Outboard height on stepped hull

[puregeek]

Trying to setup my outboard height correctly, my understanding is that im supposed to have it above the keel line. But on a hull like mine do i follow the keel line or the stepped line? Im thinking that my cav plate should be about 1" above the yellow line. Can anyone shed some light on this? Also does anyone know the purpose of the steps on these hulls.

[Geoff]

It maybe a case of trial & error . I suspect at speed there would be no water in the stepped area so if you raised it up there would be a lot of cavitation.

Is there a problem at presant or are you just curious?

Personally , I would have the cav plate lined up with the bottom of the hull , ie , the leval prior to the step or perhaps just above , pretty much where it is now.

In respect to the step , I think is is just there for drainage via the bung , it certanilly is not large enough to have any effect on the boats performance.

Perhaps it just seemed like a good idea on the day during the design process & to give the sales guy something to talk about

Geoff

[puregeek]

At cruise the cav plate is buried. I'm also getting a little porposing aswell.

[Twinfisher 4.9]

I agree with you pure, it probably should be raised. I suspect "the step" is actually supposed to allow more clear water for the prop to grip (sounds good in theory). If you are porposing then it probably may well to be too low and the cav plate should not be buried - you said at cruise, but assume you mean on the plane? Suggest as a start, move it up so the cav plate is level with the yellow line you have drawn and then play around with tilt. If that doesn't work take it up one more notch.

Steve

Edited June 7, 2014 by Twinfisher 4.9

[BWV]

Yes you want the AV plate above the keel line, height depends on how far the outboard is set back. You want to be able to see the AV plate clearly when on the plane, it should sit clear of the water level.

A simple rule of thumb is for every 12 inches of set back it should be at least 1 inch higher, in some cases this isn't enough you need to go for a run and see how the AV plate is in relation to the water level.