Mini Keels or Not

[phuelin]

I am the new owner of a granger 38 which has been extended to 40.
Due to excessive damage to the dagger board cases inside the boat I am looking to remove them and fit mini keels.
Can anybody who has carried out a similar project please help with some advise as to size and position of the new keels.
Thanks ,
Phil.

[chrisr]

why not contact tony grainger ?

details from his website ;

"International Phone: ++ 66 8 6275 2480
Mobile in Thailand : 08 6275 2480
graingerdesigns@gmail.com
Call on Facetime, Line and What's App (not skype please)

Please note we run on Indochina time which is UTC + 7 hours.

Phone calls 7am to 6pm our time please.

Please don't send us messages or documents through Facebook Messenger or other private messaging services. email works fine."

cheers,

[Tupaia]

OR NOT? Are looking to be convinced otherwise or just how to do it?

[Chotu]

Originally Posted by phuelin

I am the new owner of a granger 38 which has been extended to 40.
Due to excessive damage to the dagger board cases inside the boat I am looking to remove them and fit mini keels.
Can anybody who has carried out a similar project please help with some advise as to size and position of the new keels.
Thanks ,
Phil.

As an outright guess, I’d say make them the same surface area as the boards (but of course longer and more shallow, put their center of effort where the board center of effort is currently and use a NACA foil shape with a flat bottom for beaching.

[Scaramanga F25]

Repair and add crash boxes or make them break-away. If you like the way she sails to inward as well as off the wind and the shoal draft, repair. You will hit the bottom with mini keels too. Big and expensive job to change the hull with integrity.

[wingssail]

Originally Posted by phuelin

I am the new owner of a granger 38 which has been extended to 40.
Due to excessive damage to the dagger board cases inside the boat I am looking to remove them and fit mini keels.
Can anybody who has carried out a similar project please help with some advise as to size and position of the new keels.
Thanks ,
Phil.

The lateral load on the mini keel will be transferred to the hulls where they are glassed to them. Therefore, not only do you need the design a size and shape which is appropriate, you'll need to make sure the hull structure itself is adequate to resist the flexing and to absorb the impacts transferred to it from any potential grounding. This will probably mean reinforcing the hulls for the full length of the mini keels. If the hulls are cored, it would mean removing the core and making it solid, in my view.

You'll need more area in the mini keels than the area of the dagger boards since the mini keels will be less efficient at preventing leeway.

AND, since the dagger board trunks need to be repaired anyhow, to prevent water ingress, possibly repairing them and making new dagger boards is a better solution.

Talk to Granger

[CATJAVA]

I have a Crowther Design 85, 48ft built in 1991 in Oz. After crossing the Southern Ocean one of my boards wouldn’t fit the slot anymore. Tried reshaping the board a few times but the slot had changed shape in the middle (impossible place to fix without tearing much of my hull apart) so decided to take the easiest course. Glassed over the top&bottom of the slot making it another watertight space. My other board is fine so only use one board & works good.

What I really want to tell you is that Crowther designed this cat with Sacrificial keels. They are about 1/2 the length of the boat, 4” wide flat bottom for beaching. They taper from 4” in the front to 18” in the rear. The design allows the cat to beach slightly nose down while the stern is raised to enough to keep the rudders & off the sand. They are simply glassed onto the hulls with a glassed-in wood block in the front and back under the structural crossbeam hull support for hauling out on a trolley. I have hit a few reefs in my years which damaged the keels, but have always been able to sail and fix the keels later when I haul out or find a beach. Why don’t you ask Grainger what he thinks about these sacrificial keels? I would think he would know about them since Crowther was a famous designer. It’s not a difficult project since I just saw another cat get them after the builder dove on my cat JAVA in the Philippines to take a look at mine.
Good luck! Evan on JAVA

[Tin Tin]

Got any photos of the excessive damage you refer to? If you are new to yachting the damage may look a lot worse than it really is. Do the cases leak at the moment?