Freestyle Hull construction.

Brian_216

Brian_216

Location
Harveys Lake PA
I was just looking for input from those who have laid up hulls. If you had to do it again, what materials would you use? How thick would you go? I have been doing research on glass carbon and Kevlar. All seem to have great qualities, but also have their own place and purpose. I know there are different wants and needs from surf to flatwater, so feel free to give opinions on each. I really like the idea of not using gel coat and having layers of Kevlar on the outside of a glass hull just based on it's abrasion and tear resistance.
 
Brian_216

Brian_216

Location
Harveys Lake PA
The person I purchased the molds from did not use gelcoat, just sprayed paint in the mold first and let it dry. His reasoning was gelcoat will add weight and is the first thing to spider crack. Also long term adhesion with polyester gelcoat in an epoxy layup is questionable.
 
Breese08SJ

Breese08SJ

Location
New Jersey 732
Kevlar on the outside of the hull? Might want to rethink that idea as kevlar absorbs moisture..... which in turn will lead to de-lamination of those layers. Do yourself a favor and base your thickness off of oem superjet hull. Even if you maintained oem thickness with quality materials and methods such as vacuum bagging, you will not only be stronger but at least same weight or lighter. No one in the "Business" is going to tell you their specs or layups. Good luck
 
Brian_216

Brian_216

Location
Harveys Lake PA
Yea I didn't expect anyone big to come forward and say " yea I use this many layers of this." but there are a few that built their own who I am sure will share some insight.
 
garretonufer

garretonufer

Location
Orange County, CA
probably a good idea to take a guage and measure thickness of OEM and then determine the thickness of your material to give you a quantity value.
sounds like carbon is your best bet if you're willing to spend the cash.
 
McDog

McDog

Other Administrator
Staff member
Location
South Florida
I would recommend some gelcoat to make sure the hull is watertight. Without it it could be a big strainer and let water through. Anything else will add more man hours to the build process to get it watertight. I also say to overbuild with more layers than you think it will need if you plan to sell them to ensure strength and longevity.
 
R

ridetrp

Location
nj
Since your just getting your feet wet in this I would HIGHLY recommend gel coat for your first couple layups if sprayed at the right mils it's awesome and can't beat the finish if you use good stuff and have nice molds don't worry about the weight on that small hull you'd use a little more than half gallon for the top bottom and hood the offshore powerboats we built got used and abused in rough waters not a single problem and if it gets knicked up easy to repair, you honestly just need to build one beat it and break it and learn from there on out but I can give you a decent laminate starting point

 
Waternut

Waternut

Customizing addict
Location
Macon, GA
I just used epoxy and surfacing veil instead of gel coat on mine. With primer, the hull will be watertight just the same as gelcoat. You have to spray both anyway, it's just the order in which it's done and whether you spend half a day polishing gelcoat or half a day sanding and painting. Epoxy primer > polyester gelcoat in my book but I'm sure others will argue. I've never figured out the marine industry's fascination with gelcoat. Yes it's durable but so is a real paint job and the real paint job doesn't fade as fast, oxidize leaving everything it touches white, and it doesn't have to be buffed with a machine constantly to maintain what paint can do with the occasional hand waxing. A 5 year old boat left in the sun looks like crap without constant care. A 5 year old car left out in the sun with the same care still looks normal.
 
A

Aquaman~~~

Location
norcal
ridetrp said:
Since your just getting your feet wet in this I would HIGHLY recommend gel coat for your first couple layups if sprayed at the right mils it's awesome and can't beat the finish if you use good stuff and have nice molds don't worry about the weight on that small hull you'd use a little more than half gallon for the top bottom and hood the offshore powerboats we built got used and abused in rough waters not a single problem and if it gets knicked up easy to repair, you honestly just need to build one beat it and break it and learn from there on out but I can give you a decent laminate starting point
Click to expand...
lets see your progress on your home built
 
Crab

Crab

thanks darin...noswad!
Location
Seattle
From my composites repair class, I can tell you that 3 layers of 6oz prepreg carbon, vacum bagged and heat cured is right around 1/16" or so, we just made a mock floor panel with that layup top and bottom with nomex honeycomb core. Approximately 2' x 1' panel at about 1/2 inch thick has almost $200 in materials and expendables....now we get to hit it with a hammer and damage the core, and repair it.:bananajump:
 
S

Schmidty721

someone turf my rails
Location
WI
20oz carbon
20oz carbon
1708 biax
flow media core (helps with resin infusion then acts and a core)
1708 biax
20oz carbon
20oz carbon
epoxy resin.
About 5/16" thick, ~ 30lbs out of the mould, stock pre-07 sj bottom deck.
 
Waternut

Waternut

Customizing addict
Location
Macon, GA
Schmidty721 said:
20oz carbon
20oz carbon
1708 biax
flow media core (helps with resin infusion then acts and a core)
1708 biax
20oz carbon
20oz carbon
epoxy resin.
About 5/16" thick, ~ 30lbs out of the mould, stock pre-07 sj bottom deck.
Click to expand...

That's more than my 19' ski boat layed up with chop strand and polyester resin....just throwing that out there.
 
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