Spray rail design

Can anybody direct me to any good recent articles on spray rail design, particularly for mod vp or tunnel hulls - width, slope and height to minimise drag caused by the spray are the areas of interest.

Thanks
nevd

 

spray rails

Hi Nevd,
I'm putting spray rails onto my Thundercat, Jim Russel
from AeroMarine Research gave me some help with the
position.

Regard Asterix

 

spray rails

Thanks for your response.

How high in the tunnel did you put the spray rails and what radius are you using at top & bottom of spray rails? Are the inside faces vertical or sloping? Are the rails laterally parallel to water or turned down? How have you checked to see if the design is successful?

Regards,

nevd

 

Spray Rails

Hi nevd,
The spray rails inside the tunnel are 100mm high the tunnel is 225mm high.
The rails on the outside of the boat are 200mm high. (Rails are made of Rubber)
As yet I have not tested the boat but should have it in the water in about a week and will let you know how the rails work.
I will do a drawing of the spray rail and post it in the next day or so.
Regards Asterix

 

Hi guys, I was reading a book written by the great Renato Sonny Levi and he says spray rails total surface should be 20% of beam at the stern,so if you have 4 mtrs wide hull at the stern you can put 80 cm total in spray rails.
This is juast his opinion...but i think it is a very good opinion though!

 

Thanks for your info and comments both Fede & Asterix. Do you think the Levi comments apply to lifting strakes and not spray rails or was he referring to deep vee boats at racing speeds?

Regards,

nevd

 

Spray Rail Profile

Hi Nevd,
This is the profile of the spray rail I am using about 25mm wide and 40mm
high and it is made of a soft PVC extrusion.
regards Asterix

 

Spray Rails profile

Oops for got to attach the sketch.
regards Asterix

 

You can calculate the thickness of the spray sheet from the physics of the planing surface. The spray rail should be a bit higher than this.

 

Hello,

Can you provide any more details or some references?

Regards,

nevd