Fiberglass cloth for transom

[Joker2]

Can anyone recomend what size cloth I shoud use to layer up my new transom with? How many layers? Picking a cloth is driving me crazy, I don't want to screw it up. Thanks

[RidgeRunner]

Where are you at? If you are near a fiberglass shop they can help. Sorry I got distracted there. I layed 24 oz of woven roven into 2 layers of 1.5 oz mat and made several applications grinding in between. One of my suppliers came up with some newer multidirectional material that had the mat stitched onto the back side. I used it on the bulkheads and the bow it was heavy like 30oz and only required one layer. One thing I noted was it did not like to make a tight radius. The liner was flipped upside down and placed on a custom made table where the rotten plywood was removed with a hammer and chisel. Wet out two layers of mat and layed the coring into that and weighted it down with old batteries, steel, blocks and whatever else was handy. To eliminate air pockets holes were drilled thru the coring which allowed air and resin to squish out from underneath the coring and up thru the holes. Grind on it after drying, prep the area again, two more layers of mat and one layer of roving to seal off the coring. Right or wrong it worked and is very very strong. The coring for the transom was marine plywood and the coring used on the floor was a hard gray foam impregnated with glass, I forget the name. I did not do the entire floor with one piece, it was cut into about 6 pieces which made it easier to do in sections. All the hatches were done the same as the liner working from the backside except I did them without the use of roving and only one layer of lightweight cloth as the final layer which got gelcoat in the end. I would definitely shop around and talk to people locally. This is just the way I was tought, I figure someone will chime in and tell me where I went wrong, this is the old school way. I have never been a fan of taking the outside skin off to replace the transom but I understand why it is done. The glass on the outside is much thicker than the inside and was layed up in the mold as one piece whereby the glass on the inside was always thin and they didn't overlap to the sides very much.
I was looking at your pictures, you have a couple of hurdles to overcome since you have no inside or outside skin. IMO The inside glass needs to be put back first. The only way I can see doing so, without removing the liner, is by digging out the rest of the plywood and using what remains of the outside as a reference for your new coring. If you use plywood and leave the contour of the transom you should make it three pieces. I don't have a problem with plywood core, just know it is going to rot eventually. The plywood if cut into three pieces could be trimmed to fit in between the inside and outside glass on the sides and set into a bonding putty similar to the putty that Wellcraft used on the transoms originally and what bonds the cap to the liner. You will probably need to use a piece of wood to hold the center section to the two side pieces until you get some glass on it and spend quite a bit of time making sure the transom is uniform in shape. Use lots of putty at the sides and let it ooze out wiping up excess before drying. You could hold the sides in place by running temporary screws thru the outer fiberglass into the coring until the putty kicks. I agree with another poster, removal of the liner would give access to the critical areas inside the hull. Glassing the inside of the transom to the liner is not as good as glassing to the sides of the hull and is not politically correct. The grinding you have done on the port side of the liner is good work and exactly what you would do if you had access to the transom inside where the coring meets the sides of the hull, allow 6" to 12" of overlap when putting new glass over old and make sure you use a wax removing agent for the best bond. If I recall the outside skin was 3/8" to 1/2" thick and the inside was barely 1/8" on my CC. The cloth you choose should be heavy to allow fast buildup. I am not sure what 10oz cloth ends up being in total thickness. I think the heavier roven must be laid into the mat to help with the wet out. The glass itself is strong but must be wet out properly to attain the strength. Too much resin and it looses strength. I think I exceeded the word count, sorry. I am famous for being long winded.

[nymack66]

Call these Guys they will answer any questions you have , My supply shop :)

Crap I miss the link here it is sorry
http://www.fiberglassservices.com/catalog.htm

[BenFishin]

You will want to use a biaxial fabric either 1208 or 1708 is up to you.

1208 is 12oz cloth with .75 oz mat intergrated into it. you want to get the cloth that is woven at 45 degrees not 0/90 degrees. the 90 is fine but if you want the strongest 45 is the best bet

1708 is exactly the same thing but 18oz instead of 12oz.

I have 3 layers of 1208 on my transom.

[RidgeRunner]

Originally Posted by BenFishin

You will want to use a biaxial fabric either 1208 or 1708 is up to you.

1208 is 12oz cloth with .75 oz mat intergrated into it. you want to get the cloth that is woven at 45 degrees not 0/90 degrees. the 90 is fine but if you want the strongest 45 is the best bet

1708 is exactly the same thing but 18oz instead of 12oz.

I have 3 layers of 1208 on my transom.

Do these numbers represent what West Marine sells or is this a standard in the industry? Vinylester resin or epoxy? Three layers wet out equals what thickness?

[BenFishin]

Its a standard in the industry. I used epoxy resin by West system. Its expensive but by far the best to use. I am not sure how thick my three layers are due to the way i layed my transom in. I thickend some west with 403 and spread it all over the existing skin, then i layed in my first layer of wood which was coated with 3 coats of west. I threw bolted it in 30 places with threaded rod to make sure there were no places it didnt get pulled tight. once it hardened i removed the bolts, scuffed it up and layed one layer of 1208 cloth. when it started to kick off i put another coat of epoxy on the cloth and then through bolted the next layer of wood and let it dry. Then removed the bolts filled the holes with dowel rods soaked in west. then put two layers of the 1208 cloth on top. If i had to guess the 1208 is about 1/8th thick for 2 layers. The reason i used the lighter cloth is it is a lot easier and a more efficient way of encapsulating the wood as air pockets and areas that wont wet out are easily rolled out with a fiberglass roller. It is imperitive you get a fiberglass roller by the way