Centerboard confusion
Tufarnorth
tell me if the following is true. (1) Centerboard should be down when gong
upwind, planing or nonplaning. (2) Going upwind, centerboard down, lean on
leeward rail when planing, windward rail when not planing. (3) Going
downwind, don't use centerboard, planing or not. Thanks. Cindy
Den Fox
board all the way down. Sometimes when the wind is stronger, a lightweight
person can not hold the windward rail down. That is the time to give the
dagger a wee kick, and get it in the position where you can sail most
comfortably.
Just to be picky, (and hoping I don't confuse you) you can not "plane" with
your dagger down as you suggested. You can go very fast, but planing is
impossible. Think of it this way: Planing is skimming over the surface.
The opposite to planing is displacing, ie; part of your board is displacing
water. With your dagger down, you are locked into displacing mode.
So, Dagger Up to go planing, and Dagger Down to grip the water and claw your
way up wind.
Den
PS: Yes Ok, we could say that the fin is always displacing, but that is
being really picky. And yes, people often talk about planing with the
dagger down - "Dagger board Planing" - but that is purely slang. They mean
that the dagger is making the board rise out of the water like a hydrofoil.
(Not always desirable.)
PPS: Sorry I called it a dagger board when you call it a centre board.
Same thing.
Tufarnorth <tufar...@aol.com> wrote in message
news:19991203133502...@ng-fh1.aol.com...
RandacF
>your dagger down as you suggested. You can go very fast, but planing is
>impossible.
Perhaps being really picky, but what about railing? When you are railing
railing, aren't you at least sort of planing? You are going faster than in
displacement mode.
Randy
Den Fox
planing". I did try to cover up this loop hole when I wrote the PS about
"dagger board planing". The dagger board combined with the leeward rail
grips the water while you stand on the windward rail with all your weight
and commitment, setting the board at the optimum angle to "climb" up wind.
And you can go very fast indeed. But technically you are not planing.
Or are you perhaps describing a board which has the dagger up and planing
nicely, but you have engaged leeward rail? In which case, yes you are being
picky! ;-) I was trying to paint this picture of "planing" in really broad
brush strokes. And I'm talking Rolf Harris here!
Den
RandacF <ran...@aol.com> wrote in message
news:19991203155135...@ng-fr1.aol.com...
sailquik (Roger Jackson)
> I'm a little confused with regard to centerboards on longboards. Please
>tell me if the following is true. (1) Centerboard should be down when gong
>upwind, planing or nonplaning. (2) Going upwind, centerboard down, lean on
>leeward rail when planing, windward rail when not planing. (3) Going
>downwind, don't use centerboard, planing or not. Thanks. Cindy
Cindy/Den/Randy;
#1 To go upwind in subplaning conditions, you need the centeboard down, all the
way. And you need to "rail" the board to leeward, causing it to "carve" to
windward on the centerboard. The mast foot also needs to be all the way forward
as far as it will go. This puts as much of the lee rail as possible in the water
which increases the waterline length, hence the hull speed.
To go upwind on a longboard, in planing conditions, in my experience, you are
better off with a large pointer fin, and go upwind "on the fin" (lee rail
lowered) like you would on a large shortboard.
You can do as Den has suggested, and retract the centerboard slightly to enable
you to control the "railing up" of the upwind rail, but you are usually fighting
a battle of diminsihing returns when you do. If you get dumped by uncontrollable
rail up , you will lose alot of ground to those who are just going upwind on the
fin.
Be sure to retract the CB completely for your next jibe, or you will make the
largest jibe arc ever.
#2 Cindy, I think you've got the right idea, but when planing upwind with the
CB up, lee rail goes down, you go back to the all the way back footstraps,
mast foot comes very near the rear of the track. You want to trim the longboard
out as much like a shortboard as possible.
When going upwind in subplaning conditions, CB is all the way down, board is
railed to leeward, and controlled by standing out on or near the windward rail
(or use the beating straps if you have them). Mast foot should be as far forward
as possible to increase the length of lee rail in the water and the waterline
length.
If you have the centerboard down, and you tip the board to windward, the board
will immediately turn off the wind like you were initiating a jibe. Infact, in
lite air bumpy conditions, that's exactly how you initiate your jibes at the
jibing mark. Sometimes having the CB down adds enough stability that you are
willing to"pay the price" for the extra drag. Going downwind, in sloppy
conditions, you can also use the CB down to stabilize things in the subplaning
mode. You pay the same drag penalty, but the slightly diminished speed will get
you to the next mark sooner than falling and having to uphaul.
#3 Going downwind, or even beam reaching, unless the water is sloppy as in the
examples above, retract the CB all the way if you can. Less drag equals more
speed. But, uphauling is far slower.
Hope this heips!
Roger
sailquik (Roger Jackson) US 7011
Cert. WS Instructor (Lvl 1)
Sailworks/F2/Starboard/MPB/HPL/Chinook/Kokatat/DaKine
Phones: So. MD (301)872-9459; Avon, NC (252) 995-3204
sailquik (Roger Jackson)
>Perhaps being really picky, but what about railing? When you are railing
>railing, aren't you at least sort of planing? You are going faster than in
>displacement mode.
Randy:
I think you are at least partially correct here. But the reason it seems you are
going so much faster (and indeed you may be) has more to do with the
accelleration of the apparent wind, which produces more power as long as you
have the CB railed at the right angle to balance this increased power.
There also may be some component of "lift" from the CB which seems to almost
lift the board out of the water, if you can keep it under control.
later
RandacF
I think that railing might be closer to what is described as 4th mode sailing
(modes 1 - displacement, 2 forced mode, 3 planing) by Bethwaite in "Performance
Sailing" - involves changing the shape of the board as seen by the water by
tilting it, becomes a long and narrow shape, but very efficient. Certain
sailboats are designed to work this way when tilted over to leeward and it is
like planing. Whatever, the case, it feels more like planing than displacement
mode sailing and I think is definitely faster than hull speed (about 4.7 mph on
a longboard), unless my speedmate is way off the mark.
Randy