Strengthening a Westerly fin keel.

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steveparker

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According to a recent survey, there is some movement between our keel bolts and the 'transverse members'. The surveyor says this is a common problem with Westerlys, and that we will need to reinforce the keel by inserting some plywood and fibreglass. I'm wondering if this is doable as a DIY job, and what's involved. I'm pretty handy at joinery etc, but this is a bit of an unknown area for me. Sounds fairly pricey to get it done. Has anyone done it themselves, and if so, what does it involve exactly?

Thanks for any replies.

Steve.
 
steveparker said:
According to a recent survey, there is some movement between our keel bolts and the 'transverse members'. The surveyor says this is a common problem with Westerlys, and that we will need to reinforce the keel by inserting some plywood and fibreglass. I'm wondering if this is doable as a DIY job, and what's involved. I'm pretty handy at joinery etc, but this is a bit of an unknown area for me. Sounds fairly pricey to get it done. Has anyone done it themselves, and if so, what does it involve exactly?
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Here's what I did on my Jouster, many years ago.

* Remove keel (well, actually remove boat)

* Cut out the cabin sole and the bottom of the lockers for access

* Clean back the inside of the hull with rotary wire brush

* build up inside hull so keel flange is no longer raised

* cut shallow grooves and bed in seven stainless steel floors, 3' long by 1/4" thick by 3" wide, tapered to points, using industrial epoxy

* continue building up inside hull over 3' width: hull how tapers from original thickness about 6" beyond floors to 2+" thick above keel.

* reglass bottom of lockers

* refit keel (boat)

* make new wooden cabin sole - didn't bother trying to replace/repair original

All in all it took two of us working hard a full week to do, with a fair bit of preparation time beforehand sourcing the stainless, fabricating the floor, resins and glass. Today costs, 20+ years ago was, if I recall aright, about £300. Estimate to have it done professionally was £2000 - £3000. the repair scheme was drawn up by a naval architect, Ian Nicolson, who called in several times as the repair progressed so that he could afterwards certify that it was properly done.

It may all sound a bit complicated, but by far the hardest bits were getting access and making/fitting the floors. Once the hull bottom was accessible, the layup was fast and easy - in fact, the job was slowed down by the need to allow heat to dissipate.

The result has been fine - I have dried out on the keel numerous times and hit a rock once, without the slightest sign of movement.
 
What model is it?
I rebuilt my Fulmar's floors because the original and ridiculously thin originals had broken a few times before my ownership of the boat.
I don't think stainless is a good material for floors.Wood or foam is better.Also fiberglass has to be thoroughly abraded before laminating over and a wire brush is not suitable.In my case ,in order to avoid dust, I chiseled the whole area with a wood chisel.It took a little longer but it was clean and controllable.I shaped extra floors out of light pine taking care to round everything off.I decided a grid pattern would be stronger and that's what I used in the area at the rear of the keel where the impact of a grounding would be most felt.It is also where most of the boat's weight concentrates when ashore.The floors should taper to nothing at their outboard ends so as not to induce stresses on the hull.If this is not possible they should terminate in a "T" shape that will spread the loads.
I saw no need to remove furniture as most of the floors where expsed once the cabin sole was out of the way.
Ideally the keel should be removed but on my boat I didn't have to because the laminate is very thick so no extra glass was needed under the bolt nuts.I just laminated around them.The boat must be suspended,as mine was, or in the water while the work is being done.
I used epoxy resin and 500g/sq m roving for the job.
Not a dificult job,just lenghty.
 
30boat said:
I don't think stainless is a good material for floors.
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Well, it's what Ian Nicolson specified, and he has certificates and everything. The point, I think, was not stiffening the hull but spreading the keel load out.
Wood or foam is better.Also fiberglass has to be thoroughly abraded before laminating over and a wire brush is not suitable.
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Quite right. Sorry, it's been a long time. It was all ground back with an angle grinder too.
I saw no need to remove furniture as most of the floors where expsed once the cabin sole was out of the way.
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That would have been nice. Alas, the Jouster has an inner moulding so removing a fair bit of it wasn't a choice.
 
Orbister, thanks for that. Sounds like it might be worth getting it in a bit more detail if it was drawn up by a naval architect, so can I just clarify a couple of things there? When you say 'build up inside hull so keel flange is no longer raised', I don't quite follow your meaning. Excuse my ignorance here, but isn't the keel flange outside the hull? I've only had a brief look at our setup around the keel bolts, but I can't remember seeing any kind of flange. Also, what did you use to build it up? Just layers of glass, or did you lay any timber in there too?

* cut shallow grooves and bed in seven stainless steel floors, 3' long by 1/4" thick by 3" wide, tapered to points, using industrial epoxy

I get the impression from 'shallow grooves' that these 'floors' were bedded in on their edges rather than flat. Is that correct? If so that would then give you seven steel ridges nearly 3" deep. So if you then built up between these to create a new floor over 3" thicker than the original floor (including your original building up around the flange and then building up around the steel strips), did you have to replace the keel bolts with longer ones, or did you leave rebates around them? Or am I not picturing this right?

Thanks again,

Steve.
 
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30boat, this is a Westerly Longbow 31ft. Can I just clarify something here too? Do you mean you built some kind of timber lattice as a reinforcing base for laminating over?

Thanks for the reply,

Steve.
 
If you join the Westerly Yahoo group there are loads of pics of keels and keel strengthening, though they are usually Centaurs/bilge keelers.

My Centaur keels were beefed up before I bought the boat, it looks like an extra 4 or 5 ½" ply lateral stiffeners were glassed in each side. They are shaped to the contours of the moulding and 12 to 14" across the top edge. The glass extends maybe 4" or 6" beyond the wood bits.

Hang on I may have a pic........ Naaa can't find one.

HTH
 
steveparker said:
Orbister, thanks for that. Sounds like it might be worth getting it in a bit more detail if it was drawn up by a naval architect, so can I just clarify a couple of things there? When you say 'build up inside hull so keel flange is no longer raised', I don't quite follow your meaning. Excuse my ignorance here, but isn't the keel flange outside the hull? I've only had a brief look at our setup around the keel bolts, but I can't remember seeing any kind of flange. Also, what did you use to build it up? Just layers of glass, or did you lay any timber in there too?
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Sorry, I wasn't being very clear. On the Jouster, the fin-and-bulb keel spreads out to a flat mounting plate on top. This mates with a recess on the outside of the hull, so it's all flush when attached.

Inside the hull, therefore, the sides curve down and then "step up" quite abruptly to form the top side of the recess. That's the "keel flange" I meant, and it's the source of the problem. All they did by way of strengthening was thicken the layup directly above the keel. No tapering - 1" away from the keel it was the standard 1/4" or so thick. Hideous stress concentrations, and just not enough damn strength. The aim of the project was therefore to provide a much better join, with the keel loads spread out over about 3' x 2' (sorry, my bad earlier, the floors were 18" long - it has been a long time) rather than concentrated on the rectangle of thin fibreglass immediately around the keel top.

Is that any clearer?

* cut shallow grooves and bed in seven stainless steel floors, 3' long by 1/4" thick by 3" wide, tapered to points, using industrial epoxy
Click to expand...

I get the impression from 'shallow grooves' that these 'floors' were bedded in on their edges rather than flat. Is that correct?
Click to expand...

No, they went in "flat". The grooves were 3" wide and about 1/4" deep. Loaded with one of the Ciba 9000 series epoxies (may have been 9004, but I really can't be sure) and then had the floors squidged - technical term - down into them. Another layer of epoxy on top and then the polyester layup continued.

I think I still have Ian Nicolson's specifications for the repair somewhere - would you like me to dig them out?

Which Westerly do you have?
 
steveparker said:
30boat, this is a Westerly Longbow 31ft. Can I just clarify something here too? Do you mean you built some kind of timber lattice as a reinforcing base for laminating over?

Thanks for the reply,

Steve.
Click to expand...

Steve

The Fulmar has a higher aspect ratio keel than the Longbow but in essence they are built the same way.I cut and shaped wooden floors in a square grid pattern that were placed over the laminate,bedded on thickened epoxy and then laminated over.I believe this won't be needed in your boat because your hull is not as flat as the Fulmar's .These flat runs behind the keel are always troublesome as it is very hard to make them stiff enough to take the weight of the boat without bending .It's up to you to use or not this pattern.
One thing that's important to bear in mind is that it's the fiberglass laminate over the wooden formers that's supposed to provide most of the strength so using a very light wood or even foam,easy materials to work with,is ok.
 
30boat said:
I have to disagree,it doesn't.I wouldn't risk it in such a loaded area.
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That's your choice, of course. At the time I was earning my living designing test methods for composites as part of the Chemical Technology group at the Rutherford Appleton Lab and had access to some of the very best scientists and engineers working in the field, in conjunction with whom I chose the various resins to be used.
 
orbister said:
That's your choice, of course. At the time I was earning my living designing test methods for composites as part of the Chemical Technology group at the Rutherford Appleton Lab and had access to some of the very best scientists and engineers working in the field, in conjunction with whom I chose the various resins to be used.
Click to expand...

And just how old were the samples tested to destruction at the time?
 
oldsaltoz said:
And just how old were the samples tested to destruction at the time?
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Well, the keel is still there after more than twenty years. But if you want a technical discussion, do share your credentials. I spent two years of my life developing the international VAMAS standard test for measuring resin-metal adhesion in composites, by the way.

I love these forums. There's no advice which doesn't generate a voice from the back saying "You don't want to do it like that, you want to do it like this." Harry Enfield lives.
 
orbister said:
Well, the keel is still there after more than twenty years. But if you want a technical discussion, do share your credentials. I spent two years of my life developing the international VAMAS standard test for measuring resin-metal adhesion in composites, by the way.

I love these forums. There's no advice which doesn't generate a voice from the back saying "You don't want to do it like that, you want to do it like this." Harry Enfield lives.
Click to expand...

You are obviously far more qualified than me then because I'v only spent the last 40 odd years testing fibreglass structures to destruction, including keels.

So what would I know, just that I would never put poly resin over epoxy based on observation and a lot of time.

Avagoodweekend......

Love this forum when academics carry on.
 
orbister said:
Well, the keel is still there after more than twenty years. But if you want a technical discussion, do share your credentials. I spent two years of my life developing the international VAMAS standard test for measuring resin-metal adhesion in composites, by the way.

I love these forums. There's no advice which doesn't generate a voice from the back saying "You don't want to do it like that, you want to do it like this." Harry Enfield lives.
Click to expand...

If you're willing to take this discussion to that level, don't count me in.
 
Steve,I can give you the benefit of my ,I admit very practical, experience.My boat has done quite a few ocean miles in all weathers after the floors were reinforced.
 
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