where do you measure boom size?
Doug Smith
If a sail needs a "7 feet 3 inch" boom, what *EXACTLY* does that mean?
Does one measure from the front of the mast clamp to the inside edge of
the outhaul pullies? Or is it from the rear of the mast clamp (big
difference)? Or something else? I ask because I'm trying to find the
largest sail that can fit my boom. Thanks.
-Doug
sailquik (Roger Jackson)
>Does one measure from the front of the mast clamp to the inside edge of
>the outhaul pullies?
Doug:
I believe the industry measures boom length fron the inside of the boom end
to the front of the mast. I know this works on North, Sailworks and
Windwing.
But, it's not quite that simple. You need to have a range of at least an
inch or two beyond the specified or suggested boom length, and it usually
is not a good idea to run your booms fully extended as they are weaker
ad will flex significantly more.
I'd think you'd perhaps want a boom that will go 4-6" longer than your the
specs for your longest boom length sail.
Nothing sucks worse than being out on the water, overpowered, and have no
extra boom length in reserve to depower the sail as you downhaul more.
later
sailquik (Roger Jackson) US 3704 (301)872-9459 (In MD)
F2/North/Sailworks/Tectonics/True Ames (919)995-3204 (In Hatteras)
Lvl 1 WS Instructor
Email: sailquikmail.ameritel.net (In MD)
sail...@interpath.com (In Avon N.C.)
Bruce Peterson
We measure the boom length from the back of the clew to the front of
the mast AT THE MIDDLE OF THE BOOM OPENING. This length gets longer
if you measure at the top or bottom of the boom opening.
Bruce Peterson
Sailworks R+D
NLW TFW NM
Inside length. But don't rely on the sailmaker's published boom (or mast)
length requirements. I've seen mast requirements off by well over a foot (30
cm), and I'm sure some boom lengths are way off, too. Rig before you buy, or at
least make sure the manufacturer or your source swears you can return the sail
if their frame specs are off.
Mike \m/
Never Leave Wind To Find Wind
Vesa Kuusava
sail...@gorge.net (Bruce Peterson) wrote:
But where do you measure the mast length?
I have had quite a many Sailworks sails and they seem to
need a lot longer mast than suggested in a broshure.
Usually appr. <20-25cm longer. Why? Other sailmakers don't
seem to have the same phenomenon.
Ocku Kuusava
Sailworks R+E (rig+enjoy)
Bruce Peterson
Our rigging instructions and sail specifiactions show the nominal
rigged mast length and the recommened mast. There two values are
rarely the same length. For example the 6.5 Retro rigs with 487 cm
luff length, but we specify a 460/25 mast as the mast of choice for
this sail size. Perhaps this is where the confusion in mast length
arises.
Specifically we measure the rigged luff length from the top of the
mast at the shortest optimal headcap setting, around the front of the
mast to a point along the front of the mast opposite the rollers of
the tack pulley (or grommet) where the downhaul rope turns. To
duplicate this setting, ensure that your headcap is set as low as
possible (while still allowing the tack to be pulled completely down
to the mast base cleat), subtract your mast's length from the sail's
specified mast length to detirmine the amount of extension needed. If
your mast is longer than the sail's luff length, the resulting
difference will be the amount of headcap extension needed.
For more information check out the detailed rigging instructions on
our web page at: www.sailworks.com
Bruce Peterson
Sailworks R+D
Güven Kais
Bruce Peterson wrote:
> snip
> Bruce Peterson
> Sailworks R+D
>
I think it is a good idea to put this information specially
WHERE to MEASURE THE BOOM LENGTH
in the booklets which comes with the sails. (I am still not sure what you
meant by
"back of the clew" is this the sails or booms clew?)
It took me 5-6 days to figure out the outhaul setting of my 7.5 Retro.
Because, I had no idea that it was measured FROM the FRONT of the
mast and not the back. I measured first time when I rigged the sail and
set it to the minimum setting (~214cm) and the sail looked too flat so,
rigged it as it felt/looked good to me.
PS: what is the (if there is one) of the water trick (rigging trick) to
make the 7.5 to point better.
Regards,
Guven Kais
sjh...@wsicorp.com
In article <3548956e...@news.alt.net>#1/1,
sail...@gorge.net (Bruce Peterson) wrote:
>
> We measure the boom length from the back of the clew to the front of
> the mast AT THE MIDDLE OF THE BOOM OPENING.
>
Bruce,
Is this then the maximum boom length we should use when
rigging or is it the average (or min)?
Thanks
Steven J. Honey
Weather Services International
Billerica, Ma
BTW, I think its great that yourself and Bill Hanson read this newsgroup.
There is no better way to get information then to go directly to
the source.
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Bruce Peterson
Guven,
The boom length is measured from the back, outside corner of the clew
to the front of the mast at the middle of the boom opening. We do
this by standing at the luff side and hooking a tape measure over the
webbing behind the clew grommet and then sighting the length
perpendicular to the front of the mast. This length should correspond
to the actual inside length of your boom. Remember that this length
is for the middle of the boom opening. If you are rigging at the top
or bottom of the opening then the actual boom length could be up to 2
cm longer. Also remember that if you are using an adjustable outhaul
system (highly recommended) that your boom length may be longer still
to allow for further outhauling for top-end conditions.
To increase the windward ability of the Retro it is essential to use
the adjustable outhaul system provided. Set your downhaul to the
medium to tight setting. Run the outhaul as full as you can
comfortably hold down. As the wind increases you will need to flatten
the sail with outhaul. This tighten and leans out the foil which
gives it better drive. The key to pointing well is to first get fully
powered up (fuller sail, less outhaul) and then once fully powered up
trim back the sail for better top end control (flatter sail, more
outhaul).
Bruce Peterson
Sailworks R+D
Güven Kais
Bruce Peterson wrote:
> Guven,
>
> The boom length is measured from the back, outside corner of the clew
> to the front of the mast at the middle of the boom opening. We do
>
> snip
> To increase the windward ability of the Retro it is essential to use
> the adjustable outhaul system provided. Set your downhaul to the
> medium to tight setting. Run the outhaul as full as you can
> comfortably hold down. As the wind increases you will need to flatten
> the sail with outhaul. This tighten and leans out the foil which
> gives it better drive. The key to pointing well is to first get fully
> powered up (fuller sail, less outhaul) and then once fully powered up
> trim back the sail for better top end control (flatter sail, more
> outhaul).
>
> Bruce Peterson
> Sailworks R+D
Thanks Bruce,
I will definitely fit the outhaul system. and give it a try.
--
Guven Kais
ta...@sussex.ac.uk
Thermo Fluid Mechanics Research Centre,
The University of Sussex, Brighton, UK.
jodirb...@gmail.com
> If a sail needs a "7 feet 3 inch" boom, what *EXACTLY* does that mean?
> difference)? Or something else? I ask because I'm trying to find the
> largest sail that can fit my boom. Thanks.
> -Doug