sheet foam 15 mm thick vac down on to csm

[tunnels]

This is H65 15 mm medium density sheet perforated foam core vac bagged down onto 450 gram csm and just straight catalysed resin no thickening was done at any time . Had to clear a patch for a sail drive to be glassed directly to the hull !! glass to glass !!
Used a chisel just to prove the stick ability was 100% every sqr cm ,was then ground completely clean ready for glassing the base of the sail drive !
My point is all this carry that gets done in your small boats is almost completely laughable sometimes , when this is what could be done very quickly and simply and using sheet foam there's no filling no joins and its as smooth as on the top surface to lay the top glass over!
So what do you think ??
Take particular note of the stick ability of FOAM core !! Sure its sticks on the surface but shears just below that surface as there is almost no resin penetration into the core !! But balsa 9 mm and 12 mm core on the other hand its possible for the resin to penetrate completely from one side to the other depending on the gel time of the products you use be it polyester, vinylester or epoxy !
Remember if we had used BALSA core a chisel would be hopeless because of its stick ability , have never seen balsa ever let go no matter how its stuck down ! would have to use a grinder.
Just two things different to what you guys do and we were using sheet foam that is easy to use all in one big piece , And second vacuumed the whole sheet on one go onto 450csm glass wet out and soaking with standard Vinylester resin !, no filling no gaps and once the bag is removed then its ready for the top glass !!
My other point to all of this is regardless of the resin type you use the stick-ability makes virtually no difference so be it polyester vinyl ester or every ones favourite the over kill epoxy the bond will still be the same !

[BarryStrawn]

Looks like a good enough and low cost materials to build a sailboat. Good engineering for the application.

[tunnels]

Looks like a good enough and low cost materials to build a sailboat. Good engineering for the application.

Many people have used Foam as there chosen core for the small power boats as well AND to me its crazy the way its all done ,they are small and using sheet foam would be easier , quicker and make a far better job that using bits and small sheets !
AS long as the H80 density is ok for what they want there's no problem . And guys have stuck core into the wee power boats using wet csm before but using epoxy !! as I pointed out the resin type isn't critical !!the bond would still be the same regardless . Yachts, powerboats big or small , cars ,what ever !

[dwilfong]

My old balsa core just washed out with the hose from years of polyester wicking in moisture..................LOL
Point made.................

[powerabout]

When you say stickability Tunnels, are you including the bond from your new resin to your old surface or just your new foam and new resin?
New poly to old poly is pretty weak

[tunnels]

My old balsa core just washed out with the hose from years of polyester wicking in moisture..................LOL
Point made.................

Its not completely because of the POLYESTER wicking in moisture its because is the glass fibres not saturated 100% with the resin caused by bad workmanship and someone not doing there job properly! so don't blame the product , blame the person that used it for there lack of skills and practical working knowledge of why they were doing what they are doing and if its not done properly you get what you got .
Have seen polyester boats that are 50 years old and no osmosis inside or out side and the hulls are as sound as the day they were built .And swimming pools more than 20 years old made from polyester gel coats and resins buried in the ground , water with chemicals inside and damp soggy wet earth outside and the still ok!!, sorry like I have said many many times more than 90 % of problems mostly stem from bad workmanship and lack of practical knowledge and the 10% from bad choice of products and materials used !

[tunnels]

When you say stickability Tunnels, are you including the bond from your new resin to your old surface or just your new foam and new resin?
New poly to old poly is pretty weak

The new glass onto old glass is depended on how its prepared!!
Remember a few posts back and I spoke on using 16 grit sanding dics to get a better bond because you need to raise the glass fibres and not rely completely solely on just the chemical bond from the resin . Have seen foam cores shear but never ever once was the adhesive or resin or what ever come off the sub surface it was stuck to !

[tunnels]

Oh and just in case you think its only polyester that gets osmosis think again ! vinylester can get OSMOSIS and yes even Epoxy can get osmosis BUT not as easily ! again its the human element in all and every case that lets it down !
Soluble glass binders were a lot of cause for water wicking long time back , also fast brews of resin that did not allow time for the binders to dissolve 100% by the resin that was still trying to soak the glass filaments properly when it gelled and went hard !! So who do you going to point the finger of blame at ?? always comes back to humans one way or another !AND in so many cases its not just one single cause but a collection of a few different things all put together!!.

[powerabout]

Ploy and csm is where you see 99.9999999999 of osmosis.
Vinylester was invented for the chemical industry to be impervious to just about everything.
Still its all down to tbe quality of the chemicals and who lays it down

[tunnels]

Ploy and csm is where you see 99.9999999999 of osmosis.
Vinylester was invented for the chemical industry to be impervious to just about everything.
Still its all down to tbe quality of the chemicals and who lays it down

Theres something everyone forgets when they blaming resins and other things is the GEL COAT!!
Its the first line of defence the water has to get through BEFORE it reaches the resin and the glass fibres !In the early days all gel coats were hand brushed on all boats !! Osmosis was never heard of and I had to ask what it was !! Once spray guns became the only way to apply gel coat so the osmosis thing became the dreaded word !so whats the differences between brushing and spraying gel coats ??? something to think about !! any one what to take a guess ??
That is why these days vinyl esters are used for the first skins of a lot of boats ,for osmosis protection PLUS to help minims fibre print through. BUT as always you still cant guarantee against mindless poor workmanship and lack of practical knowledge as to why they are using it !!
CSM is still used extensively for first skins BUT the binders used for P MATTS are also a big help !!
hardly ever see E MATT used any where now days , you do understand the difference between the two and what they are ??
Osmosis happens in any water not only salt water but fresh water as well !
http://www.osmosisinfo.com/members/how_osmosis.html
http://www.smithandcompany.org/GRP/GRP.html

[tunnels]

When you say stickability Tunnels, are you including the bond from your new resin to your old surface or just your new foam and new resin?
New poly to old poly is pretty weak

one word to describe that last statement "RUBBISH"!!

[powerabout]

one word to describe that last statement "RUBBISH"!!

New poly to old poly is pretty weak, "compared to any other bond"
happy now?

[XstreamVking]

He will never stop arguing, powerabout. He is an expert, even about rubbish.

[BarryStrawn]

Yeah but polyester resin is real cheap and if used properly the results will be adequate. For some, that makes poly a superior product. For other folks with different objectives, not so much.

[tunnels]

Yeah but polyester resin is real cheap and if used properly the results will be adequate. For some, that makes poly a superior product. For other folks with different objectives, not so much.

THERE is nothing wrong with Polyester resins at all its what they are used for and how its used in combination to the different glass that's the important part, in all my working career I have never found any reason to want to use epoxy to make any thing ! Poly or vinyl ester are more than adequate to make anything ,including bit for planes !!