Re: can someone give me a time table for glassing in deck
1708 drinks far more than 2 layers of 1.5......
the 6 oz......drinks the excess....in fact....you will rarely need to add any more resin when applying a 60z finishing veil......the stuff is very light....and is just a finishing layer over the double 1.5
ok....here is the scoop.....
csm is the work horse of the industry....it is used to build
bulk and to add thickness to a laminate.
the primary reason to use csm ....is between the laminate and the sub straight .
the shorter strands of glass.... contact the sub straight many times......(as compared to a woven).
the csm will eliminate the resin rich area between the sub straight and the laminate
you must understand,,,,,,,,resin by it self is very brittle......really brittle.
lets look at this.......
ok....we have just finished glassing something......the left over resin in the bucket is now cured.
lets re use the bucket.......ok....so lets get the left over resin out of the bucket.
we do that by squeezing the sides and the bottom of the bucket. the cured resin pops out of the bucket easy.....
this is what it looks like from the top
this is what happens when you crumple it in your hands.
resin is brittle......it cannot stand stress, nor is it a good waterproofing agent alone......it
needs fiberglass. !!!!
i get a kick out of some one that wants to resin coat anything.....it means that they do not know about the physical properties of resin and glass !
(its ok for a new person to ask that question but an experienced glasser....it just kills me !)
if you were to add a single layer of csm. to the resin it would be far harder to break.
in fact.....the less resin you use......the stronger the fiberglass laminate.
the perfect ratio is 30% resin ....and 70% glass...
you cannot achieve this target ratio by hand.....to do this you need to vacuum bag the process.
however fibreglass reinforced plastics are so incredibly strong even a 70% resin and 30% glass will give ok results.....enough to make the general lamination ok..... or last for several years.
in general boat building........resin is not your friend.....glass is !
the best ratio a home builder can hope to achieve is a 50/50 ratio.
a pro, using a 1.7 (very cold melp/resin) cat rate might be able to get a 45% resin to 55% glass ratio.....but it costs too much time to achieve that goal....and a 70% resin to 30% glass ratio will work why work so hard?
that is the real beauty of frp's....a home builder can really screw up......and still get good results that achieve the goal as long as the sub straight is clean and a good bond is achieved.
ok.....now that we have that worked out.....lets look at the thickness of a laminate.
lets say you did a double layer of 1.5 and a 6oz woving with a gellcoat layer.
it would take a number of years wearing sand paper soled boots to wear thru the gellcoat surface...never mind the 6oz woven or the two layers of 1.5.v
the point of compromise of the substraight (when the wood gets worn thru) is far beyond the point of wanting to own the boat or even using the boat
people just dont realize the stregnth or the wear resistance of frp's
ok....now lets compare the difference between a double layer of 1.5 and a 6oz finishing to a single 1708 on the deck.
the 1708 knit is far thicker than the two layers of 1.5 csm and requires far more resin than the chopped. (about 5 times as much)
the cool thing about 2 layers of csm on a deck is because the next layer drinks the first excess. so you are getting closer to the magical 50/50 (fifty percent resin-fifty percent glass) what we hope for.
this combined with the silk like quality's of the 6 oz woven.....will drink excess to the point that you need no more resin on the 6 oz.....it just sucks up the excess and makes the laminate stronger ! (even though the 6oz by it self has little or no structural value by it self).
so.......we lay a layer of 1708 across the deck alone.
the layer of csm stitched across the back of the 1708 is very thin...so thin in fact that you can see the stitched fabric thru the csm.
this gives a weaker bond to the the sub straight.
now.....we continue to lay the 1708 at a ratio of 5x more resin.
what do we achieve?
a stronger deck?....why? the less glass and resin will do what we want for thirty years with no problems !
the full 1708 deck cover will add unnecessary weight for no additional purpose !
if we want to gell the deck with a 1708 wrap....we have to sand or grind to get it smooth enough to gellcoat !
three 1708 layers is as thick as the standard hull....why do we need that extra stregnth on a 1/2 inch plywood surface, when it just adds weight and bulk that we will never need?
i hope this post enlightens some one.
if i had the extra 1708 and resin.......and would not have a need for it....i would use it...but if i was saving bux and had to buy the material....i would not !
cheers
oops
seriously???