Need input on core material selection

[Smoking Joe]

50mm, 3.8 inches thick! weighs a ton! I'm sure it will work, no doubt. but most of these performance boats are concerned about saving weight.

50mm is 2 inches not 3.8. Still I also would be interested in doing the weight comparison exercise.

[Gorilla0178]

50mm is 2 inches not 3.8. Still I also would be interested in doing the weight comparison exercise.

my apologies, like I said, forgive my math. I didnt convert it to inches after dividing. that sounds a little better. I agree with the strength of a transom done that way, just never considered doing one that way.

[tunnels]

remember these are just standard run of the mill everyday family boats !! not race boats 50mm is standard required and solid id way stronger than a cored transom . to do a weight comparison first you have to understand how the transom is built then you will understand how it can be lighter but stronger !! remember the thing of shape its not a flat all the way across type transom like is standard and common of most boats !
This could be a business for some one to make new transoms and simply cut off the old and Glass on a completely new transom with a set back of say 400mm and make the splash well smaller in the process !! I would not hesitate to do it on the next second hand boat I buy make a simple mould and glass it all with feathered outside and a step back and don't even look at the old transom but cut it inside and out and replace it with a new one !! no core of any sort will be lighter stronger and more durable and never have to touch it again for ever more !!and no woven roving to be seen any where , sorry its the wrong glass for this type of construction !!!

[OFFSHORE GINGER]

http://www.boatdesign.net/forums/att...ness-chart.jpg For those interested .

[tunnels]

Its about time some one up dated that chart from Boatdesign,net !
Noah used it when he built the ark and was chiselled in stone !! but yes it has some good indications of the older materials

Try this for good specs of glass and resin on more modern and up to date info plus gives resin weights for resin infusion as well as hand laid that could help some people That are into that !!http://www.vectorply.com/newsite/search2.aspx

[OFFSHORE GINGER]

First off might i mention that ..................i posted that more or less for $hits and giggles just to give everyone a general idea keeping it simple / stupid / cut , and dry other then going with the vectorply example http://www.vectorply.com/newsite/search2.aspx considering it can sometimes be confusing for some people that have never done any fiberglass repair because ( they ) after viewing the vector ply web site will always come back and ask just what fabric do they really need to use for there project at hand ? Tunnels , like you mentioned in post # 33 , these are standard run of the mill everyday family boats ( not race boats ) , and with that in mind have you forgot that this is Scream & Fly .........which means that most boats on this forum are not your run of the mill everyday family boat . LOL

[tunnels]

most fabrics these day people are using stitched together and not woven and there is a slight difference with thickness and amounts of resin used . its easier to use wets out quicker and makes a better job than woven. Steadily most companies have been phasing out woven glass I have noticed and that's not a bad thing !! double bias with a 300 csm on one side has become the preferred glass to build decks as it draped round and over shapes better and core matts are only used on flat areas on decks only !! don't use it on hull at all , the really thin core mat used for a fibre print blocker is a dangerous layer and one bang in the side and it separates like blotting paper from end to end as it has abysmal peelablity . Have seen some terrible infusion jobs in the last 8 months and when you actually hang a stop watch on the wall its much slower and heaps more wasteful than just good old hand laying !! Yes it has its place and I feel hulls if not one of them ! and as for being stronger !! convince me !! sorry I do not believe it at all !!.
Solid glass transoms I am a convert after spending the last 8 months making, installing , and converting wooden structures used for under floor frames to 100% glass grids and marrying the whole lot together is absolutely the way power boat manufactures should be going for sure ! simple easier , lighter and quicker . Every forum you look on ther some one wanting to replace a wood transom and some one wanting to replace or repair wooden stringers etc not forgetting the floors as well !. Its changing times and boats for me are taking a back seat as I drift into amphibian light sports planes !!. And want to learn to fly them as well !!

[tunnels]

50mm is 2 inches not 3.8.inchs who would want a transom that thick ??? never seen that much thickness on the back of any kind of boat before !!

[Gorilla0178]

50mm is 2 inches not 3.8.inchs who would want a transom that thick ??? never seen that much thickness on the back of any kind of boat before !!

I apologized for that mistake. 50/12.7 = 3.93/2=1.9, so 2" is correct. my bad.

[tunnels]

6 mm = close to 1/4 Inch

12mm = close to 1/2 inch

25mm = close to 1 inch

50mm = close to 2 inch's

75mm = close to 3 inch's

100mm = close to 4 inch's

EASY TO REMEMBER AND CLOSE ENOUGH !!
I went through the conversion thing from one to the other so long ago like the 1970's sometime I have trouble now rethinking imperial again and as for all the decimals forget it !! never convert just think the closest to what you have like I have listed above !

[dwilfong]

This has bin some good reading.
I am redoing my 78 Vector and am at the point of making some decisions.
I have bin thinking of using this http://plywood.boatbuildercentral.com/products.php?id=1
Three layers of 1/2" with carbon fiber cloth sandwiched in between and also between the shell of the boat. then one on the in side. Using epoxy to glue it together.
The boat is just a shell now with the top off.
This will be a complete build up from scratch.
I have looked at Coosa and other foam boards. But the cost is just over the top.
Have any of you used Meranti BS1088 before in a build?
It is also inviting as you can get it puzzle jointed to make a one piece floor from front to back with a good seam.
Also when re coring the hull bottom thinking of CF biax and epoxy instead of glass and vinalester.
What is the difference in cloth strength as to thickness between the two?.
With the extra strength of the CF can the core be thinner, Say 3/8" instead of 1/2"?
The weight is in the resin and if you can use a thiner cloth you do not need as much resin.
Here is the CF http://www.sollercomposites.com/
Here is the Epoxy http://www.fascoepoxies.com/products.html

[OFFSHORE GINGER]

First of if you are going to go with Ply and feel Coosa is over the top as far as price goes why would you even want to go with a Ply that is lioyds certified other then a good marine grade ply from a big box store or maybe these people who are Coosa's biggest competitor http://www.spaceagesynthetics.com/th...teproduct.aspx and not to mention that soller composites are great people to work with and mill there own fabric but if you are thinking of using Epoxy why not just go with a matless cloth like 1700- Bi Ax ( no chop or continous strand mats / csm ) which should and will fill all the needs in any phase of your project which will be easier on the wallet and can be had else where opposed to Soller www.uscomposites.com www.expresscomposites.com

[dwilfong]

Thanks for the info with the links.
I will do some more research and see what is what.
The ply wood is only $60 different than the box store stuff on 4 sheets.
Big difference from $500+ difference from foam board.
Why would I not use the Meranti BS1088 over the box store ply?
The cost of the resin is where the thiner cloth will pay for its self.
Not to mention the gain in strength.
I think I will cover over the whole boat inside and out with a 4ozCF just for the WOW.
I like the glow in the dark cloth also.
Imagine a glowing boat at night.

[Matt Gent]

I've used the BS1088 Meranti, bought at BBC in Vero. It is quality plywood. I also use their house brand epoxy.

No need for CF, and no need for any glass in between the layers of wood (when using epoxy). The load is carried by the outer and inner skins.

I also use their 12oz biax cloth, in 45/45, layed up wet-on-wet on top of the plywood.

Their forum support is good, and quality materials at decent prices. If you rebuild that way and pay attention to encapsulating all the edges and holes (drill/fill/drill or insert) I think it would be solid for a long time to come.

The running surface core thickness drives stiffness; you cannot go thinner by using CF or any other cloth for a given panel span and loading. I do agree that thickened epoxy is the best bedding compound for re-coring an old hull (best secondary bonding). I chose to use SilverTip epoxy for the re-coring.

[dwilfong]

So you use the epoxy filler powder blend and mix it with epoxy to bead the foam core?
That would save a whole lot of cash as the core bond is $250+ for 5 gallons.
Back in the day at my first job working in a fiberglass fab shop. We use finally powdered asbestos and sifted it thew a sieve to get the lumps out. turned black as coal when mixed with resin Harder than steel and light as a feather. this crap stuck like peanut butter to every thing.
Set a steel ring in a lid for a centrifugal separator for alcohol mash with it. The boss read the print wrong and I had to get it out and grind all that crap out.
YA that was a JOY!!!!!!!!
Those where the days!!!!
Asbestos and resin as a beading compound. Thy don't makem like thy use to. LOL