Fitting Keel Shoes...Advice please..

[VO5]

My fin is an iron keel. A friend of mine's boat has a fin lead keel. His keel is going to be encapsulated in fibreglass extended from the hull joint downwards to the base of the keel.

This has given me the idea of doing the same with my iron keel and saving a lot of work every time she is lifted, particularly because she will be coppercoated next season.

There is no point in glassing the underside of the bottom of the keel as it is because when placed on chocks the glass would be crushed.The ideal would be for the keel to be encapsulated completely but fitted with boots ( a similar principle to horseshoes on horses' hooves).

In this way, when the boat is chocked up ashore and the keel rests on a couple of baulks of timber the underside of of the bottom of the keel is guaranteed to remain undamaged.

Have any of you had this done, or done it yourselves ?

What is the best material for the shoes and what is the best way to affix them to the underside of the keel ?

Thanks.

 

[Ubergeekian]

What is the best material for the shoes and what is the best way to affix them to the underside of the keel ?

I've got a couple of bits of lead showing at the bottom of my encapsulated keel. My plan at the moments is to dry, fill and fair it, then cover it with epoxy and a couple of layers of glass, then a couple of layers of Kevlar.

 

[penfold]

The problem will be sealing the edge of the laminate; once rust starts, it will peel the grp off the iron and generally be a complete nightmare.

 

[DownWest]

I have no experience in this, but a few thoughts. A good layer of epoxy/glass has very high compressive strength. So will probably have no probs with the wt. of your boat on wooden chocks(W. Oceanlord?) and certainly, total encapsulation is needed, with a generous overlap to the hull. As for horse shoes, a layer of one of the very high density plastics would do. But that is for expected grounding. I doubt you expect to often, so epoxy/glass is best. And be generous with it.
Some of the lighter bilge keel jobbies have put shoes of s.steel on theirs, but prob not an option for you.
A

 

[Tranona]

Can't really see the point of encapsulating a keel in GRP. You will have to blast it to perfection first and then no guarantee GRP will stick, nor that you will be able to fair it into the hull successfully. As already noted, if water gets in rust will start and the GRP will fall off anyway.

As you will have to blast, thee are well established epoxy coatings available to go on the keel before the coppercoat. These will keep rust at bay far better than a GRP skin.

A shoe is really only necessary if you take the ground regularly and is commonly fitted to GRP encapsulated bilge keels to prevent damage through abrasion - letting water in and causing rust. They are usually GRP and stuck on with Sika or similar. Cant see the point of fitting one to a fin keel though.

 

[VO5]

I've got a couple of bits of lead showing at the bottom of my encapsulated keel. My plan at the moments is to dry, fill and fair it, then cover it with epoxy and a couple of layers of glass, then a couple of layers of Kevlar.

What about the compression of this, given the weight of your boat ?

 

[VO5]

The problem will be sealing the edge of the laminate; once rust starts, it will peel the grp off the iron and generally be a complete nightmare.

At the base of the keel you mean ?

 

[VO5]

I have no experience in this, but a few thoughts. A good layer of epoxy/glass has very high compressive strength. So will probably have no probs with the wt. of your boat on wooden chocks(W. Oceanlord?) and certainly, total encapsulation is needed, with a generous overlap to the hull. As for horse shoes, a layer of one of the very high density plastics would do. But that is for expected grounding. I doubt you expect to often, so epoxy/glass is best. And be generous with it.
Some of the lighter bilge keel jobbies have put shoes of s.steel on theirs, but prob not an option for you.
A

My boat is a Westerly Sealord 39, an Ed Dubois design. The weight is 18,500 lbs unladen. The Oceanlord is a stretched Sealord in whose plug a two foot spacer was introduced to make the length overall 40'6". This stretching was done "in house" by Westerly at the time, and not the design of any marine architect.

But I digress.

My concern is the weight. I do not expect to experience any grounding. , but I do expect when laying up that the keel should rest on a couple of hefty baulks of timber on whom huge pressure will be loaded due to the weight of the vessel..

The other thing is that shoes can be fitted apparently under the epoxy at the underside of the keel, and the surface to line up horizontally inverted with the epoxy surface by using washers as distance peices.

What metal would be best as an alternative ? Lead ? Bronze ? Iron ? Stainless ?

 

[Ubergeekian]

What about the compression of this, given the weight of your boat ?

She's only three tons, and it's a long-ish keel with a fairly broad base - about 4" or so. My hope is that the Kevlar will give a bit of impact resistance for occasional groundings, most of which I hope will be deliberate. She's on a swinging mooring on the west coast, so no need to take the ground regularly.

 

[Ubergeekian]

My concern is the weight. I do not expect to experience any grounding. , but I do expect when laying up that the keel should rest on a couple of hefty baulks of timber on whom huge pressure will be loaded due to the weight of the vessel.

By an odd coincidence. I did what I believe was the first research to quantify - many years ago - the tensile stresses at the layer interface under such circumstances. As I recall, though, they are never very big - 5% or so at most. I wouldn't be too worried.

(Have just blown dust - literally - off a VERY dusty thesis to check this!)

 

[VO5]

Can't really see the point of encapsulating a keel in GRP. You will have to blast it to perfection first and then no guarantee GRP will stick, nor that you will be able to fair it into the hull successfully. As already noted, if water gets in rust will start and the GRP will fall off anyway.

As you will have to blast, thee are well established epoxy coatings available to go on the keel before the coppercoat. These will keep rust at bay far better than a GRP skin.

A shoe is really only necessary if you take the ground regularly and is commonly fitted to GRP encapsulated bilge keels to prevent damage through abrasion - letting water in and causing rust. They are usually GRP and stuck on with Sika or similar. Cant see the point of fitting one to a fin keel though.

I am not doing it. I am having it done professionally by someone with a long established track record in this niche service. I have not asked them about the underside of the keel (the foot underside, effectively). That is why I am enquiring as there may possibly be members who have had this done and I am interested and curious about the nitty gritty of it.

I can see the point in fitting them to bilge keels as these take rhe ground, and the necessity to protect the skin..
How thick are these GRP shoes you mention, do you know ? Thanks.

 

[DownWest]

Sorry, you lost me in the last bit about the shoes and washers bit. It is possible to glue some HD plastics to a well encapsulated keel, but I doubt that is your aim. Better to add a couple more layers of epoxy/glass.
A

 

[Tranona]

I am not doing it. I am having it done professionally by someone with a long established track record in this niche service. I have not asked them about the underside of the keel (the foot underside, effectively). That is why I am enquiring as there may possibly be members who have had this done and I am interested and curious about the nitty gritty of it.

I can see the point in fitting them to bilge keels as these take rhe ground, and the necessity to protect the skin..
How thick are these GRP shoes you mention, do you know ? Thanks.

I still don''t understand your logic for doing this. It will do nothing to strengthen the keel to take the weight when laying up - and anyway, can't even see why you are concerned about that!. Boats are laid up all the time resting on their keels BUT supported by a cradle (preferably) or properly positioned shores so the weight is evenly distributed.

In fact I don't think I have ever seen an iron fin keel encapsulated in GRP. No point, almost certain to fail. As I said earlier, the best way of protecting a keel from rust is shot blasting and epoxy coating. Perhaps this is what you are planning to do rather than laying up matt and resin.

Shoe is unecessary unless you are taking the ground regularly and want to protect the keel - but again only used when the keel is already GRP and needs a sacrificial shoe.

 

[mitiempo]

I also don't see the reason for this. Grit blasting will be necessary and coating with epoxy within the hour in dry circumstances otherwise rust will be starting already. Also if encapsulated checking the keel/hull joint will be rather difficult. The slightest start of oxidation and it will continue and the epoxy/glass will be pried off the keel's surface with the expanding force. All it accomplishes is letting the keel rust away out of sight. Not worth the money, time and labour.

 

[VO5]

By an odd coincidence. I did what I believe was the first research to quantify - many years ago - the tensile stresses at the layer interface under such circumstances. As I recall, though, they are never very big - 5% or so at most. I wouldn't be too worried.

(Have just blown dust - literally - off a VERY dusty thesis to check this!)

Wow ! Thanks. That's very helpful.

 

[VO5]

I also don't see the reason for this. Grit blasting will be necessary and coating with epoxy within the hour in dry circumstances otherwise rust will be starting already. Also if encapsulated checking the keel/hull joint will be rather difficult. The slightest start of oxidation and it will continue and the epoxy/glass will be pried off the keel's surface with the expanding force. All it accomplishes is letting the keel rust away out of sight. Not worth the money, time and labour.

Sounds like you have some experience or personal knowledge of this, possibly as a witness ? Please expand if you may.

I am told that the grit blasting and treatment will be as simultaneous as possible, three man team, one blasting, the other mixing and delivering, the other cleaning and applying.

The keel is double bolted throughout with very long bolts nearly all the way down, really massively overbuilt. She was built under Lloyds hull construction supervision. 42 of these are sailing out of 42 of these wonderful dreadnoughts built. One was dismasted, but none have shownto have any serious defects below the waterline to my knowledge.

I had a fright in America when she was lifted. On the hull there were three bumps, each about 3/4 " in diameter. It was suggested she had osmosis.
But because she had at least 4 layers of antifouling it proved to be bubbling between coats of the antifoul applications. There are no bumps now. Phew !

BC is a very beautiful spot, lucky chap you.

 

[mitiempo]

I once owned a 35' twin keel boat. She was custom built in Victoria and her keels were steel, with ballast in the lower section and diesel tanks in the upper sections. When the glassed keels were removed and stripped there was a large amount of rust under the glass and it was separating in many places. The skin was not damaged but the keels rusted away all the same. Properly prepared the epoxy should stick to the steel, but the smallest hint of rust and it will continue spreading. A proper sandblast and epoxy coating should give all the protection needed and will allow inspection annually. Any corrosion will be visible when hauled and not hidden.
The interface between the hull and keel probably has a bit of corrosion in a spot or two. Unless the keel is dropped from the hull this will not be taken care of but it could very well be the seed that will grow.
My current boat has an iron keel and it was epoxy treated before anti fouling was applied several years ago. No visible corrosion at last haul out and if some occurs it is easy and inexpensive to fix. I wouldn't want it glassed over.

 

[VO5]

Sorry, you lost me in the last bit about the shoes and washers bit. It is possible to glue some HD plastics to a well encapsulated keel, but I doubt that is your aim. Better to add a couple more layers of epoxy/glass.
A

The idea that was explained to me was that the washers would be slightly less than thickness of the ecapsulation, and the foot, presumably a metal one, to be level with the undersurface, bolted and with chamfered edges embedded by the encapsulation thus making the metal surface more or less equal to the fibreglass surface, thus making the undersurface continuous. I hope this explains it more clearly.

 

[VO5]

Actually, this is nonsense. I think a better propsition might be a plate in lieu of the washers, thus giving an even undersurface....and eliminating the risk of buckling.

 

[Ubergeekian]

Wow ! Thanks. That's very helpful.

It's nice to know that it has finally had some application. It was originally done, by the way, to look at possible mechanisms for the start of osteoarthritis in the knees: tensile stress between bone and cartilage at the edge of the contact patch.