Hi Ramon,
I have followed your brilliant masterclass in Huntsman building, and now along with fellow club mates, following your stunning AVL build with great interest.
I hope I may be able to shed some light on SP113 having used it throughout my recent Swordsman build, heregoes - Structural Polymer Systems are based on the Isle of Wight, and have a very helpful technical guy should you wish to call him ! although in his opinion he would not reccomend 133 and favours other products in their range,
but these come in lager bottles, are even more expensive and not available at your local model shop, which in precisely why I use SP113.
The big secret to applying is to use disposable foam mini paint rollers, (B&Q it All etc - and yes I along with the cheapskates can cut them in half with a razor saw!)
you will be amazed how roller lets you mould the glass cloth around compound curves etc, I have covered a 5foot glider fuselage with a single piece of cloth pushed
around the curves by the foam roller, it stays stuck to tiny 3/16 square Swords sprayrails without lifting, making boat hulls a doddle.
I use Davids Isopon P38 car body filler under the Halfords paint with success, and also "microballoons" filler powder you mix with resin (aeromodelling trick avail modelshops).
SP can also be thinned down with Isopropyl Alcohol available from local chemists, I have used this thinned like tap water as a primer on fast electric racers
where weight is an issue!
I reccomend going throught the pain of glass clothing from a strength and more importantly, stability point of view, my Swords has been on the water for around 18 months
and the only area I did not reinforce (transom) with cloth is now starting show stress cracks? in the paint, from the bottom of the steepV feathering out up the transom. The Americans use this system throughout on their lightweight balsa 36" class scale hydros, see
www.classicthunder website, this should keep you occupied for a few hours.
Also in the states they use the resin/cloth system over planked hulls on varnished Chris Crafts etc and the very fine weave of the glass disappears completely when finished leaving a high gloss burnished glass like finish, to coin the phrase of "boat trapped in an ice cube finish". Hope this may be of some help.
Regards Paul