Fiberglass schedule

[ondarvr]

Re: Fiberglass schedule

Don't grind off all the old build up on the hull, just leave the many layers of glass, this will keep the original stiffness if your concerned about it, and have no negative side affects. It will also cut down on the cost of epoxy and 1700.

 

[ujc]

Re: Fiberglass schedule

Could not leave the build up.....wish I could have. Looks like where the factory made the filet's with the "Bondo" they wiped the material out on the hull and it delam'ed.....so that part is all gone........just pulled right up for about a foot out.....from that point out is still solid. Thanks

 

[ujc]

Re: Fiberglass schedule

Can I run the 17 DB layers first and then to build up the hull and add stiffness with 1708 DB layed matt side up....will this work? Or should I use something else? or just use a ton of 17 OZ DB layers? Thanks to all!!

 

[Woodonglass]

Re: Fiberglass schedule

You don't use 1708 with epoxy. No need for the CSM that's attached. a 17oz or 18 oz biaxial cloth is all that's required. I would lay two layers of 17 oz cloth and then two layers on the Stringers and call it good. IMHO that would take care of the flex and strength issues for this application.

 

[ujc]

Re: Fiberglass schedule

I'm thinkin you might want to lay a couple of layers of 1708 down on the hull first and then do the stringer motor mount installs. That way the hull gets reinforced both with the pre layers and the tabbing of the stringers and MM's.

Sorry I must have misunderstood the post. The two layers of 17 DB I have lam'ed have a ton of flex. I guess all the glass and connecting the stringers to every thing else will keep the hull from flexing one foot out from the stringer. Thanks Wood

 

[Woodonglass]

Re: Fiberglass schedule

My BAD on the 1708. I'm so accustomed to working with Poly that I just automatically type 1708... Epoxy does not use CSM so you don't need it. Having seen your pics and understanding the entire situation, I'm fairly confident in my assessment that the 2 layers of 17 oz Biax covering the whole ground down area and then installing the stringers and MM's with the added tabbings which basically gives you 68oz of biax cloth and resin, will be more than adequate for your repair. I am NOT a pro like OOPS and YD but I have done my share of glass work and feel confident this would stand up to any abuse you could possibly put your boat under. The PRO's may come along and Shoot Me down but I don't think so.

 

[Yacht Dr.]

Re: Fiberglass schedule

Hello guys .. I was invited to this thread from the OP.

One thing you have to understand is that types of woven fiberglass weight is per yard ( 17 oz per running yard ). So 1700 or your db170 is basically 3'x3' ( about 1.9 oz per sq. foot of woven glass ).

CSM is per Sq. ft. ( 1.5 oz is most common in repairs utilizing poly/ve resins )

So .. look at them side by side and you have about 3 layers of biax to 4 layers of 1.5 oz CSM thickness.

I dont care how good epoxy is .. 4-5 layers of 1700 is NOT strong enough to mount your dual engines on. Lets call it 6 layers of 1700 biax .. that would equal to about 8 layers of 1.5 CSM thickness.

Alrighty then!!! All you need is 1700 biax. Two layers and it'll be a TANK!!!! The combination of the Epoxy (stronger than VE) and the 17 oz Biax (MUCH stronger than woven roving) will really make her bullet proof!!!

You probably had about 1/4" or more at the stringer/hull fiberglass thickness going out about 10". You will not be able to replace that structurally with 2-4 1700 layers.

I would suggest Tabbing your stringers in first ( at least 3 layers going up your stringers and spread out 4/8/110 "s on the hull. Then you can glass wrap the whole stringers out to 12"ish 2 times. You may have to add another 6" up and down on the stringers depending on the highth of the stringers.

Most IMPORTANT is the prep between the dry glass and the new glass. If that fails then .. well it could be a bad thing ..

If it was 21 oz Woving+mat between .. then yea probably 4 of those would do it.

The PRO's may come along and Shoot Me down but I don't think so.

Sorry Woody ..

YD.

 

[Yacht Dr.]

Re: Fiberglass schedule

Oh..I almost forgot .. is this your 1700 fiberglass?

=ujc;4View attachment 171317/QUOTE]

It looks like some kind of Graphite glass ..

Never seen Black 1700 ..

YD.

 

[ujc]

Re: Fiberglass schedule

Thanks YD!! That was the pic of the old glass seperated.......after I set it on fire to see the schedule, and it is thick...REALLY THICK.... 1/2 iINCH. Sounds like I have a TON of 1700 to lay. Just trying to get my head wrapped around the total number of layers I will need .......sounds like 10 or more layers based on a 1/4 inch starting point noted by YD to get me back to 1/2 inch properties...unless there is something else that is better that will give it strength and stiffness.

 

[Georgesalmon]

Re: Fiberglass schedule

Woven roving is thicker than knitted fabric like 1700 and you could use fewer layers to get the thickness you want. 1700 is about .030" dry, but I would guess that it would be at least 1.5mm when wet espcially in multiple layers. Resin content is very important when figuring thickness. Without going nuts with formulas and trying to firgure out exactly where you would end up and considering your going to use epoxy and considering this is not a rocket ship. IMHO if you figured 1.5mm for each layer of 1700 you would be in the ballpark when your laid up. With 18oz WR you might go to 2.5mm or even 3mm for each layer. You have to use something without a styrene soluble binder for epoxy and I don't know if WR comes that way. Try a small sample layup 10 X 10cm with 5 layers of 1700 and measure the thickness in the center. That will tell you exactly what you want to know about the number of layers you need by extrapolation (sp).

 

[Yacht Dr.]

Re: Fiberglass schedule

Thanks YD!! That was the pic of the old glass seperated.......after I set it on fire to see the schedule, and it is thick...REALLY THICK.... 1/2 iINCH. Sounds like I have a TON of 1700 to lay. Just trying to get my head wrapped around the total number of layers I will need .......sounds like 10 or more layers based on a 1/4 inch starting point noted by YD to get me back to 1/2 inch properties...unless there is something else that is better that will give it strength and stiffness.

I still think 1/2" of glass is extreme for stringer tabbing ( not to mention stringer overall lams). .. 10mm is about 3/8" .. If you keep your schedule around 3/8" with epoxy then your probably fine. You dont want to do ALL the lams at one time because of the heat factor. Might get pretty darn hot doing the lams all at one time.

Its just hard to say .. but man after 7 layers of 1700 with epoxy .. and tied in with the transom and subfloor bulkies/supports ... should be good. But its up to you on how much you want to put on there.

If the boat is using the Glass to support the power train .. then you may have to reproduce it.

I wish I could see this first hand. ..

YD.

 

[ujc]

Re: Fiberglass schedule

Thanks for the replies guys!! I wish you could see it first hand also YD. I did call Crownline again and they gave me the standard answer. replace what was there with the same thickness.........he did say to add the same stiffness.......never said why...sounds like you mabe right as to the glass supporting the power train. The old glass all checks around 10 to 13 MM from what was removed from the hull and tab area....checked about 8 places. I did several test patches about 10 inches square with 8 layers and they all come up to 6 mm.

So it looks like the plan I have will give me 6 mm versus the old glass at 10 to 13mm. Think I should do maybe 10 and call it good?
Could i do this, 7 layers up the stringers and spread out 4/5/6/7/8/9/10 and then 2 full layers out 11 and 1 layer out 12
With the falling temps, could do this in three passes

Or could I run two out 10 on the hull.......one on top of the other since I have so many to lay
Then 2 out 9, then two out 8, then two out 7....then two full covers out 11 and one out 12

I already have 6 gallons of epoxy and still need to filetwith epoxy and caulk under the stringers with PL....how much more epoxy will i need?

Option 3. add some WR to the mix?
Thanks guys!!

 

[Yacht Dr.]

Re: Fiberglass schedule

I did several test patches about 10 inches square with 8 layers and they all come up to 6 mm.

So it looks like the plan I have will give me 6 mm versus the old glass at 10 to 13mm. Think I should do maybe 10 and call it good?

Could i do this, 7 layers up the stringers and spread out 4/5/6/7/8/9/10 and then 2 full layers out 11 and 1 layer out 12
With the falling temps, could do this in three passes

Or could I run two out 10 on the hull.......one on top of the other since I have so many to lay
Then 2 out 9, then two out 8, then two out 7....then two full covers out 11 and one out 12

I already have 6 gallons of epoxy and still need to filetwith epoxy and caulk under the stringers with PL....how much more epoxy will i need?

Option 3. add some WR to the mix?
Thanks guys!!

I think in this case going with the first larger tabs then go smaller might not be a bad idea when working with 1700.

Try the 10 layers like you described in bold above and go from there.

You can probably get it done in two passings. You should grind/smoothout between lam sessions.

I have never done stringers in epoxy so I cant tell you how much to use.

Dunno about your option 3. .. sorry mebbe someone else could jump on this one.

YD.

 

[ujc]

Re: Fiberglass schedule

Thanks YD!!

 

[mrdjflores]

Re: Fiberglass schedule

Just joined in to read through this......my head i spinning, and i need an advil....thanks alot!!!!

LOL

 

[ujc]

Re: Fiberglass schedule

Me Too!!! Found another thread that repaired the same size boat......looks like they also layed 8 layers then went back and added two using 17 and epoxy

 

[ujc]

Re: Fiberglass schedule

Question, what would be the best material to bed the stringers and bulk head in on this size boat......PB or PL? The stringers are glued in place at the transom and bulk with epoxy 1/4 or so above the hull, I did coat the edges of the plywood with three coats before we installed them. Thanks

 

[ujc]

Re: Fiberglass schedule

Anything wrong with bedding with polyurethane and then going back and creating the fillets with epoxy PB? If this works, what brand of poly should I use other than PL....really hate the bubbles!! Thanks

 

[ondarvr]

Re: Fiberglass schedule

It makes little difference what you use to bed the stringers, you can use just about anything, or nothing. The point of bedding the stringers is to keep the plywood from coming in contact with the hull and creating a hard spot that may stress the gel coat, and/or laminate. Most builders of smaller boats use nothing, even many builders of larger boats use nothing, they don't even make an effort to space the plywood off the hull. Use what you like and don't over do it, any non epoxy product that is spread across the surface will interfere with the bond when you glass them in, sort of what you found in the beginning.

 

[ujc]

Re: Fiberglass schedule

Thanks ondarvr. Crownline gave me another problem, they told me to bed the engine stringers in epoxy but was told NOT to bed the bulk in anything harder than polyester putty....bondo I guess. I like the thought of having something under there to help stop any future water....in case I screw up