46 inch balsa tow boat, fiberglassing hull - RC Groups
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Dec 06, 2012, 06:25 PM
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Robert Pulse's Avatar

46 inch balsa tow boat, fiberglassing hull

Ok I have stripped the paint off the hull, Repaired the bad places on the bottom and purchased the fiberglass resin, cloth and harderner. I have never glassed a model hull before so Im asking. Do I need to seal, or pre coat the hull before applying the glass cloth? I was told I have a 4 hour window to work with this stuff.
The materials are west systems 105 and 206. On the nose of the hull it was formed from the ends of block balsa and one of the you-tube videos said the ends need to be sealed. Me not know! I have also bondoed the joints between the ply and the balsa
Last edited by Robert Pulse; Dec 06, 2012 at 06:29 PM. Reason: not complete
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Dec 06, 2012, 07:33 PM
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No! you don't have four hours before it flashes over to I-don't-think-so Robert
Without knowing that much ..you are in trouble already
More details ..cloth weight Temp of room. You can hack it or do it right. what did you patch the holes with..West systems has u-tube videos to help..Do you have the pumps or a scale for measuring?
Much Luck
Dec 06, 2012, 07:47 PM
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Robert Pulse's Avatar

West systems

I got the pumps. Was told the temp needs to be 70 degrees. cloth weight is 3/4 oz and (holes) were filled with automotive bondo

BTW that is why I am asking LOL
Dec 06, 2012, 07:58 PM
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which hardener did you get? 206 slow will give you 20 minutes work time ,205 will give you 9 minutes, 209 will give you 40 minutes, these are based on a perfect mix perfect temp. Could be less
Dec 06, 2012, 08:08 PM
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catchthis's Avatar
Should have about 30 minutes to work with it depending on how fast you can spread the resin, dont keep in in a cup more than a half inch thick for any amount of time after mixing because the stuff will put off heat and harder quick!coat the hull with epoxy first and lay the glass over the wet epoxy, this will help it stay in one place. After it's on add epoxy on top of the glass to soak it.
Dec 06, 2012, 08:27 PM
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Robert Pulse's Avatar

west systems

OOH 20 minutes Yikes its a big hull to cover in 20 minutes Latex anybody
Dec 06, 2012, 08:50 PM
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catchthis's Avatar
just spread it over the hull quick, thats half the battle! if you need to mix more its better to mix as you go along.
Dec 06, 2012, 11:27 PM
Submarines, etc.
tsenecal's Avatar
Originally Posted by capterik
which hardener did you get? 206 slow will give you 20 minutes work time ,205 will give you 9 minutes, 209 will give you 40 minutes, these are based on a perfect mix perfect temp. Could be less
you are quoting pot time, not working time. don't give the guy a heart attack. working times, pulled from:


using 206, he has over an hour to lay out and mess with the wetted cloth.
Dec 07, 2012, 01:30 AM
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Dec 07, 2012, 07:53 AM
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Robert Pulse's Avatar

West systems

I can see now I'm no better off than before I asked the question. LOL
Dec 07, 2012, 08:55 AM
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tghsmith's Avatar
pot time refers to the time that the chemically created heat gels the mixture, there has to a contained amount to trigger this, mixing your resin and then pouring it into a low tray can allow this heat to escape and slow the time.. working time will still allow you to work the resin about.. also remember you do not have to mix the ENTIRE amount of resin needed for the project at one time, the working time lets you mix smaller amounts and work across the project in stages.. as long is everything is still "wet" more resin can be added and it will all cure as one unit.. Those pita brooklyn hull halfs take around four batches of resin and about 1.5 hrs of lay-up time...(ps those fake plastic credit cards you get in the mail make great spreaders, they flex and have rounded corners so they don't snag the clothe) just remember complete mixing of parts A+B has to take place.. mix the crap out of it..
Last edited by tghsmith; Dec 07, 2012 at 09:01 AM.
Dec 07, 2012, 02:05 PM
r/c ships and workboats
A couple more thoughts. When mixing stir evenly and thouroughly so to not have any "cold" spots with in the mix. Do not "whip" or fast stir other wise introduce too many bubbles into the mix. Cut all the glass fiber material before you even mix any coating. test fit it so you have an idea of how this will lay down accross the prodject. Once it all fits, mix is mixed, apply some of the resign to the hull. Lay cloth down on to it and work the around the hul until it is in place. Use a hair dryer if you need the mix to flow evenly--but do not over heat any area as this could create a "bubble".
Where there is the balsa blocks that haven't been sealed--brush some resign onto those spaces first so it will soak in. this will allow the next coat, while wet, to soak into the cloth.
As far as the bondo is concerned, make sure you have cleaned that area as well as the entire hull with some denatured alcohol to remove the dirt and dust barrier for better adheasion. Use a spreader as previousely mentioned to help force the air out and smooth finish on the surface. Once things begin to set---DO NOT touch it or try and add any resign as this can create a negative effect and pull the glass work from th hull or even prevent damage to the work you just finished doing.
Dec 07, 2012, 03:28 PM
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tghsmith's Avatar
have lots of papertowels and newspaper ready, white distilled vinegar will clean up uncured resin(from hands, arms, eyebrows,)
Dec 11, 2012, 09:05 AM
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Robert Pulse's Avatar


I just ordered two M-tronics 30 amp speed controls for the towboat. Has anyone used the Rudder and Motor Mixer Control Unit available from harbor models and how well did it work? I have re-wired the flaps switch on my airtronics Vg600 so that it centers in the middle position and will move the flanking rudders from center to the left or right depending on the position of the switch (foreward or backward from center) It works good. I have used it on switches for sound effects and it works perfectly. I can adjust the amount of throw by adjusting the endpoint travel adjuster. Granted it is full left or full right depending on the adjustment but I can live with that for backing the tow Bob
It is at the bottom of this page
Dec 14, 2012, 04:16 PM
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Trick to applying epoxy to large area is to use 3in roller w/close nap. Put epoxy in paint tray that spreds it out and gives alittle extra time. Roll on epoxy next put on cloth next use thin squeege to work cloth flat and epoxy into cloth.Next use a foam brush to feather epoxy and to smooth out bubbles as it gases off.
I just built a 17ft cedaqr strip kayak so l got to work with alot of epoxy.
Hope this helps. Tim

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