After removing the roted timber and doing all the grinding (what a job) I have cut and primed the new ply. However, the inside of the fiberglass transome (where the ply will be glued onto) is quite uneven and has lumps and bumps.
My question is - how do I fill these voids when the ply is glued in?
Even with lots of clamps and screws I am worried about gaps between the ply and the inside of the transom skin.
I was thinking I would lay 600gsm Chopped Strand Matt onto the transome skin and then (before it goes off) put lots of resin onto the ply and clamp it into place. Does that sound right? Should I mix some high strength filler into the resin I put on the ply, as this might help fill any voids?
use sander polisher with 24 grit sand a bit flater are you glassing ply before inserting there a product called probond its its thick fiberglass im in the middle of mine i reckon the transoms the easy bit its the floor and stringers that take fore everrrr
Lots of resin provide absolutely no strength what so ever and there's no such thing as a high strength filler. Excess resin without proper use of matt or rovings simply increases weight without any strength factor.
G'day Dave
Done a few in my time so a few suggestions for what it's worth.
Get organised . Have enough helpers and make sure everyone knows what they are doing. Pour out your resin in containers ready to go so just needs catalyst. I use big syringes with measured catalyst pre loaded.
If the timber is primed with waxed resin you need to fully sand back first.
I use talc powder to make a semi paste resin that you can paint (just) onto transom and timber to take up any voids or uneveness.
Same when bonding next timber sheet but a little thinner.
I paint a resin tack coat onto the dry fibreglass transom and then apply the resin paste while it's still wet and clamp in the timber.
Fill the gaps around the edges of the timber with a thicker bog of resin and talc. The more you can do before it cures the less grinding
You will need to clamp the timber lower down on the transom as well .You may need to fix some blocks towards the front you can set some props against.
Make sure you get the catalyst right for this operation. You do not want it going off too quick or worse not at all.
Some people glass a coat of matt over the first timber sheet before the next one goes on. Nothing wrong with this either .If you use waxed resin every layer that cures must be sanded to remove the waxy film / smooth surface .By the way you can use unwaxed resin for any job as long as the last layup coat is waxed resin so you do not get that slightly sticky cured surface it leaves .
Check with your resin supplier there may be better fillers than talc these days but watch the dollars. Check the catalyst ratio with your supplier if adding filler to make paste as from memory it does slow the cure down.
Oldie - Laminating the ply is the next job before I glue in the transom. I am going to laminate together with a layer of Double Bias 450 in the middle, then clamp.
Mister - Thats exactly why I was going to lay the 600CSM onto the inside transom skin before gluing in the ply - so its not just resin. As I understand it, the key to a quality fiberglass lay up (maximum strength) is to fully wet out the glass and lay out with no gaps, bubbles or voids, and do this using as little resin as possible - does that sound right to you?
Hagar - thanks for the detailed reply. I should have mentioned that I am using epoxy resin for this job. I primed the timber wth Norseal epoxy sealer, so no sanding requied (as far as I am aware). I am going to use an epoxy resin called Bote-cote. They claim (1) their resin is thicker and easier to apply to verticle surface, although I think it could still need some filler, and (2) they say no "Amine Blush" so no sanding between layers. Sounds good if it works.
Any thoughts on laying the 600csm (binderless for epoxy) onto the inside transom skin before gluing in the ply? Should I use Double Bias 450 instead, or nothing at all?
I think you're going about it in the right way. The CSM in between the new ply and the transom will take up some gaps. Hagar is right, get it as smooth as possible B4 laminating. Mister is right and wrong. Adding a bit of cabolsil/resin paste (high density filler) to both sides of the wetted out CSM wont provied any strength in itself but it will help fill the gaps and provide a good bond (better than airspace) for the glass to the ply. My opinion would be to use a high density filler like cabosil as your thickener rather than talc which thickens but doesn't add strength IMO.
Bugger. Could have saved writers cramp if I knew you were using epoxy. You are in good hands with Stevemid giving advice now - he should be the epoxy king after his project. Worth remembering that you will have to use epoxy only now for any repairs or changes to your transom and let any future owner know also so they do not get caught trying to put polyester over it.
I will see about a pic of my transom motor mounting - may be of some interest to you .
If you want to add strenght use cotten flox, if you let the resin dry i would sand before the next layer of glass,if its still tacky then it will chemically bond,
tip.... make sure your endgrain of you ply is well sealed the end grain will suck up a bit of resin,if you run a heat gun on low heat or hair dryer around your endgrain to heat it up a bit it will help the resin get in better since your useing a thick resin.
when you finally lamiate the ply in ruff it up with some 60grit and when you run a radius fillet around the edge of you ply so the glass will roll out better around the edges try to roll the glass into the fillet for the greatest strength,have fun with it when you finish you will have learnt a lot from doing it.
Stevemid - good advice, thanks very much. I need to pick up some gear, but hope to get it glued in over the next few weeks (weekends project = slow boat to china).
Hagar - your post was very helpful. I would love to see your pics, that would be great, as I am on a steep learning curve at the moment.
Chris69 - Ive not heard of cotton flox, but will look into. I roughed up the ply before sealing, including all edges, with Norseal. Norglass say there is no point trying to apply more sealer, as the the first coat seals so well that it wont let anything penertrate the wood. However, I will go over all of the ply, in particular the edges, with epoxy resin. Good advice on rolling the glass into the fillets - I will definately do this.
Not sure if anyone is interest, but I am happy to post pictures as it progresses?
Thanks again. I am sure I will have more questions before long.
Hi there Dave as long as its sealed with what ever, Norseal is a diluted epoxy,the end grain is just one spot not many think about when putting in a transom or a new ply floor as this is were all the problems start in the beginning,the cotten flox is just ground up cotten fiber but it makes the best structual bog,ive put a hammer to my stem of my boat to show a few guys to how strong it is when mixed with epoxy,you cant do that to any polyester glass boat or ally plate with out doing damage or leaving a dent,
be carefull when you mix up epoxy with fillers once mixed spread it out in you container to lessen the reaction if its in a big lump it will get very hot...... exothermic reaction....... and will go off very fast and will reduce your working time,the joy of working with epoxy lol.
if you use the cotten flox put enough in your mixed epoxy to make a consistency like smooth mashed potatos you want it to wet out when mixed.
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