Reglassing Engine Beds - Any hints for a fibreglass virgin ?

[yogi]

Standard laminating resin contains no wax for exactly the reasons you give. In a production enviorment complete layups are often not done in one go. One reason is to not overheat the molding. If the resin contains wax the crew would have to begin the next day by washing the molding with acetone and then sanding the molding. with waxless resin this does not have to happen.
I agree that in DIY outlets you would get a waxed resin as the buyer would probably not want his job to remain tacky for years

 

[boatbuilder]

Well that just proves that you learn something new everyday. I have been using polyester resins for about 30 years and have never heard of wax in lam resin.

 

[boatmike]

Totally agree. Avoid wax unless using final layer of gel-coat. It should never be used when laminating.

 

[boatmike]

Neither have I, after 40 years! The only standard resin that contains wax is DIY tubes of gel-coat filler as far as I am aware. The inclusion of wax in laminating resin would cause big problems of adhesion between layers I would have thought....

 

[oldsaltoz]

G'day eebygum,

Drilling out the existing holes and filling them is a very good way to prevent water entering later, just make sure the hole is wider and deeper then the new fixing.

When you clean the small crack in the existing glass, take some time to check for moisture, the last thing you want to do is trap moisture in.

Before adding the hard wood strip, give the the top corners a good radius as glass will bubble on external corners, also avoid sharp internal corners as they can be weaker than a filleted internal corner.

(A) If I do it this weekend and the temperature is 5C will the epoxy cure OK ?

No, as stated by others epoxy needs some heat and humidity below 74%, so some form of heating should be used to warm the whole job and materials.

(B) How many layers of fibreglass do I need to glass over....2,3,4 ?

If using epoxy do not use CSM as it has large voids and will take more resin, this will result in less strength. epoxy resin and material should be close to to a ratio of 1 to 1, so roll out excess resin for stronger and lighter job. Standard resins run close to 3 resin to one cloth by weight weight, this puts the theory that epoxy is more expensive in some doubt as you use less resin. You should add a minimum of 4 layers assuming a glass weight around 256 grams.

(C) Can I glass all layers in one go, or do I need to do one layer, let dry and sand then do second etc. ?

Apply all layers at the same time, 4 layers should generate much heat in the conditions you plan to work in. This will allow you to consolidate the layers with a grooved roller.

(D) I know you can get different weights of fibreglass, do I go for lots of thinner lighter layers or fewer heavy layers; or should I fork out for carbon fibre.

If using epoxy use only glass mat designed for epoxy, not CSM, bi-axial or crows foot are easy to use, as you need to work this around corners, keep the glass under 300 grams or you may have problems getting to form tight over the external edges. Do not use carbon fibre.

(E) How much should I overlap the sides for strength......2, 4, 6, 8 "

Consider placing the first layer over the entire mounting block and onto the hull by about 4 inches, the next layer 2 inches onto the hull and the next 2 inches above the hull joint, the last about midway down the mount.

(F) How do I finish off .... a few coats of epoxy and painting with bilge paint

For a smooth finish and to ensure no strands are standing exposed, apply a last layer of light roving's, let this get tacky and give it at least 3 coats of resin wet on tacky to avoid sanding between coats, you can the let it fully cure, wash it with water and a plastic kitchen scourer to remove the residue left by curing, the water will no longer form beads when it's clean. give it a light sanding just to remove the gloss and apply some flow-coat for a nice durable finish.

(G) Anything else I should know ????????????

Have all the glass pre-cut and ready to place.
Ventilate the area with a fan in the companionway and have the front hatch open.
Use disposable latex rubber gloves.
Mix only enough resin for the section you are working on, small amounts can be applied before you have any problems.
Mix resin in wide shallow containers like 2 litre ice cream containers, this reduced the heat build up in the resin mix.
Clean up with white vinagar (epoxy only) then final clean with a little Acetone.
Take your time and pay attention to detailed areas, particularly corners (They should all be radiused) and roll out all air bubbles by adding a little more resin and rolling it out, ensure all glass is wet, light areas need more resin.

Hope this helps

Avagoodweekend......