I’m gearing up to build a 7ft. rc boat and plan on using 9oz. 45x45 followed by 5.7oz. carbon/kev. and another 9oz.45x45. I’ve done small test panels to check structure compatibility and for warp and all seems ok.Just more worried on the larger surfaces about warp.The 9oz. is vitually clear to reveal the carb/kev.so I’d love to use it. Any thoughts or opinions would be great.
unless your surface is flat you should have no issues with warpage on a something that size.you could even put the hybrid on th outer surface with no problem in my opinion
Thanks hojo,
You need to reinforce in all directions. Turn some of the plies 90*, equal from the middle out.
ie:
90
45
45
90
SEVEN FOOT?!?! I so want pictures of that!
You shouldn’t have too many problems making a boat shell warping. As long as the top section and bottom section are designed well, even if there is a slight amount of warp, the mating will straighten it out. Of course, this is thinking the boat is make in 2 sections. The hull, and then deck, and then attached together.
If I was you I would core it either with balsa or foam core. putting 45’s in will give you more torsional strength, but I believe it will be a overkill for a rc boat.
It’s never overkill to make a part properly. Unless flex is desired in a certain direction, the part needs to be reinforced in every direction.
It is not the same to achieve stiffnes by way of the shape of a component.
you do need to put fibers in every direction to make a part correctly.
Thanks all for your help. I’m using the 45x45 lam. and 2x2twill carbon/kev. with another 45x45 to cover strand direction,2x2twill e-glass will be used in non-carbon models. Carbon direction will be across deck (short span) as there will be bulkheads supporting the longspan. Iv’e thought about core but would need 2mm or less. So I thought carbon/kev. would be ok as a (core-laminate). As soon as I can downsize pics I’ll post’em.
Some pics prior to wetsand/polishing. The tape defines the hatch opening,the small one on the canopy is a launch/carry handle,to be spring loaded so it closes when let go.
I have 3mm foam core, so I would think a good high density foam would be able to go down to 2mm. Plus with foam, y ou don’t have to worry about sealing any drilled holes and soaking up water.
The only thing I dont like about the core is the edges not being beveled. Iv’e only used corematt in earlier hulls, true foam may be different.I may skip core all together and add another 5.7oz. of (core laminate) to high stress areas.
Well, beveling is easy 
I don’t know much about these boats, so I can’t say even if you are using enough layers. I would imagine it has to be VERY light. Just waterproof the servos and receiver before doing a full test 
Are you going by a past guideline, or just guessing the 3 layers will be enough?
How can I bevel 2mm. corematt? And Iv’e done a few layups out of the old distorted mold (polyester) and 2 lam’s of 45x45 and 2oz. matt (again polyester) is almost too much. Hull and decks weighed in at nearly 27lbs. I need them to wiegh 20-22 lbs.so I figure the carb/kev will do the trick for weight and stiffness by replacing matt. Testing will be outsourced as 3000.00 is usally spent on powerplants,drives,and rigging. These boats are usally capable of 75mph.
are you planning on vacuuming?
Yes,I will be vac. bagging out of the new mold with epoxy,old hulls were wet layup which made coremat a pain.
I meant you can bevel foam core, not coremat
If the testing out of factory is done on other stuff, I guess you have to see what happens when you buy one of your design, and test it yourself! Obviously, you can always add some uni-directional in places you need more support, like the engine mount, or keel.
Once again, can’t really say I’veworked on something as this. Wouldn’t mind HAVING one though.
I’m acually submitting a demo boat to a friend for rigging and review, his will be capable of 70+ mph. As for my own It will be rigged or powered for @55mph.The difference being twinn inline-twinns for 70+ and twinn single eng.for @55mph.not to mention a 1200.00 price diff. My largest laminate concern aside from aformentioned warp is the deck area in front of the hatch. Which will recieve carbon-tow built ring bulkheads. The airplane guys use it to stiffen their fuselages without adding the weight and bulk of wood. There will also be carbon tow in the strakes as well, as insurance against deformation under pressure. I’m investigating nomex honeycomb/foam for core for hull bottoms on fri. eve.
becareful when wet laminating with honeycomb not to suck out too much resin. often people will run there vacuum at full and the laminate will delam from the honeycomb. you will probally be best off doing half pressure. always best to do test panels first to find the best procedure for your application
Thanks all for your help.Iv’e concluded that core, balsa-foam-or honeycomb, would be over kill for the panel sizes on the hull. I’ll probably switch the 9oz. 45x45 to a ligher weight s-glass. Not see thru but stronger and stiffer.