Boat Design Forums  |  Boat Design Directory  |  Boat Design Gallery  |  Boat Design Book Store  |  Thanks to Our Site Sponsors
Old 08-20-2003, 04:41 PM
max max is offline
Junior Member
Join Date: Jun 2003
Rep: 10 Posts: 23
Location: Germany
16 M performance sailboat

Hi there,

I will do some towing tank test with a 16m sailing boat for my exames at the univerisity in Hamburg.
The main thing is to compare 3 different keel designs, as I posted some weeks ago in the boat forum ( Tandem/"racing"/cruising )
Now I developed a first lines plan for the boat and I must say Im not very experianced with it. Its my first one. So I have several questions about it and would be very pleased if someone could give me a hint.

L: 16.00m
Displ: 15.00 t
B: 4.20 m

1. I tried to keep the curve at the CL (under water) going to the transom as flat as possible. So at the end of the boat I have only 100 mm space between the transom and water surface. Would this be enough, where are the limits at this point.

2. I tried to save volume in the front of the boat and to make a sharp bow, to get the boat easier through the waves etc.
If I heel the boat for example 30 to one side (free trim) it moves down with its bow with an angle of 1.8
Is this a normal behaviour or will I get problems steering it in upwind situations, or could I even get it more skinny at the front area ?

Im also pleased if you give me somefeedback about other aspekts of the linesplan that maybe will not work.

PS: Rudder and keel are very preliminary !!!


Attached Thumbnails
16 M performance sailboat-16m-sailer.jpg  
Reply With Quote
Old 08-21-2003, 10:22 AM
dionysis dionysis is offline
Senior Member
Join Date: Jan 2003
Rep: 44 Posts: 257
Location: Tasmania, Australia
just a couple of general comments...

Hi max,

This design is really good for a first effort. A couple of points:

The reverse curve at the stem does not look right: you need bouyancy forward to stop the boat from burying into waves. There may be a problem here with anchoring as well. The rope will chaff on the hull around the water line. Better to draw it plumb.

Keel foil depth look tiny, you need area to resist leeway, and depth to resist healing moment.

The center of bouyancy seems too far back. The general requirement is about 5% aft of midcenter. This far aft gives you no lever arm to counter downtrim at the nose.

I'm not sure but 1.8 degrees downtrim at the stem, is not a good sign. Your sail thrust will dig the stem in even deeper.

Displacement is about right, and the plan view looks really good. Transom height is Ok.

You will need to run some numbers to compare your design with similar and successfull boats:

displacement to length ratio
sail area to wetted surface ratio

Hope this helps, cheers dionysis.
Reply With Quote
Old 08-21-2003, 10:27 AM
dionysis dionysis is offline
Senior Member
Join Date: Jan 2003
Rep: 44 Posts: 257
Location: Tasmania, Australia
think about prismatic coefficient too.
Reply With Quote
Old 08-21-2003, 11:42 AM
max max is offline
Junior Member
Join Date: Jun 2003
Rep: 10 Posts: 23
Location: Germany
Thanks a lot for your feedback dionysis !!!

I think you are right with the curve at the stem.

The keel is not really shown at the drawing ( sorry for that) .
The keel wich can be hardly seen with the bulb at the end, contains a metal centerboard, wich can be moved down to a total depth of 3.5 m.
I think that should be enough resist leeway. The area of the keel will be then 4% of the sail area. I want to try to reduce it as far as possible during the tank tests.

I will also get the center of bouyancy to 5% of WL backwards from midship, as you suggested.
Maybe then the bow is also not to going down that much during heeling. I will see.

The idea of comparing the boat to others is good, I did so and was able to find sail areas, L, LWL,, Displ. and so on. But for example wetted surfaces and prismatic coefficients are hard to find. In my case it is:

waterplane = 0,677
prismatic = 0,547
Displ/L = 116,55
W.S. area = 42,24 m^2

If you know any possibility to get these or even more datas from similar boats I would be glad to see them !

Thanx for all,


PS.: More comments are always welcome.
Reply With Quote
Old 08-21-2003, 01:48 PM
gonzo's Avatar
gonzo gonzo is offline
Senior Member
Join Date: Aug 2002
Rep: 2031 Posts: 11,893
Location: Milwaukee, WI
The hull looks a bit like the old IOR's without the knuckles in the aft sections. The narrow vee sections forward will make the boat go bow down when heeled. Also, it will make the boat point down, therefore counteracting the weather helm. This effect depends also on the position of the mast and keel. The further forward they are the more accentuated the effect will be.
Reply With Quote

Old 08-21-2003, 09:52 PM
dionysis dionysis is offline
Senior Member
Join Date: Jan 2003
Rep: 44 Posts: 257
Location: Tasmania, Australia

Do a seach with google for "yacht designers", and have a look through each of their sites for comparable designs. It is surprising how much information you can get from them.

good luck.
Reply With Quote

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Similar Threads
Thread Thread Starter Forum Replies Last Post
HELP ! Canting keel for 28ft performance daysailer Guest Jan Boat Design 12 03-14-2013
02:59 PM 
16' Keel boat-high performance Doug Lord Sailboats 171 11-02-2009
07:09 PM 
Sailboat as a powered cruiser? Bill Fish 6 Motorsailers 28 05-30-2007
05:46 PM 
Please recommend sailboat plans jmwalker Wooden Boat Building and Restoration 9 08-16-2005
03:38 PM 
Novice - Boat wake / performance question. jav Powerboats 10 08-09-2004
04:07 PM 

Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.

All times are GMT -5. The time now is 10:12 PM.

Powered by: vBulletin Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Web Site Design and Content Copyright ©1999 - 2017 Boat Design Net