simonfraser
Well-known member
Slight drift, but now have it appart, is here anything else you want to change add to this area ?
Now is the time to act.
Now is the time to act.
Just removed my bowsprit, to find THIS underneath. Steps for strong repair please?
- Thread starter yourmomm
- Start date
eilerts
Member
Happy new year!
This also reminds of the time I discovered a 50 cm strait crack across the hull in front of the keel. When I probed it with a screwdriver I saw lose glassfiber. I though the whole bow section planned to go somewhere else than the rest of the boat. Turn out to be a poorly done repair (cover up) by a former owner.
It looks like the steel has been glued right on the top of the gelcoat, faired with epoxy putty (reddish brown) and glassed over with epoxy. Laminating without removing the gelcoat is normally a NO-NO, but with proper de-waxing, sanding, epoxy and luck, it can work. The reason for the crack is probably that rust forced the laminate over the steel get detached, and it was not thick and strong enough by itself to withstand the forces.
Solid laminate and proper backing plates behind the nuts is the best way. When force is acting on metal plated in the middle of the laminate there is always a risk that the laminate will split at this level.
If it was my boat I would check carefully if the steel plates really stick or are only held in place by the putty around. If they are loose, I would take them up, clean both surfaces and glue them down with epoxy, before glassing them in. This will also let you inspect the laminate behind the steel. You may also make a wider putty bevel around the steel. I would also grind at least all the way to the glassfiber laminate on the outside of the gunwale down to the rub rail. This increases the adhesion and gives space for proper thickness of the new laminate.
Again, good luck!
This also reminds of the time I discovered a 50 cm strait crack across the hull in front of the keel. When I probed it with a screwdriver I saw lose glassfiber. I though the whole bow section planned to go somewhere else than the rest of the boat. Turn out to be a poorly done repair (cover up) by a former owner.
It looks like the steel has been glued right on the top of the gelcoat, faired with epoxy putty (reddish brown) and glassed over with epoxy. Laminating without removing the gelcoat is normally a NO-NO, but with proper de-waxing, sanding, epoxy and luck, it can work. The reason for the crack is probably that rust forced the laminate over the steel get detached, and it was not thick and strong enough by itself to withstand the forces.
Solid laminate and proper backing plates behind the nuts is the best way. When force is acting on metal plated in the middle of the laminate there is always a risk that the laminate will split at this level.
If it was my boat I would check carefully if the steel plates really stick or are only held in place by the putty around. If they are loose, I would take them up, clean both surfaces and glue them down with epoxy, before glassing them in. This will also let you inspect the laminate behind the steel. You may also make a wider putty bevel around the steel. I would also grind at least all the way to the glassfiber laminate on the outside of the gunwale down to the rub rail. This increases the adhesion and gives space for proper thickness of the new laminate.
Again, good luck!
yourmomm
Member
Hi thanks, I was very happy to find this! (I had been expecting nothing but rotten laminate).
Yep, I haven't finished the grinding yet. It's not easy, grinding over the bow, and down the gunwhales of a boat with no lifelines, in a force 5, on a relatively unprotected swinging mooring, and with bloody great catamaran ferries going past every 5 minutes at a rate of knots!
Ideally I'd like to remove the rub rail, but its proving a PITA, so I may not be able to get the new laminate layers right up close to it, although I'm taking the dremel down tmw, to try to grind a bit closer to it...I'll also be grinding the outer gunwhales more, too, as well as further aft of where I've covered, thus far...
I think the steel plates are fixed properly. I cant get them to budge even a mm or two, either by whacking them with a hammer from above, or below. Frankly, it would be a real mission to lift them, even if I ground out all of that putty, so I may just use that as evidence that the fixing is good. I wondered about the construction...its impossible to see behind these steel plates, so I dont know how they are fixed to the laminate, underneath. I also thought that if the top of the steel has rusted, causing that delamination above the plate, then perhaps the bottom has, too. As I say, there's just no (reasonable force) way i can get the plates to budge though. I suspect the steel plates predate the bowsprit and are an original part of the construction (rather than being glued to the gelcoat): this area was also where the original forestay was attached.
You can also see the ends of ?brass rails?, both port and starboard, running along the gunwhales, aft of where I've been grinding. That's a new construction method for me, but as I've said before, this is my first fibreglass boat, having owned only wooden boats, before.
So much for the "fibreglass=less maintenance" theory...
Will keep the thread posted on progress...
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eilerts
Member
Hi,
don't be tempted to remove the rub rail, even though it make sense during this repair. The rubber should be under tension. As soon as you get it off it starts shrinking. To put it on again will be a major PITA.
Put several layers of masking tape on the top of the rubber. You could even put some ice-cream sticks between the layers. This will give some protection against accidentally grinding the rubber. Even though I argued for grinding down to the rub rail, you should not take it too literally. Leave 5-10mm. It is a bit difficult for me to see the real distance to the rub rail from the pictures, but think you will still have enough bonding area. Before you start with the glass and epoxy, mask also off the remaining gelcoat down to the rubber. In this way you don't end up sanding away this tiny strip in order to clean up mess.
If the steel is sticking then things under is likely ok. Then don't remove it.
The number of layers will depend on the weight of your glass cloth. I tend to think 4-5mm should be good enough. If you cloth is 450g/m2 it would take 4-5 layers. Lighter cloth will need more layers, but will be easier to work with. Each layer should be in one piece, not small patches. If you find it fiddly to get the cloth to fit snugly around the bow point, or fit the area, you may start with a glassfibre band that covers the gunwale and onto the flat top. Make two pieces that overlaps around the bow point. The next layers do not go so far down and will be easier. If you have trouble with the edges of the layers raise, then finish with a band that covers all the edges and holds them down.
Most often you read that gelcoat will not stick to epoxy. That is not correct to my experience, but you will need to sand it first. It could true for some epoxies and gelcoats. If you want to be safe, fair it with thickened epoxy and paint with two-component PU paint.
don't be tempted to remove the rub rail, even though it make sense during this repair. The rubber should be under tension. As soon as you get it off it starts shrinking. To put it on again will be a major PITA.
Put several layers of masking tape on the top of the rubber. You could even put some ice-cream sticks between the layers. This will give some protection against accidentally grinding the rubber. Even though I argued for grinding down to the rub rail, you should not take it too literally. Leave 5-10mm. It is a bit difficult for me to see the real distance to the rub rail from the pictures, but think you will still have enough bonding area. Before you start with the glass and epoxy, mask also off the remaining gelcoat down to the rubber. In this way you don't end up sanding away this tiny strip in order to clean up mess.
If the steel is sticking then things under is likely ok. Then don't remove it.
The number of layers will depend on the weight of your glass cloth. I tend to think 4-5mm should be good enough. If you cloth is 450g/m2 it would take 4-5 layers. Lighter cloth will need more layers, but will be easier to work with. Each layer should be in one piece, not small patches. If you find it fiddly to get the cloth to fit snugly around the bow point, or fit the area, you may start with a glassfibre band that covers the gunwale and onto the flat top. Make two pieces that overlaps around the bow point. The next layers do not go so far down and will be easier. If you have trouble with the edges of the layers raise, then finish with a band that covers all the edges and holds them down.
Most often you read that gelcoat will not stick to epoxy. That is not correct to my experience, but you will need to sand it first. It could true for some epoxies and gelcoats. If you want to be safe, fair it with thickened epoxy and paint with two-component PU paint.
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yourmomm
Member
Thanks eilerts for that useful advice: you hit the nail on the head of guessing what I was worrying about now...how to conform single pieces of cloth to those curves! I'd pretty much decided to do what you suggest, (i think), but there's a 1" semi-circular step, aft of the flat, triangular bow section, which makes life much more difficult...
One thing you said got me thinking: you said after the first layer: "the next layers do not go so far down" (the gunwhale), which suggests to me you are suggesting putting the biggest layers of cloth (covering the whole ground out area) first? Am I being an idiot for planning to scarf the other way? (Ie progressively larger areas of cloth going down on top of each other, the smallest areas of cloth down first)?
One thing you said got me thinking: you said after the first layer: "the next layers do not go so far down" (the gunwhale), which suggests to me you are suggesting putting the biggest layers of cloth (covering the whole ground out area) first? Am I being an idiot for planning to scarf the other way? (Ie progressively larger areas of cloth going down on top of each other, the smallest areas of cloth down first)?
Akestor
Active member
Hi again
At the older post i wrote i forgot to mention:
Precut every layer of cloth you will use so it will be layed nicely at place and follow the curves etc.
Old school CSM is very easy to shape because resin melts the bonding between the strands after a while. Another thing is to avoid voids at the curves between layers. Also, if you see the new laminate is not as you expected, let it cure for 1 hour, grind it and startover!
At the older post i wrote i forgot to mention:
Precut every layer of cloth you will use so it will be layed nicely at place and follow the curves etc.
Old school CSM is very easy to shape because resin melts the bonding between the strands after a while. Another thing is to avoid voids at the curves between layers. Also, if you see the new laminate is not as you expected, let it cure for 1 hour, grind it and startover!
eilerts
Member
Not at all. You can even chose random order. I most often start with the largest. I consider two reasons; the fist apply only if you need several sessions to complete all layers. When you have finished grinding, you have a clean surface (except for some dust). If you put the largest layer first then you don't risk to contaminate this surface. You also avoid having air trapped in the small step around the previous ply. The second matters only with woven cloth; it is difficult to finish with a perfectly even top layer. When you later sand it even, you remove parts of the top ply and destroy the continuity of the fibres. Non of these will be critical in you case.
On the other hand, if you have a uneven surface when finished grinding, say from uneven depth of delimitation, then it make sense to fill in the low spots with small patches first.
In your case you can do it as you prefer. If use epoxy, light cloth and a squeegee to get rid of air, I see a reason for starting with the smallest; if the largest is laid first, you may risk to move it around with the squeegee while you try to get rid of the air in the upper layers. I have little experience with using squeegee.
As you put down the layers you need to get rid of trapped air. I always use a roller, but I see on the net that a lot of people use squeegees with epoxy. Also, the glass must be fully saturated (transparent, no white spots), but binder in excess of that will only make it weaker. Aim for glass:binder around 1:2 by weight.
I see that Akestor suggest to use CSM (Chopped Strand Mat). This is the mat with 4-5cm long fibre strands in random orientation. This is excellent for this job if you use polyester resin, but not if you go for epoxy. To keep this kind of mat together, so it does not disintegrate into pile of glassfibre, a glue has been added. The glue is designed to dissolve in the polyester, so that each fibre becomes free. Epoxy will not dissolve the glue. As a result the mat remains stiff and the epoxy cannot penetrate the fibre strand. Each strand consist of hundreds of individual fibres. In the woven cloth, the glass is held in place by the woven pattern, and no glue is used.
dom
Well-known member
Powdered CSM compatible with epoxy is readily available, but not really advisable in high strength repairs save for creating a good key layer.
yourmomm
Member
Wow eilerts you just saved me a whole lot of wasted time!
I was left thinking about your comment to check under the steel plates, so ground away all the putty and lifted them with a crowbar (didnt take much effort once the putty was gone), and look what was underneath!!! Lots of rotten laminate! So glad I followed tour advice, otherwise this whole endeavour would have been a waste of time and would have required re-doing at some point (or worse, failure of repair at inopportune moment!).
I ground away all that rotten laminate, and I think the plastic underneath is sound (see first photo, just with two putty mark's left, to place new stainless plate when its done). There is no cloth in this plastic, and it's what you thought was gelcoat: it just looks like flowcoat; would this be what they would have poured into the mould when they made the boat?
I'll take no chances with strength though, and get two new single steel plates made up, each one the same dimensions as these three pieces, pieced together. I'll then slap one of these plates underneath this weird flowcoat/gelcoat type substance as a backing, through bolt the other one on top, and then laminate over the top of all of them, to ensure strength is great. That will allow me to use it as a forestay anchor point again, if I ever want a cutter rig, even if i dont bolt the bowsprit back there....
As for CSM, I've already got my cloth, which is a mid weight biaxial. My knowledge of fibreglass is limited, so I just go by easy rules, like always use epoxy, and never use CSM. I know its much more complicated than this, but I figure these rules err on the side of caution, so are fairly idiot-proof for the likes of me...
I was left thinking about your comment to check under the steel plates, so ground away all the putty and lifted them with a crowbar (didnt take much effort once the putty was gone), and look what was underneath!!! Lots of rotten laminate! So glad I followed tour advice, otherwise this whole endeavour would have been a waste of time and would have required re-doing at some point (or worse, failure of repair at inopportune moment!).
I ground away all that rotten laminate, and I think the plastic underneath is sound (see first photo, just with two putty mark's left, to place new stainless plate when its done). There is no cloth in this plastic, and it's what you thought was gelcoat: it just looks like flowcoat; would this be what they would have poured into the mould when they made the boat?
I'll take no chances with strength though, and get two new single steel plates made up, each one the same dimensions as these three pieces, pieced together. I'll then slap one of these plates underneath this weird flowcoat/gelcoat type substance as a backing, through bolt the other one on top, and then laminate over the top of all of them, to ensure strength is great. That will allow me to use it as a forestay anchor point again, if I ever want a cutter rig, even if i dont bolt the bowsprit back there....
As for CSM, I've already got my cloth, which is a mid weight biaxial. My knowledge of fibreglass is limited, so I just go by easy rules, like always use epoxy, and never use CSM. I know its much more complicated than this, but I figure these rules err on the side of caution, so are fairly idiot-proof for the likes of me...
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eilerts
Member
Last time I tried powder bound mat and epoxy, years ago, it wetted, but the glass stayed stiff and did not bend easily. I saw no reason to try again. It could be that it dissolves slower and I did not give it enough time.
If I get the time next week I'll check if I'm spreding BS.
eilerts
Member
Short answer (it is getting late where I am).
The stuff under the plates does not look good. Even though the pictures are many and sharp enough, it is a bit hard to say what it really is, but glad you got rid of it. My first thought was that the plates were laid down in polyester body filler (some places called Bondo, I think). This stuff does not like seawater.
The shiny regularly spaced spots in the first picture is either top of corse woven glass roving that is lower or the last rest of woven roving you have ground away. You may know better. Also, the woven roving seems to be laid in clear polyester in the deck, but whitish pigmented polyester in the bow. It will look like gelcoat/flowcoat with glass fibre in.
Compared to the level outside the brown putty, how deep did you go in the midle and what is the remaining thickness?
You must keep a map in your head of how much you have removed from different places, so you are sure you replace it with enough material and get the right shape in the end.
What grinding tool are you using? The surface looks a bit uneven now, but could be I'm fooled by light angle and lack of proper scale. Before you start moulding, smoothen by hand and make sure all the edges are rounded.
The stuff under the plates does not look good. Even though the pictures are many and sharp enough, it is a bit hard to say what it really is, but glad you got rid of it. My first thought was that the plates were laid down in polyester body filler (some places called Bondo, I think). This stuff does not like seawater.
The shiny regularly spaced spots in the first picture is either top of corse woven glass roving that is lower or the last rest of woven roving you have ground away. You may know better. Also, the woven roving seems to be laid in clear polyester in the deck, but whitish pigmented polyester in the bow. It will look like gelcoat/flowcoat with glass fibre in.
Compared to the level outside the brown putty, how deep did you go in the midle and what is the remaining thickness?
You must keep a map in your head of how much you have removed from different places, so you are sure you replace it with enough material and get the right shape in the end.
What grinding tool are you using? The surface looks a bit uneven now, but could be I'm fooled by light angle and lack of proper scale. Before you start moulding, smoothen by hand and make sure all the edges are rounded.
Akestor
Active member
I forgot the repair will be done with epoxy and not polyester! ofcourse CSM is not good for epoxy resin.
Good job, now comes the laminating! ( the hard part of preperation is done)
Dont forget to blow the dust and clean well with aseton before you start.
When you are done i suggest you cover the repair with a thin nylon to protect it from night humidity or rain. You need at least 6 hours for cure in good weather conditions, but in winter next day is the fastest it can get i guess.
Just another thing for your checklist : Epoxy resin gets more dense with cold. You may have to warm it upa little bit, to be able to apply it,(before you mix it) but again that will depend on the temperature you are working.
From the west system epoxy website
"2. Warm epoxy resin and hardener before using. As mentioned, the warmer the resin and hardener, the lower the viscosity. Thinner resin and hardener will flow through pumps better, cling less to containers and mixing equipment, and mix more thoroughly. The initial chemical reaction will get off to a better start and result in more cross-linking even if the mixture cools after it is applied to a cooler surface. The thinner mixture will initially flow out smoother and wet-out porous surfaces better.
Warm the epoxy resin and hardener with heat lamps or keep it in a warm area until you are ready to use it. You can build a small portable hot box out of rigid sheets of foil-backed insulation, with a regular light bulb or an electric heating pad inside to maintain a temperature of 70°F–90°F. This method allows you to keep the warm resin and hardener close to your work and allows less time to cool off between dispensing and application.""
full article : https://www.westsystem.com/instruction-2/epoxy-basics/cold-temperature-bonding/
Good job, now comes the laminating! ( the hard part of preperation is done)
Dont forget to blow the dust and clean well with aseton before you start.
When you are done i suggest you cover the repair with a thin nylon to protect it from night humidity or rain. You need at least 6 hours for cure in good weather conditions, but in winter next day is the fastest it can get i guess.
Just another thing for your checklist : Epoxy resin gets more dense with cold. You may have to warm it upa little bit, to be able to apply it,(before you mix it) but again that will depend on the temperature you are working.
From the west system epoxy website
"2. Warm epoxy resin and hardener before using. As mentioned, the warmer the resin and hardener, the lower the viscosity. Thinner resin and hardener will flow through pumps better, cling less to containers and mixing equipment, and mix more thoroughly. The initial chemical reaction will get off to a better start and result in more cross-linking even if the mixture cools after it is applied to a cooler surface. The thinner mixture will initially flow out smoother and wet-out porous surfaces better.
Warm the epoxy resin and hardener with heat lamps or keep it in a warm area until you are ready to use it. You can build a small portable hot box out of rigid sheets of foil-backed insulation, with a regular light bulb or an electric heating pad inside to maintain a temperature of 70°F–90°F. This method allows you to keep the warm resin and hardener close to your work and allows less time to cool off between dispensing and application.""
full article : https://www.westsystem.com/instruction-2/epoxy-basics/cold-temperature-bonding/
yourmomm
Member
Yep still havent finished grinding...it IS really uneven: the product of trying to hold a grinder with one hand, and the halyards with the other, to prevent being put in the drink by passing ferries, whilst holding a working power tool. If it gets calm enough, I've decided to get in the dinghy to try to do the rest on the side, and smooth it all out a bit more evenly.
I've been really careful to try to keep a base layer over which I can laminate, and I've done so, but only just...the remaining layer is only 3-4mm. Ive gone right through in a couple of places (im thinking which will be easily filled with epoxy and thickening fibres). I've no idea how deep I've gone: at least 1cm in total (including steel plate thickness), I would say. Plenty of room to build more strength, and the bowsprit base will tell me how high I need to build. My plan was just to build up cloth layers, 3 or 4 at a time to prevent overheating, until their depth reaches just below bowsprit base, then I'll use thickened epoxy with fibres to fair, and level to the bowsprit base itself (just putting tape to the bottom of the bowsprit base to prevent it sticking to the fairing layer). With my plan to fit the smallest areas of cloth first, I can build up depth in the centre, and level to the edges. As akestor says above, if it starts getting thick in spots, i can just grind down the whole lot to level all again, and build new, bigger layers of cloth on top, until right.
I've given up any realistic prospect of getting her sailing this season, what with this job, and the collapsing-into-the-deck-mast issue, (which ive also posted on here about:
http://www.ybw.com/forums/showthrea...here-Fibreglass-structural-problem-under-mast
....so I've got all the time in the world.
I've been really careful to try to keep a base layer over which I can laminate, and I've done so, but only just...the remaining layer is only 3-4mm. Ive gone right through in a couple of places (im thinking which will be easily filled with epoxy and thickening fibres). I've no idea how deep I've gone: at least 1cm in total (including steel plate thickness), I would say. Plenty of room to build more strength, and the bowsprit base will tell me how high I need to build. My plan was just to build up cloth layers, 3 or 4 at a time to prevent overheating, until their depth reaches just below bowsprit base, then I'll use thickened epoxy with fibres to fair, and level to the bowsprit base itself (just putting tape to the bottom of the bowsprit base to prevent it sticking to the fairing layer). With my plan to fit the smallest areas of cloth first, I can build up depth in the centre, and level to the edges. As akestor says above, if it starts getting thick in spots, i can just grind down the whole lot to level all again, and build new, bigger layers of cloth on top, until right.
I've given up any realistic prospect of getting her sailing this season, what with this job, and the collapsing-into-the-deck-mast issue, (which ive also posted on here about:
http://www.ybw.com/forums/showthrea...here-Fibreglass-structural-problem-under-mast
....so I've got all the time in the world.
yourmomm
Member
Thanks akestor. Currently nigh on 30°C in the sun over here, so heat is not a problem! Rain on the other hand, whilst trying to do a fibreglass repair.....