Wet transom wood, 1982 Glasply

Yes, I get that, I was referring to the 1708 as "mat" see #6. I dont know how to do the multi quote thing.....?

Today I ground back the shell, 8", to get to fresh material. Found several voids from the original layup, suspect thats not unusual.

Also moved our lap joint up as suggested. I would post a photo but was in a hurry to get home and shower, and forgot the camera at the shop......

Will see how progress goes tommorow when we get into the "goo".....

 

Clamping the plywood transom packers into the back of the boat when they were being made is never easy and some guys are very slap happy and dont care that much .
Best way was to gun up a good wet layer of csm and wet out the ply and sit in place and special clamps were used to tighten the ply against the skin while its still unreleased from the mould , Now days i prefer to Vacumn any packers into place gets bedded better and sucks the resin up and into all the bleed holes and fills all those voids you just found .!!!!

 

Gramps, 1708 is a "combo" type of product. It has a 17 ounce layer of biax, combined with an 8 ounce layer of mat.

A lap joint will still tend to project the stress risers through the laminate, under load, even if placed higher on the transom. You may do okay with the outdrive transom (it'll take longer to propagate), but a pretty quick crack appearance on an outboard equipped boat.

 

Im a kilos and grams kinds person and just done the conversion of the 1708 to real weights and measures

Hell its a light matt (its just 500 grams ) and it has a really light csm on the back (226 grams ) as a construction layer i will be thinking twice thats for sure!!!
If you were thinking of using 1708 as a sandwich layer id want a 300 csm minimum on the otherside as well as what it already has !!.
300 grams is almost a nothing layer !!

And people have the cheek to complain when using epoxy that it uses to much resin you got to be joking !! personally i would never have a use for it any where at all !!anything less than 600 gram is like skinning glass for wooden boats in fact the 17 oz is almost that !!

 

I'm not sure where you've gotten your numbers, but maybe looking on some fabric supplier sites for comparisons from metric to SAE would help. the 17 ounce portion of the material is actually two 8.5 ounce unidie's stitched, typically at a specific orientation. This is two 288 gsm unidia's that are stitched to an additional layer of 8 ounce CSM (271 gsm). Total fabric weight is 25.1 ounces per yard (851 GSM) and the thickness, per layer is .04" or a fat single mm. In use, the mat always backs the directional fabrics, as I mentioned above. You can use heavier or lighter combo or stitch mat products if you want.

 

I wish I could afford to put a OB on this boat......it would free up a lot of space in the cockpit and I could raise the floor high enough to make it self bailing. Plus a fish hold where the motor use to live, but alas its out of my reach finacially......
It I did ever convert to a OB I would use a bracket, Armstrong type, they appear to spread the load over the width of the transom more so than one with a slashwell and direct on the transom....Do you still think the loading would be a issue....?
I know, I know, big lever, lotsa weight off the end of the boat......

 

As I mentioned, the lap joint would likely "bust out" pretty quickly on an outboard mount (bracket or not), but if well reinforced, nope, nary a problem with a bracket or transom mount, assuming load transfer issues are handled.

 

Transom is done

Finished the transom over the weekend, still have the stringers and battery trays to re-glass in. But other things to work on at the moment.

All went well for a first time fooling with fiberglass, I am sure some mistakes were made and there is are a few small air pockets. I did not care very much for the 1.5 oz CSM, reminds me of plywood’s cheap equivalent, commonly called OSB (overpriced sh*t board). CSM must stand for something similar....

My supplier (same bonehead that said not to use epoxy) said we should use it on both sides of the 1708 bi-ax, although the 1708 has some CSM on one side anyway.....?. So we used that method but not sure what the benefit is, its a pain to work with. I am sure it adds some strength but it seems like the 1708 is a much more substantial component in terms of strength.

First we ground back the existing surface/s, then added the wood using the CSM/1708/CSM between the wood and the outer skin.



Then we filled along the edges with thickened resin goo and kept pushing wetted mat back in until the joint was filled, then struck the joint with a tool to finish.



After that we finished our final layers of mat/resin and added two layers of heavy roving where the OD will mount up, but still suspect we our short of the required 2” buildup.





All in all a good weekend and am pleased with our results. Still plenty to do....

 

Yep, the bonehead strikes again. You don't need CSM (Chopped Strand Mat) with 1708, it already has it. No CSM doesn't add strength, unless it's really thick (1/4") and then it's really heavy. If you use 1708, you apply it mat down with each layer of material, which offers a mat to cloth bond, which works well with resins that need this type of bond (polyester or vinylester).

How much overlap and what material is on the hull shell, from the transom? The transom joint? Use fabric, not CSM on the tabbing and transom joint.

 

We brought the first layer onto the bottom/hull by 2 inches, overlapped each succeding layer another inch, alternating 1708/CSM, for a total of 7 layers.

 

Do you have a hard laminating roller ?? to get the air bubbles out after its wet roll it with a hard laminating roller !! makes a much nicer job and air free. like i pointed out use peel ply over the top and hard roll it and you can get a completely proffessional look and finish!! also gets rid of any surplus resin and compresses the glass so you get a better glass to resin ratio !.

 

No laminating roller..........! Sounds like a good idea though, I probably could have used my "J" roller for laminating countertops. I could see where that would have been helpful. We mostly used brushes to wet out. I could use a squeeggee on the 1708 as we would put the side with the CSM away from us.
We could squeegee the roving that we used also. The CSM is difficult to wet out as it would want to pull away at times. I learned alot and would do a few things different next time. I still do not fully understand the need for the CSM against the 1708....?
The air bubbles are rather minor, I wish we could have eliminated them but at some point you just have to move on. This project went quick from the time we decided to proceed. I did some research and talked to a few "professionals" but get tired of researching things to death and just have to jump in and get it done.
I appreciate the help I got here, I believe it is going to be plenty strong and DRY, now we need to attend to the other side of the transom, fill and prep all the holes. I need a new tube for the drain......I know they sell brass tubes that are flared on one end....I suspect brass is more durable than copper in the salt....?

 

Why no laminating roller ?? how can you do the job properly without a hard roller . thats what squashes the air bubbles out from under and within the glass that you laminated . the best size is 100mm wide and 18 mm in diameter .
Have you been using a paint roller to wet with or a brush ?? a paint roller about 150mm wide is best to use is quiick easy and makes a nice bob !!

The roller in the picture 2nd fromt the right is what you need to be using !!!!

At the end of a job squeeze the resin out of the roller and gently roll over the surface of the wet layup and soak up any resin thas laying around . peel ply and use your hard roller with just a little pressure and roll the whole surface in long strokes . this will compress the glass , push the peel ply down and bring any resin to the surface when it goes hard rip the peel ply off and you should have a nice neat job !

 

How would I know I needed one? First time I heard of it was your post.....but I can see how it would work. I have never done any glass work before.....it was a large first project.....

 

Ok !! at the begining of any post i usually like to throw a few questions to find what people know ! Guess i missed you ! you have more glassing to do so if you get a couple ! the one i discribed and a smaller diameter and just 3 inchs wide .
Tell me when you got them and theres a few things you need to learn and the reasons why and how much pressure to apply to the roller !!.

I just had a quick think and i will try to put together a general laminating sheet
How to wet out , how to roll and what to do and why etc etc