Mast track position
Scott R. Nelson
searching), and I want to get a little more serious about longboard
sailing. (Short board fanatics don't worry, I'll be spending a lot
of time on my Astro Rock too.)
The Alpha 375, being basically the same as an earlier version of the
Fanatic MegaCat, has an adjustable mast track about 18" long. I've
read all about proper mast positioning, but I still can't remember
exactly when I want to move the mast forward or back.
As I understand it, when I'm in planing conditions, I want the mast
track all the way back. When I'm going upwind, I want it all the
way forward. If I can understand why, it will be a lot easier for
me to remember where to place it.
Are there other times that I should place it all the way forward besides
when goind upwind?
Are there other times that I should place it all the way back than when
planing across the wind?
Are there times when I want it somewhere in the middle?
Any and all explanations of mast track positioning for long boards
would be appreciated.
---
Scott R. Nelson srne...@speedsail.eng.sun.com
Sun Microsystems
BIC Astro Rock (9'4"), Alpha 375 (12'4") wide variety of sails, etc.
"This year I get serious about windsurfing". (That's what I said last year.)
Tim Sercombe
> position is all to do with wetted area. Upwind, you want to maximaise
> this (something to do with lateral resistance)and therefore you want
> the mast track all the way forward. However, on reaching, you want to
> maximise speed and therefore minimise wetted area. This means mast track
> all the way back.
>
> What I have just outlined applies to fully powered up and planning
> conditions. Now since very few of us sail in these conditions (we prefer
> shortboards) that may not be of any use. So, take this as a rule of
> thumb:
>
> 1) Keep mast track in approx. center in VERY light winds and do not move
> it forward or back. Also, centre board will probably always be down. The
> only exception to this is maybe going straight down wind...
> 2) As the wind increases, move the track furhter forward of upwind and
> further back of reaching (but not all the way). Just a note about
> bringing it back. If you find that you are just off full planing (ie.
> not quite in the straps) move the mst forward a notch or two, this often
> allows the board to accelerate slightly.
>
> I hope this is of some help and others feel free to critise.
>
> Happy sailing
>
> Tim
>
> I'm not an expert but it's fun pretending.
Andrew Heron
Tim Dierauf
>Scott R. Nelson wrote:
>>
>> I just received my new Alpha 375 (Cat) yesterday (after months of
>> searching), and I want to get a little more serious about longboard
>> sailing. (Short board fanatics don't worry, I'll be spending a lot
>> of time on my Astro Rock too.)
>>
>> The Alpha 375, being basically the same as an earlier version of the
>> Fanatic MegaCat, has an adjustable mast track about 18" long. I've
>> read all about proper mast positioning, but I still can't remember
>> exactly when I want to move the mast forward or back.
>>
>As I understand it (and I'm open to correction) the theory of mast
>position is all to do with wetted area. Upwind, you want to maximaise
>this (something to do with lateral resistance)and therefore you want
>the mast track all the way forward. However, on reaching, you want to
>maximise speed and therefore minimise wetted area. This means mast track
>all the way back.
Lateral resistance is important, especially when we rail the board (ie.
bury the leeward rail). Thus, we get lift from the center board and the
entire rail. However, the most important reason for running the mast
forward and increasing the wetted length is to increase hull speed. Hull
speed, which is the top speed a vesel can go without planing, is solely a
function of length. This is why those freighters crank on by in SF Bay
even though they are not planning.
Most course boards will not plane when beating up wind, even if the
conditions will allow planing at other points of sail. Thus we maximize
hull speed (non-planing speed) by running the mast track up.
When planning, pull the mast all the way back to minimize wetted area.
When in light air, you need to find a good balance for all points of
sail. If your mast is too far forward, you will bury the bow slightly.
If too far back, you will drag your tail. The optimum position depends
on you and your board. For light air on my Equipe (1987 vintage), I
would pull the track around 4" back from the top.
Also when in light air, keep your center board down in all points of
sail. You will learn how to use it to skull through the swells and pivot
tight turns.
I strongly recommend participateing in any races that occur localy. I
lived in San Diego for four years and was totaly bored (I moved there
from San Francisco) until I bought a Windsurfer One Design, an Equipe and
started racing. Not only was it a ton of fun, but I learned a totaly new
element of our sport.
Again, happy sailing
Tim Dierauf
CSU
Fort Collins, CO
Paul Hester
>As I understand it, when I'm in planing conditions, I want the mast
>track all the way back. When I'm going upwind, I want it all the
>way forward. If I can understand why, it will be a lot easier for
>me to remember where to place it.
That's basically it. The further forward the mast track is, the
quicker the board is to plane, but the top-speed is reduced. As the
mast track is moved back, so top speed is increased, but the board will
be slower to plane. Why ? Putting the MT forward flattens off the
board, thus helping to plane initially, whereas when it's at the back,
the tail tends to dig in a bit, reducing early planing. Top speed is affected
by wetted area. With the MT forward, the nose is presses down, which means
there is a large wetted area (hence lots of drag). With the MT back, the
nose can lift somewhat, and reduce the wetted area, which in turn increases
top speed. So the mast track position on a reach depends on wind-speed
(don't put the MT right back unless powered up).
On a run, the board should be kept as flat as possible for max speed,
so the MT should be forward to help this.
Upwind, you need the board flat so that whole (leeward) rail digs
in to prevent side-slip, so MT forward. But then the board rails
& I haven't a clue where the MT is meant to be then!!!
Hope that helps.
--
Paul
pa...@cpsl.demon.co.uk
Martin Farrimond
Generally, I agree with almost all that's been said. However, there are
times when beating upwind when you'll want the mast some way back from
the front of the track.
1) When there is swell, you may find the nose burying in the backs of the
swell which is going to slow you down. Bringing the mast back help raise
the nose & thus clear the swell better.
2) As already mentioned in this thread, the most efficient way of getting
a longboard upwind is by railing it (dipping the leeward rail to give
more lateral resistance). You'll find that having the mast back
facilitates railing.
3) The Mistral Equipe II HATES having the mast right at the front in any
conditions! I never have the mast more than 2/3'rds way forward. However,
on the Alpha 375 (which I used to sail as a 1990 version Ultra Cat), you
can have the track right forward.
4) On a run in light winds - again, bring the mast back to prevent the
nose burying. In planing winds, bring it further back, grit your teeth,
raise the daggerboard & close your eyes!
Join a club, get involved with racing as Tim suggested. Racing against
others & talking to them is the best way of learning.
Happy tracking,
Martin Farrimond
K-62
Q
>
> I just received my new Alpha 375 (Cat) yesterday (after months of
> searching), and I want to get a little more serious about longboard
> sailing.
> The Alpha 375, being basically the same as an earlier version of the
> Fanatic MegaCat, has an adjustable mast track about 18" long. I've
> read all about proper mast positioning, but I still can't remember
> exactly when I want to move the mast forward or back.
> Scott R. Nelson srne...@speedsail.eng.sun.com
What Tim said sounds right to me. You may also want to find a copy
Windsurfing Mag. June '93. It has an article on course board racing by
Mike Gebhardt that details how to sail a longboard best. I find the
article a bit much as I don't use the back reaching straps or the front
upwind staps for example, but the concepts should help. If you can't find
it let me know and I can mail you a copy.
Mach 10 and Windy Too. KPG
NCSU Chemistry
NCSU Windsurfing
Raleigh, N.C.
Peter Somlo
>Upwind, you need the board flat so that whole (leeward) rail digs
>in to prevent side-slip, so MT forward.
>Hope that helps.
>--
>Paul
>pa...@cpsl.demon.co.uk
In my experience, in non-planing upwind slogs on a centerboard-less
board, it is better to tilt the board (10-15 deg.) into (not leeward)
the wind. The rocker of the board will also then help to steer upwind.
I have objective evidence to prove this: just look behind you to see
your track of bubbles etc, and then tilt the board a bit into the
wind. Immediadely you'll change course going higher. To do this,
you'll have to bring the rig more foreward, because the c.o.r. of the
board has moved forward.
Cheers, Peter
--
Dr Peter I Somlo FIEEE | M1: "Every coin has 3 sides - at least"
Microwave Consultant | M2: "The wind ain't gonna blow from where it
tel/fax: 61-2-451-2478 | ought'a, it'l blow from where it can"
Mobile: 041-926-3168 | http://www.zeta.org.au/~somlo
Martin Farrimond
>Paul Hester <pa...@cpsl.demon.co.uk> wrote:
>In my experience, in non-planing upwind slogs on a centerboard-less
>board, it is better to tilt the board (10-15 deg.) into (not leeward)
>the wind. The rocker of the board will also then help to steer upwind.
>I have objective evidence to prove this: just look behind you to see
>your track of bubbles etc, and then tilt the board a bit into the
>wind. Immediadely you'll change course going higher. To do this,
>you'll have to bring the rig more foreward, because the c.o.r. of the
>board has moved forward.
>Cheers, Peter
<snip>
It's true that on a shortboard you'd usually want to bank the board as
though steering into the wind, but on a longboard like the Fanatic Cat
which te originator of this thread was sailing, you really do want to get
it to rail ie: dip the leeward rail.
PS: You also will need to consider the use of the daggerboard. Normally,
beating upwind, you'll want it down as far as possible with (in my
opinion) the track a couple of notches back from the front (to facilitate
railing). Once the wind starts to howl, you're going to need to start
retracting the daggerboard to reduce the tendency to capsize. On the
Equipe II, when the wind is really howling (relative to a 7.5m2 race
sail), I do away with daggerboard altogether, bring the mast almost to
the back of the track, & plane upwind the fin.
Keep experimenting, find what suits you.
Martin Farrimond
K-62
Paul Hester
>>in to prevent side-slip, so MT forward.
>
>board, it is better to tilt the board (10-15 deg.) into (not leeward)
>the wind. The rocker of the board will also then help to steer upwind.
>I have objective evidence to prove this: just look behind you to see
>your track of bubbles etc, and then tilt the board a bit into the
>wind. Immediadely you'll change course going higher. To do this,
>you'll have to bring the rig more foreward, because the c.o.r. of the
>board has moved forward.
But the Cat HAS a daggerboard. When going upwind, the daggerboard
always be down. The daggerboard will produce lift when the
board is tilted (eith way). Tilting so that the leeward rail digs in
to the water means the lift from the daggerboard pushes the board
more upwind. And at higer speeds, the board windward rail will
lift out of the water as a direct result of the lift generated by
the daggerboard. This reduces wetted area and the board goes
balls-out upwind. Steering is a bitch in these conditions :)
Without a daggerboard, it probably is better to sink the windward
rail as sinking the leeward rail may footsteer the board downwind.
However, race boards have real boxy rails so sinking the leeward
rail may still be better for going upwind (without daggerboard).
On a shortboard, I always sink the windward rail to slog upwind -
no question about that one.
--
Paul
pa...@cpsl.demon.co.uk