Keels

The first wooden Corribees came with centreboards/plates. GRP Corribees came with two keel options – fin and bilge. The Corribee Owners Association Boat Register shows the fleet as consisting of Plate (1%), Bilge (54%), Fin (33%) and Unknown (12%) as of 18/7/2009. All the Coromandels in the register are bilge keel.

It’s interesting to note that there have been a few complaints regarding the stiffness of the fin keel, and people have undertaken modifications to add extra ballast to correct this, but the bilge keel has not seen any such comments.

Mono Bilge Keel – Unique but not seaworthy!

Jay Blackburn of Emily Grace has kindly written this article for this site:

20090720_EmilyGraceKeelReplacement_JayBlackburn

I found a Coromandel sitting forlornly on a used boat lot, disgusting colour like a Banana Split, however it was worse as she had a nice bilge keel to Starboard but on Port there was a tree stump! I was sure this was not a Robert Tucker special design so I decided to ask. Apparently she had broken off a mooring on Windermere and then on a lee shore had ground the bottom of her bilge keel out. Of course relieved of the strengthening force of an enclosed box the keel folded up dropping the solid cast iron ballast out to the lake bottom.

So she had been rescued and had remained afloat and dry but the ballast was still in the deep. I agreed to buy her at a reasonable price and the owner told me he would get me the ballast back – this I have to say I doubted but I thought I could scrounge enough lead. Imagine my surprise when I went to collect her and found this huge lump of iron lying in front of her.

So back to the farm and take stock. It was easy to see what was needed – a mould that was the opposite hand of the asymmetric existing keel. So with lots of measurements and many trial fittings I made the female form of ribs to fit the existing keel and then turned them over laying thin ply on the inside and body filler to make up the fore and aft profile. This was laid up with chopped strand mat and woven rovings. The ‘flat inner surface’ was made in the same way and the two halves cleaned up and fitted together. These were then joined and reinforced making a nice shaped box.

Then the boat was cleaned up, grinding the gelcoat off and tapering the hull thickness down to the joint.

Setting the new keel box up was difficult, using long battens clamped to the inner surface of the keel, these allowed me to measure off many points getting the ‘toe-in’ right. I then glassed the joint using 2” strips. I wanted to be really sure of this joint and wasn’t to certain of the chemical bond of this 15 year old hull to the week-old keel, so I decided to cut a series of inch and a half holes round the joint and continued glassing using wider and wider strips on the inside and outside. As the resin cured, the glass was pulled tight into the cut out holes bonding together from inside and out giving a mechanical and a chemical bond. Eventually there was sufficient thickness and I felt happy with the bond.

Now it was simply a matter of lifting about half a ton of slippery cast iron up from the floor over the cockpit sides, across that vulnerable floor and then through the companionway and into the keel box…

With a fork lift and a thin piece of parachute cord we started to lift. The farmers all wanted to use huge chains but I was relying on the one ton breaking strain to allow me to lower the ballast right into the keel. It went well until we got it into the cabin and found the keel is slightly forward of the hatchway and, of course, you can’t drive a forklift into the boat. Two of us heaved and pushed, moving the keel forward as it was lowered. As we were about to expire it suddenly went and slid in like a hand in a glove.

I had packed the base with a dry mix of mortar and I proceeded to pack more round the ballast making sure it wouldn’t get loose.

So now it was a case of glassing over the top and putting the cabin back together. I had taken the heads compartment out to effect the repair and now looking at all that room I decided to leave it out and put in a nice galley. I really should get round to glassing the floor back together one day too…

I know that my next job, as many have done before, is to sort out the rather badly made rudder, maybe making it slightly bigger and putting some balance on it.

So be brave and just get stuck in, it’s easy really. If you can’t finish it, call me – I’m a boatbuilder!

Source: by email

Slamming ballast

Nathan Whitworth of Kudu has kindly written this article for this site:

I have recently been told that Newbridge weren’t ever so strict on what the ballast consisted of, and I have heard stories of all sorts being found in the keels, including sand. In my case, a Mk1 bilge keel, I was apparently lucky to have found lead ingots, although unlucky by the fact that the encapsulated portion was not properly secure on the starboard side. This lead to violent slamming in a large sea when the boat rolled, and obviously required attention.

My boat had a sea toilet under the chart table, so I removed that, cut out the glassed-in ply mounting box it was sat on, and used a hole saw to drill into the encapsulated ballast area. I was surprised to find that the stack of lead ingots was free to fall from side to side, about 3 inches in all.

Corribee keel ballast

I have fixed the problem by filling the void with expanding foam, them glassing back over the holes I drilled. In my case, the encapsulated area was bone dry, so water ingress was not an issue.

If you are experiencing slamming noises from the keel, it’s worth first checking the trimming ballast forward of the main bulkhead (at least on a Mk1).

Source: onkudu.com

Dimensions

Details of the keel dimensions for sizing a trailer can be found on the trailer page.

Contribute

Do you have a story, information, brochure, manual, link or other relevant content that should be on this page? If so, we would be very grateful if you would leave it as a comment or email corribeeeditors@googlemail.com so we can post here – thanks!

2 Responses to “Keels”

  1. Hedley Says:

    Having suffered a small amount of water in the aft of the starboard keel of Moonwisp over the past few years, this year I decided I would get to the bottom of it.
    Having ruled out:
    1. Leaking Sea Cocks
    2. Cockpit mounted Bilge pump seal
    3. Windows and coach roof fittings
    I decided it had to be entering through the Keel.

    The next question was top or bottom. To determin this I drilled two small holes (one above the other about 100mm apart) in the keel bulkhead whilst afloat. Initially both were wet then only the bottom one suggesting that the leak was below the lower.

    With Moonwisp out of the water I discovered that the sole of the keel had become soft and porous at the front. Clearly to fix this the balast would need to be removed and the keel dried out. I elected to do this by cutting away the keels veritcal internal bulkead (accessible through the hatch under the quarter berth) and lifing out the 20 lead ingots and the remains of the sand and cement filler. Once fully dry (hot air gun for several hours a day over a week) and all the damaged laminate removed the keel was relaminated using epoxy resin and alternate layesr of chopped strand mat and roving (both internal and external) until the original shape was achived and I was satisfied with the bond of the internal laminate. The next job was to refit the lead, this proved to be easier than I expected and by bonding the first ingot into position with epoxy it was used as a platform to lay the first full layer of three abrest. The voides were filled by poring 7 minute concrete repair into the gaps and woring in with a paint brush on a 50 cm stick. This first layer was then encapsulated with more epoxy and roving which in effect provides a horizontal bulkhead then fitting the remaining 16 ingots filling the voids with more 7 minute mix. All that was now required was to reinstate the the veritical bulkead in the keel and paint.
    However, for good measure and to prevent this happening again I fitted Moonwisp with a pair of green oak shoes which I bonded into place with epoxy and 50mm wide roving for good measure. Works a treat and no more wet bilge.

  2. New articles this week « The Unified Corribee Website Says:

    […] Grace has written an interesting article about the unique mono bilge keel Corribee that he rescued here. Nathan Whitworth of Kudu and eCorribee have written a useful article about internet access that […]

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