grp boom

[rob50904]

Hello,
I'm planing to build a 3m long boom for a 21ft sport boat.
As i have enough grp left from the hull I was thinking of using grp for the boom. That would save a lot of money because I'd get the boom for free instead of ordering an aluminum or carbon one. Are there any drawbacks (instead of more weight/less stiffness compared to a carbon boom)?
Grp has a better stiffness/strength than aluminum, so the boom would be lighter or stiffer/stronger than an aluminum one.

I never heard of grp booms before, so I'm a little bit unconfident.

[TeddyDiver]

What kind of grp you have in mind?? For boom about all unidirectional..

[rob50904]

Yes. Two layers +45/-45 and the rest UD up to an overall thickness of 2mm. in parts of high vertical pointloads (vang, mainsheet, clew) some extra 90° fibres.