm with a ‘drop pin’ sort of
connection that totally cuts the tab loose to
freewheel. So no problem when backing up.
And if I didn’t already, let me make it clear that
even with the ‘freewheeling’, there is enough pressure
(slight, but still there)put on the tab when motoring
forward that I only install the tab when about to make
a passage. The install/un install is quite simple with
a fast-pin connection release at the top of the tabs’
axel where it joins the rest of the unit at the
bumkin.Of course this also eliminates growth on the
tab. I do not feel the tab affects the helm under
sail.
I do not know the figures comparing effective areas of
the tab to rudder but mine does work. It would be
simple to check them out if I knew the area of the
rudder itself since the other figures are readily
available. I do know, however, that mine works quite
well.
I’ve thought that the ‘kick up’ type trim tabs have an
advantage of design over our type, but the blades
always looked so vulnerable hanging out there
unsupported at the bottom end. And although they do
apparently work very well, I do not like any vane set
up that requires lines criss crossing the cockpit area
to the tiller. I have the ability to easily remove the
tiller whens the vane is steering and like the ability
to completely clear the cockpit area. I suppose a
hinged tiller would also work but again, you could not
be using a vane that steers with lines to it.
The reason I asked about the diameter of your prop is
because I too have the larger (16.75 inch?) versus the
smaller (15 inch?). The larger leaves only a minimum
distance between the blade and the deadwood at the top
of the aperture and I can get a ‘thumping’ sound from
water being thrown against that area.
Stan, Waxwing
— Rod Bruckdorfer <seagypsy@att.net > wrote:
Stan:
Thanks for the insight. Our Sabb engines turns the
larger of the two props available. Because previous
owners had not set the propeller pitch stop screws,
it is easy to over pitch the prop.John Letcher, Jr. the author of Self-Steering for
Sailing Craft discusses the size the tab in
relationship to the rudder and states the tab lift X
tab arm must equal the rudder lift X rudder arm to
achieve effective steering. The effective tab area
is called tab volume and is equal to the tab area X
the tab arm. I believe what he means in our case
is, The combined effect of the tab volume and rudder
volume is approximately doubled when the tab is
locked fore and aft. This must affect the balance
of the boat, hence the early weather helm and the
heaviness of the rudder. I suspect, if I did not
lock the tab, the effect would be negligible. We
need to lock the tab so we can back and when we dock
the boat in her slip.Fair Winds,
Rod
----- Original Message -----
From: Stan Roeder
To: bcc@yahoogroups.com
Sent: Wednesday, July 25, 2001 6:12 AM
Subject: Re: [bcc] Rudder Trim TabRod, my trim tab is similar to yours but because
of the system it uses, the tab can rotate
freely(when disengaged). However, I do feel that it
gives a little weather helm despite its ability to
line up with the laminar water flow. I suppose a
bare one inch diameter tube would have some effect,
however slight.As an indication of just how sensitive the
presence of tab is, I at one time put a 3/4 inch
leading edge ahead of the tab’s vertical axel in an
attempt to make the tab more powerful and quicker
acting. It worked a little too well and caused the
tab to be too sensitive; so much so that the more
turbulent flow of water when motoring threw a
tremendous lee helm to the point where you could
hardly hold the tiller against the pressure.So I can imagine that your tab is contributing to
the weather helm you’re experiencing. Can the tab
‘freewheel’?I will usually throw in a first reef when the
winds go much above 15 knots (estimated), which
let’s her stand up a little more and usually picks
up a 1/4 to 1/2 knot in speed.I see from your pic that you have a Sabb prop. Can
you tell me which diameter it is?Also, congratulations on your launch. Well worth
the work, huh?dry decks and warm seas,
Stan on Waxwing
ATTACHMENT part 2 image/jpeg name=side view
07-14-01sm.JPG
ATTACHMENT part 3 image/jpeg name=Chris Brad and
IDUNA - Chesapeake.JPG
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Jim, my vane is a ‘Pathfinder’ made many years ago by
a guy in San Francisco who did not mass produce them.
While the majority of parts of the unit could be
bought ‘off the shelf’, it does include some custom
cast bronze pieces that would most likely be expensive
to duplicate. I could find no patent on it.
And if I ever get a digital camera (near the bottom of
the list) I’d love to get some pix of it to put here.
Getting a ‘new’ boat? What will the hull number be?
Stan, Waxwing
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Hi Stan,
I don’t know what number I’ll be. I think 119 is about to launch. Sumio
molded 120 for himself. I guess that will make me 121.
Looked at photos of your boat today. I have all of SMC’s photo albums I have
just looked the original photos of your boat.
Wow is it beautiful.
Have you put lots of miles under the keel ?
Jim
----- Original Message -----
From: Stan Roeder <waxwingers@yahoo.com >
To: <bcc@yahoogroups.com >
Sent: Thursday, July 26, 2001 12:54 PM
Subject: Re: [bcc] Rudder Trim Tab
Jim, my vane is a ‘Pathfinder’ made many years ago by
a guy in San Francisco who did not mass produce them.
While the majority of parts of the unit could be
bought ‘off the shelf’, it does include some custom
cast bronze pieces that would most likely be expensive
to duplicate. I could find no patent on it.
And if I ever get a digital camera (near the bottom of
the list) I’d love to get some pix of it to put here.Getting a ‘new’ boat? What will the hull number be?
Stan, Waxwing
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Jim, Yes, many miles. Never had the desire to go
around the world and so have been living on and
cruising her for the past 21 years. Most of the time
in the tropics (both coasts of Central America)and the
last 11 in the Caribbean. My mate of 35 years still
loves the boat and refuses to live ashore.
We are hull #22. It seems a very short time ago when
we picked up our bare hull from Sam and trailered it
north to San Francisco to finish her out. It’s ironic
that the only thing we had Sam install other than the
deck was the walestrake and covering board because I
wasn’t sure I could do that work back then.
But after we got beat up by hurricane Georges in
Puerto Rico (1998)it was just those two things (plus
the bulwark)that we sailed down to Trinidad to replace
and did it ourselves.
And one thing I’d like to note here is that during the
reconstruction we of course had to expose the hull to
deck joint, now 20 years old(hull layed up in '77).
And that joint was still perfect. Not a single
fastener showed signs of leakage around it despite a
lot of pressure put on the hull by a Panama Canal tug
in 1981; and of course a lot of time too.
So you can’t go wrong with your new BCC. To my mind
there is no other boat built with equal quality that
fulfills the need for blue water cruising so well. It
is big enough. It is fast enough. It will take care of
its crew when things get tough. And it’s so damn good
lookin’ it draws a crowd everywhere it goes.
Good luck with your new boat.
Stan, Waxwing
— James Hiller <jhiller@ameritech.net > wrote:
Hi Stan,
I don’t know what number I’ll be. I think 119 is
about to launch. Sumio
molded 120 for himself. I guess that will make me
121.
Looked at photos of your boat today. I have all of
SMC’s photo albums I have
just looked the original photos of your boat.
Wow is it beautiful.
Have you put lots of miles under the keel ?
Jim
----- Original Message -----
From: Stan Roeder <waxwingers@yahoo.com >
To: <bcc@yahoogroups.com >
Sent: Thursday, July 26, 2001 12:54 PM
Subject: Re: [bcc] Rudder Trim TabJim, my vane is a ‘Pathfinder’ made many years ago
by
a guy in San Francisco who did not mass produce
them.
While the majority of parts of the unit could be
bought ‘off the shelf’, it does include some
custom
cast bronze pieces that would most likely be
expensive
to duplicate. I could find no patent on it.
And if I ever get a digital camera (near the
bottom of
the list) I’d love to get some pix of it to put
here.Getting a ‘new’ boat? What will the hull number
be?Stan, Waxwing
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