Fixing a hole in the slug's keel

dylanwinter

dylanwinter

Well-Known Member
Joined
28 Mar 2005
Messages
12,954
Location
Buckingham
www.keepturningleft.co.uk
I ran the slug aground on the rocks off Cromer - I was trying to get in close to film the pier and I have a large scale chart and did not know there were any rocks there - well I do now

details here

http://www.youtube.com/watch?v=2AH1-V2pf_k

The damage is small area about 1 inch by 3 just half way along the box keel. The fibres have been crushed inwards - enought o leak but not enough to shove a finger through

How do I fix the hole

getting access to the inside of the box keel would require cutting a hole in cabin floor - which is part of the inner moulding

I have epoxy, and I have woven fibreglass cloth and tape from when I built the bosnum boxes for the cockpit. I have no epoxy filler left.

I need to scrape off the antifoul and see how far the stress cracks go - at the moment I have no idea


what do I need to do to fill the hole - does anyone have any pictures of such a repair in progress

secondly I go aground a lot - and I was thinking about putting some wear strips on the bottom of the boat

at first I thought about bonding wood to the bottom

- too hard to get a good join - especially working upside down

then I thought about stainless steel rubbing strips - too expensive and I would need to drill holes in the keel - don't want to do that

I have a friend who has a canadian canoe - he puts isopon on the wearing parts - just at the turn of the bow where it always gets dragged.

Would it be sensible to cover the bottom of the box keel with isopon - I figures that if it sticks that is great - if it breaks off I have lost nothing.

I am not botheres about speed - at all

Your thoughts please gentlemen

Dylan
 
For keels on Gwylan we put several layers of matt on the bottom of each keel with f/glass as a sort of sacrificial strip. Not pretty, never going to do too much damage to the performance. But I hope it worked this summer when some of the short cuts were a bit shorter than they should have been
 
Sorry to hear bout that. I think it's perfectly repairable though. If it were my boat, I'd give up for the rest of this season though. I'd get it lifted out on to the hard, expose all the damage, power-wash it to death and then leave it to dry out properly for a few months before attempting any repair. I'm sure epoxy and glass will be fine but would need to see more about the nature, position and extent of the damage to comment. I wouldn't be too bothered about drilling holes in the hull. Avocet has a bronze block to act as the bottom rudder bearing. It is bolted through holes in the fibreglass in 4 places and sealed on a bed of mastic-like stuff and has been like that form many years without leakage.

Idon't know whether stainless would be the right stuff to use (or any sheet metal) to make a "shoe" because it might deform if you hit something and hide some fibreglass damage that would then go un-noticed.
 
Firstly, the damage probably looks much worse than it is; don't be discouraged. If you can get access to the inside of the hull where the hole is, then it is probably worth laying a couple of layers of matting epoxied there to both reinforce the area and provide a strong backing to the external repair. Remember, the area must be dry and oil free, so after drying clean with white spirit and then finally with acetone. Make sure you have keyed the area with something like 80 grit sandpaper before laying up your matting. Start with a slightly smaller layer and place increasingly large ones (½ an inch all around) on top.

For the external repair, remove the sealant you have put on the hole to allow it to drain and dry out. Clean and degrease as above. If necessary grind/file back to sound material. Your external repair should consist of layers of matting laid up to provide the structural strength finished off with gel coat to improve the waterproofing of the repair. You may need to include some form of former to help get the shape right such as a piece of wood made to fit in the keel.

Resist the temptation to lay up loads of layers or a great thickness of epoxy filler in one go as it will overheat as it goes off and may be worse than useless.

As for your idea of some form of sacrificial protection. I would suggest that strips of wood, suitably treated and fitted to the keel would be best. Ideally these would be attached in such a way that they could be easily replaced and so it might prove possible to fit studs onto which they can be secured with nuts. It is significant that the hole is half way along the keel, not at the front which you would have thought would have been at greater risk. Therefore some form of fixing of a long piece of wood along the whole length might be of benefit.

Finally, if it all goes wrong, don't give up. Just remove what isn't good enough and have another go; that is the beauty of GRP.
 
excellent instructions - thanks

I am out of acetone - screwfix don't do it anymore - any ideas who will supply in these difficult times


oldfatgit said:
Firstly, the damage probably looks much worse than it is; don't be discouraged. If you can get access to the inside of the hull where the hole is, then it is probably worth laying a couple of layers of matting epoxied there to both reinforce the area and provide a strong backing to the external repair. Remember, the area must be dry and oil free, so after drying clean with white spirit and then finally with acetone. Make sure you have keyed the area with something like 80 grit sandpaper before laying up your matting. Start with a slightly smaller layer and place increasingly large ones (½ an inch all around) on top.

For the external repair, remove the sealant you have put on the hole to allow it to drain and dry out. Clean and degrease as above. If necessary grind/file back to sound material. Your external repair should consist of layers of matting laid up to provide the structural strength finished off with gel coat to improve the waterproofing of the repair. You may need to include some form of former to help get the shape right such as a piece of wood made to fit in the keel.

Resist the temptation to lay up loads of layers or a great thickness of epoxy filler in one go as it will overheat as it goes off and may be worse than useless.

As for your idea of some form of sacrificial protection. I would suggest that strips of wood, suitably treated and fitted to the keel would be best. Ideally these would be attached in such a way that they could be easily replaced and so it might prove possible to fit studs onto which they can be secured with nuts. It is significant that the hole is half way along the keel, not at the front which you would have thought would have been at greater risk. Therefore some form of fixing of a long piece of wood along the whole length might be of benefit.

Finally, if it all goes wrong, don't give up. Just remove what isn't good enough and have another go; that is the beauty of GRP.
Click to expand...
 
VicS of this parish
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Doesn't have any suggestions as to suppliers

I'd probably get small quantities from a chandlers, larger quantities from glass fibre suppliers. eg http://www.cfsnet.co.uk/acatalog/CFS_Catalogue__Acetone_533.html

Be wary of nail varnish remover. Possibly not acetone and possibly containing other ingredients that would balls-up the repair.

Dylan:

FWIW One job I have to do is remove the old toilet and make good the old outlet hole ( If you have ever come across the "Ball Head" you will know what I mean.)

I will almost certainly opt for epoxy resin rather than polyester. All the recommendations point to that as the better option.
Not used it before so will be interesting. Built the boat from separate mouldings so used to polyester and glass mat.
 
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I can confirm that nail polish remover has no Acetone, unless it's very old stock; it has been declared a carcinogenic Cancer causer. :eek:

Re the Original post:
You say the rear or the keel box looks like it has been crushed, or has been deflected back and up? this is the more common damage.

When you lift out next try to support the Hull weight and not the whole boat and keel, all boats change shape when lifted and this changes the loading on stress points. Doing a repair with the loads in the wrong areas can stress the new work.

Start on the inside and remove all but solid glass with good colour, light areas will be stressed. When finished grinding the inside, start on the outside.

Again remove all but solid glass and then try to get a moisture reading. Do no more till moisture levels are acceptable or you waste time, effort and money.

I would also advise you to remove the antifoul around the top of the keel and check for cracks in the gel-coat caused by the grounding force pulling the front of the keel down.

If you do see cracks, grind them till you see solid glass, wet the area with a little Acetone and observe the areas that dry last, if it's in a line it may well be a crack and further grinding and wetting will be required, again do nothing till moisture levels are acceptable.

As this is a potential high stress are you should only epoxy resin and woven cloth, not CSM.

As you are short of filler you can collect the material that was ground off and mix with new epoxy resin if required or spend some time cutting up off cuts of cloth into tiny bits.

I assume you have knowledge of using epoxy and stitched cloth so will skip this bit.
However, you when you lay up an area and leave it to cure before adding more layers, be sure to wash the surface with a running hose and starting at the high point hose and rub the area with a plastic scotch-brite kitchen scourer, this will remove the residue left by the curing process, you will know it's all gone when the water no longer forms beads like on a polished car, this must be done before sanding or you will just spread the contamination.

Also so save a lot of sanding on the outside, as you complete each area put a piece or peel ply over it and a prop to hold it in place, when cured just peel it off to reveal a nice flat or curved finish.

Also note: all areas repaired should have 3 to 5 coats of epoxy resin painted over to protect and seal them.

You can paint the repaired areas with a coat of flow-coat (Resin and pigment of almost any colour) Flow coat is just like gel coat but has wax added so no need to cover it.

Trot down to your local boat builder or repairer with a steel container and ask them for some Acetone.

Hope this helps.

Good luck.
 
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I'd strongly suggest getting at it from the inside if it's reasonably possible. If it isn't, once you have the hole made and cleaned, it would be a good idea to put in a backing piece to support the repair as you make it. If, for example, the hole is 3" x 1", make a 4" x 2" patch, put araldite all the way round the edge, then post it through the hole, turn it round 90 degrees and pull it back against the hull (screw through the middle) till the glue sets. This will give you a nice solid base on which to build up the repair.

Two bits of good news, maybe, are that fibreglass hulls like yours are massively redundant in strength, so all you really need to do is keep the water out, and that the joy of working in GRP is that if it all goes wrong you can just grind it back and start again!

Good luck!
 
third party only

Habebty said:
Could insurance contribute? If you would like some help I live fairly close (40 mins)
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The rocks at Cromer are insured but the slug is not

I felt I needed third party because of the time I spent on the broads and the damage the slug could do should the anchor drift

v kind of you for offering help

I am sure between me and the advice from this board I can fix it.

I built a wooden boat five years ago so I can handle the epoxy

I was obviously a bit peeved while on the slip -

I felt guilty about subjecting my wife (and dog) to the experience.

It was quite frighteneing to be at sea and pumping for 15 minutes out of every 30

I realised that the demise of the 45 year old billge pump would be quite serious and if I am going to get the sluig in a fit state for the north sea and Scotland then it will need to spend a fair bit of money on the boat. It has all been done on a lick and a spit and a shoestring up until now.

However, I am feeling much more positive. I can fix the hole and spend the winter afloat filming the marvelous north norfolk coast.

The paid part of the website went live in April - a stupid time to launch it - it will be interesting to see what happens when the evenings start closing in and people put their boats ashore and discover that there is still nothjing on the telly.

I am hopeful that I will get more subscribers to the films - $4.99 for 50 episodes of the journey plus all the other vlogs and boats filmed along the way seems like a reasonable deal - but only if you have paypal

Another sailor who is a classic boat owner and TV producer did put a pilot together


http://www.youtube.com/watch?v=knQG3PB7-q8

but he could not even get any of the commissioners to look at it

On the bright side

this bloke

http://www.thesailingchannel.tv/

Has taken a set of HD films off me and is going to re-cut them for the Americans

It will be interesting so what the Americans make of the word "twassock"

Dylan








D
 
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dylanwinter said:
I am out of acetone - screwfix don't do it anymore - any ideas who will supply in these difficult times
Click to expand...

Force 4 sell it. At their Deacons shop in Bursledon they have half-litre cans up to 20 litre drums. I don't know how their prices compare, but it doesn't feel expensive.

Pete
 
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