pre preg/ vac bagging and resins

is there any one out there building rc yachts using pre preg and if so is there any advantage to using is on such a small boat(except to get an even resin coating at the corect ratio which can be obtined by vac baging.

if no one is using pre preg is any one vac bagging/ autoclaving / post curing or all of the above.

what trpe of resins are people using any which brand and why.

When the Apprentice knows more than the Mentor its time to quit!


I vac bagged a test hull. It was a carbon hull, and i used west system epoxy. I used west because it’s what i had at the time. These where just tests to see how light i could get a hull. I was very pleased with the results, lighter than i could ever do by hand, no worries about air bubbles or anything like that.

The two main bennefits of this is that you can go lighter than your competitor, or the stay the same weight and use heavyeir fabrics.

I know allot of the USOM guys are using vac keel fins. I think Bantocks are prepreg pressed into an alloy mold.


This question is a good illustration of the limitations of information that can be obtained on the internet. Fact is virtually all of the suppliers of r/c race boats use vac bag and/or prepregs, however, they rarely if ever post on the net. If you are interested in obtaining specific information, try talking to some of the builders directly. In Australia try Mirage or BG Yachts as a starting point.

thanks roy i was just wondering as to what ppl on here were using but looks as though not many ppl want to tell me ah well ill just have to do some tests for my self to see what works and what is not worth doing at the moment im vacing every thing that goes in to the hull but i didnt do the hull so its way to heave a bit of a wet lay up but ah well

When the Apprentice knows more than the Mentor its time to quit!

Have you seen the International One Meter Compendium site (
It has quite some useful info and a page dedicated on construction techniques, were leading builders explain, briefly, how they ?do it?.


I use vac bagging for complex shapes, but not pre-pregs.I also use an oven up to 60 degrees C. With vac bagging you get a much better layup around tight corners particually. I use Sp systems Ampreg 20 resin system.
It’s great to be allowed to play with models in a full on professional ‘big boat’ workshop!

Luff 'em & leave 'em.

I’ve been vacuum bagging wingmasts over a foam core, using West System epoxy. This was done in an attempt to reduce weight aloft & increase the potential for lateral mast bend. The weight has gone down from over 400g (balsa/spruce 68" mast) to 130g (using 3oz cloth). Resin weight is under 50% of the glass. My cores are cut on a CNC hot wire cutter by a fellow in California using DOW Hi-Load 60 foam The bagging technique derives from what the model airplane guys are using:

Bill K
AMYA 11052

We use pre-preg cloth in different flavors with everything from carbon fiber, to epoxy graphite to simple glass sandwich around clegicel foam cores. All of them have their good points and draw backs… but the most important factor is it gives you complete control over the amount of material. 2nd would be extreme strength compared to weight. Different materials handle curves and corners in different manner.

These are not commonly used by the home builder because of the equipment that is used. I hate to say “needed” because you can get around it… but having a 700 degree heated press that can produce one ton PSI comes in kinda handy. You can squish the heck out of it with one of those dudes. Using a pos/neg mold that allows you to shape both sides of the part at the same time means you have complete control.