Hull boat design practice poor man's composite idea

I have decided to build in foam composite so was thinking of a mock up.
Parameters i came up with
1) inexpensive
2) full size
3) similar weight to regular layup
4) easy to do so i could potentially try multiple changes to the design over time
5) hold up for a reasonable amount of time i am thinking a summer or more

Different Methods considering at this time Open to more

Gripper/ultra light boat building methods kind of (my original idea)
1)use pink or blue foam cut in shape of boat attach with drywall screws and glidden gripper as seam glue until dry then take out screws coat those spots before next layer

2) cut and lay fiberglass screen on top of the foam use that to make a composite more glidden gripper over it to wet it in and provide a bonding surface.

3) on bottom use 1 more layer gripper with fiberglass mesh used in concrete strengthening wet with glidden gripper let dry and bottom coat with bed liner(polyurea 100%)

4) sides use window screen on tight curves for second layer and use fiberglass mesh for areas that will need additional strengthening

5) for flat areas that need more flat strength such as bulk heads and sole and top deck in the composite add corrugated twin walled plastic sheeting along with the idea above.
This should be fun hearing all the feed back..please present facts of how to improve or how it won't work so can adjust to make better not just opinions.

Cheapie old school full build method ( forum suggestion open to more)

1) using traditional final design boat building methods

2) keep costs down by hunting lowest prices
suggestions like buy fiberglass lowest cost china, any epoxy with 100% solids low prices


Another idea or variation is using stucco materials.



boat will be tested in 4 feet water on local river/ponds

EDIT: , if resin is being considered it should only be Epoxy (100% solids) since we are working with foam.

 

outside shell I am considering best options as with the whole thing.
maybe alklyd enamel on both sides or whatever inexpensive idea that would hold up...

another option :garage floor paint looks pretty inexpensive 5 gal for 100$

Another fiberglass that looked really promising was the mesh used in stucco for house that was in the price range

 

to have a full size mock up to play around for a summer sounds like money well spent

For movement power source.
1) could make tarp or tyvek sail drive.
2)could use outboard from other boat or add a couple trolling motors.
it would give me in-depth knowledge that computer modeling just can't give.

 

What scale of a boat?

 

If you want inexpensive, plywood is the way to go. The materials you are listing are going to cost you more, even if you were to build out of polyester and mat.

 

Am I right to understand that you are thinking about:
1. making full size "test " boats
2. Keeping cost of "test" boat under say $1000 each?

 

100%. Same size my garage is 24' deep double bay 9' to rafters so that is biggest size possible. I'm only thinking about a mock up of one boat but maybe changing it repeatedly until I think it's the best of what I want for a final design

 

. Hey Gonzo I have read your comments in a few different forums and I value your opinion even if you are off base once in awhile it's better advice then most give... You might be right ply might be cheaper... But a couple points made me come up with this.. I want to build in foam in future so this is better learning experience.. I want it to be closer model to real deal, faster build. Thanks for input love your comments on a couple different forums

 

Foam is a viable building material, but it's the laminate schedule and fairing, that'll kick your butt and budget. This is why plywood often is the more attractive choice.

 

Yep, I costed out and it's crazy cheap alot less like $600 materials but not fitted out just shell and bulk head sole foam built in furniture (sizes and weights not buy actual furniture) in locations put sandbags in boat for added weight in the same locations... borrow outboard off or trolling motors batteries off my other boats to try..

 

I sourced a couple of my ideas from... Sawfish build idea. And. Foam wars video. Thought I could use hot wire cutter and get it close can't think of guy who made cat hulls with underlayment as easy way to cut nice shapes ... Using it as male mold... Foam makes it easy to flip with come along or engine hoist to composite bottoms of each hull before joining... Keeps it light... Final build will have to rent space...this stuff to work with is allot cheaper so if I want to redesign it... I only used some play money

 

Good laminates cost that is why I want to save the cash i can for a final build.. good point. the fairing is important I should spend the time on them . I should show you my shaping idea so you can give me your educated opinion.

 

I built a 5' x 9' removeable cabin top/dingy with 1.5" packing crate foam core, .25" ply and epoxy/fiberglass.
Mostly to be light, test shape and to see how it would work.
Your idea has merit and for us shade tree boat designers it is more fun to do than to study.

 

Another thought.
I run a stucco company and we use large blocks of foam 6" x 24" x 48" to make shapes ( key ways, curved bands)
It does not absorb water and bonds well (in my shade tree tests) with epoxy .
You could make boat sections out of 1/4" ply at 24" spacing and put the foam between.
We also use different fiberglass mats from light and flexible to high impact strength.
Heck we also use a polymer based mortar to skim over the foam in 1/8" coats.

 

Guys, you have a good point I was thinking small catamaran if it seams do able or flat bottom boat if I can't. The 100% fiberglass mesh used with concrete or stucco for the price. Here's a stucco fiberglass link. For price consideration. EIFS Fiberglass Mesh & Fiberglass Lath Price List - Sunline Technical Fabrics http://www.sunlinemesh.com/mesh-pricelist. The 4.3 oz reinforcing mesh for $16 for 9.5"x 150' looks like something that might be good to work with.. let's take everyone's ideas that are willing to follow through, save our money for the final design and do it right!!
we should do small samples and test so we can get numbers to learn .