SailNet Community

SailNet Community (http://www.sailnet.com/forums/)
-   General Discussion (sailing related) (http://www.sailnet.com/forums/general-discussion-sailing-related/)
-   -   Keel Help! (http://www.sailnet.com/forums/general-discussion-sailing-related/98006-keel-help.html)

linapark97 03-30-2013 04:44 PM

Keel Help!
 
Alright I'm a student designing a boat on the computer and it has to have the jest of the boat. None of the complicated scaling and measurements have to be on the design, but I was wondering if a full keel gives better stability than a fin keel. My boat is just supposed to sail to a designated location, its focus is not speed but stability since it its supposed to anchor down. Basically its supposed to be a kitchen boat so the cabin is mostly a huge kitchen that you can enjoy your time cooking more professionally. So a full keel or a fin keel? Regarding sails, it has a main sail and a jib. The dimensions are 8 feet high, not including the mast, 45 feet long, 8 feet wide, and the mast is 36 feet high. I have no clue what the hell I am doing to be honest, I just want to get this over with so please help! :(:confused::D

deniseO30 03-30-2013 05:12 PM

Re: Keel Help!
 
Quote:

Originally Posted by linapark97 (Post 1010032)
I have no clue what the hell I am doing to be honest, I just want to get this over with so please help! :(:confused::D

Suggestion; Join the boat design and wooden boat forums.

Which software are you using?:rolleyes:

linapark97 03-30-2013 05:15 PM

Re: Keel Help!
 
Quote:

Originally Posted by deniseO30 (Post 1010050)
Suggestion; Join the boat design and wooden boat forums.

Which software are you using?:rolleyes:

Google Sketch Up. It restricts many aspects of my design.:mad:

msmith10 03-30-2013 05:25 PM

Re: Keel Help!
 
I'm not a naval architect and I'm not sure what you mean by stability, but I'll give it a shot:
There are 3 movements the boat can make while sitting in one spot: roll, which is the boat rocking from side-to-side; pitch, which is the boat going up and down in the front (bow); and yaw, which means the front of the boat going from one side to the other.
If by stability you mean continuing in a straight line (tracking), a full keel is better. If you mean preventing the boat from rocking side-to-side (rolling), it's a matter of getting the maximum amount of weight the farthest down underwater- either full or fin could do this but typically a long fin with a heavy bulb on the end would be the approach. If you mean stability at anchor, so someone inside could cook in your floating kitchen, a full keel will keep it pointed into the wind better while a fin keeled boat may tend to yaw more (the front will head from one direction to the other). Again, though, a long deep keel with a lot of weight at the bottom will do better to prevent rolling.
I'm not sure about pitching - I would think that a fin keel with weight concentrated in the center of the boat would be more prone to pitch than a full keel spreading the weight more along the length of the boat.

Did you choose your dimensions? 8' is very narrow for a 45' boat- she's going to sit very low in the water and won't have much form stability (that's another topic).

msmith10 03-30-2013 05:38 PM

Re: Keel Help!
 
By the way, why would anyone want a sailing kitchen?

mad_machine 03-30-2013 05:44 PM

Re: Keel Help!
 
if you want good stability at anchor.. why not a catamaran? It could be a LOT wider than 8 feet (and most are), sail decently, and when sitting at anchor, you have all that width and roll stability

Jeff_H 03-30-2013 08:33 PM

Re: Keel Help!
 
I would suggest that you look at other successful designs for clues. I would suggest that you look at designs from the hand-drafting days. If you are going to draw a boat and have never designed one it can be helpful to look at existing successful designs for get sense of proper proportions for dimensions and weights. For example, a mast on a 45 footer would be closer to 60 feet.

You might want to look at something like Farr Yacht Design which was a successful design from the hand draft days and which was a simple design to draw and understand.

As to full vs fin keels,stability comes from a range of factors and the choice of either keel type has no direct connection to the stability of the vessel.

UncleJim 03-30-2013 10:54 PM

Re: Keel Help!
 
Sounds like a student looking for someone to do his homework so he doesn't have to stay awake in class

deniseO30 03-31-2013 08:33 AM

Re: Keel Help!
 
Quote:

Originally Posted by linapark97 (Post 1010052)
Google Sketch Up. It restricts many aspects of my design.:mad:

there is actually free boat design software out there. "freeship" is one.
Thing is unless you are learning the design process of boats. You really are going to have difficulty. The reason I suggested you join wooden boat or boat design forums is that reason. Guys are always posting hypothetical designs.

Siamese 03-31-2013 10:10 AM

Re: Keel Help!
 
Jeeesh!......just copy an existing boat. How do you think all the other designers do it?


All times are GMT -4. The time now is 08:02 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012