lee helm in light air
warbees
Greetings:
I recently purchased a little Capri 13 to scoot around the lake in. Its
a daggerboard dinghy with only a mainsail. My previous experience has
been on larger boats, and while this boat is a lot of fun, it does have
a weird little trait that I'd like to get some advice on.
At times, while sailing along close hauled, full lee helm is required to
keep a heading. This usually happens after a wind shift or change in
wind velocity. Peering over the side of the little beggar, we're hove
to, moving sideways (Just like Lyn and Larry tell ya to do to save your
ass). I ease the main, foot off, pick up speed and we're sailing again.
My question - if you choose to accept it -
A) am I missing a HUGE wind shift (like 40 degrees), OR
B)is the boat reacting to a change in wind velocity (i.e less wind
velocity, less boat speed, relative wind moves aft, 4)suddenly we're
hove to.) OR
C)is it just that its a wee little boat compared to my previous wessels
and
D) Why Lee Helm ?
Thanks in advance for the free instruction.
Barry W.
Thomas Webb
Lee helm is common in light winds. I don't know the Capri particularly,
but the best option in most small boats is to move weight forward. This
will increase weather helm and probably also reduce wetted surface.
Also make sure that your dagger board is all the way down.
-tom.
Chuck Minnich
shoud move the center of effort forward which puts it forward of the
center of lateral resistance (keel) turning the boat downwind causing
you to move the tiller alee to counteract.
I suspect the problem of accidental heaving to is caused by overtrim on
the main. It's easy to miss a wind shift to windward - not as obvious
as when the sail luffs.
--
Captain Chuck
Remove ".RemoveToRespond" in Address to Reply
Thomas Webb
Chuck Minnich wrote:
>
> I wrote:
> >... move weight forward. This
> > will increase weather helm and probably also reduce wetted surface.
> > Also make sure that your dagger board is all the way down.
> Are you sure moving the weight forward increases weather helm? This
> shoud move the center of effort forward which puts it forward of the
> center of lateral resistance (keel) turning the boat downwind causing
> you to move the tiller alee to counteract.
Yes, as a _rule_ trimming the bow down will increase weather helm. As
you suggest, this will rake the rig forward and and move the center of
effort of the rig forward, but typically the CLR of the hull and
appendages will move much more rapidly with with changes in trim. For
instance, peapods are sailed without rudders. On them tacking is
achieved by moving the crew forward and jibing by moving the crew aft.
In the extreme case, if you stand on the bow of a small boat the stern
will come clear of the water and, lacking any lateral resistance, will
blow downwind. There may be other benefits to trimming the bow down in
light airs. Planning monohulls typically have very square sections aft
and rounder sections forward. Trimming the bow down may reduce wetted
surface by loading up the rounder, lower surface area, sections and also
may give the boat a lower prismatic coefficient by making the stern
effectively pointier. Both of these will reduce resistance in the low
speed range of the boat. Finally, if trimming the bow down does
increase the weather helm, then the rudder will provide some of the lift
needed to overcome leeway. The effects of this change are complex, but
experience in most boats shows that having the rudder provide a bit of
lift gets the boat to weather a bit faster.
-tom.
Chuck Minnich
Thomas Webb wrote:
>
> Chuck Minnich wrote:
> >
> > I wrote:
> > >... move weight forward. This
> > > will increase weather helm and probably also reduce wetted surface.
> > > Also make sure that your dagger board is all the way down.
> > >...
> > Are you sure moving the weight forward increases weather helm? This
> > shoud move the center of effort forward which puts it forward of the
> > center of lateral resistance (keel) turning the boat downwind causing
> > you to move the tiller alee to counteract.
> ...
>
> Yes, as a _rule_ trimming the bow down will increase weather helm.
Ok, I stand corrected. I don't have experience on small boats.
Is my other speculation that he is accidently heaving to because of
overtrim on the main caused by a wind shift to weather a possibility?
--
Captain Chuck
Remove ".RemoveThisToRespond" in the address to reply
Thomas Webb
Chuck Minnich wrote:
>
> > Chuck Minnich wrote:
> Is my other speculation that he is accidently heaving to because of
> overtrim on the main caused by a wind shift to weather a possibility?
> --
> Captain Chuck
> Remove ".RemoveThisToRespond" in the address to reply
Chuck,
Yes, I think you are right on here. I suspect the sails and the dagger
board are stalled. Easing the sheets, heading off and "moving weight
forward :)" should help...
-tom.
Paul Kamen
I think he just needs a little more heel angle in the light stuff. This
is really a much bigger effect than mast rake or fore/aft boat trim.
--
fish...@netcom.com
http://www.well.com/~pk/fishmeal.html
-"Call me Fishmeal"-
Jim K
On 7/23/97 2:10AM, in message <33D5A0...@easyliving.com>, Chuck
Minnich <captchuck.Re...@easyliving.com> wrote:
> Thomas Webb wrote:
> >
> > Lee helm is common in light winds. I don't know the Capri
> particularly,
> > but the best option in most small boats is to move weight forward.
I would suggest easing the sails a bit and letting the boat build speed.
Lee helm during light conditions can be a result of the rudder wanting to
follow an excessive amount of leeway.
Sail a little lower and faster to allow the keel to generate some lift.
>
> I suspect the problem of accidental heaving to is caused by overtrim on
> the main. It's easy to miss a wind shift to windward - not as obvious
> as when the sail luffs.
Which is why tell tails on the leach are so important, right?
It's amazing how much over trimming the main can kill your speed.
--
Jim K. ! Opinions: You want? I got!
ji...@ili.net ! No warranty expressed or implied