i’m new and stuck on a daggerboard.

[Menno]

Hello, i’m using Delftship for a month now and started with my 3rd model.
I must say it’s alot of fun drawing with Delftship but now i’m stuck…

i’m trying to draw small boat with a lee board this time but i’ve noticed that this lee board does’nt have any influence on the lateral point.
is it because it’s not actually attached to the hull? and how can i solve this? should i attach it somehow?
[attachment:1]Hollandse boot 03.fbm[/attachment]

Don’t mind my English spelling as it’s not my native language.

[giorgio zuppin]

Hi menno, I cannot see your .fbm attachment: Maybe you’ve forgot to >>add file.
Try again and maybe I can help.
bye, Jurgen.

[Menno]

There you go
[attachment:1]Hollandse boot 03.fbm[/attachment]

[Menno]

Hope this time goes better

[Menno]

Hope it works this time.

[giorgio zuppin]

Yes Menno, it has worked.
Nice design and the boat is very typical I think.
Anyway the daggerboards or zwaard, they affect the hull’s hydrostatics: move them
upright for one meter and see the changes on the hydrostatics report.
Changed: displaced volume, block coefficient etc, and of course the metacentric height.
It doesn’t matter if a part is joined fisically to the model, it has to be a part of – a
layer for ex. – and of course have a displacement beyond the waterline.
Hope it will help you.
Bye, Jurgen.

[Menno]

Thanks for your response,

And i have learned a new word again(daggerboard)

I think i have to dive into the whole hydrostatics stuff before i start asking questions because i still don’t understand what’s going on.
But, i’m simpy to greedy and curious to not ask….. 😛
for example when i delete that dagger board, the lateral area point does’nt move while i was expecting it to move backwards as without that dagger board that’s where the most of the lateral area is located.
And, i’ve read that people who draw trimarans have a problem with hydrostatics (daggerboard next to a hull gives same situation?)

The main reason why i need that lateral point to be right is to, when i ad sails, to be able to put the sail point just behind it so the boat has a natural tendency to sail almost at a straight course by itself (with a bit tendency to stir up ofcourse).

[giorgio zuppin]

Well, the lateral area point does not, apparently change, because the daggerboards are longitudinally close to it: try to move them fully astern and you’ll see.
Take care : when you say “deleted” for a layer it must be fisically deleted not only
“not visible” , otherwise it will appear in the hydrostatics report.
Anyway, my advices on hydrodinamics does not come from a true expert,
my technical knowledge belongs to other fields.
Bye and enjoy the software. Jurgen

[giorgio zuppin]

Hello Menno, I have to make a public statement:
Due to my deep ignorance of theory, what I wrote was, probably
Wrong.
It happened that I was concerned about the topic so I did what a technician
must do. Experiment.
So I sketched a simple model – test.fbm, attached – and what it came out was:
The centre of lateral area refers to the centerbord or midship section, if you
place an object away from y=0, it is not considered.
The same object placed as a center keel and moved along the ‘x’ coordinates
will give you the information that you have required.
Well that’s a lesson about improper speech is’nt it?
With apologizes, Jurgen.

[Menno]

Funny… i just was about to respond whit the same conclusion after some experimenting i did on it.
Anyway, thanks for your effort 😉

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