Thoughts on hiring a naval architect....

[lascraigus]

I have no experience in yacht design, but I do enjoy the research and all that jazz (call me crazy, but I should have been an engineer).........I was wondering if anyone here would have any idea typically how much would it cost to get a naval architect to review something like this as to it's worthiness to one day float, sink, or any other intermediate state of rest.......
just fyi:
beam: 7ft, 6in
LOA:16ft
draft: 3ft, 6in
mast height: 22ft

[Doug Lord]

Interesting concept! I'd suggest you e-mail Eric Sponberg-he is very knowledgeable regarding performance sailing designs and a real nice guy as well-he'll help you.

Eric W. Sponberg
Naval Architect
Sponberg Yacht Design Inc.
St. Augustine, Florida
www.sponbergyachtdesign.com

[lewisboats]

At a glance...you may wish to provide a flatter bottom so the boat can plane. with that round bottom there isn't much lifting surface to support the boat at speed. Most performance hulls like that have a wide flat-ish bottom with a tich of rocker but with almost a straight though slightly upward run aft. This also gives some stability to stand up to the sail too. You don't show a keel but long twin rudders...this would put your Center of Lateral resistance too far aft and make the boat uncontrollable if there wasn't a keel further forward under the sail.

Just an observation.

[Guest625101138]

You are probably better off just sticking it up here for comment. I do not see any great merit to it but others might or at least be prepared to give more detailed comment.

Other ways are to state what you would like to achieve rather than having something in mind that you want detailed. It could end up a dog but at least you created the dog.

A less expensive way is to build a model of reasonable scale where the things that break can be easily fixed. It will highlight basic issues with the shape.

Another way is to look at boats that are close to the performance you are seeking and compare what you have come up with them. You might need to ask questions to get an idea of the differences.

I expect for about a days work at say $1500 you might get an answer about viability and weaknesses of the design. Going from there to something you could build in that size is probably a weeks work if it is the sort of thing the NA is doing and does not have to go into all the detail from scratch.

Rick W

[lascraigus]

Thanks for the replies!

Doug: I will look into emailing Eric. Thank you for the contact info!

Lewis (I'm assuming that is your name I have not placed the keel in the conceptual model yet. I do have a program running which can do analysis of weight and shape based upon materials used (TouchCad) and thereby gives the center of gravity and the center of buoyancy and all that. Just have not done it as of yet. I have noticed what you mentioned on other craft of similar design in regards to a flatter hull shape aft...there is a boat sailed in Europe (www.seascape18.com) that unfortunately is not on the US market. Check out the link as this is exactly what I am shooting for...

Rick: Thank you for your comments. I have the abilities to create a scaled down model (thank god for those many years of architecture schooling....many restless hours cutting balsa and foamcore...) hehe

[lewisboats]

I think if you compare your model to the picture under the specifications link you will notice that while the bottom in the site's picture is rounded it is significantly flatter with a firmer chine area than I see in your design. Like I say...just my observation but I think you will need more bearing area in order to plane properly. An experiment would be to draw a waterline across the transom that represents .15 m or your anticipated draft without appendages on your hull and compare it to the picture below. You can just see the waterline across the bottom of the transom. Notice that the area highlighted is very wide and flat...indicative of a shallow wide bottom.

[lascraigus]

http://gizmodo.com/5391195/ankida-ya...lery/gallery/1

[Doug Lord]

From a design perspective the semicircular sections are similar to the K1 keelboat that is designed to sail at an angle of heel. The designer says:
"It is designed to sail heeled so that the bulb weight provides righting moment and hence contributes to sail carrying power and potential speed as well as reducing the likelihood of capsize. In gusts the stability of the K1 increases as it heels, ensuring a smooth sailing motion. "
On the other hand, the very similar sized Bongo is designed to sail relatively flat with its planing hull.
Both are fairly narrow on the waterline-K1 is probably a bit skinnier....
==============
K1
----------
LOA 15'
Beam 4'3"
weight:
a. hull 99lb
b.keel 132lb
sailing weight(minus crew) 275lb
SA 118 sq.ft. (up and down)
http://www.k1sailing.com/
===========
Bongo
---------
LOA 15'2"
Beam 6.5'
weight 350lb
SA:
a. up 112sq.ft.
b. down 259 sq.ft.
http://www.sailabongo.com/m/_general...T=1&riPageID=2

[lascraigus]

Hmmm. So what to do....what to do! Makes sense that the keel bulb does help...guess I have to draw one now! For now, and since I just cannot help myself (imitation is the highest form of flattery) I know I know......not practical for a sailboat of this size.....

[Doug Lord]

Are you trying to evoke the appearance of an Open 60 or Mini 6.5? There is nothing wrong with that-the 2.4 Meter is a successful small keelboat designed to look like a small 12 meter.These boats are characterized very wide transoms ,canting keels, big rigs and are designed to sail primarily off the wind. No one has done a boat in this(15-16') size range to look like an Open 60 to the best of my knowledge-there is always a first time--- Good Luck!

[lascraigus]

why yes. yes I am! I have not found anything close to like you said though i'm afraid. Ah well. I'm just going to plod along and see what goes! While making scale models sends chills up my spine (again too much architecture) the end result would give me something to base "real world" performance. I have been on staff here at the college I graduated from for almost 10 years and I know some people who work in the mechanical aerospace department who I think could set me up with a testing tank! Thanks for your comments Doug! Greatly appreciated.

[lascraigus]

I see you are from Cocoa Beach! I used to go there every summer when my brother lived there.......Tiki Bar @ the tail end of the pier......good times. good times. I miss it there.

[Doug Lord]

Here are some good shots of a mini 6.5: http://www.owenclarkedesign.com/Prod...erSailerSports
--------
Heres a Sailing World review of the "Open 5.7" one design(30 grand)-the smallest I've found....http://www.sailingworld.com/sailboat...ear-48589.html

[lascraigus]

An Open 5.7!! THAT is what i have been after! THanks.

[Perm Stress]

If You build a scale model, to test sailing abilities of Your design, make it big. Otherwise, You will need to greatly increase area of appendages. Detailed explanation on it is a bit complex. Basically, You need to keep Reynolds number at foils big enough at certain minimum speed. I learned it hard way. I am working at article on subject (In Lithuanian at the moment ). As a rule of thumb, at ~2.5m of model LWL, the scale area of keel and rudder could be the same. At 1.3m of model LWL, the scale area of keel need to be increased ~2 times. And so on...


Good luck with Your efforts!