Laminate thickness question?
 

Hello, Can some help me? I am in the process of replacing stringers in a 22' scarab, in the bilge area were the motor mount brackets were. the original laminate was about 3/8 to 7/16 " thick. I am ready to start replacing the laminate with epoxy and glass, how many layers of 1700 biax is required to duplicate 7/16? Or can some one suggest a lay up schedule using epoxy? I need the 7/16 so the mounts end up in the same place. Thank in advance for any comments

I'm in the same proverbial boat( excuse the pun) I'm replacing the same stringer and could use the advice!

[QUOTE=38 X;3697746]I'm in the same proverbial boat( excuse the pun) I'm replacing the same stringer and could use the advice![/QUOTE

Maybe we will get lucky

its not necessary to duplicate the thickness and counterproductive to using the high end laminates in the first place. The whole purpose for using epoxy is to build a lighter/stronger laminate based on technology rather then bulk strength. Standard layup for stringers is two full layers with one or two layers of tabbing staggered in. If it were me i would either adjust the thickness of the core or move the stringers as necessary. Or for simplicities sake make a new mount or re drill

you will love the 1700 as opposed to 1708, wets out sooooo much nicer and its way easier to balance.

(that standard layup is actually just my standard layup for a mid size boat . . . . i would assume the rest on the industry to be similar :D)

Just save the money and use polyester Resin and a regular 1708 mat. You will save money on resin and get your thinkness you are looking for. Just a FYI 5 gallons of resin is about $125 and the 1708 is about $10 a yard on average.....Its what Dave was trying to tell you. I just made it a bit more simple to understand LOL....

pretty much lol :D


i hardly use epoxy on anything unless its a full composite build(foam stringers, etc) or a very high performance race build. I prefer vinylester to anything.

Exactly what dave said "just increase the core" if you need mounts to exactly match up. For example, the stringer I replaced on my '76 magnum had a plywood 1/2" core, but laminant thickness was more than 5/16" on either side. I replaced the 1/2" with 3/4" ply and decreased the laminant thickness by almost half........I used vinylester & 1708.

Thanks Guys, For the information, as this is the first time
( newbie), I have already built the stringers, as the original were built, ( like a Box), 97 22 wellcraft Scarab style, I have also already started the process with epoxy, all of the fillets were done with epoxy, cabosil and chopped strain, I also glued all of the inner joints in the stringer boxes with T-88. I wanted to use polyester but there was just so much hype on the net about it coming apart, I guess I fell victim to a fear based fasle sense of fiberglass, so now its to late as the poly surely wouldnt stick to the filets. I guess the best thing to do is what Dave suggested, Have the mounts rebullt. I built a jig and bolted the mounts to the Jig and then took them loose from the original Stringers because I know nothing about how to set up a motor in a boat, I figured it would be easier to build it exactly as the factory did.

Should the staggered tabbing should it be 1700 as well?

Thanks for great responses, you guys are great.

Hey, should I glue another peice of plywood, like 3/8" think to the stringer that I built , just in the motor mount area transom to 1st bulk head of course, to make it thicker? and then re-filet?

Since you've already started w/epoxy yes, 1700 is the best for a staggered tabbing. I like your quote though, "false sense of fiberglass"....I must use that! lol

That's a good question for Dave.........Can't go wrong with the pros here!

Well, I figure either rebuild the Motor Mount, or add a peice of plywood to the striner I already built. By the way the stringer from the bulk head back to the transom is already 1 1/2 thick ( 2 pieces of 3/4 laminated together), thats the way it was from the factory. another 3/8" surely would be a strong core.

Yep, you most certainly can get creative with the process. Thats exactly what i did in my Scarab, the original center board was four layers thick of 3/4". Musta weighed two hundred plus pounds when i took it out (:eek:). I re did it as just two layers and just built a stand off pad where the mounts go. Kept everything right where it should be.

Its easy to get drawn into the hype of epoxy, its fantastic to use but far beyond what many of us really need and many times not worth the hassle. I cant say anything bad about the process its just over marketed in my opinion. The reason why stringers and transoms fail 99.9% of the time is not because of what was used but rather how it was used.

Thanks Dave, Youve made my mind up Im going to make up the differnce in the mounts, Im happy with my decision to use epoxy, somehow I just feel better about it. must be a mental thing.

Thanks to everyone who responded to this thread.

I will apologize now, cause obviously i am a moron when it comes to this....but uhhh what to you use to secure the stringer to the transome and to the bottom of the boat? i re-read over both pages here and every bit of that was greek to me...think i followed the ply wood part and yeah i was lost..

I have been recruited to help out 38 X with his fiberglass work, lol.

He has a hole that is rotted around the edge. Would it be okay to cut out all the rot and fill in the hole with a 2 part foam and then use 2 layers of polyester resin and 18oz E-Glass? Or should we fill in the hole we cut out with layers of plywood like is in there now?

I cut mine pretty accurately and if i need a gap fill and fillet i will use ATC's Corebond or a mix of Cabosil. The stringer will free stand, once you get the first layer on its pretty secure. Heres a couple cross sections of a good stringer layup. Pending on your needs you can stagger in one, two or three tabs. Hate to say it but i rarely fillet the joint or bed the stringers in compound on standard replacements, i cut them close enough to not need it. I also think that first single flat layer i put down helps box the stringer in and makes it a strong "T" joint structure and ensures that its uniformly sealed all the way around.