I believe that all variations of centerboards and rudders are 100% fiberglass.  Even if there is something else at the core, grinding and reglassing should be a viable strategy for the edges.

Peter Nyberg
Coventry, CT
s/v Silverheels (1988/2016)

> On 2023-05-24, at 05:57:42 EDT, Jeff Smith Photo wrote:
>
> While applying bottom paint, I noticed a 4" crack on the leading edge of the DB. 
> Is the board fiberglass? If so grinding out the void and reglassing should not 
> be a problem.  If iron it may be more difficult. 
> 
> Best Regards
> Jeff Smith
> www.<a href="http://JeffSmithPhoto.Net">http://JeffSmithPhoto.Net</a>
> 732-236-1368
>