Paul H

[hilux38]

Hi,

Could somone please tell me how the strakes which run for and aft of pwer boats work? and how effective they are? Something to do with beam on seas?

Paul

[Wynand N]

Hi hilux38

Strakes or spray rails are a part of control working with various factors within the overall hull design on powered craft.

In a nutshell, when the craft is heeled, the flow of water on the rails/strakes produces a stabilizing force. It also prevent the water from remaining attached to the hull and this reduces the wetted contact, a significant resistance factor for a planing craft.

An added bonus of the strakes above the water is to keep (hopefully) the bow wave and spray from your beer.

Fair winds

Wynand Nortje

[hilux38]

Thank you for your reply Wynand, so does this mean that the longer (from bow to stern), and more strakes there are the better?

I looked at one aluminium hull, 8m, and there was only one strake on each side of the hull which went only half way toward the stern. What would this mean? would it be effective?

cheers,
Paul

[navinod]

The number ans size of spray rails doesn't follow a precise formula. They can be used to detach water and spray from the hull surface and provide a lifting force that can improve planning status and speed. The number of spray rails depend on how big is the surface between chine and centerline. Non continuos rails may help propellers to work in a compact and pure flow, not disturbeb by these elements. Outboard or sterndrives have no problems with spray rails, but submerged props, surface drives or water jets may be influenced by spay rails.

[hilux38]

cheers for the info navinod,
regards,
Paul