Maximum beam ?

1) Where in theory, or your oppinion should a sailing boat have it's largest beam?

2) If the CB (center of buoyance) clearly is behind the middle, the hull will dip towards the front (bow?).
Is it a good way to compensate for this by putting ballast behind the middle to?

3) Are there any good (strait and logic) sites on designing hulls on the web?

 

I do not know if there are any straight away hull designs on the net. It is probable that there is.

It actually does not matter if you CB is behind the middle of the ship. What matters is: where is CB according to CG (Center of gravity). So if you have a clue where your CG is, you can calculate if you ship will trim with its head down or with the rudder down.

 

So what about the widest point (widest beam). For airfoils the highest should be as far back as possible... wich is somewhere about 60-70% back on the corda (length).

On a sailing boat it must (?) be a problem to have an arrow like profile from above since CB will move very far back. ....wich will move ballast, daggerboard and rig far back. :?:

 

In theory there is no optimum because it is dependent on many factors, like you have mentioned yourself in your last reply. Read C.J. Marchay's "Seaworthiness, the forgotten factor", maybe you'll find your answer there.
To my opinion it should be just aft of the mast, but that's because I like old Dutch fishing boats.
Why're asking bro???

 

What airfoils are you referring to? All the airfoils I've seen have had the maximum thickness situated between 30 and 50% of the chord length from the leading edge.

On a sailing yacht, the max. beam is normally situated somewhere around 55-65% of the waterline length from the stem.

 

Is that to get production boats to look like IMS designs or am I way off with that assumption?

 

Starting out

Instead of letting your thoughts just drift around like this, why don’t you get a good book on design? After you read up on the subject you will be able to ask a much better formed question. The answer will also make more sense to you. You are missing some of the basic points in design and I don’t think that a forum like this can teach you all the you need to get your thoughts anchored or organized in this field.

 

Robert,

Is that your reply to my post??


Peter

 

Peter,
I am new to this, the posting part not the boat part. I see after I made the post it looks like I am replying to you. That is not the case; I am trying to reply to the start of the thread. I don’t think you need any help at all; you appear to have a good handle on what’s going on.

 

Thats shitty data from old books. Basicly all modern foils are like I said. But, it also depends on materials. The foils I mention need modern high performance materials and high precision rigs or moulds. (I'm not talking supersonic).

 

Trying to hold on, getting there!!

 

Any examples, Slowmo?

 

That's certainly NOT "shitty data from old books". It's what used on all sailing yachts!
Please give us some examples - show us that you know what you're talking about!

 

I hate to say it, but yes - you are way off! 99% of all modern yachts (by modern I mean yachts from the last 30 years or so) have the mast situated somewhere around station no. 6 (i.e. 40% of the DWL, measured from the stem) and the max. beam somewhere around station no. 4 (i.e. 60% of the DWL, measured from the stem).
OK - maybe it's only 95%, but still...

 

Sorenfdk,

So, the answer is "No" the ORC(IMS) rules have not influenced the design of production boats?!
Sorry to ask again, just didn't get your answer?! My mistake.