just some stuff i think i know on glass work

[davidroland]

hi guys im new here but have some info that may help some one.i have made race car bodies and some transome and other work.
1 poly vinal ester(i think thats right)is a flexible frp resin
2 resin(polyester) wont cure over some epoxy it will on some.
3 epoxy will cure on resin.
4 dont use store bought resin-it is usualy old and usualy causes greiff
5 resin does not like to cure on pine woods(most plywood)the pine oils contaminate it(sometimes itll cure anyway)
6 use a paint roller its faster-- but put it on as thin and dry as possible and go back to any dry spots after it wets out and pick up with a dry(damp)roller any excess
7 get an air buble roller and remove any air possible(not real important unless your nasa)--not pushing down on paint roller when wetting out and then rolling it on down with dry(damp)after it wets out helps keep air bubble (microscopic almost) to a minimum.no excuse for big air bubbles.it helps to start in middle of peice and work out.
8 a good filler/thickner is micro ballons(microscopic hollow glass beeds)and it adds no weight and sands easy(dont use in layups!)
9 wear protection!!!this stuff is dangerous to long term health expesicly when its gassing!!!!!
10 some ideas for making your pads--might save some time
bend a form out of sheet metal--for a mold--not a plug-making the insides the shape and deminsions you want for the outside of pad.
bondo any radius ect you may need
coat mold/form on inside with pva mold release(not wax as the resin will bond to the bondo through even thick wax.)
use gellcoat if you want to(you wont have as many pin holes)to fill
lay up your glass how ever thick you might want(use mat for first layer for smothness
add any wood you might want(stringers)
after it cures(for days after you think its cured--unless you want the chance for distortion )
now mabey fill it with expandable high density foam for extra stiffness and bonding area
grind hull where you want to bond it plus about an inch out side this area
now switch to epoxy and bond it on- clamp with tape or straps(ratchet tiedowns)and pad it with wood so you dont distort it.if you mold a flang on to pad you can screw or rivet it on(do this before you bond--all holes drilled ect--and you can even put it an tight and check fit ect before its permant they can be removed and holes filled after it cures.
after it cures put an inch or 2 wide strip of mat around the edges(grind it deep enough so that most of it will be below the surface(so you dont sand it all away)rember--epoxy now not resin--sand it and smothe it with bondo(unless your nasa--then use epoxy with micro ballons for filler.
i do this kind of stuff for race cars all the time---works good and saves time and money in long run---let me know what you think and pass along your ideas--im a good student and a 1/2 baked teacher!!!!!!!
things with engines is fun aint they(is it moters with starting engines or vice versa?)

[sho305]

Sounds pretty good. When you make a sheet metal mold for a pad, how would you get it to fit the hull? Do you fit the mold close at the edges...? I want to pad a vee but it has the contours of the hull, so I was thinking of making it out of wood and bonding/laying it up piece at a time to get the fit. Everyone seems to do that, but it would be nice to try different reliefs before I do it permanent. I'm thinking a temp pad. Have to make a new dock first to park the boat at now.:rolleyes:

[davidroland]

hi sho
if i were doing it i would make the form/mold the size and shape of the pad plus the thickness of the sheet metal(galvanized works pretty good--but if you do bondo in it it can pull loose when pulling the part--no real problem as it is easy to repair for the next one)the whole point in doing it this way is that you get a smothe surface with out all the work as the inside of the form is what we are gona use.
if you dont have the use of a bending brake--
you can do a decent job of bending the sheet metal by clamping it to the edge of the bench and puting angle iron on it lined up with the edge of the bench(clamp with large c clamps) and the bend line then take a 2x4 or some thing and put it on the peice hanging off the bench and push and or hamer your bend into it(can bend up or down)the angle iron needs to be fairly stout as you can only clamp near the ends unless the peice getting bent is fairly narrow--in this case it just might be--i draw better than i write--if you need i can make some sketches and then get my son to help me scan and send.no problem if you want.
the sheet metal dont need to be verv heavy(thick) as the spans will be short and it wont sag--expesily if you have it on a board or something.dont do it in the sun as your resin may get away from you before its all worked out--put in sun only if you have problems with it cureing.heat during cureing can cause shrinking and distortion---expesily in a metal mold!!
if you want to try several shapes in a day you could leave a flange around pad and screw it to the hull with silicone sealer or something(assumeing the screws and flang would not be to much drag and keep you from getting up on the pad in the first place
if you lay out the holes and drill them in the form they will show up in the part so that several pads could have same screw pattern--counter sunk screws would work good if the flange is not to thin--i would think that for short term carefull use that the thicknes of the head would be more than enough and probably could be even thiner than that with part of the counter bore in the hull
you should be able to make 2or3 forms from one sheet of steel
my understanding of planinghull design is that it is verry important to keep the trailingedge(transom end)bend as sharp and as close or more than 90deg as possible so that the water can shed cleaner for less drag---water following around and up the transom would cause unnessary drag.
on stuff that is hard to get measure ments or to picture in my head the shape i use posterpaper paterns and templates and tape and strings ect to get it right and get the shape im after quicker
modeling clay is good for temporary changes in the mold and the pva works good on it
if you do the counter bore trick or do use screwholes get some thin superglue from a modleairplane hobby shop andput a little on the raw edges to stop water from wicking up the fibers into you pad--do this on all unfineshed edges---any where fibers are exposed--this stuff also works prety good for fixing stress cracks and other damage as it wicks its way up the fibers real good--resin will cure on it--i have even fixed delaminations by drilling through surface into delam and flooding through the holes with superglue--this stuff(the higer quality stuff)can(i say can because of all the variables)be stronger than resin---experiment its fun-just be carefull and keep a close eye on things
we suposed to do this anyway right!!!!!!!!!!!!!!!!!!

[davidroland]

P.S.
if i didnt make it clear you should be able to bend up your mold out of one peice of material with no joints except for at the back corners--a couple of rivets here would do it--thet will show up in your part but can be eaisly filled--2 part glazing puty(kinda like bondo but smother and denser)works good and is prety tough after it cures a few days--the realy thin stuff comes in a squeez type bottle and is realy only good for pinhole filling--the thicker stuff is in a can---if it is still to thin leave the top off a while(days mabe)and keep stiring it from time to time---this will let the solvents leave it and thicken it up a little----ive also used laqure thiner and or acetone to thin it when needed.
weare gloves!!!!!!latex works ok and you can change them often as they are cheep------
warning-------washing resin and other stuff of your hand ect with acetone -thiner ect puts it right into your blood stream in seconds
atleast a friend of mine in the military was tought this in a clas on the subject

[Techno]

If your like me and do get it on you a scotch brite pad and soap and water take it off. As aggressive as this sounds it more or less rolls or balls the resin up off your skin.
Using any solvent is a loosing battle since your taking the oils out of your skin. Then stuff sticks better and your skin gets dried out on top of it.
Keep doing it and your skin cracks open like in dry weather.

BTW acetone shouldn't be used with latex gloves. It dissolves the gloves and they fall apart.
The nitrile type last a lot longer and give a better protection. Easier to put on and take off too.

[davidroland]

thanks techno
no mater how careful i am i still seem to get it somewere on my body.
i use the latex sergical type and just throw them away--10bucks for 100 or so
sometimes i go through several pair on one resin batch if im having to reach into the work.
when your working with glass and get the itches(glass fibers in skin)from handaling-sanding-swipe a pair of you old ladies panty hose get in a hot shower to open your pores and spread the panty hose material out with your hand and rub in one direction--it will grab the fibers and pull them out--dont go back and forth as that breaks them off and your stuck with the itches awhile.
let the pantyhose dry and put them back where you got them and you can have some real fun!!!!!!!!!!!just kidding on that last part--we would all lose our crew cheifs and wouldnt be able to race any thing but slotcars!!!!

[sho305]

Thanks for the info! I'll have to see if I can rig up something after I get a couple rpojects out of here.

My problem is the hull has more rise at the bow, so my pad will have to change as it goes forward. Even though I am only going about 6-7' long, it is a different contour by then on this hull and I need to blend the forward part in. I did autobody for a while so I am familiar with the solvents, bondo, etc. Just the mold part I did not use. After thinking about it, it might be faster/easier to make a mold even out of wood/etc than making the pad on the hull in pieces. If I could get a mold right, I could even make and install it without flipping the boat.:)

[davidroland]

hi sho
you should be able to fit your mold to the hull to get your change in shape from front to rear of the pad .if you make a poster paper patern (in plan veiw with bends and all) for the front you should be able to transfer it to the mold and then fill in the blanks as i would assume that once you get past the lenght of the poster paper the rest would be straight lines.
i was thinking that to--that you could do it on the trailer and if a temperary mounting could be used you might be able to try several with out even leaving the lake.
if the rise is realy complex you might want to make 2 molds and then join the 2 parts--you can hold the 2 parts togeather with tape and shim it till its straight or even screw from inside of part into sheet metal or wood or what ever(and superglue help hold things in place) and put one layer of glass(just wide enough to bond parts) to get it stuck then take the screws out and glass it all good (this will cover up screw holes)just rember that secondary lay ups are not as strong(after resin cures)but i have not had problems with it in real life--if it was a horrible problem we would never be able to repair the stuff in the first place.
bondo and stuff seems to bond to glass real good.one time i hit a concrete rail road tressle and put a big hole in my boat--i did the structral part of repair then used bondo to fill low spots and after i got it smoth i covered the whole area with light cloth(not mat)and put a couple coats resin to fill weave -bolcked it smoth and its held up for over 15 years---and this was done from under neath!!!!if i ever do it agin ill turn that sucker over!!!! while were on this subject ---when working overhead with this stuff you can tape the dry glass in place and after wetting out the rest carefully remove tape and finish wetting out.
whats you wife think of panty hose trick???
later
P.S. if you do use wood make sure it is with out oils in it (pine is a nono)even through the mold release it seems to screw up the cure prosess---pva mold release does work beter than wax on this but not always--you can paint the wood and that helps.
lotus(car mfg)used to use latex paint for mold release and then it would pull out and stay on the part and was used as the primer!!!!!never have gotten around to trying it though.

[sho305]

I did my transom with west epoxy, and I'll tell you that stuff sticks! For most of the pad I can screw/bolt through the hull on this one if I need to. I can't get to the inside of the forward part on it. I want to glass a 1/2" of ply tapered at the transom all the way up for some extra strength first, then the pad with some relief...I hope about 10" if I can @2-3" height. The problem is finding out how much first.

Wish I could make a sliding pad on it somehow...still thinking on that.;) Was considering running two aluminum angles down the existing bottom, then making a pad with holes in the sides for pins or bolts to slide it...not sure it can be done easily enough to be worth the hassle. It could be done poorly just enough to find the right spot, then glassed or remade permanent I suppose. This is a slow boat, but a testing apperatus for my faster hull if I do it before that one.

[davidroland]

hey sho
been tied up for awhile
i like the addjustable pad idea--man if you could do it like power trim!!!!
dont know if developing a pad(non adjustable) on one boat and the using it on another would give the desired results as the changes in hull weight and in shape might require totaly diffrent shape ect---maby some of the boat experts could anser that one--i just dont know that much about boat hulls.
keeo me posted!!!

[sho305]

Indeed they are different hulls, this is mostly a construction practice thing and in case I don't like how it handles, etc. Had to make some cash so I am full of cars right now, but I hope to get a temp pad on one before fall anyway. Should have two cars out of here today if all goes well.

So far I am thinking of making the last 2' of the pad removable and ariated at the seam. Then I could cut or replace that section to tune. I'll get rid of this bayliner after I get another hull running so no need to get too fancy with it. In adding this pad to a running hull, I should be able to do that without any strength issues and I'll put a base of ply under it anyway. I can easily make that removable section have a channel under it so it gets air from the relief. The problem with the sliding thing is strength, or you would have a large step due to the thickness of it where it is hollow. Maybe if it was aluminum welded up; I'd try that on a hull I would keep. Only need maybe 8-12" of adjustment. I want only a small 1/4" step in this pad or I think it will not work well on this small 16' hull.

I thought of making the last 3' or so of the pad adjust for a hook/wedge, but I think the relief is what will change balance better. I am guessing a hook will change high speed attitude/handling more. This one not fast enough for that anyway.;)