glass lay up information for boat speed boat

[elegant bass]

:) hi need some info on how to calculate glass thickness on speed boat do have the mould to build the boat but don't have the glass lay up information if any one would shed some light on this project of mine i`ll appreciate your help.
raffi
17ft x 6ft beam don`t have any photos yet will post photos asap thanks in advance

[Cobra1racer]

Well if it's a "speed boat" are you going to race it?? Are you going to beat it to death on big waves? Knowing what you plan on doing with it will determine the lay-up that you will need. A light boat in big waves SUCKS and a heavy boat racing will SUCK as well.

[tunnels]

Hi
Be carefull and choose the types of glass you use .
Woven Roving is tough but uses more resin to wet out ,the same weight of a fabric will use less resin and make a stiffer panel .
When laying up a power boat hull start laying glass from the bow and go up the transom .
Joins should have a minimum over lap of 3 inches any where .
Allways overlap glass into the chine and into the keel so it doubles up . The keel is always the first part of a hull to get grounded and the more glass there the better . The chine joins should be from the bottom of the hull , then the top sides coming down over the top and lapping 2 to 3 inches .
The dirrection of Overlaps in glass for hi speed boats is very important because if the skin gets a punchure from hitting a partly submerged object at speed and the water pressure gets in it can and will hydralic layers of glass completely off the hull .
Scary stuff specially when you are 20 miles off shore and it happens and you look out the back of the boat and see a sheet of glass sinking into the deepths .
Hell! how much is still left are you first thoughts and can i get home or even just to dry land again some where .

[hsbob]

you'll have to do a web search. i see some fininate element SW program based on glass parameters but did write the sites down. the cost was too high for my small repairs. there's a lot of seat of the pants requirement that are based on good experience. its all a matter of how close do you want to go. the marine artectitect [sp] have some site with good data.

[Cobra1racer]

What did he say???????????????????

[Cobra1racer]

You can start at which ever end you want. I always started at the back and went foreward. But one thing is a must. Start in the bottom and work your way up the sides. Why you ask. Well if you do dthe sides first and lean over the wet stuff to get to the dry stuff in the bottom to the center of the mold, you stand a 100 percent chance of getting your tally wacker wet from resin. And BOY DOES IT BURN!! For me 20 CC's of MEK to 3/4 gallon of resin. Wet out the whole side, top to bottom and then come back and roll it out. A good amount of the air was out of it, just from being wet and sitting. And for the transom, never have a seam in it. I always cut a piece for the transom that would over lap the bottom and sides of the other glass. This way you will keep it flat, better for the wood to bond too.

[tunnels]

You can start at which ever end you want. I always started at the back and went foreward. But one thing is a must. Start in the bottom and work your way up the sides. Why you ask. Well if you do dthe sides first and lean over the wet stuff to get to the dry stuff in the bottom to the center of the mold, you stand a 100 percent chance of getting your tally wacker wet from resin. And BOY DOES IT BURN!! For me 20 CC's of MEK to 3/4 gallon of resin. Wet out the whole side, top to bottom and then come back and roll it out. A good amount of the air was out of it, just from being wet and sitting. And for the transom, never have a seam in it. I always cut a piece for the transom that would over lap the bottom and sides of the other glass. This way you will keep it flat, better for the wood to bond too.


Weights and measures
Right you need GOOD ACCURATE scales and a suitable container (glass possibly) FOR CATALYST with CC scales marked on it .
Measure dont guess , so each brew of resin goes off at the same speed as the one before and you have peace of mind that it is going to go to the same hardness as well . Plus you know how much time you have to work with it .
To little catalyst and you have soft resin that will never reach it full hardness , now the other end ,to much and it becomes brittle and wont take the knocks .Check with the supplyer as to the correct catalyst ratios you can safely work in most resin work within 3/4 persent to 1 1/2 persent so the resin will get to its correct hardness.
Get my drift !!DONT GUESS !!!!!.
If you have a problem with the resin at some stage down the track because you are over catalyzing or under catalyzing and you go to the manufacture and if they do a sample test you have no came back and no product warranty .
Aways back i delt with temprature and humididty and keeping you glass dry and your resin at a suitable temprature .
Might be time to refresh these points again in this case .

[elegant bass]

boat is for skiing with family and friends if it ends up heavier hull should i use chop mat or other type of material please specify thanks.
planing on putting two stringer 12mm thick each glass all over + center keel stringer false floor 12mm ply transom3x12mm ply glassed in between each ply. planning on having the hull 8mm thick 12mm transom 6mm sides and top deck is this OK or to light. can i use one type of chop mat or different weight. thanks for all the input.
raffi

[Cobra1racer]

1 1/2 oz mat for the skin, 1708 for the strength. I used some free 3 oz mat once, once is all it took to like 1 1/2 oz. Put extra 1708 in the corners, they take a beating. Buy a roll of mat and a roll of 1708 bi-directional (50") and one drum of resin, and a gallon of MEK. How many colors of gell (5 gallons total) and a five gallon can of acetone. Keep the scraps of mat and bi to tab the deck to the hull.

[elegant bass]

thanks for your information i`m hading to buy all the product you have mentioned i`ll put some pics as i go thanks for all your help.
raffi:)

[hsbob]

in that case post the picture first. i thought you were designing a new hull. if we can see what your doing the suggestion maybe better.

[elegant bass]

:D i do have the mould need to go and pick it up from workshop tomorrow i will put some photos of the mould

[elegant bass]

:) photos of the mould
what you think of the lay up strenght
white gel coat,1layer off 230,1x600 chop strain mat,1xtraxcil 768g,1x600 chop strain mat,2mm core mat,1x600 chop strain mat,
double on chine stringer base and transom.
17mm stringers x3,
transom x3 17mm ply glass in between
12mm floor glass top and bottom.
hp 150hp or 200hp outboard
is this set up be OK any input please

[tunnels]

core mat - dont use any thickness core matt in the bottom !!!.
does any one know what corematt is surposed to be used for ???? .

It found its way into the boating industry through a back door and was never designed for boating.

I have been in the industry since 1972 and it took quite some time for me to find out where and what it was meant to be used for as well . Then i realised why there were failures when it was used in certion applications , one being hull bottoms .

Its not a trick question just interested to know what you think its surposed use is !

Looking forward to this !!

[elegant bass]

core mat is for flat side panels and top deck front part

[tunnels]

Ok core matt comes from the industrial side of glassing ,its used as a material to displace resin and a stiffening core for panels of any shape because when its wet out it will form and stick into almost any shape its laid into . Its best in the center of a lay up . used mainly for panels in buildings and the like . The worst thing you can do with core matt is under wet it . If you read the instructions it say how much resin to use per sqr mtr depending on the thickness . Its really just a fine glass cloth impregnated with Q cells to displace a good percentage of resin that would normally be use to make a solid glass panel of a given thickness . It has good compression strength so you can bolt and screw into it and dosent crush like a normall core would . Not good to use in panels that flex a lot as it will and does shear and come appart . Ok to use in Hull sides as long as they dont flex to much , Its used as a glass replacement to manufacture a panel of a given thickness . It displaces resin and makes the panel a bit lighter in weight with the added bonus of making the panel a bit stiffer .
Like most things used for the boating industry they were originally designed for other applications not boats .
If you need a core 5 mm (1/4 inch )thick you are better off using a foam or balsa sheet as it will be lighter and more ridged only on flat areas . you can use 5 mm core matt stripes to go around corners and then carry on with one of the other cores on flat surfaces .
Its good and easy to use just remember what its designed for .

[elegant bass]

thanks for all your information i be posting progress photos as i do stage by stage.:)

[Cobra1racer]

Core mat in that little boat? I'll go back and read.

[Cobra1racer]

core mat is for flat side panels and top deck front part


Yup, and since his side are so short he won't need it in there. But the deck should get some. if they spend any time walking on it or laying on it.

It might be better to convert your metric to english. Cuz I don't know what those materials are, mat yes the rest???????????

[elegant bass]

:D thanks to all for the information i have ordered material as you mentioned
Cobra1racer thanks for your input will post updates as i go thanks

[GregAdams]

I will read this thread again when I get a chance. A few points to start with Bass. Cobra and Tunnels are obviously very knowledgeable. You won't go wrong following Tunnels advice.
Before you go shopping there was a critical typing error in one post. You need MEKP ( catalyst). Not MEK ( solvent).
Use 225gsm ( 3/4 ounce ) Chopped Strand Mat for your tie layer ( skin coat ). It is much easier to work with and gives you a better result. 225 CSM has less filaments per strand of glass. Therefore the strands are finer. So it will sit in tight corners better. Bridging in those tight corners causes voids behind the gelcoat. You are an amateur so you need to do things the easy way. That's not meant to be an insult Bass. It's meant to be helpful. After the tie layer has set and you have checked it for voids, you could back it up with a 450gsm ( 1 1/2oz ) CSM and let it set, before laying in the rest of the laminate. This will reduce print through. Especially if you decide to use Woven Rovings. If you do use WR don't put it near the gelcoat.
I know you probably know this but it is worth repeating. Use UNWAXED Resin. Do not use waxed resin!
For your application I wouldn't use Coremat in the hull sides. Use the same laminate in the sides as in the bottom.
Get used to metric. I have worked in composites with both metric and imperial, and metric is MUCH easier to use. Get some metric scales and a metric catalyst dispensing bottle. Hope this helps.

[elegant bass]

thanks for your advise GregAdams i am planing on using tie layer 230gsm than 450gsm,thahanks again for your advise. any advise is good advise as i am new to glassing, i am going to enroll in night tafe glasses to learn more on working whit GRP
PS:have decided not to use core mat on the side.:D

[Cobra1racer]

Whats in a "P". Greg, if you can get your hands on a couple of sheets of 1/2" balsa, that would be better in the deck than core mat. It would be lighter. The last thing you want is a heavy bow. I used a material called Travera Core, still have a bunch of it. The stuff was like a spong, took allot of resin to wet it out. Just a little FYI. Good luck. IMO 3/4 oz mat is a waiste of time, kinda like catching water with a siv. Thats up to you.

[elegant bass]

back from my vacation i`ll be starting work on my boat will post progress pics.:D

[tunnels]

Chop strand matt comes in 2 forms , one is E matt that is held together with emmulsion binder and take a bit longer to wet out with resin . The other is P matt and this wets out easyer and over all is a fraction stonger because the resin saturates the fibers better .
If you use fabrics there come with a layer of csm sticked on the back side already but its best to finish with csm on top .
Resins for repairs and rebuilds its better to use vinylester resins as the stick better and is stronger than polyester . Epoxy is the best !
Waxed and unwaxed resins - use unwaxed resins during the build process as they allow better bonding with each layer ,finishing off with a waxed resin to get away from that sticky finish that is hard to keep clean and dust and the like loves to stick to .
The wax is a liquid that can be added to your unwaxed resin , you only need a small amount and dont over do it !!.
Just remember that if you want to reglass any thing over the top of a waxed surface its will need to be ground and cleaned with acetone to give a good wax free surface to bond to .

[mike farmer]

I hope this helps with whats in a [p]

Methyl ethyl ketone peroxide (MEKP) is an organic peroxide, a high explosive similar to acetone peroxide. MEKP is a colorless, oily liquid whereas acetone peroxide is a white powder at STP; MEKP is slightly less sensitive to shock and temperature, and more stable in storage.

Dilute solutions of 30 to 60% MEKP are used in industry and by hobbyists as the catalyst which initiates the polymerization of polyester resins used in glass-reinforced plastic, and casting. For this application, MEKP is dissolved in dimethyl phthalate, cyclohexane peroxide, or diallyl phthalate to reduce sensitivity to shock. Benzoyl peroxide can be used for the same purpose.

MEKP is a severe skin irritant and can cause progressive corrosive damage or blindness.

MEKP, acetone peroxide and HMTD have all been reported to be the explosives used in the alleged 2006 transatlantic aircraft plot


Butanone is a manufactured organic chemical. It is a colorless liquid with a sharp, sweet odor. It is a ketone, also known as methyl ethyl ketone (MEK).

Butanone is produced in large quantities. Nearly half of it is used in paints and other coatings because it will quickly evaporate. It dissolves many substances and is used as a solvent in processes involving gums, resins, cellulose acetate and nitrocellulose coatings and in vinyl films. It is also used in the synthetic rubber industry, It is used in manufacturing plastics, textiles, in the production of paraffin wax, and in household products such as lacquer, varnishes, paint remover, a denaturing agent for denatured alcohol, glues and as a cleaning agent. It is used for synthesis of methyl ethyl ketone peroxide, a catalyst for some polymerization reactions. It is highly flammable. It is not considered a large health threat.

Butanone occurs as a natural product. It is made by some trees and found in some fruits and vegetables in small amounts. It is also released to the air from car and truck exhausts.