Difference between revisions of "Re bedding Keels"

From Westerly Wiki
Jump to: navigation, search
Line 28: Line 28:
 
0.50 inch dia.    30 lb ft;
 
0.50 inch dia.    30 lb ft;
  
For comparison see torque values given in Westerly literature here [[Westerly Procedure for Leaking Keel Bolts]]
+
For comparison see torque values given in Westerly literature which can be found below in "Westerly Procedure for Leaking Keel Bolts"
  
 
But if it don't leak don't touch it.
 
But if it don't leak don't touch it.

Revision as of 15:23, 13 May 2014

The iron keels on a Westerly Centaur splay outwards so that the leeward keel is vertical and the windward keel is acting as a counter weight whilst healed over sailing. This gives a better sailing performance compared to other bilge keelers with vertical keels but can put great loads on the keel to hull joints. Older Centaurs and other bilge keel Westerly yachts have to be strengthened inside the keel stubs to prevent flexing which results in cracking. The great flexing and bending forces incurred whilst sailing and whilst grounding when the tide goes out will eventually cause to hull to keel joints to break down.

The iron keel is butt jointed to the molded in GRP keel stub and held in place by six stainless steel studs with large washers and nuts. Sealant is applied to the contact surfaces to prevent water leaks but this sealant will eventually dry up and break down. Most manufacturers would give an effective life of the sealant as being around twenty years. You can make a temporary repair by applying sealant to the outside but it will not last. The only way is to remove the keel, scrape away the sealant and replace it. It is important to prime the cleaned surfaces before fresh sealant can be applied as otherwise it will not stick.

The keel does not have to be removed completely and in fact it is only necessary to separate the hull and keel by a couple of inches to allow the joint to be cleaned primed and repacked. You will need to build a steel and timber support around the keel to lock the lower edges of the keels in position relative to each other and take the weight of the keel.

You should then loosen the keel stud nuts and run a blade around the old sealant in the joint to help the keel and hull part. The vessel can be lifted one side at a time with the other side still supported on its keel and in this case it is possible to maintain the engagement of the keel bolts with the holes in the keel stubs.

To lift the vessel either a crane can be used or as per Ref 2 two chain hoists attached to some form of substantial framework, or per Ref 3 hydraulic jacks under the hull can lift from below. The keel will initially lift with the hull and the two will need to be persuaded to part preferably using several(4)wooden wedges inserted into the hull keel joint. It might take some shifting and you will need to watch out for your feet and hands. When eventually parted block off the hull and make everything safe before you clean away the old sealant and prime the cast iron mating face.

The job is within the scope of amateurs for just the cost of the sealant alternatively boatyards such as Retreat Boatyard on the Exe, Deacon's on the Hamble and Madge Marine in Chichester could do it for you for around £1,000.00 per keel.

The sealant that would have originally been used on your Westerly is called Marineseal 033. It comes in two packs of putty which have to be carefully mixed together by hand. It is designed to remain flexible for at least twenty years and can be bought from Marine Mastics Ltd who are based in Waterlooville close to where Westerly's were built.

Fosroc Nitoseal 600, a polysulphide sealant and primer MS2 are recommended in Ref 2 as a more modern alternative.

Tightening Down Keel Stub Nuts

The torque settings for stainless studs are

1.25 inch dia. 180 lb ft;

1.00 inch dia. 130 lb ft;

0.75 inch dia. 80 lb ft;

0.50 inch dia. 30 lb ft;

For comparison see torque values given in Westerly literature which can be found below in "Westerly Procedure for Leaking Keel Bolts"

But if it don't leak don't touch it. If you do need to remove keel nuts for some reason, then do one at a time, eg remove one and refit and torque down before you tackle the next one, that way you stand less chance of disturbing the keel hull seal.

Other Sources of Water around Keel Bolts

If you find water around your keel bolts it may not be a keel leak. On the Centaur water from the bilge can spill over into the port keel bolt area. When the boat is heeled sufficiently there is a path for bilge water to pass under the cooler box to the port keel bolt recess where it becomes trapped. Water in the bilge may come from the stern or from a leaking fresh water tank up front.

Another possibility is a leaky sink or tap dripping into the starboard keel bolt recess and becoming trapped there.

Geoffs Experience with Weoghi

I spent ten years with leaking keels having had two goes with yard help to solve the problem.

Eventually took off what I thought was gel coat on the exterior to find much Isopon-type soft filler that had been used to fair the stub. The laminate clearly had not been rolled neatly into the stub mould and was very thin in places indeed in two place there were cracks in the laminate. Also the aft bolt had of necessity to be well forward of the after end of the keel as there was just not meat enough either in the stub or the keel to take a bolt so one can imagine that waving around and propagating a crack in any sealant to move further forward.

Also the washers under the bolt heads were not bedding evenly at the base of the stub as the stub had been internally laid up with a curve and in a couple of places (where the cracks were) the washers were catching on the sides of the stub.

Then:

1 - the stub was re-laminated (after grinding off around three layers of existing laminate); 2 - the inside was cleared out to give a proper bearing to the washers; 3 - the keel was dry grit blasted to take an epoxy primer; 4 - the stub was epoxy coated; 5 - Sikaflex 292 (the adhesive variant) (with its recommended primer first) was then used in multiple runs to form a bead (25mm diameter - half round) along the keel-stub join. 6 - the keel was then epoxy filler faired and then had multiple coats of Primacon 7 - then antifoul

So far (touch wood) four years later and a number of lift-outs at which the bead could be inspected all is well. The filler also is not (yet?) peeling away.

Definitely feels like it goes faster with the faired keel - but purely subjective feel, I took no measurements.

For what it worth, I'm sure there are other solutions.

Westerly Procedure for Leaking Keel Bolts

Westerly's recommended procedure for leaking keel bolts here File:Keel Bolts.pdf

Resources

Marineseal 033 available here:

Trade Sealants Ltd (Marine Mastics.com) Tel: 02392 251321

Trafalgar Yacht Services

Nitoseal 600 available here: Fosroc Construction Products – Coleshill Road, Tamworth, Staffordshire, B78 3TL Telephone: 01827 262222. e-mail sales@fosrocuk.com

References

Ref 1 WOA Magazine Winter 2003 Pages 66-68 Re-bedding keels by Paul Shave and Don Sinclair

Ref 2 WOA Magazine Winter 2000 Repairs and maintenance to cast iron keels, Paul Shave

Ref 3 WOA Magazine Pageant Keel Stub Repair and Avoiding Damage when Drying Out Bilge Keelers by Paul Shave


Back to Hull, Keels and Rudder