Home made composits

[oneoldude]

Has anyone tried home made composits?<br /><br />For example, resin mixed with sawdust, wood chips or other available material might make a great inexpensive "composit" to replace a rotted transom. The resin would soak and encapsulate the wood leaving no route for water to flow along the grain like in real wood and would render it rot proof. But how about strength? How long should the fibers be?<br /><br />How about chopped glass fiber as used in blown insulation?<br /><br />There might be some common construction foams (polyurethatne?) that can successfully be laminated with cloth and polyester resin to make inexpensive "composit" panels.<br /><br />How about that light weight sheathing board?<br /><br />Has anyone done this sort of thing?<br /><br />Any experience to share? Ideas?<br /><br />Know of any web sites that cover this sort of thing? I could not find any.

 

[crab bait]

Re: Home made composits

good idea.. you be the guinea pig an get back to us.. ..<br /><br />i think your 'saw dust' way is a good one along with chopped glass an carbon fibre.. !!<br /><br />an i know it would work if'n you routed say a 1/4 inch flute every say 6 to 8 inches apart in the finished substrate an epoxy in an 1/4 kevlar rope..

 

[Mark42]

Re: Home made composits

I have had thoughs of doing something with fiberglass and resin in place of the Seacast product for transom repair. The Seacast will cost about $400 for 10 gal not including shipping. <br /><br />Was thinking about 5 gallons of resin mixed 50/50 chopped fiberglass. A lot cheaper than Seacast.

 

[prockvoan]

Re: Home made composits

Talcin power is used to make a paste,chop strain too!Seacast,I never mess with it.If the transom is bad,I just replace it the right way,not put a patch.That goes for all rot!

 

[18rabbit]

Re: Home made composits

Chopped fiberglass is commonly used as an additive to mold around odd shapes. Available in 1/4 and 1/2 inch lengths from U.S. Composites. I have a couple bar stools from the early 60’s that have the seats made from molded fiberglass with chopped strands … about 2” long.<br /><br />I’m told West System’s MicroFibers are tiny cotton strands coated with talc to keep them lofty for mixing. Also thickens the mix as Prockvoan mentions.

 

[Grant S]

Re: Home made composits

I've used sanding dust from my beltsander as an additive to make glue. Sawdust is probably a bit coarse.<br /><br />If working with wood, stick to epoxy resin.

 

[qaztwo]

Re: Home made composits

I use chopped glass, believe the tech term is milled glass looks like baking soda, for all my bounding applications. I've heard of talc, saw dust and cotton flox also used. Milled glass I was told is about the stongest for bounding, I paid about $3 a pound for the stuff. Used about 3 to 4 pounds and about 2 gallons of epoxy to make my engine mounts, 4 feet long 5 inches high out of 3/8 inch ply. attached my new ply transom, and glued down the stringers and bulk heads. Now I'm out of expoxy, maybe santa will be nice and bring me some more.

 

[crab bait]

Re: Home made composits

yeah,, the 'elves' can't keep up with da stuff..!!

 

[oneoldude]

Re: Home made composits

Originally posted by Mark42:<br /> I have had thoughs of doing something with fiberglass and resin in place of the Seacast product for transom repair. The Seacast will cost about $400 for 10 gal not including shipping. <br /><br />Was thinking about 5 gallons of resin mixed 50/50 chopped fiberglass. A lot cheaper than Seacast.

Yes, the cost of Seacast is high. It is to avoid such costs that I started this thread. <br /><br />A couple years ago local high buck boat builders (I live in Florida) were using very high density foam panels for transom material in their "no wood" boats. My local resin supplier said you could do the same thing with very high density two part pourable foam. I can't remember the density now but perhaps 25# was the number. The idea was to pull out the rotten wood, plug the holes, pour in the foam and done! The stuff was lighter than wood, hard as a brick, extremely stiff and strong and very easy to shape and drill but it was expensive. <br /><br />It seems to me that using a 50% resin/50% chopped glass fiber mix would certainly do the job if heat of curing did not crack the casting. Properly done it would probably last forever. But it would be extremely heavy.<br /><br />Are there any fiberglass engineers on this forum?

 

[oneoldude]

Re: Home made composits

Originally posted by prockvoan:<br /> Talcin power is used to make a paste,chop strain too!Seacast,I never mess with it.If the transom is bad,I just replace it the right way,not put a patch.That goes for all rot!

The idea here is to remove the transome in its entirety and use a composit for the entire transom. Just like Seacast, only cheaper.

 

[18rabbit]

Re: Home made composits

Fwiw, if you built a wooden (marine plywood) transom using the appropriate resin or epoxy, it’s not likely to rot anytime during your lifetime. A healthy chunk of boat rot can be marked up to sloppy and/or inappropriate boat building techniques...and owner neglect...stuff like leaving water sitting in the boat during the off-season.<br /><br />The pix I have seen on this form of boat repairs that members do shows quality that is nothing less than a billion times better than any manufacturer does.

 

[oneoldude]

Re: Home made composits

Originally posted by 18rabbit:<br /> Fwiw, if you built a wooden (marine plywood) transom using the appropriate resin or epoxy, it’s not likely to rot anytime during your lifetime. A healthy chunk of boat rot can be marked up to sloppy and/or inappropriate boat building techniques...and owner neglect...stuff like leaving water sitting in the boat during the off-season.<br /><br />The pix I have seen on this form of boat repairs that members do shows quality that is nothing less than a billion times better than any manufacturer does.

I am certain what you say is absolutely true. However, if there is a less labor intensive way of achieving a supurb quality result in a short period of time that is also very cost effective why not give it a try. It leaves more time to go fishing!

 

[jimmythekid]

Re: Home made composits

"I am certain what you say is absolutely true. However, if there is a less labor intensive way of achieving a supurb quality result in a short period of time that is also very cost effective why not give it a try. It leaves more time to go fishing!"<br /><br />when it comes to boats, I don't think what you just said is even possible, I agree with 18rabbit, if yer gonna keep the boat, do it right, if yer not do it cheap, but tell the new owner how you did it.

 

[JB]

Re: Home made composits

Hmmmm.<br /><br />On repairing/replacing a bad transom on an otherwise quality boat I am with 18rabbit. Marine grade plywood and superior technique will produce a superior transom.<br /><br />Trying to make a project cheap or easy in my experience produces an inferior result. I might do it on a (inferior quality boat not to be named)that I was preparing to sell, but never on a high grade boat.<br /><br />That said, I have cast home-made composites when I was developing racing kart engines from chainsaw engines back in the 50s and 60s. I made a mix of polyester resin, Cab-O-Sil (diatomaceous earth) and glass fibers about 1/2 to 1" long and poured it into homemade molds to make special intake manifolds, rotary valves, reed cages and cooling shrouds for prototype engines. The result was very strong, light and resistant to both heat and vibration.<br /><br />What worked well was later cast from aluminum or fabricated from aluminum plate.

 

[lawyertob]

Re: Home made composits

Hmmmm,<br /><br />Maybe I am missing something here. Seacast is about $165 for five gallons...including the fiber. Poly resin is like $100 for 5 gallons and you have to get the fiber seperate...I'm not sure I see any great cost savings. Not to mention the fact that (from my limited experience with resin) I would guess that 5 or especially 10 gallons of resin would get VERY hot if you made it as one pour. Also, (I know that Seacast is also a poly resin base, but it has 'secret' ingredients)...but most poly resin is pretty brittle, I know that Seacast has some flexibility, but I would think that a transom poured with regular resin would be awfully brittle. Finally, if it didn't work, then it would be nearly impossible to get the junk back out.<br /><br />Admittedly, this is far from my area of expertise, so this might not even be...<br /><br />Just my $0.02 worth,<br />Joe

 

[BillP]

Re: Home made composits

Joe,<br />Seacast is probably using poly CASTING resin. It is made to pour thick without getting too hot or being brittle. When poured thick it gives off tiny pinhead sized air bubbles but they are few and far between so structure isn't compromised. Cure time is typically much longer than regular resin. I poured a few hatchcover tables with it and remember it was less cost than regular poly laminating resin...but I can't remember how much less. I would bet the farm that Seacast is using chopped fiberglass fibers for their "secret ingredient". It would be easy to replicate seacast but I don't know if you would save much money unless buying wholesale. <br /><br />Even chicken wire, screen, steel rods, etc would work with casting resin for strength. Cabosil, microballons, cotton fibers, etc are thickeners and reduce strength.<br /><br />I think untreated wood in production boats is in it's final years...mfgs are using it less and less and pt or composite more and more. Untreated ply (even marine) is now the cheapest method and likely shortest lifespan. Pt and composites don't rot if they get wet...they just get heavy.

 

[oneoldude]

Re: Home made composits

BillP,<br /><br />Thanks for the info.<br /><br />You are right that commercial boats are rapidly moving to PT and no-wood designs. It only makes sense. Those are clearly better ways to go. But in an industry (boat building) that is as old as mankind it takes a long time for change to take place. Fortunately it does take place or we would still be using goat skins stretched over a frame.<br /><br />I live in Sarasota Fl where Well Craft, Donzi, Chris Craft, Famous Boats, and others have, or used to have, factories. On top of the well known marques there are some small high-buck custom builders as well. I have seen some beautiful small boats made here. One manufacturer, I can't recall the name, made canoes with the alternating wood strip technique and in the middle ply (wood inside and out) was a carbon fiber hand lay up. They were stunningly beautiful, light and tough as nails. But REALLY expensive.<br /><br />All this means that I am very lucky becuse I can purchase almost anything I want for boat repair locally. Indeed, there is a wholesaler of resins, glass, etc. about three miles from my house that sells to the public. Of course the public pays retail.<br /><br />I joined this forum because I am in the process of restoring and modifying a little 15' utility boat into a flats fishing boat. I wanted to gain insight from members of this forum on the smartest, quickest, most efficient way to get the job done. I have not been dissapointed. Forum members have, for the most part, been wonderfully kind and helpful. I will be using their advice and will continue to ask for help and information as I need it. Hopefully I will be able to give as well as take as time goes on.<br /><br />The beginnings of my project can be found at: http://www.shareaproject.com/projectTut.php?p=10 Wish me luck with it.<br /><br />Thanks to all for a great internet experience.

 

[oneoldude]

Re: Home made composits

BTW this is what is in Seacast. I took it from the Seacast MSDS:<br /><br />SEACAST POURABLE TRANSOM - LIST OF INGREDIENTS (100%)<br />Vehicle: Blend of proprietary polyester resins<br />Weight: 36 %<br />Solvents: styrene weight 18 % (CAS# 100-42-5 TLV 100pp)<br />Pigments & Extenders: (dry materials) weight 51 % - Titanium Dioxide (CAS# 13464-67-7), Calcium Carbonate (CAS# 14807- 96-6), Silica (CAS# 60676-86-0) and Inert Fillers (CAS# 14807-96-6)

 

[Mark42]

Re: Home made composits

Maybe I am missing something here. Seacast is about $165 for five gallons...including the fiber.

Joe, I checked out Seacast for my boat. The transom on my little boat is 20"x58" and 1.75" thick (interior space) that comes to 2030 cu in of space. The 5 gallon kit fills 1000, so I need at least two, and the current price I see is $180/5 gal being $360 plus $24 for hardner plus shipping. I figured about $400.<br /><br />Accoring to their website, a 5 gallon bucket is 3/4 full of Seacast, the fiber glass mixed with it brings it to the 5 gallon volume.<br /><br />In Poly it would be 7gal of resin and hardener, locally about $180 plus fillers and glass to simulate Seacast. Should probably use slow hardener to keep temps down.<br /><br />I think that marine ply with poly resin will give a good result for much less. But I like the solid plastic result of Seacast.<br /><br />I know water got into my transom. It's not bad yet, but I plan on transom repair this summer if I have time. So I'm always looking for a good Seacast alternative that is still a sound repair.

 

[Mark42]

Re: Home made composits

This site has some interesting materials. Rigid expanding foams up to 15lbs/cu.ft. and an interesting additive EP9009 that "When added to epoxy, urethane or polyester, this liquid plasticizer blend increases cured toughness, resiliency and flexibility". Sounds like something to add to a poly based transom to reduce its brittleness.<br /><br /> Eager Plastics