Fibreglass Hull Repair 

The problem with using polyester is that is shrinks slightly as it cures and is a poor adhesive. If their is impact such as the bottom of the keel in the video it will easily delaminate. This video is aimed at DIY in a front yard who do not have a fancy workshop. Most will go to their local boatshop or hardware store and buy a fibreglass repair kit and wonder why it has peeled off after running up on the beach a few times.

Thanks Catfish, Good point on cleaning up before glassing as we did this video to show how to fibreglass and not the preparation process. It is not necessary to take back to bare glass if the substrate is sound when using Epoxy Resin. The important thing is to make sure the surface is clean and well sanded. The best way to clean the surface is HOT soapy water and scour pad. Do not use solvent as it can actually spread contamination and maybe there is a video in showing the potential problems using solvent. Once cleaned sand with 80 grit sand paper and fully abrade the surface. That way it provides an excellent key to apply the Bote Cote Epoxy Resin. NEVER use polyester resin to do fibreglass repairs as it is a very poor adhesive. It is great for building Fibreglass boats & Thinga-ma-jiggies applying wet on wet. Once cured it does not stick well to its self or other surfaces. Also as it cures it shrinks and is under tension ready to pull away when stressed. Refer to the following link for additional information - www.boatcraftnsw.com/wp-content/uploads/2015/03/DMS-FRP-Explained-140409.pdf . Hence the reason we did not and will not use polyester resin to glue anything or for fibreglass repair. If the hull in the video had of been repaired using Polyester there is every chance it would de-laminate over time from impact from rocks etc when running up on sand or from taking on and off the trailer. Also when doing video's I have found it important to concentrate on one subject to keep it concise and short. Thanks for bringing the preparation to my attention. There is heaps more info @ www.boatcraftnsw.com

Good Evening Island Mike, I am sorry but you are wrong. Polyester is great for building boat hulls or other odd ball shaped doo-ickies where you are applying the resin to glass Wet on Wet so that it can chemically bond to the previous layer. Once cured the next layer relies on mechanical bonding and it does not adhere well - it is a poor Adhesive plus polyester shrinks as it cures and is always under tension and it will easily de-laminate. I provided a link to "Fibreglass Explained" in my original response and you obviously did not read it so I will attach it again - www.boatcraftnsw.com/wp-content/uploads/2015/03/DMS-FRP-Explained-140409.pdf . I recommend you read it to gain an understanding of the difference between Polyester, vinylester & Epoxy Resin. You are right, polyester will not stick to epoxy and any repaired surface needs to be painted with a Polyurethane such as the AQUACOTE water based 2 pack paint. I will also provide you with a practical example. We have a customer who repairs Fibreglass truck panels damaged in accidents. They used to use Polyester Resin and regularly had de-lamination warranty claims. They came to us for a solution, and they now use the EPOX-E-Glue which is a thixotropic version of the Bote Cote Epoxy Resin. You are a trill seeker if you are using Polyester Resin to glue anything or do repairs with Fibreglass fabric. I used to be naive like yourself and it cost me many hours of work along with wasted money. Do some tests for yourself; glue different fibreglass panel sections, Timber to polyester infused fibreglass together with polyester & Epoxy and see the difference. The other problem with polyester is the Catalyst - It is highly toxic. Google MEPK and see what comes up. Basically you are a thrill seeker if you use Polyester to do anything other than make fibreglass shapes such as boat hulls, Monocoque shapes such as caravans, tanks etc. I hope this helps clarify your confusion or poor advice received from others. Dave Giddings

i do fiberglass work for a living... it's all about prep with poly... it wont stick if you got a dirty painted surface period. you need to sand down to the previous layers under the gelcoat to get proper adhesion.

Good Morning Catfish Hunter, That does not mean it is a good adhesive and I see the results of poor fibreglassing practices all of the time due to the poor adhesive qualities of polyester Resin. Cheap and nasty is what I call it and some poor bugger id going to have to be killed by a repair delamination and their boat sinking before it will sink in. Its simple, Polyester Resin is a poor adhesive and if put under any significant stress it it will de -laminate. Whereas, Epoxy Resin is the ultimate man made adhesive and will not pull away with good wear resistance and will still be going 30 years down the tracklong after the poly repair has long since failed. Dave

Good Evening Mike, That is correct. Have you read my previous corro which explains Polyester is fine for building boat hulls and other Doo-ickies where you can put layers down wet on Wet. I suggest you read my previous post. Then you need to go and get the the Bote Cote Technical data sheet from our website @ www.BoatcraftNSW.com and compare it to a polyester tech data sheet. It is like comparing "chalk & Cheese" or "Apples & Oranges". I even gave a practical example of why you should not use poly ester for repairs. Do some homework and you will easily see polyester achieves a weak bond and readily de-lamiates when put under load or shock loadings. Regards, dAve

Good Morning Daniel, It pays to grind the surface back to fibreglass at the crack. We ground back the surface around the damaged area. If doing a temporary repair, you will get away with cleaning the surface with a Scour Pad and hot soapy water to clean the surface. Or use wet N dry sand paper instead of the scour pad and scuff the surface. Wash off with fresh water and then fibreglass using Epoxy Resin (make sure it is modern technology like Bote Cote as it is much safer to use). You may find the video's you were watching were using polyester resin. It has very poor adhesion plus it shrinks as it cures and is always under tension and delaminates easily if knocked or you hit something. Whereas, Marine Grade High Solids Epoxy Resins are much stronger. Make sure it has no solvent in it. If doing a permanent repair it pays to grind out the Gelcoat in a saucer shape to ensure the finished fibreglass surface does not protrude above the remainder of the surface like a sore thumb. There is more info in the comments below. Dave

Thank you

James where abouts are you? Hard to answer questions without photos...

Sounds like you have been having fun. It depends how bad the damage is. If superficial, I would leave it unless it looks unsightly. As the epoxy on its own will not help greatly. If the damage is through to the fibreglass with damage to the fibreglass, then it is worth sealing with Bote cote Epoxy Resin and Double Bias Tape.

Good Evening Petrus, You do not need a lot. - Bote Cote Epoxy Resin - Why - It is based on modern technology and much safer & easier to use than other epoxies. Check out - www.boatcraftnsw.com/products/epoxy/bote-cote/ for more info. - 265 Gram or heavier Double Bias fibreglass fabric. - Peelply - Acetone - to clean your gear. - Vinegar - To clean you. - Plastic to save getting epoxy everywhere - Cheapy brushes - Hot soapy water to clean before sanding - Course sand paper to abrade the surface. Our email is Bote.Cote@optusnet.com.au if you want further advice or purchase product. Thanks for your interest. Dave

Thanks Dav, appreciate the prompt response, going to check it out!

one more question, you mentioned using epoxy glue, do you just mean resin in this instance, also, am I right in understanding that you added the acetone into the resin mix? 10%? this will be my first time working with fibre glass and it's a pretty important repair so don't wanna stuff it up :)

Good Evening Petrus, Where are you located? I did list resin in my previous reply above. The only time you add acetone is to wet out fibreglass. Regards. Dave Giddings

Hi Dav did check out the site, and interested in trying your products I'm located in Caboolture, a small suburb just north of Brisbane. I was a little confused cause in the video you talk about using Glue (I guess that's just another name for resin?). As you can probably tell I'm pretty green when it comes to all this stuff. Kind regards

Good Morning Nate, The Fabric we used was 435 gram Double Bias Fibreglass fabric tape. We have it specially made for doing repair work and joints where high strength is required. It bends around curves easily and being heavy duty was ideal for repairing the hull on the Careel 18 as it builds up a stronger and thick layer quickly.

Sorry Brett a lot of our video's are done on the run and we try and keep them short & Sweet. Every now and again we will do a long video which tends to have most of the info. Always happy to correspond if you have any questions.

A good comment and the answer is - Yes & No. Yes if you large % and it penetrates timber . It has to release for the epoxy to cure. This leaves it porous. Hence the reason to only use 10% when wetting out Reinforcement fabric which helps it wet out but flashes off before the epoxy Gels. You should never use solvents in epoxy when coating timber or other porous surfaces. Several companies sell solvent based epoxies that contain 50 to 60% solvent (Toluene & Xylene) which are know irritants which can affect your respiratory system and cause hypersensitivity. They definitely weaken the epoxy bond as they leave it porous. We have a very good info sheet on our website @ Boatcraftnsw.net / products/bote-cote & scroll down to Information Sheets then select "Water Resistance of Epoxy Coatings". Whereas, Bote Cote uses NO if you add TPRDA to the Bote Cote for the 1st coat. This is a dilute form of resin with some other goodies that enables the Bote Cote to penetrate as far, if not further than the solvent based stuff and it is building a water proof layer from the 1st coat. Go to the Bote Cote section of website and there is an info sheet on "Timber Saturation".