Help with fiberglass hull needed!!

[tim slocum]

My predreadnought Missouri BB11 project has been stalled for a while now because of a problem Im having with the hull.I have a fiberglass hull that I am converting for my project.Well,I altered the bow by cutting out a V shaped piece and was going to bring the two side back together.This is hard to describe,I hope you can see what Im trying to do.Anyway,I've tried 2hr epoxy to bond the two sides back together and it failed to hold. :confused: Because of the shape of the bow,it's very hard to clamp the to side together.I think Ive overcome this,by drilling a hole and running a bolt through the hull to hold the two sides together.Do you think bondo spot putty would hold?I'd really like to get past this problem and proceed to next one :rolleyes: HELP,ADVICE PLEASE!!

[patmat2350]

Your hull is likely built with polyester resin (as opposed to the more expensive epoxy)... epoxy glue will only give the appearance of sticking, then Pop! Even after sanding etc.
Use polyester resin as glue, perhaps thickened with talc or microballoons. If the joint is under stress (wants to pop apart), then a mechanical tie may be needed too.

Spot putty ("glazing putty") has zero strength.

Pat M

[pmpjohn]

Epoxy will not stick well to polyester. You will need to sand and scrub with acetone the area you want to stick. Clamp the sides in position and lay in FG cloth and polyester resin 2-3 inches back on both sides of the seam. This will give the strenght of the cloth and a much larger bonding area.

John

[Aerominded]

Interesting and timely subject since I have recently aquired several polyester hulls that I plan to build out- I am a big fan/user of West System Epoxy so I thought I would go to them to see if West can be used for bonding various parts to poly hulls- I got an emphatic yes!

West pointed to many examples of how their epoxy is used in the repair of polyester boats and in new construction, where hulls may be polyester with the bulkheads bonded in using epoxy/glass... I will be doing some of my own tests over the summer...

If I understand what you are doing Tim, it sounds like there is a lot of "pre load" in the joint you are making and it may require more material to make it work...

[tim slocum]

Would Epoxy finishing resin work? I found a product called Z poxy.It says that its good for bonding fiberglass cloth.Patman,what brand of polyester resin would you suggest and where can I purchase some?Aerominded,yes the area is some "pre load" in the joint.

[Aerominded]

My comments are only based on what West System says about their product... not sure if all epoxies are the same so I'm not sure about Z poxy... Like I said, I will do some of my own testing to be convinced! :)

I understand a lot of folks have had good luck bonding motor mounts, stuffing tubes etc to poly hulls using autobody filler... I'm just not sure how well that is suited to doing a neat job of installing decks, etc...

[towboatjoe]

Regular 2 part epoxy you buy in the twin tube will not work. In fact it is not waterproof and will break down after prolonged emersion in water.

Epoxy finishing resin on the other hand is anotr thing and, used with fiberglass mat, will do the necessary job of bonding polyester hulls.

I do all my hulls with epoxy finishing resin and 3/4 oz fiberglass mat. Example of how I do it can be viewed at http://www.towboatjoe.com/hulls.htm

Bondo will work, but talking about serious sanding! That stuff get really hard.
One thing to remember is you can put epoxy over polyester, but you can't put polyester over epoxy. The polyester will go wacko, sometimes it'll crack and split, other times it won't even cure correctly.

In any kind of hull modification or repair you have to sand the area good and use mat to reinforce the resin. Resin alone will not hold.

[der kapitan]

Tim, Aerominded and Towboat Joe are telling it like it is with epoxy and polyester resins, and I don't think I could add much to their input.

I'm not too familiar with West System epoxy, so I can't say if it'll work well or not for you.

However I have used Bondo autobody filler on certain applications as an adhesive for years with very good luck.

Just remember that it is porous, and needs to be sealed with paint to prevent water being absorbed.

[tim slocum]

Thanks everyone, alot of food for thought.Towboatjoe, thanks for the link,very informative,I bookmarked it.Im torn between polyester or epoxy finishing resin.The polyester is stronger,but the epoxy is easier to mix.Do you guys think the epoxy would be strong enough if I use mat.As I mentioned earlier there is tension on the joint.

[der kapitan]

Thanks everyone, alot of food for thought.Towboatjoe, thanks for the link,very informative,I bookmarked it.Im torn between polyester or epoxy finishing resin.The polyester is stronger,but the epoxy is easier to mix.Do you guys think the epoxy would be strong enough if I use mat.As I mentioned earlier there is tension on the joint.
Tim, find a way to take out the tension at all costs, it may save your skin in the long run. ;)

[Umi_Ryuzuki]

Tim, find a way to take out the tension at all costs, it may save your skin in the long run.

You need to repair and attach the pieces together and even "finish" the joint before you fiberglass across the area.

If this takes brass rods, plywood, or other bracing the pieces should be solidly connected before you fiberglass. As far as "finish", the joint should closely resemble the finish you want after fiberglassing. This way you don't spend too much time sanding and glazing the area you are repairing.

[green-boat]

Tim,

This is just a thought but epoxy and polyester resins are a plastic. How about applying some heat from a heat gun to soften the plastic to the point where you can get the two halves into position, clamp them together and let them cool. Then you can resin them over to close them up.

[killick]

....Definitely use the "Mat"....! If in doubt at all go with the poly resin and made absolutely certain -- no matter which compound (poly or epoxy resin) you decide to use -- that you have sanded ANY other adhesives off and that you are down to the "original" fibreglass. Make sure the hull cannot "come apart" until it has properly cured. (......"Duct Tape" ??)

Best of Luck--!
Paul.

[tim slocum]

Bondo's Fiberglass Repair Kit #420.It includes polyester resin, liq.hardner,fiberglass cloth(what oz?)and a plastic spreader.After the posts I recieved,I decided to go with polyester resin for strength.This will be my first experience with this stuff,but I need to learn about it for future builds on my to do list.Sometime in the next few days I'll try to fix my hull and let you know what happened.Any final words of wisdom for a first time fiberglasser??

[pmpjohn]

Carefully measure the resin and hardener and stir stir stir and then stir some more.

John

[Aerominded]

Any final words of wisdom for a first time fiberglasser??

Plan ahead and work quickly! :)

cut the mat / cloth and carefully work out how you are going to position it- have all of your tools ready to go, before mixing the resin- you won't have much time to work with polyester resin it once it is catalized... don't go too crazy with the amount of resin- use only enough to wet out the glass- excess is just waste- also, I understand that to a degree, polyester resins air dry so thin layers cure better and form stronger bonds.

Plan ahead and work as quickly and neatly as you can! :)

I build with epoxy resin so don't really know much more about poly

One other thing, have fun! :)

[Umi_Ryuzuki]

Wear rubber gloves, and don't be afraid to put your hands on the job.
Holding the fiberglass in place while you brush out the excess resin, or
trying to press out air bubbles is easier to do when you can get your
hands into the "mess".

;)

[tim slocum]

Someone mentioned in an earlier post to use spray adhesive to hold the cloth in place while you apply the resin,but I think they where talking about epoxy resin.Can you use this technique with polyester also?I just happen to have a new can of 3M spray adhesive that I could use.When I tried to 2part epoxy the sides together I used ALOT of epoxy,so theres ALOT of sanding to do first.Also, in the extreme bow the fiberglass was originally pretty thin,can I fill the area with polyester resin?This area is directly below the area I'm bringing together.Maybe I could use a little more than I need and let the excess flow down into this area?

Also, how long should I let the resin dry,before unclamping it?

[Umi_Ryuzuki]

Personally, I felt that the resin did not adhere as well to the hull when held in place with Super77. So I always brush the resin over the hull first.

I have also tried letting a bond coat of resin cure to tacky and then applying the fiberglass, and felt it had the same result. not as good adherance or lamination.

[Aerominded]

Oooo, yes, forgot to mention gloves... very important...

Re: spray adhesive, polyester is very sensitive to other chemicals and could be a real mess if it reacts badly with super 77, etc., but I have not tried that so it might work...

[tim slocum]

OK ,get rubber gloves and skip the super 77 adhesive. Brush on some resin first,then the cloth,then more resin,saturate cloth with resin and wait for it to dry....right?Unclamp it in 24hrs? 36?

[Capt Cal]

get yourself a box of latex gloves and put on at least 3 pairs per hand so when you start laying in the resin and things start getting a little sticky peel off the first set of gloves,and keep going

[Aerominded]

Tim, I just re-read one of your previous posts... be sure to remove all of the epoxy from around the area you plan to bond with polyester... you want to sand back to the original substrate for the best bond and to prevent the poly from reacting with the epoxy... :)

[Umi_Ryuzuki]

OK ,get rubber gloves and skip the super 77 adhesive. Brush on some resin first,then the cloth,then more resin,saturate cloth with resin and wait for it to dry....right?Unclamp it in 24hrs? 36?

Squeege with the brush, plastic squeegee, or your gloved hands, as much resin out of the cloth as possible. The cloth should lay as close to the hull as you can press it.

Excess resin will run, and can cause the cloth to pull droop and wrinkle.

[Prins Willem]

I have used Bondo Polyester resin and automotive weight cloth alot with good results. Aerominded was correct in stressing having the mating area clean and free of contamination. I am concerned about the stress in the bow from pulling the two sides together. It may never work out and you may have problems with cracking down the road, especially when you think about a R/C boat being bounced around in the car, sitting in the sun on the shore then getting put in cool water. All these forces are working against each other. Before you mix the resin be very sure you are satisfied with the structural integrity of the bow. One other thing. Bondo resin has a strong odor. Use in a well ventilated area.

[tim slocum]

Prins Willem, Thanks for the advice and Welcome to the forum.I have given some consideration to using some brass tubing to mechanically connect the two sides together first and then fiberglass the seam.But first,I need to get some time to do this.With the strong odor,I will do this outside and the weatherman says rain until Sunday.

[Aerominded]

Hee hee, definately do this outside! I love the smell of polyester resin and Bondo but it nearly landed me in divorce court a year or so ago! ;)

The otherhalf likes good ventilation! :)

[Prins Willem]

Hi Tim,

I was giving it some more thought today and I want to suggest you play around with the resin a bit before you tackle your hull. If you have some scrap plywood laying around mix up some resin and cut some cloth. You will get a feel for how the stuff behaves. A tip on mixing resin. I purchased some 1oz measuring cups from Hobbytown USA. They are packaged by K&B manufacturing. I measure out as much resin as I need in 1oz increments into a plastic container. A measuring cup from bleach or fabric softener works very well. Margarine tubs, cottage cheese containers, even tuna fish cans will serve. Just make sure they are very clean. 1" to 1 1/2" disposable brushes work well for application. Practice makes perfect.

I have to thank you for giving me a topic to add to the Wisconsin Scale Boating Association website. I wrote up some of these tips for our tips and tricks section. As the website admin I'm always looking for new ideas for the site.

Unless your a submariner stay on top.

[Aerominded]

...Wisconsin Scale Boating Association website... As the website admin I'm always looking for new ideas for the site.



Prins, I had the pleasure of visiting the WSBA website a week or two ago- good stuff! Looks like you guys have a lot of fun there in Wisconsin! :)

[Prins Willem]

We do what we can with what we have. It is a privilege being in a club with so many great guys. Fortunately clubs full of great people are not rare. I had the opportunity this spring to meet a few of the Southeast Boat Modelers (Atlanta) at their pond site. The jovial atmosphere and camaraderie made me feel right at home.

[Aerominded]

This is a great hobby that way! :)

[DT56]

Most small containers of polyester resin I've seen offered for sale are a finishing resin, that has a wax additive to insure a complete surface cure. Finishing resin will require sanding between subsequent laminations to insure adequate bonding. Polyester laminating resin, without the wax additive is available from resin suppliers or some boat repair shops. The wax additive is also available to convert laminating resin to finishing resin.

When using polyester resin, it's best to pre-coat any wood with resin and allow to cure, prior to encapsulation or bonding. Additional styrene additive is available from resin suppliers for increasing bond strength with wood.

[time4420]

Hee hee, definately do this outside! I love the smell of polyester resin and Bondo but it nearly landed me in divorce court a year or so ago! ;)

The otherhalf likes good ventilation! :)


I hear 'ya!

[time4420]

Epoxy will not stick well to polyester. You will need to sand and scrub with acetone the area you want to stick. Clamp the sides in position and lay in FG cloth and polyester resin 2-3 inches back on both sides of the seam. This will give the strenght of the cloth and a much larger bonding area.

John

Epoxy WILL stick to poly. No problem. Boats are repaired every day all over the world with epoxy over poly.
Grind down to the original laminate, clean with denatured alcohol(does NOT have water in it)Coat with acetone or styrene(styrene is better)when bonding, coat the bond area with resin, if you are laminating, for poly, use laminating resin(no wax). the only time to use Finnish resin is on the last coat. You CAN use Finnish resin to laminate but L resin is better. If the Finnish resin cures before the next layer is laid down, then you have to de wax and ruff up with 60 to 80 grit paper before laying up the next layer or it won';t last.
When bonding ALWAYS use a piece of mat(not cloth. cloth has poor adhesion properties)in between the two bonding surfaces. This is very important. Always. Take 2 pieces of cloth and bond them together. Now take two pieces of mat and bond them together. Let them cure and the pull them apart. The cloth will come apart easily but you'd be lucky to separate the mat, at the bond, at all.
Epoxy is better for bonding then poly. Make sure you use the mat that is compatible with epoxy if it is your choice. I would poly for laminating in every case because epoxy is just not necessary. We are dealing with scale boats and scale boats are not even close to having to deal with the stresses of full scale. (Or unless the smell of poly restricts the use of it).
If it is wood that your bonding, I can't stress enough to first coat the wood with a thinned poly(25% styrene or acetone) and let cure. Do this with L resin. This is the most important procedure when bonding wood. The resin, thinned gets sucked into the wood and make a far superior bond. Then continue with mat. Again, don't use cloth. It is very important,also, to get rid of excess resin because if the resin cracks the the crack will travel right into the laminate. Roll the work area out with a grooved roller and remove excess resin with a brush. If you use a brush to work the mat then you will distort the mat, make more work for yourself and wind up with a mediocre to poor bond/lay up.
Feel free to bond under tension. Just make your bonding strong and hold the pieces in place until the resin is fully cured. If the resin has been catalise3d properly according to the abiant temps, the resin should be ready for handling in an hour. Let sit for 12 hours before placing under load.
Most resins will change color when catalyzed. Mix THOUGHOULY. For maximum efficiency, the pot life of poly should be 30 min. Best temps to work in is 70-80 D. The general rule for small amount of poly is 12 drops of catalase to one ounce of poly. Stay away from thickened poly if you can. If you can't, thin with acetone but styrene is better if you can find it. There is no acetone in poly but there is a lot of styrene. Styrene is the smell in poly.
DO NOT USE ANYTHING TO HOLD THE GLASS IN PLACE! Coat the area with resin to hold the glass.
Do not let the resin start to kick before applying the glass. Absorption of resin will be effected.
Capn. Cal.
Excellent advise! Not a lot of people know of that advantage. I probably would have failed to mention that myself.
Again, don';t use the brush to squeegee out the glass. Get a grooved roller at a marine store or go online and order one. 1/2" dia. or less for modeling.

[der kapitan]

Time 4420, that was very good information that you put forth in those paragraphs. :)

For me, the grooved rollers are a must-have for layups and laminations---. ;)

Acetone is good for cleanup and minimal thinning, but styrene monomer is the best for thinning polyester resin. :p

As for gloves, I don't wear them, but I DO use disposable brushes---. :o

[time4420]

Thak you der kapitan,
Also, you may convert lay up poly to finish by adding wax. I've used candle wax mainly.
Cut a small square of wax and then shave it into thin slices. Heat it up in a double boiler until melted then heat the resin the same way. The resin only has to be warm not hot. 100DF or so. Mix wax into resin. 3/8" square piece of wax will do a quart of resin. I prefer PVA though. PVA sands right off, there's no hassle mixing, it just brushes on and rinses of with warm water.
When you use a waxed resin you HAVE to de wax or else you'll just push the wax around.

[Greg W]

I would think a strong mechanical joint first would be very important. Some hulls I have seen had a series of small holes drilled into both mating surfaces and are then sewn together with carpet thread, then reinforced and glassed over The old "Pea Pod" sailboats were built that way. Greg

[der kapitan]

I think that there is enough good information provided in this thread to give a relative novice a decent head start. :)

The newbie should bookmark these pages, in fact, I think that I will---. ;)

[time4420]

I would think a strong mechanical joint first would be very important. Some hulls I have seen had a series of small holes drilled into both mating surfaces and are then sewn together with carpet thread, then reinforced and glassed over The old "Pea Pod" sailboats were built that way. Greg


I do beleive thet procedure is called "stitch and glue".
That was done just to hold the pieces together for glassing.
In a properly done bond of wood, the wood will split before the bond will break. :)

[Ironman929]

Thak you der kapitan,
Also, you may convert lay up poly to finish by adding wax. I've used candle wax mainly.
Cut a small square of wax and then shave it into thin slices. Heat it up in a double boiler until melted then heat the resin the same way. The resin only has to be warm not hot. 100DF or so. Mix wax into resin. 3/8" square piece of wax will do a quart of resin. I prefer PVA though. PVA sands right off, there's no hassle mixing, it just brushes on and rinses of with warm water.
When you use a waxed resin you HAVE to de wax or else you'll just push the wax around.
Seems like alot of effort. Why not get some resin with the wax already in it?

[time4420]

...just a bit of info. Maybe you ran out of finish resin and all you have is lay up resin and a garage full of candles...maybe the stores are closed, use your imagination.
I don't use wax or wax resin at all unless I'm in an area where I can't rinse after curing. I use PVA.

[FightingSailor]

You really do want to match up materials for a permanent change as you described. Use polyester on polyester, epoxy on epoxy etc... Also use a heat gun on the the area when you bring the sides together. I have had a bit of experience in this area epoxy will hold perhaps for a short while but eventually it will fail.

[time4420]

[QUOTE=FightingSailor]You really do want to match up materials for a permanent change as you described. Use polyester on polyester, epoxy on epoxy etc... QUOTE]

I agree with poly on poly for repairs and lay ups but when bonding, epoxy is stronger, don't ya think?.

[ADAGIO]

Tim,

This is just a thought but epoxy and polyester resins are a plastic. How about applying some heat from a heat gun to soften the plastic to the point where you can get the two halves into position, clamp them together and let them cool. Then you can resin them over to close them up.

G'day Tim from the other side of the world (at the moment the Summer and warm side).

Tim, as Umi and Greenboat have said, and others have said in their own way, there is a straightforward way to address your problem.
Yes, polyester is plastic and will deform under heat, say from a hairdryer but don't overdo it.
The local epoxy man, Boatcraft Pacific of Loganholme in Brisbane, says that the best way to ensure that 24hour epoxy sticks to polyester is to clean it and then aggressively sand it, for which he recommends at least 80 grit, fit the mechanical bits such as bolts, as Umi says, leave it alone for a few days to properly cure out, then use the same epoxy with fairing compound (powder).
Sand the fairing compound pretty quickly as it will go bloody (Aussie word for really very) hard over the next week or two. Sand, fair and finish as you will.

Job done, easy peasy.

[FightingSailor]

[QUOTE=FightingSailor]You really do want to match up materials for a permanent change as you described. Use polyester on polyester, epoxy on epoxy etc... QUOTE]

I agree with poly on poly for repairs and lay ups but when bonding, epoxy is stronger, don't ya think?.


I would still say use poly and Glass cloth. Of course this is only based on my experience over the years, I can't back it up w/ numbers, I do know what (and what not) has worked for me.

[time4420]

You really do want to match up materials for a permanent change as you described. Use polyester on polyester, epoxy on epoxy etc... Also use a heat gun on the the area when you bring the sides together. I have had a bit of experience in this area epoxy will hold perhaps for a short while but eventually it will fail.

You've had an epoxy bond fail?

[gbrobbins]

If I missed it in this thread I have a question. I have used Bondo to glaze over a coat of epozy. The hull is plywood and strong. If I then want to fiberglass the hull will I have a problem with the Bondo under the fiberglass????

If I don't fiberglass and just paont, will I have problem with the Bondo.

G B Robbins
:confused:

[time4420]

You can paint over bondo.
Bondo is polyester resin thickened with talk. Don't go thicker than about 1/4" thick or it will probably crack.
On a 1:1 boat I would not use poly over epoxy...I would use epoxy over epoxy but we are not talking about the same stresses. Not even close.
Tomorrow at my shop, I'll lay up a test piece. I'll lay up some mat over epoxy and wet it out with poly then, after full cure, I'll try to break the laminate apart at the bond............be back tomorrow eve.
Dennis

[der kapitan]

Actually, Bondo is a butyl-resin based product, and shouldn't really stick to epoxy, but does a good job of faking it, if you roughen the surface. ;)

Go figure---. :)

I keep a gallon bucket of the stuff in my shop at all times for those impossible jobs---. :D