[NYCAP123]

Originally Posted by Henning

Interesting.... I'm going to assume you haven't spent any time at sea... I think they may sell well as sculptures. As functioning vessels, not so much so.... form is driven by function to a great extent and function is determined by mission, so I suggest you first think about "What is this vessels job?".

You need to get that thinking back into the small yacht arena. It's all speed and how does it look at the boat show. Black hulls, light composites, fancy furnishings. Sea worthy? What's that?

[CODOG]

Well, you asked for 'critique', and you got some. Your crime it seems is to start with the fantastique, bypassing the basics. Easily fixed if you have the stomach for it.
How will you be marked on the project ? If a pass is down to aesthetics then ignore us and stick with the bling...if the project demands some substance then do some research into sail boat design. I'd guess the software you are using can punch out some figures for an enclosed volume ? A realistic relationship between volume, mass and balance with a heady mix of force and levers thrown in may seem rather out-there straight off, but at your stage in life it pays to gain advantage over the rest of the class. Enough info to get a great heads-up is out there if you really want it.

[vling]

Henning, thank you for the valuable feedback. You'd be right to assume I haven't spent time at sea, except for once when I was little we went fishing on a family friend's catamaran.
This is a conceptual charter pleasure yacht, for use in the Mediterranean mainly, with main inspiration for the hull coming from ancient Greek Triremes, although I know this form is probably not as efficient as it could be. In this revision, I have moved the center of the sails and bulb to the Beam WL, which farther back than most ships. (and behind the CLP, which is another problem I'm wrestling with) The Beam is also farther back than the Beam WL. (does this create more issues?) I was looking at aircraft carriers and how the hull spreads out at the top to accommodate a large flight deck. This hull does spreads in the same way at the rear but to a lesser degree.

Here's a couple screenshots how how it's looking now. Again I really appreciate the feedback guys, I hope by the time this is finished, it will be somewhat believable :P.

[CODOG]

I reckon the spear-like bow will dig in when the hull is heeled over and tend to turn the hull away from the heel with considerable force. IMO its not a good hull shape for a rig that heels the boat. Triremes relied mainly on oar power...they had basic sails that worked best with the wind behind them, they cant have heeled much or the oar ports would have been underwater.
There is no rudder....I assume you plan to have one.
The appendage connecting the keel bulb to the hull looks extremely large (is that a stairway inside it ?) This large appendage will have a large volume...this large volume will give a lot of buoyancy directly under the hull, which will directly counteract / negate the weight of the keel bulb...obviously having an affect on the amount of sail you can carry etc.

[Henning]

Originally Posted by vling

Henning, thank you for the valuable feedback. You'd be right to assume I haven't spent time at sea, except for once when I was little we went fishing on a family friend's catamaran.
This is a conceptual charter pleasure yacht, for use in the Mediterranean mainly, with main inspiration for the hull coming from ancient Greek Triremes, although I know this form is probably not as efficient as it could be. In this revision, I have moved the center of the sails and bulb to the Beam WL, which farther back than most ships. (and behind the CLP, which is another problem I'm wrestling with) The Beam is also farther back than the Beam WL. (does this create more issues?) I was looking at aircraft carriers and how the hull spreads out at the top to accommodate a large flight deck. This hull does spreads in the same way at the rear but to a lesser degree.

Here's a couple screenshots how how it's looking now. Again I really appreciate the feedback guys, I hope by the time this is finished, it will be somewhat believable :P.

Ok, that top view brings up another issue. When a sail boat works to weather, it inclines, figure it will lay on its side about 30 degrees. Now, consider that and how far aft you've placed your maximum beam, which controls your longitudinal center of bouyancy. When you combine that factor with your fine bow entry and the fact that it is reversed, you will quickly realize that when she heals over, you will drive the bow deep under water due to the combined leverage and lack of forward bouyancy.

[CODOG]

We are so off the wall it doesn't really matter, but his maximum beam isn't affecting his centre of buoyancy. His maximum waterline beam may be however, and looking at the drawings I'd say its almost exactly between the two mid masts, almost directly above the centre of bulb...looking at his hull form under the waterline, I'd say the LCB is close to maximum beam at waterline. The waterline plane is almost aerofoil shape, hard to see at first.
Still, wrong shaped hull whichever way you crack it, but I see scope to improve it hydrodynamics wise and keep the main thrust of the concept.
Looks like it was done in Rhino or similar ? Can the OP measure the volume below waterline and see where the centroid is relative to the masts / bulb ?

[Henning]

Originally Posted by CODOG

We are so off the wall it doesn't really matter, but his maximum beam isn't affecting his centre of buoyancy. His maximum waterline beam may be however, and looking at the drawings I'd say its almost exactly between the two mid masts, almost directly above the centre of bulb...looking at his hull form under the waterline, I'd say the LCB is close to maximum beam at waterline. The waterline plane is almost aerofoil shape, hard to see at first.
Still, wrong shaped hull whichever way you crack it, but I see scope to improve it hydrodynamics wise and keep the main thrust of the concept.
Looks like it was done in Rhino or similar ? Can the OP measure the volume below waterline and see where the centroid is relative to the masts / bulb ?

If you want to compare it to an airfoil, it's flying backwards. The bow is to the right and a reversed wave piercing type. The stern is the bit with the overhang.

[vling]

Originally Posted by CODOG

We are so off the wall it doesn't really matter, but his maximum beam isn't affecting his centre of buoyancy. His maximum waterline beam may be however, and looking at the drawings I'd say its almost exactly between the two mid masts, almost directly above the centre of bulb...looking at his hull form under the waterline, I'd say the LCB is close to maximum beam at waterline. The waterline plane is almost aerofoil shape, hard to see at first.
Still, wrong shaped hull whichever way you crack it, but I see scope to improve it hydrodynamics wise and keep the main thrust of the concept.
Looks like it was done in Rhino or similar ? Can the OP measure the volume below waterline and see where the centroid is relative to the masts / bulb ?

I think we are on the same page as far as relationship between beam and CP.
I've attached an image of approximate WP's of the current design (rev v2e), and an earlier version (rev g) to help clear things up. Rudder is something that still needs to go in, I'll have roughed in soon.
Welp, it seems like the main message here is to get rid of the reversed bow, so I'll grab the clipper bow from the earlier version to try it out. What do you think about the pinched bow and stern as in Rev. G?

Thanks again for the advice!

[CODOG]

Originally Posted by Henning

If you want to compare it to an airfoil, it's flying backwards. The bow is to the right and a reversed wave piercing type. The stern is the bit with the overhang.

Yup, I sussed that from the first post....the OP's reference to a Trireme and the direction the sails were facing sort of helped.

[Henning]

Originally Posted by vling

I think we are on the same page as far as relationship between beam and CP.
I've attached an image of approximate WP's of the current design (rev v2e), and an earlier version (rev g) to help clear things up. Rudder is something that still needs to go in, I'll have roughed in soon.
Welp, it seems like the main message here is to get rid of the reversed bow, so I'll grab the clipper bow from the earlier version to try it out. What do you think about the pinched bow and stern as in Rev. G?

Thanks again for the advice!

Still, once she lays on her side with the rail down, and with her shape, she will definitely go rail down when pressed to weather, her maximum beam and bouyancy will shift aft, and even shift aft of her longitudinal center of mass, so she's going to try to drive the bow under.

[PropBet]

While it looks fun on paper, might I recommend a few points of reading which may help in regarding to the overall design and functional seaworthiness once in the water. (if you end up going that route with this or any other design)

Hydrodynamic Modeling Of Sailing Yachts - Harries / Abt / Hochkirch
Manual Of Yacht And Boat Sailing And Architecture - Kemp
Principles of yacht design - Larsson, Eliasson

Enjoy-

[Garry Hartshorn]

Also worth a read is

"Seaworthiness the forgotten factor" by C.A. Marchaj
"Aero-Hydrodynamics of sailing" by C.A. Marchaj
"Skene's elements of yacht design" by Francis S. Kinney ( out of print )

[vling]

I read a bit from Principles of Yacht Design, aside from the paragraph long equations and enough graphs to make a baby wombat cry, I think I got an idea of how wrong my hull was. Also read some more from Understanding Boat Design by Ted Brewer.

Here is the latest revision. I got the hull better balanced this time, and got rid of the reversed bow. The flare at the top is less drastic now. Would a double ended hull be possible for a boat this size? I couldn't find much info on double ended hulls this large.

CODOG - This is being done in Alias studio. I'm sure there's a way to measure volume but I don't know how (still learning the program).

[vling]

Syracuse V2Q progress shots.

[PropBet]

Looking better.
Add proper keep / bulb, chop off the extended keel on the aft, and you'll pick up a another 2 or 3 knots by reducing drag and how much of the boat you are pulling through the water.