Midship interceptor

[rwatson]

The best part about this idea is that the application lends itself to variable useage.

The surface could be made retractable, so it does not have to be used all the time, unlike a stepped hull.

[HJS]

A boat moves in three media, water, air and sea, all with different characteristics.

Highly simplified as follows:
The interceptor works in principle only in the boundary layer.
The boundary layer thickness depends on the speed and the forward-surface length, in addition to the water features.
The lifting force from interceptor is dependent on its depth in relation to the boundary layer thickness.
The lifting force from the planing surface is due to its shape, angle of attack and speed.
There is an optimum for how much lift is taken from the surface and interceptorn.
The interceptor depth must be adapted to the load and speed.
Will the interceptorn lift be to large decreases in the forward length and thus the boundary layer thickness, with that the interceptorn lift collapses.
But it is much more complicated in the case of a V-hulled, which moves in and on the water. At high speeds the stagnation line crosses the interceptor and the whisker spray divers foreword and transverse.
Therefore, do not fully apply the above remarks concerning the interceptor depth.
How the optimum depth of the amidships interceptor must be is tested at the moment on my boat.

And there is much more to figure out.

js

[tom28571]

HJS,

If the stagnation line gets anywhere near the interceptor, it seems that all bets are off on what happens. If that is the case, what happens when the boat is dancing around on top of the water? It appears that an interceptor is useful only if it can be kept with solid water ahead of it. Steps don't seem to have this problem to that extent.

[HJS]

Latest testrun!

js

[tom28571]

Jurgen, I sent you a PM.

[Alexjava]

Hi Everybody.

Can somebody explain to me what is Interceptor exactly? How does it work?

[HJS]

Look at
www.sassdesign.net
Boat w midship interceptor

js

[Ad Hoc]

The "interceptor plate" concept is nothing new...has been used for years.
You'll even get many waterjet manufacturers offer 'built-in' interceptors, saves you having to design and install separate hydraulics, neat.

[daiquiri]

Originally Posted by Ad Hoc

The "interceptor plate" concept is nothing new...has been used for years. You'll even get many waterjet manufacturers offer 'built-in' interceptors, saves you having to design and install separate hydraulics, neat.

I don't recall seeing it around. Though the idea is so simple that it is really strange that nobody has thought of it before.
Can you give some reference reading (or some photo, drawing etc.) for what you wrote?

[Ad Hoc]

Daiquiri

Just look at any KaMeWa or MJP waterjet...it's one of the options. MDI uses them too for motions:
http://www.maritimedynamics.com/prod...terceptors.htm

In these papers the deisgn uses the interceptor plates as ride control devices too not just for resistance...this is a nice benefit of interceptor plates...speed and motion control. Has been used as both for several years now too.
http://media.bmt.org/bmt_media/resources/29/paper2.pdf

also see
Theory and Practice of Application of the Interceptors on High-speed Ships
Gregory Fridman et. al., St-Petersburg State Marine Technical University (SMTU), Russia
Experimental Investigation of Interceptor Performance
Sverre Steen, Norwegian University of Science and Technology(NTNU), Norway

[daiquiri]

Ok, I've read it. What you are talking about is a well-known solution - see my post at pag.1 of this discussion (post #6).

But it is not the same thing. Here we have an interceptor plate mounted at the mid-hull, with aeration holes behind it. Two characteristics which makes it very different from a traditional transom-mounted interceptor plate.
This solution is a mix of transom interceptor plus Dynaplane concept plus aerated stepped-hull concept.