Re: T spars
What do you mean by a T spar? A spar for a spirit leg of mutton sail on
most of Bolger's designs is round or a square section and the forward end is
held in a snotter. If you are asking about a T section spar (If cut in the
center the cross section would form a T shape) I think just a wood stick the width
of what is called for and a similar piece glued on the bottom standing
vertical to the main spar.
On the other hand Fred Shell does a leg of mutton sail where the spirit does
not go forward of the mast as it does with a snotter. Fred's spirits are
curved so that the sail takes the same form from which either side the wind
comes from. The forward end has a T. This T is a shorter stick that is crossways
to the spirit and secured with one screw so it can pivot a bit. This part is
notched near the ends so it can be held by the sail lacings to the mast.
I have sailed both types, The Fred Shell system does not have that
distortion in the sail that a straight spirit gives you on one tack or the other, but
I never noticed on my Car Topper any difference on either tack and that boat
has the Bolger system with the snotter. I think on the whole I prefer the
snotter as with that you have a line to tighten the spirit boom to flatten or
let the sail take a more effective curve.
John Meacham
************************************** See what's free athttp://www.aol.com
[Non-text portions of this message have been removed]
most of Bolger's designs is round or a square section and the forward end is
held in a snotter. If you are asking about a T section spar (If cut in the
center the cross section would form a T shape) I think just a wood stick the width
of what is called for and a similar piece glued on the bottom standing
vertical to the main spar.
On the other hand Fred Shell does a leg of mutton sail where the spirit does
not go forward of the mast as it does with a snotter. Fred's spirits are
curved so that the sail takes the same form from which either side the wind
comes from. The forward end has a T. This T is a shorter stick that is crossways
to the spirit and secured with one screw so it can pivot a bit. This part is
notched near the ends so it can be held by the sail lacings to the mast.
I have sailed both types, The Fred Shell system does not have that
distortion in the sail that a straight spirit gives you on one tack or the other, but
I never noticed on my Car Topper any difference on either tack and that boat
has the Bolger system with the snotter. I think on the whole I prefer the
snotter as with that you have a line to tighten the spirit boom to flatten or
let the sail take a more effective curve.
John Meacham
************************************** See what's free athttp://www.aol.com
[Non-text portions of this message have been removed]
I think Bolger also mentions a bit of end plate effect for the
sail.....
--- Inbolger@yahoogroups.com, "graeme19121984" <graeme19121984@...>
wrote:
sail.....
--- Inbolger@yahoogroups.com, "graeme19121984" <graeme19121984@...>
wrote:
>was
> IIRC a while ago on the dwforum group's list someone asked
> about "cross", and Tom Jone's "X" sectioned spars. I think Tom H
> supplied the numbers relative to round and square sections. Round
> best, followed not too far behind by square, but then there wassection
> daylight between the rest!
>
> From the same amount of wood a hollow square (or rectangular)
> was much better (stronger) than a cross, and not a lot harder tosometimes
> fabricate. Nevertheless, if you look at PCB's sparring you'll
> see narrow T or + stiffeners used to stiffen a wider sparperpendicular
> to the main stress. A lot of times though these are serving anywayas
> something to put a hole through to position a line on the spar. HTHtracking
>
> Graeme
>
>
> --- Inbolger@yahoogroups.com, "sierraclb1728" <josh1728@> wrote:
> >
> > Hello all,
> > I've tried a few internet searches but have had no luck
> > down information regarding the construction of a T-spar that canbe
> > used as a boom, and possibly as a gaff. This is for a Micro-sized
> > boat.
> > Thanks,
> > Josh in California
> >
>
Josh,
relative is the word. Depends on what with what.
Four pieces of half-by-four costs near or exactly the same, is the
same amount of timber, but is much stronger joined into a box
section. The T section has simpler construction relative to the box,
but the box isn't all that hard. The box section can be much lighter
for a given strength, and weight aloft has a large adverse effect on
a sailboat under sail. Ross Lilistone has long experimented with box
sectioned spars of tapered timber staves top and bottom with ply
sides and reckons they're very good for the job. That's a high
recommendation IMHO.
I can't recall anything particularly on the net that I could direct
you to for more on PCB's T-, or partial + sectioned gaffs, yards,
and booms other than to look closely at his sailplans generally.
For example, three somewhat comparable gaff mainsail rigged boats of
the same 19' 6" length spread over about thirty years:
In Otter the 84sqft mainsail 9' 6" boom has cap of 3/4" by 3 1/2" on
a T leg of 3/4" by 2" (I would have thought the stresses worked the
other way?) and the verticle 9' 8" gaff is a 1 1/2" plank tapered to
3/4"square;
Later in Otter ll the 148sqft mainsail 14' 3" sprit (compression
only) is 2 1/2" square, but may be a box with 1/2" walls, and the
nearer horizontal than verticle gaff is still a plank tapered from
2" square;
Later still in the AS-19 the 157sqft mainsail spars, 13' top and 14'
bottom, both seem spec'd to be of box section.
All the booms are more or less end sheeted, only the peak hoist of
Otter ll is spread by two parts.
Graeme
relative is the word. Depends on what with what.
Four pieces of half-by-four costs near or exactly the same, is the
same amount of timber, but is much stronger joined into a box
section. The T section has simpler construction relative to the box,
but the box isn't all that hard. The box section can be much lighter
for a given strength, and weight aloft has a large adverse effect on
a sailboat under sail. Ross Lilistone has long experimented with box
sectioned spars of tapered timber staves top and bottom with ply
sides and reckons they're very good for the job. That's a high
recommendation IMHO.
I can't recall anything particularly on the net that I could direct
you to for more on PCB's T-, or partial + sectioned gaffs, yards,
and booms other than to look closely at his sailplans generally.
For example, three somewhat comparable gaff mainsail rigged boats of
the same 19' 6" length spread over about thirty years:
In Otter the 84sqft mainsail 9' 6" boom has cap of 3/4" by 3 1/2" on
a T leg of 3/4" by 2" (I would have thought the stresses worked the
other way?) and the verticle 9' 8" gaff is a 1 1/2" plank tapered to
3/4"square;
Later in Otter ll the 148sqft mainsail 14' 3" sprit (compression
only) is 2 1/2" square, but may be a box with 1/2" walls, and the
nearer horizontal than verticle gaff is still a plank tapered from
2" square;
Later still in the AS-19 the 157sqft mainsail spars, 13' top and 14'
bottom, both seem spec'd to be of box section.
All the booms are more or less end sheeted, only the peak hoist of
Otter ll is spread by two parts.
Graeme
--- Inbolger@yahoogroups.com, "sierraclb1728" <josh1728@...> wrote:
> The idea is to
> take two long pieces of one-by-four lumber, for example, and
fasten
> them together lengthwise so that in cross-section, they look like
a
> T. They are strong compared to the size of lumber used to
construct
> them because no matter which way you try to bend them, you're
always
> trying to bend one of the joined pieces in line with it's wide
> dimension. A clever use of less-expensive materials to make a
> relatively strong spar.
I should have been more clear. And I thought T-spar was a widely
accepted (and descriptive) term.
The spar I'm talking about can be used as a boom in a gaff rig -- I
know the terminology well enough (I'm not talking about a leg-o-mutton
sail) and I actually clapped eyes on this animal a while back but am
seeking info regarding construction, dimensions, etc. It can be used
virtually anywhere a round or square spar can be used. The idea is to
take two long pieces of one-by-four lumber, for example, and fasten
them together lengthwise so that in cross-section, they look like a
T. They are strong compared to the size of lumber used to construct
them because no matter which way you try to bend them, you're always
trying to bend one of the joined pieces in line with it's wide
dimension. A clever use of less-expensive materials to make a
relatively strong spar.
Sorry if I sounded testy at the beginning.
accepted (and descriptive) term.
The spar I'm talking about can be used as a boom in a gaff rig -- I
know the terminology well enough (I'm not talking about a leg-o-mutton
sail) and I actually clapped eyes on this animal a while back but am
seeking info regarding construction, dimensions, etc. It can be used
virtually anywhere a round or square spar can be used. The idea is to
take two long pieces of one-by-four lumber, for example, and fasten
them together lengthwise so that in cross-section, they look like a
T. They are strong compared to the size of lumber used to construct
them because no matter which way you try to bend them, you're always
trying to bend one of the joined pieces in line with it's wide
dimension. A clever use of less-expensive materials to make a
relatively strong spar.
Sorry if I sounded testy at the beginning.
> Thanks,
> Josh in California
>
I think you're tolking about a type of leg'o mutton sprit sail. The part you describe is the sprit. I've seen images of the rig but never a real one. I think the cross on the "T" is a piece in a sleeve with the end of the sprit stuck in a center hole.
----- Original Message -----
From: sierraclb1728
To:bolger@yahoogroups.com
Sent: Friday, April 06, 2007 5:21 PM
Subject: [bolger] T spars
Hello all,
I've tried a few internet searches but have had no luck tracking
down information regarding the construction of a T-spar that can be
used as a boom, and possibly as a gaff. This is for a Micro-sized
boat.
Thanks,
Josh in California
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[Non-text portions of this message have been removed]
IIRC a while ago on the dwforum group's list someone asked
about "cross", and Tom Jone's "X" sectioned spars. I think Tom H
supplied the numbers relative to round and square sections. Round was
best, followed not too far behind by square, but then there was
daylight between the rest!
From the same amount of wood a hollow square (or rectangular) section
was much better (stronger) than a cross, and not a lot harder to
fabricate. Nevertheless, if you look at PCB's sparring you'll sometimes
see narrow T or + stiffeners used to stiffen a wider spar perpendicular
to the main stress. A lot of times though these are serving anyway as
something to put a hole through to position a line on the spar. HTH
Graeme
about "cross", and Tom Jone's "X" sectioned spars. I think Tom H
supplied the numbers relative to round and square sections. Round was
best, followed not too far behind by square, but then there was
daylight between the rest!
From the same amount of wood a hollow square (or rectangular) section
was much better (stronger) than a cross, and not a lot harder to
fabricate. Nevertheless, if you look at PCB's sparring you'll sometimes
see narrow T or + stiffeners used to stiffen a wider spar perpendicular
to the main stress. A lot of times though these are serving anyway as
something to put a hole through to position a line on the spar. HTH
Graeme
--- Inbolger@yahoogroups.com, "sierraclb1728" <josh1728@...> wrote:
>
> Hello all,
> I've tried a few internet searches but have had no luck tracking
> down information regarding the construction of a T-spar that can be
> used as a boom, and possibly as a gaff. This is for a Micro-sized
> boat.
> Thanks,
> Josh in California
>
Hello all,
I've tried a few internet searches but have had no luck tracking
down information regarding the construction of a T-spar that can be
used as a boom, and possibly as a gaff. This is for a Micro-sized
boat.
Thanks,
Josh in California
I've tried a few internet searches but have had no luck tracking
down information regarding the construction of a T-spar that can be
used as a boom, and possibly as a gaff. This is for a Micro-sized
boat.
Thanks,
Josh in California