What is a MKII? - SailNet Community
Member

Join Date: Oct 2004
Posts: 81
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 16

What is a MKII?

Sorry for the newbie question, what is a MKII?
Also, can someone also explain the term "hull speed" please.
Thanks again.
42ndstreet is offline

Old 12-06-2006
Senior Member

Join Date: May 2006
Location: Sarnia ON
Posts: 695
Thanks: 3
Thanked 5 Times in 5 Posts
Rep Power: 15

Many manufacturers made upgraded or modified versions of the same boat. A C & C 27 for instance had 5 variations starting with a MK I on up to V.

Hull speed is the theorectical maxium speed that a displacement hull can go. It is based on the water line length, the formula is the square root of LWL times 1.34.
A boat with a water line length of 25 feet will have a hull speed of 6.7 knots. Basically the fastest it will go unless surfing etc. Not all sailboats can attain their hull speed reaching or beating.
Gary M is offline
Member

Join Date: Oct 2004
Posts: 81
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 16

Thanks Gary
42ndstreet is offline

Old 12-06-2006
Senior Member

Join Date: Dec 2002
Location: Maryland
Posts: 526
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 18

MKII translates to "Mark 2." It signifies the second edition of something, such as an airplane or a boat. It was originated by the British. The U.S. used to use "dashes" to denote the same thing, i.e. "-2".

Hull speed is usually described as maximum theoretical hull speed, which, for a displacement boat such as a keel boat, is calculated by taking the square root of the waterline length of the boat in feet and multiplying it by 1.34. This is the theoretical fastest speed at which the hull should be able to go through the water, although in reality such hulls can go faster. Wind, waves, and sail trim all factor into the speed.
SailinJay is offline
Old 12-06-2006
Senior Member

Join Date: Dec 2002
Location: Maryland
Posts: 526
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 18

Must have been typing my message when Gary was sending his.
SailinJay is offline
Old 12-06-2006

Join Date: Feb 2006
Posts: 136
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0

Some of the changes from model to model were dramatic. For example, a C&C30 - MK1 has a PHRF (rating for racing - the lower the number, the faster the boat) of 174. The C&C 30 - MK2 has a PHRF of 144. Obviously the newer boat is much faster, but that does not necessarily make it better for you intended use. When looking at boats, it is important to know the variations of each model.
captlar is offline
Old 12-06-2006
Telstar 28

Join Date: Mar 2006
Location: New England
Posts: 43,289
Thanks: 0
Thanked 20 Times in 15 Posts
Rep Power: 19

Of course hull speed is only calculated that way for displacement monohulls... not planing hulls, hydrofoils or multi-hulls.

Sailingdog

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Telstar 28
New England

You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

—Cpt. Mal Reynolds, Serenity (edited)

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
.

sailingdog is offline
Old 12-07-2006
Senior Member

Join Date: Jun 2005
Location: New Orleans
Posts: 2,261
Thanks: 10
Thanked 55 Times in 52 Posts
Rep Power: 15

Quote:
Originally Posted by Gary M
Many manufacturers made upgraded or modified versions of the same boat. A C & C 27 for instance had 5 variations starting with a MK I on up to V.

Hull speed is the theorectical maxium speed that a displacement hull can go. It is based on the water line length, the formula is the square root of LWL times 1.34.
A boat with a water line length of 25 feet will have a hull speed of 6.7 knots. Basically the fastest it will go unless surfing etc. Not all sailboats can attain their hull speed reaching or beating.
I recall being told the multiplier was about 1.3 for a "slow" boat, up to 1.5 for a "fast" one, leaving us to figure out which was which (though we pretty much knew). Nowadays boats have the Polar diagrams which supposedly figure this out for us.

I was also told that rather than being an absolute limit (in displacement mode), hull speed was the point at which any additional speed required way too much additional energy to be practical. For example, if a 20-knot destroyer took that 25-footer in tow, the hull would be going more than 7 knots (somehow), it wouldn't be practical under one's own power.
nolatom is offline
Old 12-07-2006
Senior Member

Join Date: Dec 2002
Location: Maryland
Posts: 526
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 18

Rousmaniere's "Annapolis Book of Seamanship" uses 1.34.
SailinJay is offline
Member

Join Date: Oct 2004
Posts: 81
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 16

Thanks again for the information. You guys are all a big help.
42ndstreet is offline

Message:
Options

By choosing to post the reply above you agree to the rules you agreed to when joining Sailnet.

## Register Now

In order to be able to post messages on the SailNet Community forums, you must first register.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.

User Name:
OR

## Log-in

 Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)