Polyester / glass 'speedstrip'

[medusaboat]

If a Polyester / glass pultrusion were formed in the section of Cedar 'speedstrip', but hollow, would it not be possible to build up a lightweight hull in a relatively (compared to Cedar / epoxy) cheap material that could then be sheathed with Polyester / glass?

I know that C flex is kinda like a similar idea, but it cannot be built as a cored hull.

I have not researched this idea at all - it just came into my head this morning, any input would be appreciated.

Happy boating.

[Raggi_Thor]

Do you mean to use cedar strips and polyester?
It will be cheap and it will rot and fall apart.
Polyester is not a glue and it's not a water barrier.

[medusaboat]

No,
I am suggesting that the 'strip' be a polyester/glass pultrusion, but shaped like a hollow cedar strip.
I appreciate that polyester resins are not as good an adhesive as epoxy, but I am not trying to glue anything other than Polyester to Polyester.

The advantage of my suggestion is that you can build a hollow, light, strong structure out of just Polyester. Think more hollow C-flex than Cedar strip / epoxy.

[Raggi_Thor]

But polyester/glass has a density of 1.5(?)kg/l while cedar is 0.3 or 0.4!
I think the only reason to use poyester is to save money, and to do that you need a mold so you can produce one boat per day.

[medusaboat]

Ok, but you are forgetting that the GRP pultrusion has, on a 45mm x 15mm strip, only half (or less) the sectional area (as it is hollow). In addition to this it will not absorb any of the adhesive / sheathing resin.

I agree that for ultimate money saving a female mould is the way to go, but for one off's and amateur construction Cedar strip, and my Polyester pultrusion in particular may have some merit.

In addition, and once again reffering to amateur construction, Polyester is a much more pleasant material to work with than Epoxy.

[Roly]

"Polyester is a much more pleasant material to work with than Epoxy"

As long as you don't inhale it. Styrene made me get out of the industry.
How is the poly pultrusion made, what does its x-section look like? Curious thought!
As an aside- we have used cedar and polyester together and often the cedar retards the poly so much it will not go off.We switched to epoxy for cedar stringers.

[Raggi_Thor]

I also think epoxy is healthier, or less harmful.
Your idea may have some merits but I think cedar (or spruce) and epoxy is better all in all.

[fiberglass jack]

should work but i have notice in the past that pultrution parts always seem to have a lot of wax in the resin and dosest bond well with polyester and you got to use epoxy.

[waikikin]

I've seen some jobs where foam & uniglass strips have been used, seemed to work well.Jeff.