Fibreglassing

[Stanfo]

Hi Raiders

got a little glass boat on saturday. (not the flashest thing ever but you have tostart somewhere) Most of the hull is solid but a few cracks and weak points one seat in paticular, I was intending to just patch it up but have no experience with fibreglass. do I just put some fibre matting over the cracks then lather in the liqid coating? any help would be appreciated. the other queston i have is to do with the transom, I plan on putting a 4hp moter on the back but should I reinforce it first?

[Flightmanager]

G'day Stanfo ,

Its not a hard job , but a bit messy . If you make a mistake , it is easily fixed , just rip out the first attempt , and try again .

PREPARATION:

Fibreglass repairs are usually done on the back of the laminate. This is to reinforce the laminate prior to finishing the outer surface.

The surface to be repaired must be free from oil, grease, paint or any other contaminant to ensure maximum adhesion. If solvents are used, dry surface before rough sanding a minimum of 75mm around area to be repaired.

APPLICATION:

1. Preparation completed, tape over any holes on the outer surface.

2. Cut or rip the glass to the size of the sanded area. Several layers will be necessary to build laminate to the required thickness for strength. If the area to be repaired is larger than 200 square mm, rip glass to manageable sizes for ease of wetting out.

3. Use table to calculate the amount of resin needed for the job.20cm by 10cm fibreglass mat - use 20ml resin and 0.4ml catalyst (MEKP)

500mm by 500mm fibreglass mat - use 500ml resin and 10ml catalyst (MEKP)

1metre by 1metre fibreglass mat - use 1 litre resin and 20ml catalyst (MEKP)

Wear safety gear as recommended. Have a piece of cardboard, plastic etc. on which to wet out fibreglass.

Thoroughly mix the resin and catalyst (MEKP). Working time is around 15 minutes in warm conditions. Lay glass patch on cardboard and thoroughly wet out with resin - use a clean paintbrush for application. Coat the sanded area with resin and lay on the wetted out fibreglass patch. Work area with paintbrush to remove any air bubbles or wrinkles. Build up 3 - 4 layers and allow to cure (about 1 hour in warm conditions). Sand area and apply extra layers as required.

4. Remove tape from outer surface before curing is completed. It may be necessary to fill any deep cavities in this area, but leave surface slightly under filled.

5. Sand under filled area to provide a good adhesion with fillers or finishing coats.

[a] If repaired surface is to be painted, fill with automotive bog, allow to cure, sand smooth and paint as per paint suppliers instructions.

For a gelcoat finish, apply gelcoat to slightly overfill the repaired area and allow to cure. When cured sand smooth with wet & dry sand paper, finishing with a very fine grit paper, and polishing.

6. Clean up brushes etc. with acetone.

Avoid skin and eye contact

Wear chemical goggles or full face shield, natural rubber gloves and overalls

Store in a cool area away from direct sunlight, ignition sources, organic and combustible materials

Use with adequate ventilation. Wear a respirator if inhalation risk exists

Keep containers closed at all times.

First Aid Emergencies:

SWALLOWED - Give water to drink. 1 - 2 glasses. DO NOT induce vomiting. Seek medical attention without delay.

EYES - Immediately irrigate with water. Hold eyes open. Flood with water for at least 15 minutes. Seek medical attention without delay.

SKIN - Wash skin thoroughly with water and soap. Remove contaminated clothing and shoes and launder thoroughly before re-use.

INHALED - Remove person to fresh air. Keep warm and quiet, Seek medical attention without delay.

SPILL / LEAK - Wear breathing apparatus and protective clothing. Extinguish ignition sources. Recover as much as possible and destroy remainder at approved landfill.

FIRE - Wear breathing apparatus and protective clothing. Evacuation of the area may be necessary. Use alcohol foam, dry chemical or carbon dioxide to control fire/cool area. Contain run off.

Ross

[Stanfo]

thanks for the prompt and detailed response Flightmanager, any ideas on reinforcing the transom?

[IWANNABROCK]

thanks for the prompt and detailed response Flightmanager, any ideas on reinforcing the transom?

I would use a piece of marine ply about 6inches bigger then motor mounting plate with marine sikaflex spread on it,mount it to transom with a stainless bolt in each corner,this will spread the weight of motor and should be sweet. nice little rig,will get you up the river.

[Stanfo]

thanks that souds like a great way to do it , Ive got the sikaflex but where do Iget marine ply from?

[pelican]

Sika is at most boating stores and a fair few hardware stores in amongst all the other sealants and silicones.

With Dinghys like that the board goes on the outside and you may have to make it double thicness in the middle where the clamp goes otherwise the glass lip on the edge of the dinghy will get wrecked and it adds a lot of strength.

Just be a bit careful and before you go ahead strap on the outboard with a bit of wood under it and see how much it flexes when you push the outboard as if it was pushing the boat. Most that don't have strengthening were not designed to have an outboard and can be very weak and you may find the transom height not right for the outboard.. Depends a lot on whether you are going to put around or get it up and planing.

Consider extening the transom strengthening board to the side edges of the dinghy for the first 100mm as bit will let it last longer if you give it a hard time. A smaller board on the inside or small peice of ally will stop

Good run down on fibreglassing above and the keys to remember is that it only sticks well to a well abraded surface and in your case that should be down to the old fibres. Have a really good look at the rest of the dinghy and check what other damage has been done as it would be pretty hard to crack that seat without some serious weight or impact.

[The Iceman]

I wouldnt use marine ply to mount the motor Try a plastic bread cutting board instead

[Jason Sunn]

Hi Stanfo,

You could also use a good outdoor ply (instead of marine ply as it is very expensive) and then just paint it with a good quality sealant paint or even glass it over once attached to the transom.

You can get outdoor ply at most wood suppliers (I purchased mine at Bunnings)

Agree on checking the boat out further as it would have been a decent blow to crack the seat like that.

Nothing better than working on your own boat though and enjoying the finished product.

Cheers Sunnyboy1

[Stanfo]

thanks for all the advice raiders, the guy i got it off used to drag it down through his padock to get to the creek (behind a car)so their maybe unforseen damage but if all goes well then i should on the water soon