How may layers of Fiberglass.....wow

hey, I don't want to sink or any thing like that so before I start could anyone tell me how many layers and of what oz. I would need for something like a
40ft speed boat, or maybe a 40ft bertram....I have heard it takes anywhere from 1.5 inches to 5 inches of mat/roving 20oz for these type and size boats...

 

WOW, that part of your statement is correct, the rest about thickness is WAY overbuilt.

A 40 footer would be about 12mm thick average.
Normally, if using solid glass layup you start with .5mm gelcoat, followed by tissue glass, then 2x 300gsm CSM, then 900gsm Rovings then 300gsm CSM, this would be repeated about 5 to 7 times and finished with a peel ply cover slip to make it all lay nice and flat and remove excess resins. The peel ply also creates a perfect finish for installation of bulkheads etc later.
Alternatively you may use -45, 90, 0, + 45 layup arrangements for the woven rovings, this creates better longitudinal strengths.

Be careful not to just jump into this if you have access to a mould, it is really a structured design that is required, not a 2 minute lesson on the internet.

The bow areas, the working waterline section at the bow and the transom all require different layup schedules, so if you intend to build, you really must take this further.

If on the other hand you are just being inquisitive, the above should help.

 

Layup schedule:

No, I actually want to build this thing.......

Let me see if I get what you are saying:
1). .5mm gel-coat...ok, got that.
2). -45,90,0,+45: ok this is the orinetation of the fibers in the glass, got that...
3). what does this mean: "tissue glass" do you have another name for that? Like, say, "1 oz.mat"
4). Also, what is 2x 300gsm csm. I get the "2x to be two times". But, I don't understand the 300gsm CSM part...

 

12mm = .47 inches.....so about, on average half of an inch.
Also, the USCG requires fire resistant resin, vinyl ester, right.
It is going to take me a while but I'm going to get everything in my head before I start infusing resin

 

Ratrace, you should consult with a marine architect or engineer to determine the optimum layup schedule for the boat you plan to build. I recommend that you speak with Dave Gerr. He is located in Manhattan.

There are many variables to consider, not all which can be addressed in this forum.

 

Thanks Eagle Boats,

You are absolutely correct, and resin infusion......have you done this before ratrace2.

I am concerned that you may be biting off a lot more than you can chew, if you have worked in glass to the level of infusion, why are you asking basic schedule questions.

Mate, boatbuilding is not exactly rocket science I know that, but there are MANY basic things that have to be understood before you just get a mould and build a boat.

I work in China doing QC and tech training there, the place is full of people building boats, but very few boatbuilders.

Now please do not get me wrong, it is quite feasible for someone that has not built a boat before to do just that, in fact most of the best boats ever built are by amateurs (because they have the time to do everything as best as possible, commercial builders HAVE to build to a price or go out of business), but please get professional advice before doing a fusion job, it is a very costly mistake if it goes wrong, not something that is easily repairable (basically forget the repair side if the fusion fails).

You will have to get a layup schedule for the particular design that you have in mind, there is no generic version available as every boat is different.

I can readily present you with one for traditional solid layup in displacement mode, as that is going to be overbuilt, composite is another matter, and you are talking about fast boats anyhow, get pro advice mate, and it will save you time and money.

Oh, and all the best too, nice to see someone doing their own thing.

 

The path to finding the right layup schedule: Critical

Wow, you guys are the best. You have given me some really good "paths" for further questions and research for this boat. I'll get more in depth regarding lay-up schedules for and the calculations thereof for composites. Got any good sources.

 

marine Engineer: How to contact

Is he going to charge me a $1000 a word????? Dave Gerr.

 

40 footer layup schedule: hypothetical

____________Oh, I get it: your 300gsm CSM is 300 grams per square meter Chopped Strand Mat, right. You get me a little off keel when you speak in metric terms. And, the 900gsm Rovings would be--somewhere about 28.94 oz. Roving. Hell, I got that in the basement now.

So, your presented "hypotetical" layup schedule--I call it hypothetical for legal reasons, I don't want someone reading this and thinking it is the universal schedule and making alot of trouble for themselves because of our discussion.
________.5mm get-coat ,1/2 inch
________CSM 300 gsm/10 oz
________CSM 300 gsm/10 oz
===============================
_______Roving 900gsm/29 oz.
_______CSM 300 gsm/ 10 oz.
=================================
______Roving 900gsm/20 oz.
______CSM 300gsm/10 oz.
++++++++++++++++++++++++++++++++++
Continue this until you achieve 12mm or about 1/2 inch in thickness

 

Hi Ratrace2, It is not just a matter of achieving a specific thickness glass. The hull and shape would most probably require the glass to be layed up in a specific way to obtaing more trength and stiffness.

I guess what the guys recommend you do is to get some advice from someone in the know. This person should be able to suggest where to put more glass and how and where to do what in the hull, and on such a big rig, when, it's not going to be an afternoon jobby, trust me. If you do contact such a person and he charges you a little fee it could save you much more in material and performance, it's not just a matter of throwing the glass and resin in to get it over with. I would also strongly suggest you work a schedule out (with this consultant) for when to start what. No use you do the gelcoat but you have to go away for the weekend... it will ruin the process. Same applies for the other layups... there are timing involved in all of this.

 

Comments are inserted above into the original text............................
What would you recommend for a layup calendar. One layer a day. One in the morinning and one in the afternoon.....what's your take on the best way to proceed.........Thanks, you guys are the best.....there is so much knowledge lurking behind these computer terminals.....

 

Ideally after you prepared the mold, the gelcoat goes in, usually two layers but depends on the mold. A time window for the gelcoat to green some must be allowed before you could start glassing. There are a lot of factors to consider, the time of day and if you're working in a cool or hot place. A hot place get the resin to cure real quick and would require less hardner. As for the layers and layers of glass and resin... ideal would be to do the whole layup in one go so everything becomes one solid part, but not always possible. Just think your process wrt to the hull through properly... no use saying oh blimey I should have done this or that, now it's too late what a mess

 

I don't understand what this is trying to say:
"Just think your process wrt to the hull through properly..."
Honestly, I think doing all the layer of a boat this size in one "shot" would create so much heat that something would warp..
Has anyone read the book "The Elements of Boat Strength" Parnine recommended it.

 

I just ran into Dave Gerr's book:

Name: Elements Of Boat Strength
Author: Dave Gerr
ISBN: 0070231591
Binding: Hard
Pages: 368
Publication Date: 2000

Have you read it?

Who are the ABS...do I have to have a certificate of class onboard?.....WOW

 

Good book, but somewhat conservative.