Mastfoot placement

Mastfoot placement

Post by Jan Wille » Sat, 04 Jul 1998 04:00:00


I have seen several comments on mastfoot placement in the last couple of

weeks. But I'm getting the feeling something is very wrong with them.

I'm talking now about the "early planing=mastfoot far back" theory,
which
everyone is using. I talked with some other surfers and they didn't
understand
a thing of it.Here is what we came up with:

* Mastfoot far forward = bigger planing surface = early planing,
  but also a longer wet surface, resulting in a lower maximum speed
  and lowered manouvrability. Some claim they can jump more easily,
  some don't notice the difference.
* Mastfoot far backward = Small planing surface = very late planing
  but also a small wet surface = high speed and high manouvrability.
  In chop and waves the board is better controllable because of the
higher
  position of the nose.

And for the mastfoot trim:

* In light winds, place the mast as far forward as possible, and then
bit
by bit move it backwards until the board still starts planing easily and
the
manouvrability is acceptable, so (almost) planing jibes are no problems
anymore.

* In high winds, place the mast as far backwards as possible, and only
move it forward when you can't control the board anymore because it
is bouncing to all directions, or you just are scared sailing with
absurd speed.

* In chop the mast should be further back, preventing the diving of the
nose while
planing (Only quite flat boards)

Any comments?
--
Jan Willem Eckhardt
--------------------------|
Metal's my religion,      |
it's the only way to live |
--------------------------|--|

-----------------------------|----------|
http://www.zeelandnet.nl/people/eckhardt|
----------------------------------------|

 
 
 

Mastfoot placement

Post by sailquik (Roger Jacks » Sun, 05 Jul 1998 04:00:00

Quote:
>* Mastfoot far forward = bigger planing surface = early planing,
>  but also a longer wet surface, resulting in a lower maximum speed
>  and lowered manouvrability. Some claim they can jump more easily,
>  some don't notice the difference.

I think we are talking apples and oranges here. The original thread was
aobut early planing on early planing type boards. Not too many of us "Jump
early planing boards as they are very large, thick, and wide so the plane
early. Most of them would break if jumped much.
Boards with a rockerline designed for jumping (far different from those
designed to plane early) may respond better to having the mast foot
pressure futher forward.
Also, boards that are designed for B&J type sailing usually have some tail
rocker. Lite air planers have all the rocker forward and a short planing
flat aft. If you apply the mastfoot pressure too far forward, you drive
rocker into the water and defeat the planing flat. Makes for a very rough
slow ride.Even in flat water (very flat water  in <12 mph windspeed) if you
drive the rocker forward of the flat at the back into the water,  the board
planes later, and takes alt more wind to get on/maintain a plane.

Quote:
>* Mastfoot far backward = Small planing surface = very late planing
>  but also a small wet surface = high speed and high manouvrability.

Yes, if youhave a wave or B&J board with lots of tail rocker,  and a thin,
narrow profile at the back.
But the modern lite air planing board or lite air race board is designed to
be pumped onto a plane, with the rider's weight on the back of the board
where the board is wide and thick.
Quote:
>  In chop and waves the board is better controllable because of the
>higher  position of the nose.

Sorry, if you are really moving, the nose is not higher, it's at the
optimum height, which, depending on the conditions the board was designe
for may in fact be quite low as this presents the planing flatto the water
at the proper attitude.
Quote:

>And for the mastfoot trim:

>* In light winds, place the mast as far forward as possible, and then
>bit
>by bit move it backwards until the board still starts planing easily and
>the
>manouvrability is acceptable, so (almost) planing jibes are no problems
>anymore.

Sorry, Jan, but doing this will stop most lite air planing boards from ever
planing at all, or at least until the windspeed increases to the point
where planing wouldn't be a problem.
Quote:

>* In high winds, place the mast as far backwards as possible, and only
>move it forward when you can't control the board anymore because it
>is bouncing to all directions, or you just are scared sailing with
>absurd speed.

This sounds about right!
Quote:

>* In chop the mast should be further back, preventing the diving of the
>nose while
>planing (Only quite flat boards)

Nope! Putting the mast foot back should not be about raising the nose, It's
about getting the board to an attitude where it "skips" over the chop on
the designed planing surface.
later
sailquik (Roger Jackson) |Ph # in Md. (301) 872-9459
Lvl 1 WS Instructor      |    in N.C. (919) 995-3204
F2/Sailworks/North/True Ames/Rainbow

 
 
 

Mastfoot placement

Post by Ian Knigh » Fri, 10 Jul 1998 04:00:00

Quote:

> I have seen several comments on mastfoot placement in the last couple of

I've always thought mast foot placement theories were over complicated.
I put faith in the board designer and put it a bit forward of the middle
of the slot with big sails and bit back with smaller.

As I see it mast foot placement has two functions. 1. It alters the rake
of the rig and 2. It  acts as a third leg when we sway  back and forward
(while in the straps ) to trim the board.

Although we lean on the mast foot to change trim, it doesn't take over
control  of trim.   A tripod is pretty versatile and our ability to
balance/trim is not critical on the placement of the third leg.  We will
simply lean back or forward  to a trimmed position and hold the boom in
the appropriate place no matter what. If the mast foot is forward we
will have automatically raked the rig back  to compensate.  

Fine tuning the mast foot position is important if you worry about
"closing the gap"  

Ian

 
 
 

Mastfoot placement

Post by sailquik (Roger Jacks » Sun, 12 Jul 1998 04:00:00

Quote:
>I've always thought mast foot placement theories were over complicated.
>I put faith in the board designer and put it a bit forward of the middle
>of the slot with big sails and bit back with smaller.

Sorry, but you either aren't going fast enough, or aren't paying attention.
Look at where the water comes out from under your board. If it's not at or
behind the front footatraps, you are mis trimmed (mast too far forward) or
you don't hve enough wind or sail to really get going.
Quote:

>As I see it mast foot placement has two functions. 1. It alters the rake
>of the rig and 2. It  acts as a third leg when we sway  back and forward
>(while in the straps ) to trim the board.

Mast foot placement has very little if anythig to do with the rke of the
sail. The rtake angle is pretty well defined but the sail designer. The
foot of the sail needs to be just about parallel with the deck of the
board.
If, by "tripod effect" you mean applying mast foot pressure, then yes, you
are o to something. Going upwind, jibing and high speed control all depend
on mast foot pressure.
Quote:

>Although we lean on the mast foot to change trim, it doesn't take over
>control  of trim.   A tripod is pretty versatile and our ability to
>balance/trim is not critical on the placement of the third leg.  We will
>simply lean back or forward  to a trimmed position and hold the boom in
>the appropriate place no matter what. If the mast foot is forward we
>will have automatically raked the rig back  to compensate.  

Huh???? We hang on our harness lines, well beind the CE of the sail, and do
most of the board trim with our feet. Both fore and aft trim, and
athwartships. It's the feet that trim, and the mast foot pressure that
drives.
Quote:

>Fine tuning the mast foot position is important if you worry about
>"closing the gap"  

No! Mast foot position on a shortboard is about whether you go fast, or
slow, whether you get beat to death by the chop, or skip over it.
On a longboard, mastfoot position can mean about an extra 5 degrees
of upwind (with speed) ability. Moving it back, when sailing off the wind,
can make a board far less sticky over the swells and chop.

sailquik (Roger Jackson) |Ph # in Md. (301) 872-9459
Lvl 1 WS Instructor      |    in N.C. (919) 995-3204
F2/Sailworks/North/True Ames/Rainbow