Hulls 101: chine, strake, or spray rail?

[Old Hickory]

In "Overhauling" I posed a question concerning the correct nomenclature for a particular part of a checkmate hull. Mark suggested that Coop would probably know the answer; so I decided to let all of you guys throw in your .2 cents

Heres the thread and a pic of the part in question:

http://checkmate-boats.com/forums/showthread.php?p=431720#post431720



Here's my quote:

"I do have a technical question regarding chines. Would the "pseudo" part I was refering too be more correctly described as a "spray rail"?

I was always under the impression that the "chines" were located where the hull sides meet the bottom(a little grayer on rounded chine than it is on hard chine hulls). Today it seems that strakes are more often applied to the ridges and planing surfaces on the bottom of the hull. Where as once upon a time when boats were built using "lap strake" method; strakes ran all the way up the sides and were many times used interchangeably, descriptive wise, with chines.

Hence, why I used "pseudo strake", since it dosn't fit the modern definition of either a "chine" or a "strake". I'm guessing it's a spray rail but I'm not sure. Any help with the nomenclature would be appreciated; because when I finally post this in my blog, I want descriptions and terms to be as accurate as possible. thanks in advance"

So what is it fella's; a chine, strake, or splash rail? You may want to knock back a few before you answer:cheers

Hick

 

[Old Hickory]

oops; didn't mean to hit the "reply" button.

 

[Blizz]

I would think that it's just a line to break up the side of the hull as it would have very little effect if any on anything while underway. It would also add abit of rigidity to the sidewall of the hull.

 

[175checkmate]

Looking at the picture I would say its 90% cosmetic. It would also provide a small amout of plash control.

Here is the definition of a Strake:
"An improved V-bottom hull for sport/utility boats is formed with intermediate lifting strakes along the aft half of the hull bottom. Such intermediate strakes are positioned laterally along the boat bottom between the planing pad step and the chine. These intermediate strakes are proportioned to provide a strake riser face width that is about 1 in. or greater and a horizontal tread width of the strake of less than about 3 in. An included angle between the tread surface and the riser face is preferably between about 95° to about 110°. The riser face intersection with the adjacently higher bottom surface panel is faired with a longitudinal fillet."

A chine: On a deep dead rise hull there was a problem with a large wetted surface, less lateral stability, poor buoyancy and forward lift, and a very wet ride. Think solid V that is smooth from the center of the V to the sides of the boat.
Each chine decreases the overall deadrise angle of the hull. Chines provide some flat surface area in the water, which means more lift compared to an angled surface. The boat will draw less water and will have greater roll stability, and chines can deflect spray which would be thrown up. They can also cause pounding in heavy waves, because if they are large enough to really be effective, they are also large enough to prevent the boat from slicing cleanly into a wave.

 

[Old Hickory]

Looking at the picture I would say its 90% cosmetic. It would also provide a small amout of plash control.

Here is the definition of a Strake:
"An improved V-bottom hull for sport/utility boats is formed with intermediate lifting strakes along the aft half of the hull bottom. Such intermediate strakes are positioned laterally along the boat bottom between the planing pad step and the chine. These intermediate strakes are proportioned to provide a strake riser face width that is about 1 in. or greater and a horizontal tread width of the strake of less than about 3 in. An included angle between the tread surface and the riser face is preferably between about 95° to about 110°. The riser face intersection with the adjacently higher bottom surface panel is faired with a longitudinal fillet."

A chine: On a deep dead rise hull there was a problem with a large wetted surface, less lateral stability, poor buoyancy and forward lift, and a very wet ride. Think solid V that is smooth from the center of the V to the sides of the boat.
Each chine decreases the overall deadrise angle of the hull. Chines provide some flat surface area in the water, which means more lift compared to an angled surface. The boat will draw less water and will have greater roll stability, and chines can deflect spray which would be thrown up. They can also cause pounding in heavy waves, because if they are large enough to really be effective, they are also large enough to prevent the boat from slicing cleanly into a wave.

Thanks for the detailed definitions. That is, for the most part, my understanding of chines and strakes. It looks as if I'm going to call this a spray rail, unless emphatically informed otherwise. Where, BTW, did you get your text?

 

[175checkmate]

The text came from the copy and paste. Did some searching on the web to find the definitions. I knew what they where and what they did, but the definition is worded better.

 

[Boston Predictor]

I really dont think there is a techincal name for that part of the hull. Spray rail sounds fine, but its just a body line more or less. I dont think it serves any specific purpose other than aesthetics, but I could be wrong.