Keel on a planing hull

[GeoffSChapman]

I am about to add a shallow (30cms) keel to a 9m60 loa planing hull.
This is mainly to protect the prop via a bar between the keel and the extremity of the rudder as the boat will be used for pro fishing (nets).
How long should this keel be, I would guess it could start about midway.
I wouldn't want to lose too much manouverability or speed.
Would a short 1metre length be enough
Geoff
Uniquest Marine

[boby boy]

I recomend you start from midway but you could go shorter.

[Dutch Peter]

Geoff,

1 meter would be enough, as it surves only the purpose of protecting the prop.
Do you let it extend beyond the prop?

[AlaskaFisherman]

I am a drift gill net fisherman and our gill nets will catch/hang up on any non smooth surface.

[gonzo]

The drag on the keel will drop the top speed but increase manouvearability.

[gnesailing]

Have you considered Foils?

Just thought I would beat doug lord to the punch on this one.

[GeoffSChapman]

After reading your comments and looking arround, I reckon I'll go for the 1 metre length, I'm looking to protecting the prop with a stainless bar or tube extending from the keel to link to the bottom of the rudder, hopefully to deviate any ropes or nets, I'll try to keep the whole thing very smooth.
I would hope that the short piece of keel would favour directional stability at low speed, because I have suffered with single engined planing boats trying to park them in marinas. With a 4 bladed prop you go too fast and when you flick into neutral the boat goes where it likes!

My customer fishes with nets that he lets out over the back of the boat and then turns arround the fish shoal, eventually lifting the nets back in with a wheel in the bows.
He will have a hydraulique crane on the deck aft and winches on each side aft of the doghouse (I'm not sure what he will do with them?)

How do you mean Foils? legs on either side of the hull?
I'm interested

Geoff