RS300 transom
Printed From: Yachts and Yachting Online
Category: General
Forum Name: Repair & maintenance
Forum Discription: Questions & tips on the subject
URL: http://www.yachtsandyachting.com/forum/forum_posts.asp?TID=3415
Printed Date: 11 May 25 at 3:01am
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Topic: RS300 transom
Posted By: ratface
Subject: RS300 transom
Date Posted: 19 Sep 07 at 8:51pm
  Help?  ------------- http://www.blym.org.uk/ - BLYM http://www.blym.org.uk/hydrs/index.htm - Hertfordshire Sailing team Uk-Cherub 2644 Laser 4000 -4089 |
Replies:
Posted By: JimC
Date Posted: 19 Sep 07 at 10:27pm
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You need
angle grinder carbon cloth (check the class rules don't get funny about carbon repairs though) some cheap glass (even chopped stand matt OK) epoxy resin peel ply parcel tape several pairs disposable gloves sharp scissors your mother doesn't want again. There are lots of ways of doing this, but I think I'd make a little mould... Remove rudder fitting. Put your broken off piece back, cover the entire area with parcel tape, and using your cheap glass make a moulding over the area. This needs to be pretty thick to be solid, use about 10 layers of the stuff. Leave to cure, then pull off. You'll use this later to get everything level. Cover it with parcel tape. Now take the broken bit off. Using a small angle grinder or a file grind back the laminate. You want to start just below the top screw holes of the rudder fitting (these are best left untouched so you can locate the fitting) and grind back so that it is chamfered getting to all the way through at the crack. You should end up with a vaguely oval area of decreasing thickness of laminate. Leave parcel tape on all the surrounding structure. Now take carbon cloth. You will use several layers of this to fill back the area you've ground out. Each layer a bit larger than the next. Measure up each piece, wet it out with epoxy, and put it on. Each successive layers should have the fibres at 45 degrees to the one before, eg one cross wise, one up and down, one crosswise etc It will compress down enormously when you've finished, so should be well above the local surface as you put the last layers on. I wouldn't be suprised if its 6 layers. Now add a layer of peel ply - maybe two or three. Now clamp your mould down over the top. You'll need to arrange something to hold it in place firmly. Leave to cure. Remove mould remove peel ply If laminate is well below the surface or the rest of the boat go back and add more layers or carbon, if its within a millimetre you're OK. When the laminate is at the right height fill any holes or low points with filler and epoxy, sand down any high points Remove parcel tape with squished out epoxy on, double check surface now absolutely level with the rest of the transom and correct if necessary. Drill the two new lower holes for the fitting, paint white, bolt on fitting again. While this isn't an especially hard job its got muchos hassle about it. Possibly not the best task to be your first epoxy/carbon job. Alternatively you could ring up RS and ask for a price. You're hardly going to have the first boat that has hit a rock with the rudder blade and bashed the transom a bit... You'll probably end up paying 60 quid to get all the materials you need, although you'll also have 90% of it left afterwards, so if they charge anything under three figures its probably worth getting them to do it. |
Posted By: Guest
Date Posted: 19 Sep 07 at 10:51pm
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Does it matter if the boat is built using polyeter (if indeed it is ..)? ------------- |
Posted By: Paramedic
Date Posted: 19 Sep 07 at 11:07pm
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Don't use epoxy on a polyester built boat. Carbon and peel ply are unnecessary. Other than that Jim's description should work |
Posted By: Isis
Date Posted: 20 Sep 07 at 1:10am
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The 300 is epoxy built. Peel ply is only unnecessary before you've used it really... Once you have its a different story. ------------- |
Posted By: charlie1019
Date Posted: 20 Sep 07 at 8:16am
| A friend of mine suffered the same fate and sent the boat off to Winder. I have a feeling the repair was the best part of £500, however, most of his transom had gone! |
Posted By: JimC
Date Posted: 20 Sep 07 at 8:58am
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Carbon is not essential. If the class rules prohobit it I wouldn't use it. But we are talking about a repair in a very high load area of the boat. We also hve a guy who, from the context, hasn't an enormous amount of experience. The repair needs to be at least as strong as the original structure, so needs all th help it can get. Carbon is advisable. Its not going to use enough for the money to be an issue.
As for peel ply being unnecessary - you could do the job without it, but with it you'll get a better and neater result, better bonding if you need to go for another layer, better fibre to resin ratio and easier release. Not essential, but again, highly advisable. Once you've used it you always do. |
Posted By: No. 5
Date Posted: 20 Sep 07 at 1:31pm
Why not? |
Posted By: ratface
Date Posted: 20 Sep 07 at 3:39pm
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i have had this happen before(but only up to the point in the 1st pic) and had it done by a local boat builder(who shall not be mentioned). i would say since then its had 2 weeks? worth of sailing in it in a variety of wind strengths and has become what it is now... will this always happen after everytime it gets repaired? or would JimC's method make it strong enough to last ------------- http://www.blym.org.uk/ - BLYM http://www.blym.org.uk/hydrs/index.htm - Hertfordshire Sailing team Uk-Cherub 2644 Laser 4000 -4089 |
Posted By: JimC
Date Posted: 20 Sep 07 at 4:07pm
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If I did it I wouldn't expect it to break again unless I hit something very solid. But it would take me quite some time - at least a couple of hundred quid at pro boat builders rates.
I should have said - do you have good access to the interior of the boat? I can't remember quite how the 300 is laid out. If I could get tools in to seriously sand down the inside of the transom (if you can't significantly abrade the current surface this isn't worth doing because the new laminate won't stick well enough) I'd put a patch of a couple of layers of carbon about 200 * 150mm over the whole of the fitting area and overlapping onto the bottom of the shell which, together with the outside repair, would end up stronger than new, if a few dozen grammes heavier. |
Posted By: ratface
Date Posted: 20 Sep 07 at 6:54pm
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nope i cant access the indside of the hull at the back... even if i was to put a hatch there it wouldn't really take one
------------- http://www.blym.org.uk/ - BLYM http://www.blym.org.uk/hydrs/index.htm - Hertfordshire Sailing team Uk-Cherub 2644 Laser 4000 -4089 |
Posted By: Paramedic
Date Posted: 20 Sep 07 at 7:38pm
Because the two resins have differant properties. If the repair is in an unstressed area you might get away with it, but if it's a loaded area and you use epoxy on a polyester boat the epoxy is harder and less flexible then the rest of the boat. This means that if the boat does flex ( as it always will under load) it comes to an abrupt halt at the repair and what usually happens is that the repair starts to come away from the surrounding material. I thought 300s were polyester? It's been a while since i've seen one though! |
Posted By: craiggo
Date Posted: 21 Sep 07 at 7:21am
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I though 300s were epoxy not polyester.
Most of the temporary repairs that have taken place at Nationals by LDC have needed re-doing in epoxy following the event. Polyester is I believe easier to work in a short period of time but as has been said can come away from the surrounding area in time due to the different expansion and elastic properties between it and epoxy. Paul |
Posted By: Rob.e
Date Posted: 21 Sep 07 at 1:20pm
The 300 is Epoxy. Don't think this is the boat that had the accident on the way to the nationals, this used to belong to one of the class stalwarts, and it's driving me mad trying to remember his name! It originally had pro-grip all over the inside. Think it was the guy who did the website....I had to do turns at the windward mark at the Lee nationals after touching this boat ------------- |
Posted By: No. 5
Date Posted: 21 Sep 07 at 1:41pm
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Thanks Paramedic. I assume the same is also true for vinylester built boats? |
Posted By: Isis
Date Posted: 21 Sep 07 at 1:53pm
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Idealy yes no5... though vinylester isnt too far from epoxy in terms of properties
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Posted By: JimC
Date Posted: 21 Sep 07 at 2:21pm
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Its more complicated... polyester on epoxy is a no no, because the styrene in the unreacted polyester attacks the epoxy surface and you don't get much of a bond. Epoxy on the other hand will grip polyester very well - probably better than more polyester does, but you do have to consider the difference in the other properties.
The moral of the story really is don't buy polyester boats... Cheap knockabout boats are best in thermoplastic, performance boats are best in epoxy. |