New Posts New Posts RSS Feed: Daggerboard - use of?
  FAQ FAQ  Forum Search   Register Register  Login Login

Daggerboard - use of?

 Post Reply Post Reply Page  123 6>
Author
Captain Morgan View Drop Down
Far too distracted from work
Far too distracted from work
Avatar

Joined: 03 Sep 08
Location: United Kingdom
Online Status: Offline
Posts: 211
Post Options Post Options   Quote Captain Morgan Quote  Post ReplyReply Direct Link To This Post Topic: Daggerboard - use of?
    Posted: 15 Sep 08 at 2:04pm

This might seem like a silly question, but the daggerboard/centreboard is moveable for a reason. However, after a couple of inversions where the daggerboard dropped completely out of the slot, I have started to sail my boat with the board fully down on all points of sail. I've checked my speed using GPS, and can't find much appreciable difference with the board fully down, or otherwise.

Training tells us that the board should be fully down when beating, half way up when reaching and up when running. Long established classes such as the Wayfarer (and especially Laser) for example, seem to follow these rules.

But, I've looked into this further and found that some more modern classes (e.g. RS, especially those with bungee which goes over the top of the daggerboard when it's fully down) don't seem to bother raising the daggerboard once the water is deep enough after launching. My current race training has also highlighted that the daggerboard should be lowered *before* the gybe mark - something that I've never had the nerve to do, but so far I haven't had any bad experiences!

  1. So, is gybing with the board down a bad idea?
  2. Stability on the run is improved, but as for the boat "tripping over" the board as it gybes, does this really happen?
  3. Is it really worth moving the board up and down for different points of sail? The increase in drag can't be that much, can it?

Any thoughts/suggestions please!

Back to Top
Black no sugar View Drop Down
Really should get out more
Really should get out more
Avatar

Joined: 04 Dec 04
Location: Somewhere between Brighton and Lancing
Online Status: Offline
Posts: 3941
Post Options Post Options   Quote Black no sugar Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 08 at 2:16pm

In a Topper, lifting the daggerboard in a reach and a run makes a big difference in light to medium winds.
In a top force 4 and above (18knts upwards), I leave the daggerboard down at all times.
Might not be the right technique, but every time I tried lifting it for the run of a gybe, I ended up pushed here and there by the waves and straight in the drink.

I'm sure you're going to have plenty of various answers depending on type of boats, usual sailing conditions and sailing skills.

Back to Top
ChickenTack View Drop Down
Newbie
Newbie
Avatar

Joined: 10 Sep 08
Location: United Kingdom
Online Status: Offline
Posts: 9
Post Options Post Options   Quote ChickenTack Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 08 at 2:35pm

It really does depend on the class of boat that you sail.

In a laser when its really blowing I usually leave the board 3/4 down to make it easer to keep it flat on the beat.

In anything assy i never take the centreboard up (mostly due to lack of arms/ability to keep the boat flat) but i have seen it done in RS400s

Apart from that i normally follow the guidelines

Regards,

Will

Crews union: beause its hard to be humble when you know you're so great!
Back to Top
dics View Drop Down
Far too distracted from work
Far too distracted from work


Joined: 05 Oct 05
Online Status: Offline
Posts: 317
Post Options Post Options   Quote dics Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 08 at 4:01pm

The 300 foils are really too big for the boat. I raise the board as the "guidelines". However, when sailing in a stiff breeze, due to the size of the board it is a must to have it up 9-12 inches on the beat as it makes sailing the boat up right a lot easier.

 

Back to Top
alstorer View Drop Down
Really should get out more
Really should get out more
Avatar

Joined: 02 Aug 07
Location: Cambridge
Online Status: Offline
Posts: 2899
Post Options Post Options   Quote alstorer Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 08 at 4:26pm

As said, at the level where it begins to make enough of a difference to your performance, it really depends upon the boat. Skiff-type boats tend to leave it down for several reasons:

  1. Not enough time/too much sideways pressure to adjust it during bearaways and round-ups
  2. different sideways forces may require the board to be down
  3. less for crew to get caught on- not so much space on an RS800 especially once you figure in the centre main sheet and traditional kicker

as far as I can figure out, anyway. Sone do have levels to bring the board up a bit in high winds (at faster speeds, the losses of lift are offset against less adverse righting moment for overall greater efficiency) especially on flat water- in waves, there's more chance of stalling the foil.

Raising a centreboard does different things to raising a daggerboard. Raising a centreboard moves the pivot point of the boat aftwards. What this does is increase lee-helm. This helps the boat point deeper downwind more efficiently- very useful with a traditional spinnaker or the canting bow-sprit of the RS400*. Raising a daggerboard significantly (like on a Laser or Topper) does do this somewhat as well, though not to the same degree.

If you find you have a problem with the daggerboard falling out on capsizing- do you have a bit of elastic pulling it forward? On a Laser, you should have a length taught through the front of the board and round the front eye on the boat, running either side of the mast. On a Topper, there's a single line that should go round the mast and clip to itself. On both, this holds the top of the board forward in the case, meaning it shouldn't drop down when there's no side-load on it. That should stop it falling out when inverted, or at least leave enough sticking out for you to grab and pull the rest out.

As for speed- absolute speed is not the key in racing, it's what's variously reffered to as Speed to the Mark, Speed Made Good or Velocity Made Good (VMG). Two boats at the same absolute speed can have very different VMG.

I'm bound to be corrected on some technical points here, and look forward to being so. We all never stop learning.

*had a go on one last week for the first time- they point scarily deep. It's just un-natural if you're used to more conventional systems...



Edited by alstorer
Back to Top
feva sailor View Drop Down
Posting king
Posting king
Avatar

Joined: 03 Sep 08
Location: United Kingdom
Online Status: Offline
Posts: 186
Post Options Post Options   Quote feva sailor Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 08 at 5:43pm

in my feva (aesametric gennaker) i dont actually go on a run for long and so i generally only go as low as a broad reach.

 

because of this i need the board down .

also as the bow is out when planing you lose the "grip" so the board keeps in contact with the water so the bow doesnt swing back on to the run

Back to Top
mike ellis View Drop Down
Really should get out more
Really should get out more
Avatar

Joined: 30 Dec 05
Location: United Kingdom
Online Status: Offline
Posts: 2339
Post Options Post Options   Quote mike ellis Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 08 at 6:40pm

any RYA trining teaches you to have the board as suggested. however in the 600 i only bother to raise it on dead runs in the light stuff, otherwise there isn't enough time, and the boat gets even less stable, and its harder to bring the boat upright after you do piss it in.

As for centreplates, im not really sure about why but i know when i used to crew in a fireball when it got windy we swung the board back more for upwind to match raking the rig back i think.

600 732, will call it Sticks and Stones when i get round to it.
Also International 14, 1318
Back to Top
tmoore View Drop Down
Really should get out more
Really should get out more
Avatar

Joined: 01 Nov 07
Location: Wales
Online Status: Offline
Posts: 880
Post Options Post Options   Quote tmoore Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 08 at 7:02pm

in high winds i actually have the board deeper in the water during the run than on a tight reach simply because it makes the boat more stable. in windy stuff then raise the board upwind in order to stop the boat 'tripping' in the gusts. in an assymetric i would never raise the board unless i was going downwind without the kite or something.

gybing with the board down is fine aslong as your timing etc is right. if your timing isnt up to it then a raised board with make it more forgiving by reducing the heeling force after the gybe. personally i always leave the board in the 300 as without it the boat is just so much more unstable....

Landlocked in Africa
RS300 - 410
Firefly F517 - Nutshell
Micro Magic RC yacht - Eclipse
Back to Top
G.R.F. View Drop Down
Really should get out more
Really should get out more
Avatar

Joined: 10 Aug 08
Location: United Kingdom/Hythe
Online Status: Offline
Posts: 4021
Post Options Post Options   Quote G.R.F. Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 08 at 8:27pm
I've investigated this a lot from a newcomers perspective.

Coming as I do from a world that dumps the plate totally the moment the
board planes offwind and rakes it a tad aft in windy weather to prevent
'railing' (the board tilting up on its edge like a boat heeling)

As usual depending who you ask you get conflicting advice, we ruined
half a season in the RS500 arguing over kicking the plate after an ex
scorpion helm had a go whilst i was away one weekend and immediately
kicked the plate back impressing jumanji, but he was on a two sail reach
which is fine, but the moment you put the kite up, you're best off leaving
it down, because the centre of effort shifts so far forward with the kite up
anyway.

I think alstorers explanation rings true, our Alto will go deeper with the
plate kicked back, especially with the pole canted to weather, but you do
induce lee helm.

We've yet to dump the plate totally, it's another control on the to do list,
bringing the method to do it to the helm. Usually by the time we could do
with it, we're fully wired and flying..

We knocked it back a tad on sunday upwind, investigating just how much
faster we could be sailing lower and faster up wind, it seemed to work, we
stretched our legs a fair few boat lengths from a nearby 505 that had
appeared to be catching us.

Edited by G.R.F.
Back to Top
mike ellis View Drop Down
Really should get out more
Really should get out more
Avatar

Joined: 30 Dec 05
Location: United Kingdom
Online Status: Offline
Posts: 2339
Post Options Post Options   Quote mike ellis Quote  Post ReplyReply Direct Link To This Post Posted: 15 Sep 08 at 8:47pm
but how much did you fall to leeward of them GRF?
600 732, will call it Sticks and Stones when i get round to it.
Also International 14, 1318
Back to Top
 Post Reply Post Reply Page  123 6>

Forum Jump Forum Permissions View Drop Down

Bulletin Board Software by Web Wiz Forums® version 9.665y
Copyright ©2001-2010 Web Wiz