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Old 23 January 2012, 11:33   #21
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Although I'd love to do a job like this I am in the middle of my exams and only get one day a weekend free.
I can't afford to have it done for me either. maybe if I could find another SR4 without an engine cheap..?
why would an external Fibreglass patch not work? is it a case of not lasting or just plain dangerous?

some more pictures

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Old 23 January 2012, 12:52   #22
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It is not just a simple matter of a minor patch. This area of the hull takes a lot of force, particularly when landing from a 'little air'. As you can imgine, the force tries to push this part of the hull, where the chines are sited, upwards, and in effect, into the hull void. If left unattended it will fail, the only questions being by how much and when. So. to get the structural strength from an external patch would mean that the patch would be very substantial. Infact, even with careful preparation, I doubt that sufficient strength could be achieved by an external patch. The reason it has failed is because it is a high stress area, probably with too light a lay up as stated by Ribraff, and having seen how hard you work it ..............
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Old 23 January 2012, 13:07   #23
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Quote:
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It is not just a simple matter of a minor patch. This area of the hull takes a lot of force, particularly when landing from a 'little air'. As you can imgine, the force tries to push this part of the hull, where the chines are sited, upwards, and in effect, into the hull void. If left unattended it will fail, the only questions being by how much and when. So. to get the structural strength from an external patch would mean that the patch would be very substantial. Infact, even with careful preparation, I doubt that sufficient strength could be achieved by an external patch. The reason it has failed is because it is a high stress area, probably with too light a lay up as stated by Ribraff, and having seen how hard you work it ..............
Hmm I see, and it was already like that when I bought it! honest just had a external patch on it.

what do you guys reckon if I use fibreglass on the outside to first reconstruct the shape and give me something to work on, then cut a hole in the deck in front of the console (luckily the gash is in front of it) make braces out of...? not sure what to make them out of and no idea if marine ply would hold up. then fibreglass and epoxy them in to act as support finally lots of liquid epoxy to add more strength.
I would also like to add some closed cell expanding foam when i'm finished to secure a fuel tank in the deck.

what does everyone think then?

here's a very bad sketch up, triangle represents brace shape. so supporting the V
hull is a rectangle because I'm terrible at art. red represents gash and yellow is epoxy+ fibreglass.
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Old 23 January 2012, 13:51   #24
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Not sure whether I am missing your point or not, but if you think that you can access the hull void in the appropriate area without lifting the console, why bother putting bits of wood in there? Get in with a grinder of some sort, clean the area up on the inside and build up layers of glass mat. If I was doing it I would use chop strand mat, but some of the professionals on here may well advise woven matting, to get the strength in the right directions? Once you have accessed the right area, and cleaned up the surrounding area, the actual repair should be straight forward. Just try not to get too high on resin fumes
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Old 23 January 2012, 14:12   #25
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Nathan, from what I can see and having met you I think this is well within your ability. As Ian said if you cut a hole on the deck in front of the console ( as small as possible and in the correct place- measure lots of times before you cut as your going to have to seal it back up). Lay some suitable matt and build it up inside. It wont need to be pretty ! Then the outside becomes a cosmetic issue which can be filled and sanded as needed.

Then once its all solid, replace the hole you cut in the deck ( with the bit you chopped out) glass that all back in and seal it all up and back out on the water.

I's say its maybe a few days patient work for you and will stand you in good stead as a learning experiance.

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Old 23 January 2012, 14:13   #26
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I thought of using braces to provide support and prevent any caving in etc.
How much glass mat are we talking about? Building up a thick layer from the bottom of the hull like 2-3 inches? Or do I think it needs more support than it actually needs?

Also what is supplied in the overpriced chandlery kits to glue down the fiberglass? Is it any old 2 part epoxy or something special?

I can get high off the fumes? *note to self: do not wear breathing mask*
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Old 23 January 2012, 14:16   #27
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Am pretty sure someone on here can list what you may need. Lots on here have done this type of stuff .....which explains a lot as a result of fumes ......

I'm guessing google/youtube will reveal lots of how to stuff.Have a search on here for searider refurb threads and you'll seehow things are under the deck.
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Old 23 January 2012, 14:33   #28
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I thought of using braces to provide support and prevent any caving in etc.
How much glass mat are we talking about? Building up a thick layer from the bottom of the hull like 2-3 inches? Or do I think it needs more support than it actually needs?

Also what is supplied in the overpriced chandlery kits to glue down the fiberglass? Is it any old 2 part epoxy or something special?

I can get high off the fumes? *note to self: do not wear breathing mask*
Nathan,
cfsnet.co.uk is good source of the raw materials, they also have some good info on fibreglassing on their web site. I have also found them to be a very prompt service. There are others of course. I would use a good polyester resin, fair bit cheaper than epoxy
You might want to re-think the face mask when grinding out
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Old 24 January 2012, 14:14   #29
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Hi Nathan, as a rule you need to grind the damaged area inside the hull, thus prepareing the old glassfibre, so the new bonds well, alow at least 100mm overlap from damaged area, then apply resin and 2 chop strand mats, making sure you force all the air out by rolling,leave to dry then roughen the area again using corse sand paper, then repeat with 2 more layers of choped stand, when this has cured you can then sort out the outside by again prepareing the old gelcoat as before, I would make a new keel guard using a biaxe type woven matt and resin, make sure you overlap the damaged area by at least 100mm, then fill and sand ready for painting. regards Mark
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Old 24 January 2012, 14:17   #30
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4 layers of CSM
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Old 24 January 2012, 14:18   #31
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would you not agree then Ian ?
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Old 24 January 2012, 14:30   #32
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Definately not. It is a hgh stress area of the hull, and I would look at many more than 4 layers, even using 600gram mat. There is no need to let it dry between layers, or roughen between layers, slap it on, and as you say, roller each layer. Assuming the use of polyester resin, and not epoxy, the resin remains chemically active for a few days, so obtaining a good bond between layers is not a problem.
2 to go.
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Old 24 January 2012, 14:38   #33
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Fare comment Ian and I wouldnt disagree, maybe even a biax mat as well? I think Nathan has the ability and determination to do the job well, I really want to enchorage young people like him, kind regards Mark
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Old 24 January 2012, 14:38   #34
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Quote:
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some more pictures
doesn't look quite as serious as I first thought - and I would certainly tackle that.

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Then once its all solid, replace the hole you cut in the deck ( with the bit you chopped out) glass that all back in and seal it all up and back out on the water.
I'd be tempted to use a round "inspection hatch" to cover the hole - much easier to fit and make a neat job of that than trying to make the deck good again - it looks in the latest pics that everything would be within arms reach of a single hatch sized hole?. BUT ignore me if Biffer or someone who does this for a living tells you that is a stupid idea.
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Old 24 January 2012, 15:01   #35
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Thanks for all the advice; I've ordered 1x4M of 450GSM along with 4KG of Polyester Resin
As far as layers go Im planning to use a lot, the boat will be sold on in a few months and I don't want to put anyone else at risk.

I'm just hoping it's not a complete mess when I open up the deck

I'd like to put a 30 litre plastic fuel tank in the deck before I seal it. (I'm already running out of deck space!) My question is would it be safe to use a Plastic fuel tank. There is a picture of the same tank on the first page. I would use a very small inspection hatch positioned directly above the filler cap to fill and turn on/off the air valve. I would run the fuel line about 30cm under the deck coming out inside the console then joining up with the other fuel lines.
The flooding hull has been blocked up btw.

Thanks agian
Nathan
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Old 24 January 2012, 15:07   #36
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The Hole Story?

OK, in the interests encouraging Nathan, and to give him some more technical detail, here is how I would tackle the job. It sounds a lot, but once you get into it, it will not take very long.
IF I was doing this I would first make sure that I could get to the damaged area on the inside of the hull. If I could do this without lifting the console - result I would cut the deck to access this area. As Pete says, put this piece to one side as you will need to re-fit it later on. It is my view that you will need to do this to get adequate access to the damaged area, you need to assess this.
Get hold of some kind of grinder, and ground away at an area 4" to 6" either side of the damage. You need to grind away any flow coat (white stuff!) or other surface dis-colouration to expose the glass strands. At a pinch a stiff rotary wire brush could also be used for this, but I find that the bits of wire flying off can get into some really annoying places
I think that it is fairly safe to assume that a contributor to this hull failure is an 'economical' lay up, so I would now try to gauge the thickness of the hull in the area of the damage. What I would try to achieve is a new lay-up that is 2 to 2.5 times the original hull thickness, but a minimum of 1.5 inches. You will need to try to get a datum for this, markings on the inside of the hull with a straight edge between or similar, can be used to measure the thickness of the new matting, as the depth of the mat is difficult to judge when laying it in.
Having cleaned up the inside of the hull you need to cover over the split on the outside of the hull, basically to stop resin dripping through. I would tape on some polyester sheet, but anything that the resin will not adhere to should be fine.
I would use 600gram CSM mat, others might have different views. The greater part of the strength of the finished layup comes not from the resin but from the glass fibres embedded in the resin. So a good idea is to use a roller, to squidge out excess resin; I find a grooved roller squidges the mat better. You can get these from CFS. Often the resin squidged out from one layer is enough to thoroughly 'wet out' the next layer, depending on how generous you are when you apply the resin.
Cut pieces of the matting to fit the area that you have cleaned up. Have these ready to hand when you start applying the resin. Now mix the resin. I normally use a 2% mix, 2 cc of catalyst in 100cc of resin. Do not mix much more than 0.5 litres of resin at one go, as you may find it going off before you can apply it, depending on the temperature.
A good idea is to get a box of the cheap disposable gloves that most pharmacies sell, saves a lot of hand scrubing later on.
I use cheap paint brushes to apply the resin, but I have heard of all sorts of applicators, even chopped up sponge!
Lay your first piece of mat on the prepared area and wet it out with the resin. You will find that the mat will start to come apart as the resin soaks in, this is expected, the glass fibres of the mat are only loosely held together by a binding agent, which dissolves in the resin. Roller this mat to ensure intimate contact with the old glass fibre, and to squidge out excess resin.
Now lay on one piece of matting after another to the required depth, rollering each piece of matting once it is mostly 'wet out'. Do not worry if the resin of the lower layers starts to 'go off', it remains chemically active, and thus you can form a good bond to it, for a few days! I would make the matting of the lower layers wider than the upper layers, to produce a rounded mound effect, but maintain a sensible thickness across the split in the upper layers. As Pete mentioned, this job does not have to be pretty, just pretty strong
To finish off the job properly, apply a liberal application of flowcoat (gelcoat with wax in it) to your masterpiece. And there you have it, the important bit of the job is done.
All you now have to do is close off the deck, finish off the outer surface of the hull, and apply seawater, preferably at no less than 20 knots
So things you need for this job are,
1. Some form of saw to cut into the deck, rotary, jigsaw, or even at a pinch hand saw
2. A grinder, either an angle grinder or at a pinch a grinding wheel and arbour in a pwer drill, although these are difficult to get hold of these days
3. 600 gram CSM mat
4. Polyester resin and catalyst
5. Flowcoat. I would suggest you get the pre-mixed stuff, saves messing about
6. Polyester sheet or similar to temporarily close off outer surface of hull
7. Self adhesive tape for above
8. Gelcoat to finish off outer surface of hull
9. Wet and dry for outer hull surface finishing off
I can give you more detail on how I would close off the deck and finish of the gelcoat if you wish, neither is particularly hard.
OK, I have been thinking about this; I probably have too much time on my hands as I am off work with a particularly noxious virus.
Lecture complete, comments from the professionals would be nice
0 to go
Arrgh, whats happened, have I miscounted
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Old 24 January 2012, 15:27   #37
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That virus must be pretty bad!
Very very helpful and just what i needed
Would i need to gelcoat the outside again if it's a painted hull or could I use something else like epoxy filler or would that not protect the hull from the water?
I think I’m pretty much sorted now, just need some good weather and I can get stuck in
Really looking forward to it! Thinking about it, It might work out cheaper than a weekend out on the boat!
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Old 24 January 2012, 15:40   #38
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Well done Ian, very good method statement, I hope you recover soon regards Mark
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Old 24 January 2012, 16:12   #39
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and a pair of safety goggles if you are grinding and a mask to avoid inhaling the dust. Might seem boring but better to spend the time mending your boat than sat in eye casualty!
Good luck
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Old 24 January 2012, 16:14   #40
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I guess the Hull was originally Orange?, do you know if it is white Paint on the Hull now or Gelcoat?
If you're going to go down the 'cut a hole in the Deck route' I would also finish by sheathing the outside of the repair with a 600 GSM or two and then fairing it in.
If you're not too worried I would use Gel coat over the top of the repair area, use several coats of Gel with a Wax in Styrene additive in the last one and then flat back.
Alternatively use a two pack paint like International Perfection. This'll give you a good hard finish.
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